WO2006105168A2

WO2006105168A2 - Enhancing immune responses with bacterial exotoxins

Info

Publication number: WO2006105168A2
Application number: PCT/US2006/011423
Authority: WO
Inventors: Patrick M. Schlievert; Marnie L. Peterson
Original assignee: Regents Of The University Of Minnesota
Priority date: 2005-03-29
Filing date: 2006-03-28
Publication date: 2006-10-05
Also published as: WO2006105168A3

Abstract

The invention features methods of enhancing immune responses, methods of increasing expression of major histocompatibility complex (MHC) class I molecules on the surface of cells, and methods of delivering antigens or antigenic peptides to the cytoplasm of cells.

Description

Enhancing Immune Responses with Bacterial Exotoxins

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

OR DEVELOPMENT Some of the research described in this application was supported by grant

HL36611 from the National Heart, Lung, and Blood Institute of the National Institutes of Health. The government has certain rights in the invention.

TECHNICAL FIELD

This invention relates to immune responses, and more particularly to the use of bacterial exotoxins to enhance immune responses.

BACKGROUND

Despite significant progress in the understanding of vertebrate immune systems and ways of generating immune responses to a wide variety of immunogens, there remains a need to develop more effective methods of activating and/or enhancing such responses.

SUMMARY

The invention is based in part on the finding that certain bacterial exotoxins have activities that endow them with the ability to generate exceptionally potent immune responses to themselves and to enhance immune response to other immunogens. The invention provides methods of generating enhanced immune responses (cellular immune responses as well as antibody-producing immune responses), methods of enhancing expression of major histocompatibility complex (MHC) class I molecules on the surface of a cell, and methods of delivering antigens (or antigenic peptides) to the cytoplasm of a cell. More specifically, the invention provides a method of enhancing an immune response. The method involves: administering to a vertebrate subject an isolated immune-enhancing bacterial exotoxin or an isolated functional fragment of a bacterial exotoxin; and administering to the vertebrate subject an immunogenic stimulus. The bacterial exotoxin can be a bacterial superantigen (SAG), e.g., toxic shock syndrome toxin 1 (TSST-I), a staphylococcal enterotoxin (SE), or a streptococcal pyrogenic exotoxin (SPE). Alternatively, the bacterial exotoxin can be a bacterial pore-forming protein. The immunogenic stimulus can be, for example, a cancer-specific immunogenic stimulus or an infectious microorganism-specific immunogenic stimulus.

The invention also features a method of enhancing expression of a major histocompatibility complex (MHC) class I molecule on the surface of a cell. The method involves: contacting a cell with an isolated bacterial exotoxin or a functional fragment thereof, the contacting resulting in an increase in expression of a MHC class I molecule on the surface of the cell or a second cell; and confirming that there is an increase of expression on the surface of the cell or the second cell. Methods for measuring the level of expression on the surface of a cell include fluorescence microscopy, fluorescence flow cytometry, immunohistochemistry, immunoprecipitation and electrophoresis, and immunoblot analysis. The contacting can be in vitro and the method can involve: providing a plurality of cells from a vertebrate subject; contacting the cells with the bacterial exotoxin, or the functional fragment thereof, in vitro; and assessing the level of expression of the MHC class I molecule on the surfaces of the cells. In addition, the method can further involve after the contacting, administering the cells, or the progeny of the cells, to the vertebrate subject. Alternatively, the method can involve: administering the bacterial exotoxin to a vertebrate subject; and assessing the level of expression of the MHC class I molecule on the surfaces of a plurality of cells obtained from the vertebrate subject. The bacterial exotoxin can be a bacterial SAG, e.g., any of the SAG listed herein. Another embodiment of the invention is a method of delivering a polypeptide antigen (e.g., a full-length polypeptide antigen or an antigenic fragment of a polypeptide antigen) to the cytoplasm of a cell. The method involves contacting a vertebrate cell with an isolated bacterial pore-forming protein, or a functional fragment thereof, and an isolated polypeptide antigen. The cell can be an antigen presenting cell (APC). The contacting can be in vitro and the method can include: providing a cell from a vertebrate subject; and contacting the cell with the bacterial pore-forming protein, or the functional fragment thereof, in vitro. The method can further involve contacting the cell in vitro with the isolated polypeptide antigen. Alternatively, after contacting the cell in vitro, the cell can be administered to the vertebrate subject. After administration of the cell to the vertebrate subject, the polypeptide antigen can be administered to the vertebrate subject. Alternatively, the method can involve administering the bacterial pore-forming protein and the polypeptide antigen to a vertebrate subject. The bacterial pore- forming protein can be, for example, α-hemolysin.

As used herein, the term "bacterial exotoxins" refers to bacterial superantigens (S AG) and bacterial pore-forming proteins. A bacterial pore- forming protein is a polypeptide that either, per se, or in a multimeric (e.g., dimeric, trimeric, tetrameric, pentameric, hexameric, heptameric,octameric, nonameric, or decameric) configuration with one or more other identical polypeptides, with one or more different polypeptides, or with one or more identical and one or more different polypeptides, can form a pore in the cell membrane of a vertebrate cell (e.g., a red blood cell or an epithelial cell) and thereby facilitate the passage of molecules (e.g., antigens such as full length proteins or fragments of proteins) from the extracellular environment to the cytoplasm of the vertebrate cell.

"Polypeptide" and "protein" are used interchangeably and mean any peptide- linked chain of amino acids, regardless of length or post-translational modification. Polypeptides for use in the invention include those with conservative substitutions. Conservative substitutions typically include substitutions within the following groups: glycine and alanine; valine, isoleucine, and leucine; aspartic acid and glutamic acid; asparagine, glutamine, serine and threonine; lysine, histidine and arginine; and phenylalanine and tyrosine. In general, variant polypeptides with conservative substitutions will contain no more than 40 (e.g., no more than: 35; 30; 25; 20; 15; 13; 11; 10; nine; eight; seven; six; five; four; three; two; or one) conservative substitution(s). All that is required is that the variant polypeptides have at least 20% (e.g., at least: 30%; 40%; 50%; 60%; 70%; 80%; 90%; 95%; 98%; 99%; 99.5%; 99.8%; 99.9%; or 100% or more) of the activity of the wild-type polypeptide. As used herein, an "isolated" agent (e.g., an immune-enhancing agent, an immunogenic stimulus, or non-specifically acting factor) is an agent that either has no naturally-occurring counterpart or has been separated or purified from components which naturally accompany it, e.g., in tissues such as pancreas, liver, spleen, ovary, testis, muscle, joint tissue, neural tissue, gastrointestinal tissue or tumor tissue, or body fluids such as blood, serum, or urine. Typically, a naturally occurring biological agent is considered "isolated" when it is at least 70%, by dry weight, free from other naturally occurring organic molecules with which it is naturally associated. Preferably, a preparation of an agent for use in the invention is at least 80%, more preferably at least 90%, and most preferably at least 99%, by dry weight, that agent. The degree of isolation or purity can be measured by any appropriate method, e.g., column chromatography, polyacrylamide gel electrophoresis, or HPLC analysis. Since an agent that is chemically synthesized is, by its nature, separated from the components that naturally accompany it, the synthetic agent is by definition "isolated."

Isolated agents, and additional compounds useful for the invention, can be obtained, for example, by: (i) extraction from a natural source (e.g., from tissues or bodily fluids); (ii) where the compound is a protein, by expression of a recombinant nucleic acid encoding the protein; or (iii) by standard chemical synthetic methods known to those in the art. A protein that is produced in a cellular system different from the source from which it naturally originates is "isolated," because it will necessarily be free of components that naturally accompany it.

As used herein, a "fragment" of a polypeptide is a segment of the polypeptide that is shorter than the corresponding full-length, mature, wild-type polypeptide. An "antigenic" fragment of a polypeptide is a segment of the polypeptide that is able to be recognized and bound by an antibody or, once bound to an major histocompatibility complex (MHC) molecule (class I or II), to be recognized and bound by an antigen specific receptor (TCR) on a T cell. Fragments, including antigenic fragments, of polypeptides are generally at least five (e.g., at least: six; seven; eight; nine; ten; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 30;

35; 40; 45; 50; 55; 60; 65; 70; 75; 80; 85; 90; 95; 100; 120; 140; 160; 180; 200; 250; 300; 350; 400; 450; 500; 600; 700; 800; 900; 1,000; 1,500; 2,000; or even more) amino acids long.

As used herein, "operably linked" means incorporated into a genetic construct so that expression control sequences effectively control expression of a coding sequence of interest.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, the present document, including definitions, will control. Preferred methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting. Other features and advantages of the invention, e.g., enhancing immune immune responses, will be apparent from the following description, from the drawings and from the claims.

DESCRIPTION OF DRAWINGS

Fig. 1 is a bar graph showing the amounts (in pg/ml) of interleukin-1/3 (IL- 1/3), tumor necrosis factor-ce (TNF-α), interferon-γ, macrophage inflammatory protein-3α: (MIP-3Q;), interleukin-6 (IL-6), and interleukin-8 (IL-8) by human vaginal epithelial cells (HVEC) after 3 h and 6 h culture with Staphylococcus aureus MNSM bacteria.

Fig. 2 is a line graph showing the relative amounts (in counts per minute; CPM) of ³⁵S-labeled toxic shock syndrome toxin 1 (TSST-I) binding to HVEC at several times of incubation of the HVEC with ³⁵S-labeled TSST- 1.

Fig. 3 is a bar graph showing the levels of cytokine (Fig. 3A) and chemokine (Fig. 3B) proteins in the superaatants of HVEC cultures after exposure to S. aureus TSST-I (100 μg/ml) for 3 h and 6 h. DETAILED DESCRIPTION

In view of the various activities of bacterial exotoxins (i.e., bacterial superantigens and bacterial pore-forming proteins), they can be used to elicit potent immune responses to themselves and to enhance immune responses to other immunogenic stimuli. While the invention is not limited by any particular mechanism of action, some mechanisms by which these exotoxins can generate enhanced immune responses are recited below.

Superantigens (SAG), e.g., toxic shock syndrome toxin-1 (TSST-I), the staphylococcal enterotoxins (SE) and the streptococcal pyrogenic exotoxins, elicit both inflammatory cytokine, growth factor, and/or chemokine production by both non-lymphocytic cells (e.g., epithelial cells and macrophages) (see, e.g., Example 4 below) and lymphocytes (e.g., CD4+ or CD8+ T cells). These non-lymphocytic as well as the lymphocytic soluble mediators can then act directly or indirectly (e.g., via other non-lymphocytic cells) on lymphocytes (e.g., CD4+ and CD8+ T cells and B cells) to enhance cellular and/or antibody producing immune responses. In addition, as shown in Example 4 below, SAG such as TSST-I have the ability to enhance the expression of major histocompatibility complex (MHC) class I molecules, both classical and non-classical, on cells such as epithelial cells and can thereby enhance the ability of such cells to present antigenic peptides to MHC class I- restricted T cells, most, but not all, of which are CD8+, some also being CD4+.

Moreover, bacterial pore-forming proteins (e.g., Staphylococcus aureus α- hemolysin, streptolysin O, streptolysin S, Bacillus anthracis protective antigen, a Panton Velentine leukocidin component, a porin, Listeria monocytogenes cytolysin, aerolysin, or diphtheria toxin) by virtue of their ability to elicit inflammatory factor production in, for example, epithelial cells or by the action of the inflammatory molecules released by cells killed, dying, or damaged as a result their pore-forming activities, can similarly enhance immune responses. In addition, pore-forming proteins can effect entry of exogenous polypeptide antigens, or fragments of such antigens, into the cytoplasm of vertebrate (e.g., mammalian) cells (e.g., antigen presenting cells (APC) such as interdigitating dendritic cells, generally referred to herein as "dendritic cells") and hence into the MHC class I antigen presentation pathway of such cells. These cells can then present to relevantly specific T cells MHC class I molecule-bound antigenic peptides that have either per se entered the cells or are produced by the antigen processing machinery of the cells from the Ml- length polypeptide antigen or fragment of the antigen that entered the cells. Upon recognition of and binding to MHC class I molecule/antigenic peptide molecular complexes on the surface of the target cells, MHC class I restricted functional T cell precursors can differentiate into functional (e.g., cytotoxic and/or soluble factor- producing) T cells. Already functional T cells (e.g., cytotoxic T cells (CTL) or cytokine-producing T cells), upon recognition of and binding to MHC class I molecule/antigenic peptide molecular complexes on the surface of the target cells can either kill the target cells (where the functional T cells are CTL) or can secrete cytokines (where the functional T cells are cytokine-producing cells).

The methods of the invention are described below.

Methods of Generating and/or Enhancing Immune Responses

The methods of the invention involve generating and/or enhancing immune responses and can include, for example, administration to an appropriate subject of, or culturing with cells from an appropriate subject, an immune-enhancing agent (see below) without any other immunogen. Here the immune-enhancing agent acts as both an immune-enhancing agent and an immunogen. Moreover, a protein immune- enhancing agent can be administered or cultured together with a fragment (e.g., an antigenic fragment) of the full-length protein immune-enhancing agent as an immunogenic stimulus. However, generally an immunogenic stimulus and a separate immune-enhancing agent are administered to an appropriate subject or cultured with cells from an appropriate subject. In addition, more than one (e.g., two, three, four, five, six, seven, eight, nine, ten, 12, 15, 20, or even 30) immune-enhancing agent and/or more than one (e.g., two, three, four, five, six, seven, eight, nine, ten, 12, 15, 20, or even 30) immunogenic stimulus can be used. The immune-enhancing agents useful for the invention include bacterial exotoxins (i.e., SAG and pore-forming proteins) and variants of such proteins. Such variants include fragments (e.g., antigenic fragments) of the molecules, deletion mutants, or addition mutants. Immune-enhancing agents can also be bacterial exotoxins or any of the above variants thereof that have amino acid sequences that are identical to corresponding wild-type sequences but contain no more than 100 (e.g., no more than: two; three; four; five; six; seven; eight; nine; 10; 12; 14; 17; 20; 25; 30; 35; 40; 50; 60; 70; 80; 90; or 100 ) conservative amino acid substitutions. Variants, with and without conservative substitutions, have at least 20% (e.g., at least: 30%; 40%; 50%; 60%; 70%; 80%; 90%; 95%; 98%; 99%; 99.5%; 99.8%; 99.9%; or 100% or more) of the immune-enhancing activity of corresponding full-length, mature, wild-type molecules. Methods for comparing immune-enhancing activity of two or more molecules are well known in the art.

Exotoxins of interest include, for example, TSST-I, staphylococcal enterotoxins (SE; such as SEA, SEB, SEC, SED, SEE, SEG, SHE, SEI, SEJ, SEK, SEL, SEM, SEN, SEO, SEQ, SER, SES, SET, or SEU), streptococcal pyrogenic exotoxins (SPE; e.g., SPE A, C, and G, H, I, J, K, and L), streptococcal superantigen, streptococcal mitogenic exotoxin Z, Panton Valentine leukocidin, staphylococcal α-, β-, J-, and δ-hemolysins, streptolysin O and related heptamer pore-forming cytolysins, streptolysin S, and Bacillus anthracis protective antigen.

The immunogenic stimulus used will depend on the entity to which it is desired to generate or enhance an immune response. The methods of the invention can be employed for any purpose involving the generation of an immune response. Thus, they can be used for generating antibodies for use as, for example, diagnostic agents, purification reagents, research reagents, or passive immunotherapeutic agents. In addition, they can be used, e.g., for deriving antigen-activated lymphocytes for use in drug (e.g., immunopotentiating or immunosuppressive drugs) screening, diagnostic tests, or passive immunotherapy protocols. Naturally, the methods of the invention can be applied to the treatment of, or prophylaxis from, diseases such as infectious diseases and cancer. Cancers of interest include, without limitation, breast cancer, lung cancer, colon cancer, pancreatic cancer, renal cancer, stomach cancer, liver cancer, bone cancer, hematological cancer (e.g., leukemia or lymphoma), neural tissue cancer, melanoma, ovarian cancer, testicular cancer, prostate cancer, cervical cancer, vaginal cancer, bladder cancer, or any other cancer recited herein.

Moreover, the methods of the invention can be applied to the treatment of, or prophylaxis from, infections by any of a wide variety of infectious microorganisms. Relevant microorganisms can be viruses, bacteria, mycoplasma, fungi (including yeasts), and protozoan parasites. Bacteria of interest include, without limitation, Staphylococci (e.g., S. aureus, S. intermedins, S. epidermidis, and other coagulase negative Staphylococci), Neisseriae (e.g., N. gonorrheae and N. meningitidis), Streptococci (e.g., Group A Streptococcus (e.g., S. pyogenes), Group B Streptococcus (e.g., S. agalactiae), Group C Streptococcus, Group G Streptococcus, S. pneumoniae, and viridans Streptococci), Chlamydia trachomatis, Treponemae (e.g., T. pallidum, T. pertenue, and T. cerateum), Haemophilus bacteria (e.g., H. ducreyi, H. influenzae, and H. aegyptius), Bordetellae (e.g., B. pertussis, B. parapertussis, and B. bronchiseptica), Gardnerella vaginalis, Bacillus (e.g., B. anthracis and B, cereus), Mycobacteria (e.g., M. tuberculosis and M. leprae), Listeria monocytogenes, Borrelia burgdorferi, Actinobacilluspleuropneumoniae, Helicobacter pylori, Clostridium (e.g. C. perfringens, C. septicum, C. novyi, and C. tetani), Escherichia coli, Porphyromonas gingivalis, Vibrio cholerae, Salmonella bacteria (e.g., S. enteriditis, S. typhimurium, and S. typhi), Shigella bacteria, Francisella bacteria, Yersinia bacteria (e.g. Y. pestis and Y. enter ocolitica), Burkholderia bacteria, Pseudomonas bacteria, and Brucella bacteria. Mycoplasmal organisms of interest include M. pneumoniae, M. fermentans, M. hominis, and M. penetrans. Fungal organisms (including yeasts) of interest include, without limitation, Candida albicans, other Candida species, Cryptococcus neoformans, Histoplasma capsulatum, and Pneumocystis carinii. Protozoans of interest include, without limitation, Trichomonas vaginalis, Plasmodium falciparum, P. vivax, P. ovale, P. malariae, Entamoeba histolytica, Toxoplasma brucei, Toxoplasma gondii, and Leishmania major. Relevant viruses include, without limitation, human immunodeficiency virus (HIV) 1 and 2, human lymphotropic virus (HTLV), measles virus, rabies virus, hepatitis virus A, B, and C, rotaviruses, rhinoviruses, influenza virus, parainfluenza virus, respiratory syncytial virus, adenoviruses, parvoviruses (e.g., parvovirus B 19), roseola virus, enteroviruses, papilloma viruses, retroviruses, herpesviruses (e.g., herpes simplex virus, varicella zoster virus, Epstein Barr virus (EBV), human cytomegalovirus (CMV), human herpesvirus 6, 7 and 8), poxviruses (e.g., variola major and variola minor, vaccinia, and monkeypox virus), feline leukemia virus, feline immunodeficiency virus, and simian immunodeficiency virus.

As used herein, an "immunogenic stimulus" is a stimulus delivered to a T cell or a B cell via an antigen-specific receptor (TCR and BCR, respectively) expressed on the surface of the T or B cell. More commonly, but not necessarily, such a stimulus is provided in the form of an antigen for which the antigen-specific receptor is specific. While such antigens will generally be protein, they can also be carbohydrates, lipids, nucleic acids or hybrid molecules having components of two or more of these molecule types, e.g., glycoproteins or lipoproteins. However, the immunogenic stimulus can also be provided by other agonistic TCR or BCR ligands such as antibodies specific for TCR or BCR components (e.g., TCR α-chain, TCR β- chain, or immunoglobulin (Ig) variable regions) or antibodies specific for the TCR- associated CD3 complex or the BCR-associated complex. Immunogenic stimuli (as used herein) do not include antigen-non-specific stimuli provided by non-specifically acting factors such as, for example, cytokines, chemokines, or growth factors (e.g., interleukin- (IL-) 1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-10, IL-12, IL-13, IL-15, an interferon (IFN; e.g., IFN-α, IFN-β, IFN-γ), granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony stimulating factor (GM-CSF) or tumor necrosis factor-α (TNF-α)), co-stimulatory molecules, adhesion molecules, or immunological adjuvants (see below). Nevertheless such non-specifically acting factors (as well as others recited herein) can also be administered to appropriate subjects or included in the cell cultures described below.

Antigens useful as immunogenic stimuli include alloantigens (e.g., a MHC alloantigen) on, for example, an antigen presenting cell (APC) (e.g., a dendritic cell

(DC), a macrophage, a monocyte, or a B cell). Methods of isolating DC from tissues such as blood, bone marrow, spleen, or lymph node are known in the art, as are methods of generating them in vitro from precursor cells in such tissues. Also useful as immunogenic stimuli are polypeptide antigens and peptide-epitopes derived from them (see below). Unprocessed polypeptides are processed by APC into peptide- epitopes that are presented to responsive T cells in the form of molecular complexes with MHC molecules on the surface of the APC. Useful immunogenic stimuli also include a source of antigen such as a lysate of either tumor cells or cells infected with an infectious microorganism of interest. APC (e.g., DC) pre-exposed (e.g., by coculturing) to antigenic polypeptides, peptide-epitopes of such polypeptides or lysates of tumor (or infected cells) can also be used as immunogenic stimuli. Such APC can also be "primed" with antigen by culture with a cancer cell or infected cell of interest; the cancer or infected cells can optionally be irradiated or heated (e.g., boiled) prior to the priming culture. In addition, APC (especially DC) can be "primed" with either total RNA, mRNA, or isolated TAA-encoding RNA. Alternatively, antigen as an immunogenic stimulus be provided in the form of cells (e.g., tumor cells or infected cells producing the antigen of interest). In addition, immunogenic stimuli can be provided in the form of cell hybrids formed by fusing APC (e.g., DC) with tumor cells [Gong et al. (2000) Proc. Natl. Acad. Sci. USA 97(6):2716-2718; Gong et al. (1997) Nature Medicine 3(5):558-561; Gong et al. (2000) J. Immunol. 165(3):1705-1711] or infected cells of interest. Methods of fusing cells (e.g., by polyethylene glycol, viral fusogenic membrane glycoproteins, or electrofusion) are known in the art. In discussing these cell hybrids, the tumor or infected cell partners will be referred to as the immunogenic cells (IC). Cells or cell hybrids can be used (as immunogenic stimuli) untreated or they can be metabolically inhibited (e.g., by irradiation or exposure to a drug such as mitomycin-C) so as to substantially ablate their ability to divide. Tumor or infected cells used per se as an immunogenic stimulus or as IC for the production of cell hybrids are preferably, but not necessarily, derived from the subject to be treated or the subject from which cells (e.g., T cells) used for in vitro methods (see below) are obtained. Where the cells are from a different donor, they will preferably share one MHC haplotype with the subject to be treated or the subject from which cells used for in vitro methods are obtained. APC used to form cell hybrids will also preferably, but not necessarily, be derived from the subject to be treated or the subject from which cells used for in vitro methods are obtained. In the production of cell hybrids, either the APC or the IC will be preferably be from, or MHC-compatible with, the subject to be treated or the subject from which cells used for in vitro methods are obtained. Alternatively, the APC and/or the IC can share one MHC haplotype (i.e., be semi-allogeneic) with the subject to be treated or the subject from which cells used for in vitro methods are obtained. However, as the cells or hybrids used as immunogenic stimuli will frequently be used in the presence of APC of the subject to be treated (e.g., in in vivo applications) or donor of cells for cultures, they can be fully MHC incompatible with the subject to be treated or the subject from which cells used for the cultures are obtained.

Also useful as immunogenic stimuli are heat shock proteins bound to antigenic peptide-epitopes derived from antigens (e.g., tumor-associated antigens or antigens produced by infectious microorganisms) [Srivastava (2000) Nature Immunology l(5):363-366]. Such complexes of heat shock protein and antigenic peptide are useful for facilitating or enhancing uptake of antigenic peptides by APC. Heat shock proteins of interest include, without limitation, glycoprotein 96 (gp96), heat shock protein (hsp) 90, hsp70, hspl lO, glucose-regulated protein 170 (grpl70) and calreticulin. Immunogenic stimuli can include one or more (e.g., one, two, three, four, five, six, seven, eight, nine, ten, more) heat shock proteins isolated from tumor cells or infected cells. Such tumor or infected cells are preferably, but not necessarily, from the same subject (i) whose immune responsiveness is to be enhanced by a method of the invention or (ii) from whom cells for in vitro methods of the invention were obtained. The tumor or infected cells can also be obtained, for example, from another individual having the same or a related tumor-type or infection as the subject. Alternatively, the heat shock protein can be isolated from mammalian cells expressing a transcriptosome prepared from tumor cells or infected cells of interest.

Immunogenic molecules can be derived from a wide range of infectious microorganisms. Immunogenic stimuli can be, for example, any of the above- described immune-enhancing agents. Examples of relevant microorganisms include any of those listed above. Relevant microbial proteins include, without limitation, the B subunit of heat labile enterotoxin of E. coli [Konieczny et al. (2000) FEMS Immunol. Med. Microbiol. 27(4):321-332], heat-shock proteins, e.g., the Y. enterocolitica heat shock protein 60 [Konieczny et al. (2000) supra; Mertz et al. (2000) J. Immunol. 164(3):1529-1537] and M. tuberculosis heat-shock proteins hspόO and hsp70, the Chlamydia trachomatis outer membrane protein [Ortiz et al. (2000) Infect. Immun. 68(3):1719-1723], the B. burgdorferi outer surface protein [Chen et al. (1999) Arthritis Rheum. 42(9):1813-1823], the L. major GP63 [White et al. (1999) Vaccine 17(17):2150-2161 (and published erratum in Vaccine 17(20- 21):2755)], the N. meningitidis meningococcal serotype 15 PorB protein [Delvig et al. (1997) Clin. Immunol. Immunopathol. 85(2);134-142], the P. gingivalis 381 fimbrial protein [Ogawa, (1994) J. Med. Microbiol. 41(5):349-358], the E. coli outer membrane protein F [Williams et al. (2000) Infect. Immun. 68(5):2535-2545], influenza virus hemagglutinins and neuramindases, retroviral (e.g., HIV) surface glycoproteins (e.g., HIV gpl60/120), or retroviral tat or gag proteins. CTL are by virtue of their ability to kill target cells that are infected with any of a wide variety of intracellular pathogens (e.g., viruses, or intracellular bacteria and protozoans) potent mediators of immunity to such pathogens. Thus, since the methods of the invention are efficient at enhancing CTL responses, they can be used for prophylaxis and/or or therapy in infections with such intracellular pathogens. In addition, helper T cells release a wide variety of cytokines that mediate pathogen-destructive inflammatory responses.

As indicated above, immunogenic stimuli useful in the invention can be any of a wide variety of tumor cells, APC "primed" with tumor cells, hybrid cells (see above), tumor-associated antigens (TAA), peptide-epitopes of such TAA, and APC "primed" with TAA or peptide-epitopes of them. As used herein, a "TAA" is a molecule (e.g., a protein molecule) that is expressed by a tumor cell and either (a) differs qualitatively from its counterpart expressed in normal cells, or (b) is expressed at a higher level in tumor cells than in normal cells. Thus, a TAA can differ (e.g., by one or more amino acid residues where the molecule is a protein) from, or it can be identical to, its counterpart expressed in normal cells. It is preferably not expressed by normal cells. Alternatively, it is expressed at a level at least two-fold higher (e.g., a two-fold, three-fold, five-fold, ten-fold, 20-fold, 40-fold, 100-fold, 500-fold, 1, 000- fold, 5,000-fold, or 15,000-fold higher) in a tumor cell than in the tumor cell's normal counterpart. Examples of relevant tumors that can be used per- se or as a source of antigen (see above) include, without limitation, hematological cancers such as leukemias and lymphomas, neurological tumors such as astrocytomas or glioblastomas, melanoma, breast cancer, lung cancer, head and neck cancer, gastrointestinal tumors such as gastric or colon cancer, liver cancer, renal cell cancer, pancreatic cancer, genitourinary tumors such ovarian cancer, vaginal cancer, bladder cancer, testicular cancer, prostate cancer or penile cancer, bone tumors, and vascular tumors. Relevant TAA include, without limitation, carcinoembryonic antigen (CEA), prostate specific antigen (PSA), prostate specific membrane antigen (PSMA), MAGE (melanoma antigen) 1-4, 6 and 12, MUC (mucin) (e.g., MUC-I, MUC-2, etc.), tyrosinase, MART (melanoma antigen), Pmel 17(gpl00), GnT-V intron V sequence (N-acetylglucoaminyltransferase V intron V sequence), PRAME (melanoma antigen), β-catenin, MUM-I-B (melanoma ubiquitous mutated gene product), GAGE (melanoma antigen) 1, BAGE (melanoma antigen) 2-10, C-ERB2 (Her2/neu), EBNA (Epstein-Barr Virus nuclear antigen) 1-6, gp75, human papilloma virus (HPV) E6 and E7, p53, lung resistance protein (LRP) BcI -2, and Ki-67. Both CTL and helper T cells have been shown to be efficient effectors of tumor immunity.

The immunogenic stimuli useful for the invention include any of the above- listed protein molecules and variants of such molecules. For protein immunogenic stimuli, such variants include fragments (e.g., antigenic fragments) of the molecules, deletion mutants, or addition mutants. Immunogenic stimuli can also be the protein immunogenic stimuli or the above variants that have amino acid sequences that are identical to corresponding wild-type sequences but contain no more than 100 (e.g., no more than: two; three; four; five; six; seven; eight; nine; 10; 12; 14; 17; 20; 25; 30; 35; 40; 50; 60; 70; 80; 90; or 100 ) conservative amino acid substitutions. Variants, with and without conservative substitutions, will have at least 20% (e.g., at least: 30%; 40%; 50%; 60%; 70%; 80%; 90%; 95%; 98%; 99%; 99.5%; 99.8%; 99.9%; or

100% or more) of the immunogenicity of corresponding full-length, mature, wild-type molecules. Methods for comparing immunogenicity of two or more molecules are well known in the art.

Also useful for the invention are fusion proteins containing, as one domain, one or more of any of the above the polypeptide immune-enhancing agents, immunogenic stimuli, or non-specifically acting factors (e.g. cytokines) listed above. Additional domains in such fusion proteins can be additional functional domains or signal peptides. Such fusion proteins can also contain immunoglobulin heavy chain constant regions (e.g., mouse IgG2a or human IgGl heavy chain constant regions) or portions of such constant regions (e.g., CH2 and/or CH3 domains). Useful additional domains include those that facilitate purification of the peptide, e.g., a sequence containing six histidine residues.

Polypeptide immune-enhancing agents, immunogenic stimuli, and non- specifically acting factors useful for the invention include those described above, but modified for in vivo use by the addition, at the amino- and/or carboxyl-terminal ends, of a blocking agent to facilitate survival of the relevant polypeptide in vivo. This can be useful in those situations in which the peptide termini tend to be degraded by proteases prior to cellular uptake. Such blocking agents can include, without limitation, additional related or unrelated peptide sequences that can be attached to the amino and/or carboxyl terminal residues of the peptide to be administered. This can be done either chemically during the synthesis of the peptide or by recombinant DNA technology by methods familiar to artisans of average skill.

Alternatively, blocking agents such as pyroglutamic acid or other molecules known in the art can be attached to the amino and/or carboxyl terminal residues, or the amino group at the amino terminus or carboxyl group at the carboxyl terminus can be replaced with a different moiety. Likewise, the peptide compounds can be covalently or noncovalently coupled to pharmaceutically acceptable "carrier" proteins prior to administration.

Also of interest are peptidomimetic compounds that are designed based upon the amino acid sequences of polypeptides of interest. Peptidomimetic compounds are synthetic compounds having a three-dimensional conformation (i.e., a "peptide motif) that is substantially the same as the three-dimensional conformation of a selected peptide. The peptide motif provides the peptidomimetic compound with the ability to activate an immune response (in the case of immunogenic stimuli) or enhance an immune response (in the case of the immune-enhancing agents). Peptidomimetic compounds can have additional characteristics that enhance their in vivo utility, such as increased cell permeability and prolonged biological half-life.

The peptidomimetics typically have a backbone that is partially or completely non-peptide, but with side groups that are identical to the side groups of the amino acid residues that occur in the peptide on which the peptidomimetic is based. Several types of chemical bonds, e.g., ester, thioester, thioamide, retroamide, reduced carbonyl, dimethylene and ketomethylene bonds, are known in the art to be generally useful substitutes for peptide bonds in the construction of protease-resistant peptidomimetics.

Molecules useful as immune-enhancing agents, immunogenic stimuli, and non-specifically acting factors can be produced by any of a wide range of methods known in the art. They can be purified from natural sources (e.g., from any of the cancer cells or infectious microorganisms listed herein). Smaller peptides (fewer than 100 amino acids long) and other non-protein molecules can be conveniently synthesized by standard chemical means known to those in the art. In addition, both polypeptides and peptides can be manufactured by standard in vitro recombinant DNA techniques and in vivo transgenesis using nucleotide sequences encoding the appropriate polypeptides or peptides (see Nucleic Acids section below). Methods well-known to those skilled in the art can be used to construct expression vectors containing relevant coding sequences and appropriate transcriptional/translational regulatory elements. See, for example, the techniques described in Sambrook et al., Molecular Cloning: A Laboratory Manual (2nd Ed.) [Cold Spring Harbor Laboratory, N. Y., 1989], and Ausubel et al., Current Protocols in Molecular Biology [Green Publishing Associates and Wiley Interscience, N. Y., 1989].

The transcriptional/translational regulatory elements referred to above include but are not limited to inducible and non-inducible promoters, enhancers, operators and other elements that are known to those skilled in the art and that drive or otherwise regulate gene expression. Such regulatory elements include but are not limited to the cytomegalovirus hCMV immediate early gene, the early or late promoters of SV40 adenovirus, the lac system, the trp system, the TAC system, the TRC system, the major operator and promoter regions of phage A, the control regions of fd coat protein, the promoter for 3-phosphoglycerate kinase, the promoters of acid phosphatase, and the promoters of the yeast α-mating factors.

The expression systems that may be used for purposes of the invention include but are not limited to microorganisms such as bacteria (for example, E. coli and B. subtilis) transformed with recombinant bacteriophage DNA, plasmid DNA, or cosmid DNA expression vectors containing nucleic acid molecules encoding enhancing agents or immunogenic stimuli; yeast (for example, Saccharomyces and Pichia) transformed with recombinant yeast expression vectors containing a nucleic acid encoding enhancing agents or immunogenic stimuli; insect cell systems infected with recombinant virus expression vectors (for example, baculovirus) containing a nucleic acid encoding enhancing agents or immunogenic stimuli; plant cell systems infected with recombinant virus expression vectors (for example, cauliflower mosaic virus (CaMV) or tobacco mosaic virus (TMV)) or transformed with recombinant plasmid expression vectors (for example, Ti plasmid) containing a nucleotide sequence encoding; or mammalian cell systems (for example, COS, CHO, BHK, 293, VERO, HeLa, MDCK, WI38, and NIH 3T3 cells) harboring recombinant expression constructs containing promoters derived from the genome of mammalian cells (for example, the metallothionein promoter) or from mammalian viruses (for example, the adenovirus late promoter and the vaccinia virus 7.5K promoter). Also useful as host cells are primary or secondary cells obtained directly from a mammal and transfected with a plasmid vector or infected with a viral vector.

Cells transfected or transduced with the expression vectors of the invention can then be used, for example, for large or small scale in vitro manufacture of immune-enhancing agents or immunogenic stimuli by methods known in the art. In essence, such methods involve culturing the cells under conditions that maximize production of the polypeptide and isolating the polypeptide from the culture, i.e., the cells and/or the culture medium.

For the methods of the invention, it is often required that the immune enhancing agents, immunogenic stimuli, and non-specifically acting factors be purified. Methods for purifying biological macromolecules (e.g., proteins) are known in the art. The degree of purity of the macromolecules can be measured by any appropriate method, e.g., column chromatography, polyacrylamide gel electrophoresis, or HPLC analysis.

The methods of the invention can be applied to subjects, or cells from subjects, of a wide range of vertebrate species, e.g., humans, non-human primates (e.g., monkeys, baboons, or chimpanzees), horses, cattle, pigs, sheep, goats, dogs, cats, rabbits, guinea pigs, hamsters, gerbils, rats, mice, and birds such as chickens, turkeys, eagles, and canaries. The immune-enhancing agents, immunogenic stimuli, and non-specifically acting factors can be from any of these species. Generally, but not necessarily, the immune-enhancing agents, immunogenic stimuli, and non- specifically acting factors will be of the same species as the subjects.

The methods of the invention can be performed in vitro, in vivo, or ex vivo. In vitro application of the methods can be useful, for example, in basic scientific studies of immunity. They can also be useful as assays (e.g., diagnostic assays) for, e.g., T cell responsiveness to a tumor-specific or infectious microorganism-derived antigen where T cell proliferation can be low and possibly undetectable in the absence of immune-enhancing agents. The methods can also be useful for growing up large numbers of T cells (e.g., tumor infiltrating lymphocytes (TIL)) for adoptive immunotherapy of cancer or infectious diseases. In the in vitro methods of the invention, lymphoid cells (consisting of or including T cells and/or B cells) obtained from a mammalian subject are cultured with any of the above-described immune enhancing agents and generally immunogenic stimuli. The lymphoid cells can be from a subject pre-exposed to a relevant antigen (in any of the forms described above); alternatively, the donor of the lymphoid cells need not have been exposed to the antigen. The cultures can also be supplemented with one or more non-specifically acting factors (e.g., cytokines, growth factors, or chemokines) recited above. The cultures can also be monitored at various times to ascertain whether the desired level of immune responsiveness (e.g., CTL, helper T cell activity, or antibody level) has been attained. The methods of the invention will preferably be in vivo or ex vivo (see below).

Such methods are generally useful in enhancing immune responsiveness in subjects with, or likely to develop, cancer and infectious diseases. The enhancement of T cell responsiveness effected by the methods of the invention can result in decreased levels of cancer cells or infectious microorganisms. The methods of the invention can be applied to mammalian subjects (e.g., toxic shock syndrome (TSS), anthrax, human breast cancer, or melanoma patients) alone or in conjunction with other drugs and/or radiotherapy.

In Vivo Approaches The in vivo methods of invention are generally useful for enhancing immune responses in appropriate subjects. Such immune responses can be prophylactic or therapeutic. However, the responses enhanced need have neither prophylactic nor therapeutic efficacy. They can be used, for example, to produce large amounts of antibody or large numbers of activated T cells for use in passive, adoptive immunotherapy, in diagnostic tests, or in basic scientific studies of, e.g., immunity, infectious diseases, cancer.

The methods of the invention can be used, for example, for prophylaxis from, or therapy of (a) infectious diseases due to any of the infectious agents listed herein; or (b) cancers such as any of those listed herein. In addition to being useful for the treatment of a wide variety of diseases, in cases where a subject is at relatively high risk for a cancer (e.g., prostate cancer in men over 50 years of age, lung cancer in a tobacco smoker, or melanoma in a subject with multiple nevi), appropriate methods can be used for prophylaxis. In regard to infectious microorganisms, the methods can be particularly useful in the prevention and/or therapy of diseases involving intracellular microorganisms (i.e. infectious agents that replicate inside a cell), e.g., viruses such as influenza virus or HIV, intracellular bacteria such M. tuberculosis, and intracellular protozoans such as P. falciparum or any of the other infectious agents listed herein. The methods can also be useful, for example, in prevention or treatment of infections with, extracellular pathogen (e.g., bacteria) that can persist within host vertebrate cells, e.g., staphylococci and streptococci. Subjects at risk of developing an infectious disease will be those present in a geographic region in which there is, or there is likely to be, an epidemic or in which there has been or is likely to be a, for example, a bioterrorist attack involving the use of, for example, B. anthracis or variola virus. As used herein, "prophylaxis" means complete prevention of the symptoms of a disease, a delay in onset of the symptoms of a disease, or a lessening in the severity of subsequently developed disease symptoms. "Prevention" means that symptoms of the disease (e.g., an infection) are essentially absent. As used herein, "therapy" means a complete abolishment of the symptoms of a disease or a decrease in the severity of the symptoms of the disease. As used herein, a "protective" immune response is an immune response that is prophylactic and/or therapeutic.

In one in vivo approach, an immune-enhancing agent, and optionally an immunogenic stimulus and/or one or more nonspecifically acting factors (see above), is administered to the subject. Generally, the substances to be administered will be suspended in a pharmaceutically-acceptable carrier (e.g., physiological saline) to form a composition that is administered orally, transdermally, intrarectally, intravaginally, intranasally, intragastrically, intratracheally, or intrapulmonarily, or is injected intraveniously, subcutaneously, intramuscularly, intrathecally, or intraperitoneally. They can be delivered directly to a site of infection or tumor cells, e.g., to a tumor or a tumor bed following surgical excision of the tumor, in order to kill any remaining tumor cells. Alternatively, they can be delivered to lymphoid tissue (e.g., lymph nodes or spleen) draining the site of infection or tumor. The dosage required depends on the choice of the route of administration; the nature of the formulation; the nature of the patient's illness; the subject's size, weight, surface area, age, and sex; other drugs being administered; and the judgment of the attending physician. Suitable dosages are in the range of 0.001-100 mg/kg. Wide variations in the needed dosage are to be expected in view of the variety of immune-enhancing agents available and the differing efficiencies of various routes of administration. For example, oral administration would be expected to require higher dosages than administration by intravenous injection. Variations in these dosage levels can be adjusted using standard empirical routines for optimization as is well understood in the art.

Administrations can be single or multiple (e.g., 2-, 3-, A-, 6-, 8-, 10-, 20-, 50-,100-, 150-, or more fold). Encapsulation of the substances in a suitable delivery vehicle (e.g., polymeric microp articles or implantable devices) may increase the efficiency of delivery, particularly for oral delivery. Immunogenic stimuli, and/or non-specifically acting factors can be administered before at the same time as, or after administration of the immune-enhancing agents. hi addition, adjuvants can be used together with the immunogenic stimuli. Suitable adjuvants include cholera toxin (CT), E. coli heat labile toxin (LT), mutant CT (MCT) [Yamamoto et al. (1997) J. Exp. Med. 185:1203-1210] and mutant E. coli heat labile toxin (MLT) (Di Tommaso et al. (1996) Infect. Immunity 64:974-979]. MCT and MLT contain point mutations that substantially diminish toxicity without substantially compromising adjuvant activity relative to that of the parent molecules. Other useful adjuvants include alum, Freund's complete and incomplete adjuvant, and RJBI. hi addition, one or more of the above-listed cytokines or growth factors can be administered (by any of the routes recited herein) to the subject, before, at the same time as, or after administration of the enhancing agents and, optionally, immunogenic stimuli. Moreover, where tumor cells, APC, or hybrid cells are used as the immunogenic stimuli, such cells, can express on their surface or secrete either (a) one or more recombinant costimulatory molecules (e.g., B7.1 or B7.2) and/or (b) one or more recombinant cytokines or recombinant growth factors such as those listed above, e.g., GM-CSF. Cells expressing on their surface or secreting the above recombinant molecules will have been transfected (stably or transiently) or transformed with one or more nucleic acids (e.g., expression vectors) encoding the molecules. Alternatively, a polynucleotide containing a nucleic acid sequence encoding a polypeptide immune-enhancing agent can be delivered to cancer cells or a site of infection in a mammal. Expression of the coding sequence will preferably be directed to lymphoid tissue of the subject by, for example, delivery of the polynucleotide to the lymphoid tissue. Expression of the coding sequence can be directed to any cell in the body of the subject. However, expression will preferably be directed to cells in the vicinity of the tumor cells whose responsiveness it is desired to inhibit. In certain embodiments, expression of the coding sequence can be directed to the tumor cells themselves. This can be achieved by, for example, the use of polymeric, biodegradable microparticle or microcapsule delivery devices known in the art.

Another way to achieve uptake of the nucleic acid is using liposomes, prepared by standard methods. The vectors can be incorporated alone into these delivery vehicles or co-incorporated with tissue-specific or tumor-specific antibodies. Alternatively, one can prepare a molecular conjugate composed of a plasmid or other vector attached to poly-L-lysine by electrostatic or covalent forces. Poly-L-lysine binds to a ligand that can bind to a receptor on target cells [Cristiano et al. (1995), J. MoI. Med. 73, 479]. Alternatively, tissue specific targeting can be achieved by the use of tissue-specific transcriptional regulatory elements (TRE) which are known in the art. Delivery of "naked DNA" (i.e., without a delivery vehicle) to an intramuscular, intradermal, or subcutaneous site is another means to achieve in vivo expression. In the relevant polynucleotides (e.g., expression vectors), the nucleic acid sequence encoding the enhancing compound polypeptide of interest with an initiator methionine and optionally a targeting sequence is operably linked to a TRE such as a promoter or enhancer-promoter combination.

Short amino acid sequences can act as signals to direct proteins to specific intracellular compartments. Such signal sequences are described in detail in U.S. Patent No. 5,827,516, incorporated herein by reference in its entirety.

Enhancers provide expression specificity in terms of time, location, and level. Unlike a promoter, an enhancer can function when located at variable distances from the transcription initiation site, provided a promoter is present. An enhancer can also be located downstream of the transcription initiation site. To bring a coding sequence under the control of a promoter, it is necessary to position the translation initiation site of the translational reading frame of the peptide or polypeptide between one and about fifty nucleotides downstream (3') of the promoter. The coding sequence of the expression vector is operatively linked to a transcription terminating region. Suitable expression vectors include plasmids and viral vectors such as herpes viruses, retroviruses, vaccinia viruses, attenuated vaccinia viruses, canary pox viruses, adenoviruses and adeno-associated viruses, among others.

Polynucleotides can be administered in a pharmaceutically acceptable carrier. Pharmaceutically acceptable carriers are biologically compatible vehicles that are suitable for administration to a human, e.g., physiological saline or liposomes. A therapeutically effective amount is an amount of the polynucleotide that is capable of producing a medically desirable result (e.g., decreased proliferation of cancer cells) in a treated animal. As is well known in the medical arts, the dosage for any one patient depends upon many factors, including the patient's size, body surface area, age, the particular compound to be administered, sex, time and route of administration, general health, and other drugs being administered concurrently. Dosages will vary, but a preferred dosage for administration of polynucleotide is from approximately 10⁶ to 10¹² copies of the polynucleotide molecule. This dose can be repeatedly administered, as needed. Routes of administration can be any of those listed above.

Ex Vivo Approaches

Lymphoid (T and (CD4+ Tcells and/or CD8+ T cells) and/or B cells) (e.g., peripheral blood mononuclear cells (PBMC)) can be obtained from a subject (e.g., a human cancer or infectious disease patient), or another suitable donor, and exposed in tissue culture to an immune-enhancing agent and, optionally, any of the immunogenic stimuli listed herein. Alternatively, or in addition, the cultures can contain other cell types (e.g., epithelial cells, macrophages, monocytes, DC, or red blood cells) that can act as, for example, APC or upon which the immune-enhancing agent act to cause the release of soluble immunoregulatory factors (e.g., cytokines, growth factors, or chemokines). The cultures can also contain any of a variety of non-specifically activating factors (see above). The resulting cells, which can include the exposed cells, the progeny of the exposed cells, or a mixture of both, are then introduced into the same or a different patient. Prior to the introduction, the cultures can be monitored as described above for in vitro methods. Another ex vivo strategy can involve transfecting or transducing cells obtained from the subject with a polynucleotide encoding one or more immune-enhancing agents. The transfected or transduced cells are then returned to the subject. The cells can be any of a wide range of types including, without limitation, hemopoietic cells (e.g., bone marrow cells, macrophages, monocytes, dendritic cells, T cells, or B cells), fibroblasts, epithelial cells, endothelial cells, keratinocytes, or muscle cells. Such cells act as a source of the immune-enhancing agent for as long as they survive in the subject. Alternatively, tumor cells, preferably obtained from the subject but permissibly also from an individual other than the subject, can be transfected or transformed by a vector encoding an enhancing compound. The tumor cells, preferably treated with an agent (e.g., ionizing irradiation) that ablates their proliferative capacity, are then introduced into the patient, where they secrete the enhancing compound.

These ex vivo methods include the steps of harvesting cells from a subject, culturing the cells, transducing them with an expression vector, and maintaining the cells under conditions suitable for expression of the enhancing compound. These methods are known in the art of molecular biology. The transduction step is accomplished by any standard means used for ex vivo gene therapy, including calcium phosphate, lipofection, electroporation, viral infection, and biolistic gene transfer. Alternatively, liposomes or polymeric microparticles can be used. Cells that have been successfully transduced can then be selected, for example, for expression of the coding sequence or of a drug resistance gene. The cells may then be lethally irradiated (if desired) and injected or implanted into the subject.

It is understood that the methods of invention can involve combinations of the above in vivo and ex vivo approaches. Thus, for example, an immunogenic stimulus can be provided in the form of a peptide-epitope and the immune-enhancing agent in the form of either a nucleic acid encoding it or cells transformed with a nucleic acid encoding it.

The methods of the invention can be applied to any of the diseases and species listed here. Methods to test whether a given modality is therapeutic for, or prophylactic against, a particular disease are known in the art. Where a therapeutic effect is being tested, a test population displaying symptoms of the disease (e.g., infectious disease or cancer patients) is treated by a method of the invention, using any of the above described strategies. A control population, also displaying symptoms of the disease, is treated, using the same methodology, with a placebo. Disappearance or a decrease of the disease symptoms in the test subjects would indicate that the method was therapeutic.

By applying the same strategies to subjects prior to onset of disease symptoms (e.g., presymptomatic subjects considered to likely candidates for cancer or infectious disease development (see above)) or experimental animals in which an appropriate disease spontaneously arises or can be deliberately induced, e.g., multiple murine cancers, the method can be tested for prophylactic efficacy. In this situation, prevention of onset of disease symptoms is tested. Analogous strategies can be used to test for the efficacy of the methods in the prophylaxis of a wide variety of infectious diseases, e.g., those involving any of the microorganisms listed above. Prior to delivery of the immune-enhancing agents of the invention to a subject

(e.g., a human subject), the subject can have been affirmatively identified as being in need of an enhanced immune response. Thus, a subject can, for example, have been identified as having, as being at risk of developing (see above), any of the cancers or infections recited above. Alternatively, the subject can have been identified as having, or likely to develop, a compromised immune system due for, example, to an inherited immunodeficiency, an immunodeficiency disease (e.g., ADDS), radiation therapy, or chemotherapy. Methods of Enhancing Expression of MHC Class I Molecules on the Surface of Cells and of Delivering Antigens to the Cytoplasm of Cells

The invention includes a method of enhancing expression of one or more types of MHC class I molecules on the surface of a cell. The method involves contacting a cell with one or more of the immune-enhancing agents (e.g., SAG) recited herein. Methods for determining whether expression of a MHC class I molecule on the surface of a target cell is enhanced by an agent of interest are well known in the art and include, for example, fluorescence microscopy, fluorescence flow cytometry, immunohistochemistry, immunoprecipitation and electrophoresis, and immunoblot analysis. Expression can be enhanced, for example, two-fold, three-fold, four-fold, five-fold, 10-fold, 20-fold, 30-fold, 50-fold, 75-fold, or even 100-fold. While generally the cell on which expression of the MHC class I molecule(s) is enhanced will be the cell contacted with the immune-enhancing agent, it can also be a cell on which expression of the MHC class I molecule(s) is enhanced by the action of one or more factors produced by (or on) a contacted cell or by one or more factors produced by (or on) a cell in response to one or more factors produced by (or on) a contacted cell.

The contacted cell can be any vertebrate cell. In addition, the cell on whose surface the expression of an MHC class I molecule is increased can be any vertebrate cell that naturally expresses, or can be induced to express, one or more types of MHC class I molecule. Thus, both types of cells can be, for example, hemopoietic cells (e.g., bone marrow cells, macrophages, monocytes, dendritic cells, T cells, or B cells), fibroblasts, epithelial cells, endothelial cells, keratinocytes, muscle cells, or neuronal cells. Of particular interest are APC such as dendritic cells, macrophages, monocytes, or B cells. MHC class I molecules can be classical or non-classical MHC class I molecules. They can be, for example, human classical HLA-A, B, or C molecules or non-classical HLA-E, F, or G molecules.

The methods can be in vitro, in vivo, or ex vivo. In vitro methods involve culturing cells to be contacted, and any other vertebrate cells required where the cells contacted are not the same as those on which expression of MHC class I molecules are up-regulated by the appropriate immune-enhancing agent(s), with one or more (see above) immune-enhancing agents. Cells in cultures can be monitored at various time points to test for levels surface MHC class I molecule expression. Such cultures can be used in, for example, screening of drugs that inhibit enhancement of MHC class I molecule expression and for generation of cells with enhanced MHC class I expression which can be useful as, for example, as highly sensitive target cells for CTL that are to be used for therapy of, for example, cancer or infectious diseases such as AIDS. The cultures can contain other cells unrelated to the actual enhancement of MHC class I molecule expression, e.g., T lymphocytes (e.g., CTL or CTL precursors) to be activated by the cells (e.g., APC) whose MHC class I molecule expression is enhanced. Moreover the cultures can contain one or more (see Methods of Generating and/or Enhancing Immune Responses) of the above described immunogenic stimuli and/or non-specifically acting factors.

In vivo methods involve administering the immune-enhancing agent(s) to a subject on or in which the cell on whose surface expression of a MHC class I molecule is increased resides. The subjects and methods and parameters of administration are the same as those described above for Methods of Generating and/or Enhancing Immune Responses. Ex vivo methods include analogous methods to those described above for Methods of Generating and/or Enhancing Immune Responses. Thus, cells from a subject can be cultured with immune-enhancing agents (as described above for in vitro methods of enhancing MHC class I molecule expression) and, once a desired level of MHC class I expression has been obtained, the cells (and/or the progeny of the cells) can be returned to the subject or another subject. Moreover, cells from a subject can be genetically transformed with nucleic acids encoding one or more immune-enhancing agents and returned to the subject, or administered to another subject, as described in Methods of Generating and/or Enhancing Immune Responses.

The invention also provides methods of delivering an antigenic polypeptide or a fragment of such a polypeptide to the cytoplasm of a cell. The method involves contacting the cell of interest with one or more bacterial pore-forming protein such as those listed above, e.g., ct-hemorysm, or any of the above-described variants (including those with the indicated numbers of conservative substitutions) of bacterial pore-forming proteins. All that is required of such variants is that they have at least 20% (e.g., at least: 30%; 40%; 50%; 60%; 70%; 80%; 90%; 95%; 98%; 99%; 99.5%; 99.8%; 99.9%; or 100% or more) of the pore-forming activity of corresponding full- length, mature, wild-type molecules. Methods for comparing pore-forming activity of two or more molecules are well known in the art. The wild-type and variant pore- forming molecules are referred to as pore-forming agents.

Establishing the amount of pore- forming agent to use for any particular cell of interest would be within the ability of one skilled in the art. A useful amount of a pore-forming agent with which to contact a cell of interest would be an amount that would facilitate entry of an antigen of interest into the cytoplasm of the cell such that the cell is able to present the antigen (if an antigenic peptide) or a peptide fragment of the antigen to an appropriate T cell. Moreover after the contacting, the treated cell will not be substantially compromised by the contacting, i.e., the cell will have substantially the same ability to present a test antigenic peptide bound to a MHC class I molecule to a T cell that a corresponding untreated cell has. A treated cell that has substantially the same ability to present a test antigenic peptide bound to a MHC class I molecule to a test T cell (e.g., a T cell of a T cell clone) as a corresponding untreated cell is a cell that has at least 20% (e.g., at least: 30%; 40%; 50%; 60%; 70%; 80%; 90%; 95%; 98%; 99%; 99.5%; 99.8%; or even 100% or more) of the ability of the corresponding untreated cell to present the same test peptide bound to the same MHC class I molecule to the same T cell (or a T cell of the same T cell clone as the test T cell, where the test T cell is a T cell of a T cell clone).

The cells can be any vertebrate cells capable of presenting antigen to T cells. While such T cells would preferably be MHC class I-restricted T cells, they can also be MHC class II-restricted T cells. Thus, appropriate cells include any of those listed above for methods of enhancing expression of MHC class I molecules on cells. The cell can be contacted with any protein antigen of interest (or fragment of such a protein antigen) at the same time as, or after, being contacted with the pore-forming protein. Antigens of interest can be, without limitation, any of the protein immunogenic stimuli listed herein. Moreover, the cells can be contacted with any of non-specifically acting factors listed herein.

The methods can be in vitro, in vivo, or ex vivo. In vitro methods involve culturing cells to be contacted with one or more (see above) bacterial pore-forming agents. Any of the antigenic proteins, or fragments thereof, listed above can be added to the cultures at the same time as, or after, the pore-forming agent. Cells in cultures can be monitored at various time points for their ability to present appropriate antigenic peptides to T cells (e.g., activated CD4+ or CD8+ T cells with the specificity for a relevant antigenic peptide) by methods familiar to those skilled in the art. Such cultures can be used in, for example, screening of drugs that inhibit processing of protein antigens and/or presentation of antigenic peptides and for the generation of cell populations enriched for cells (e.g., APC) that present antigenic peptides of interest in association with MHC molecules on their surface. Such cells can be administered per se to subjects for active immunization against the relevant antigenic peptides or they can be used, for example, to generate activated T cells (e.g., CTL), which can be administered in passive immunization protocols to relevant subjects. The cultures can contain other cells, e.g., T lymphocytes (e.g., CTL or CTL precursors) to be activated by the cells (e.g., APC) to whose cytoplasm the antigens or antigen fragments are delivered. Moreover the cultures can contain one or more (see Methods of Generating and/or Enhancing Immune Responses) of the above described immunogenic stimuli and/or non-specifically acting factors.

In vivo methods involve administering the pore-forming agent(s) to a subject on or in which the cell resides. The subjects and methods and parameters of administration are the same as those described above for Methods of Generating and/or Enhancing Immune Responses. Ex vivo methods include analogous methods to those described above for Methods of Generating and/or Enhancing Immune Responses. Thus, cells from a subject can be cultured with pore- forming agents and antigens (or fragments thereof) (as described above for in vitro methods of enhancing MHC class I molecule expression) and once a desired level of antigenic peptide presenting ability has been obtained, the cells (and/or progeny of the cells) can be returned to the subject or another subject. Moreover, cells from a subject can be genetically transformed with nucleic acids encoding one or more pore- forming agents and returned to the subject or administered to another subject as described in Methods of Generating and/or Enhancing Immune Responses. Such cells can a act as a source of secreted pore-forming agent(s) or the pore-forming agent(s) produced by the transformed cells (e.g., APC such dendritic cell lines) can form pores in the transformed cells themselves in order to facilitate entry of appropriate antigens into the transformed cells. Those skilled in the art are entirely familiar with methods for generating genetic constructs encoding, e.g., variant pore-forming agents containing appropriate signal sequences that will facilitate secretion of pore-forming variant or insertion and formation of a pore in the cell membrane of a transformed cell.

Compositions, kits, and articles of manufacture

The invention also provides compositions containing one or more of the above-described immune-enhancing agents, and optionally, one or more of the above- described immunogenic stimuli and/or non-specifically acting factors and/or adjuvants. For example, an immune-enhancing agent can be a component of an injectable composition, which is injected into or applied to a appropriate part of a subject's body, e.g., the skin or a vein. Whether provided dry or in solution, the compositions of the invention can be prepared for storage by mixing them with any one or more of a variety of pharmaceutically acceptable carriers, excipients or stabilizers known in the art [Remington's Pharmaceutical Sciences, 16th Edition, Osol, A. Ed. 1980]. Acceptable carriers, excipients, or stabilizers are nontoxic to recipients at the dosages and concentrations employed, and include: buffers, such as phosphate, citrate, and other non-toxic organic acids; antioxidants such as ascorbic acid; low molecular weight (less than 10 residues) polypeptides; proteins such as serum albumin, gelatin or immunoglobulins; hydrophilic polymers such polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, arginine, or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrans; chelating agents such as EDTA; sugar alcohols such as mannitol, or sorbitol; salt-forming counterions such as sodium; and/or nonionic surfactants such as Tween, Pluronics, or PEG. Alternatively, the immune-enhancing agent(s) can be a component of a cream or solution to be applied topically, optionally in combination with any known non-toxic delivery agent and/or penetrant, and one or more of the immunogenic stimuli and/or non-specifically acting factors and/or adjuvants listed herein.

The compositions of the invention can be provided in the form of a kit or article of manufacture, optionally also containing packaging materials. Where one or more immunogenic stimuli and/or one or more non-specifically acting factors and/or one or more adjuvants are supplied with one or more immune-enhancing agents in a kit or article of manufacture, all of these components of the kit or article or manufacture can be provided in a single vessel, in separate vessels, or some together in one or more vessels and others in separate vessels, hi the kit or article of manufacture there can optionally be instructions (e.g., on the packing materials or in a package insert) on how to use and administer the composition(s).

The following examples serve to illustrate the invention and not to limit it.

EXAMPLES

Example 1. Materials and Methods Bacteria

S. aureus strains MN8 and MNSM are typical menstrual TSS (mTSS) isolates that are positive for (i.e., expresses) TSS (toxic shock syndrome) toxin-1 (TSST-I). Low passage samples of the organism are maintained in the inventors' laboratory in a lyophilized state. MNSM and MN8, representatives of the major class of mTSS S. aureus isolates, are tryptophan auxotrophs, with S. aureus pathogenicity island 2 (SaPI2) containing tst (the gene for TSST-I) inserted within the tryptophan operon, bacteriophage type (29/52), and the same multilocus enzyme electrophoresis profile as the majority of TSS isolates [Musser et al. (1990) Proc. Natl Acad. Sci USA 87:225-229]. hi vitro, S. aureus MNSM and MN8 produced approximately the same concentration of TSST-I as other mTSS isolates (range of TSST-I production by strains was 3 ug/ml to 100 ug/ml). MNSM and MN8 were positive for the staphylococcal enterotoxin A (SEA) gene by PCR, but made less than 75 pg/ml of SEA when cultured in a dialyzable beef heart medium [Blomster-Hautamaa et al. (1988) Methods Enzymol. 165:37-43]. It was determined that S. aureus at a cell concentration 1 x 10⁹/ml corresponded to an absorbance at 600 nm of 1.2.

The day prior to use, S. aureus MN8 (or MNSM) were cultured on chocolate agar plates. The bacteria were prepared for use by scraping them directly from blood or chocolate agar plates into 10 ml of keratinocyte serum-free medium (KSFM; Gibco Life Technologies, Carlsbad, CA) without antibiotics, washing them one time with 10 ml of KSFM without antibiotics, and adjusting them to the indicated concentration based on absorbance at 600 nm; actual cell counts added to epithelial cells were determined subsequently by plating, culturing, and colony counting.

S. aureus RN4220 (pCE107) transformed with pCE107 was cultured in a pyrogen-free dialyzable beef heart medium containing erythromycin (5ug/ml) for production of TSST-I [Murray et al. (1996) Infect. Pmmun. 64:371-374]. Strain RN4220 has been shown to lack endogenous SAG production. The plasmid pCE107 is a high copy number plasmid containing tst.

S. aureus strain MNNJ was used for production of SEB [Yarwood et al. (2002) J. Bacteriol. 184:1095-1101].

Escherichia coli containing pET28b with a speA insert was used for production of streptococcal pyrogenic exotoxin A (SPE A) [McCormick et al. (2000) Toxins and superantigens of group A streptococci, p. 43-51. In V. A. Fischetti (ed.), Gram-positive pathogens, American Society of Microbiology].

Generation of Immortal Human Vaginal Epithelial Cells

Immortal human vaginal epithelial cells (HVEC) were a gift from Dr. Kevin AuIt of the University of Iowa, Iowa City, IA, and were generated as described below. Primary normal human epithelial cells were isolated from premenopausal vaginal hysterectomy tissue obtained from a patient who did not have cancer using methods that have been previously described for the isolation of human foreskin epithelial cells [Halbert et al. (1992) J. Virol. 66:2125-2134]. The E6 and E7 genes of human papillomavirus type 6 have weak immortalizing activity in human epithelial cells. Cells were grown in KSFM (Gibco Life Technologies) on plastic and passaged with a 1:4 split using trypsin-EDTA solution (Ix trypsin-EDTA (ethylene diamine tetraacetic acid); 0.25% trypsin, 0.1% EDTA; Mediatech, Inc., Herndon, VA). Early passage cells were doubly transduced with retroviruses expressing HPV- 16 E6/E7 (a gift from Dr. Denise Galloway, Fred Hutchinson Cancer Research Center, Seattle, WN) and the reverse transcriptase component of telomerase, hTERT (obtained from the Geron Corporation), and selected in 50 μg/ml G418 as previously described [Kiyono et al. (1998) Nature 396:84-88]. Both Rb/plό¹¹^⁴* inactivation and telomerase activity are required to immortalize human epithelial cells [Kiyono et al. (1998)]. Cells surviving selection (V428) had high levels of telomerase and became immortal without crisis, whereas normal untransduced cells senesced at about passage 9.

Superantigen purification TSST-I was partially purified by ethanol-precipitation (75% final volume) from late stationary phase culture fluids of S. aureus RN4220 (pCE107) grown at 37⁰C with high aeration (200 rpm) and resolubilization in pyro gen-free water [Blomster-Hautamaa et al. (1988)]. TSST-I was purified to homogeneity by thin layer isoelectric focusing in pH gradients first of 3 to 10 and then 6 to 8 [Blomster- Hautamaa et al (1988)]. SEB was comparably purified from S. aureus strain MNNJ, except that the second isoelectric focusing pH gradient was 7 to 9 [Yarwood et al. (2002)]. SPE A was similarly prepared from a pET28b clone [McCormick et al. (2000)]; in this case the second isoelectric focusing gradient was pH 4 to 6. The SAG migrated as visible, clear bands in the opaque background of the gradients with pis of 7.2 for TSST-I, 8.5 for SEB, and 5.0 for SPE A. After isoelectric focusing, ampholytes were removed following 4 days of dialysis against pyrogen-free water. Analysis of the purified toxins ( 5ug) by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and silver staining [Laemmli (1970) Nature 227:680- 685] showed them to be homogeneous. In addition, the proteins, at concentrations of 1 mg/ml, were negative for lipopolysaccharide (endotoxin) as tested by Limulus assay (Sigma Chemical Company, St. Louis, MO). The TSST-I and SEB proteins lacked detectable hemolysins (a, β, and δ), protease, and lipase as tested in bioassays and compared to standards (described below).

Scanning electron and confocal microscopy

Single cell suspensions of S. aureus MN8 were cultured in KSFM (without antibiotics) with HVEC previously grown to confluence in transparent cell culture inserts (Becton Dickenson Lab ware, Franklin Lakes, NJ) at 37⁰C for up to 6 h to assess adherence and growth of the strain on the epithelial cells. After 6 h, the surface was washed with PBS (phosphate buffered saline) to remove non-adherent cells, and the HVEC with bound staphylococci were fixed for scanning electron microscopy (SEM) according to instructions provided by the University of Minnesota SEM facility. A Hitachi S-800 instrument was utilized to visualize S. aureus MN8 adherence and replication on HVEC. HVEC were also examined by confocal microscopy at the University of Minnesota Biomedical Process Imaging Laboratory to assess TSST-I effects on cell morphology following co-culture with TSST-I at concentrations of both 10 ug/ml and 100 ug/ml in KSFM at 37⁰C.

TSST-I receptor determination on HVEC ³⁵S-labeled TSST-I was prepared from the RN4220 clone as described previously [Blomster Haumtamaa et al. (1988); Davis et al. (2003) Am . J. Obstet. Gynecol. 189:1785-1791]. Briefly, the bacterial cells were grown to a cell density of 5 x 10⁸/ml in 50 ml beef heart dialysate medium, and then 10 mCi ³⁵S-methionine was added. The culture was then incubated overnight at 37⁰C with high aeration (200 rpm). Finally, TSST-I was purified by ethanol precipitation, resolubilization in water, and isoelectric focusing. Experiments to assess TSST-I binding to HVEC were performed at 4⁰C to prevent toxin internalization by the cells. HVEC were cultured in 75 cm² flasks (BD Falcon, Bedford, MA) until confluent (approximately 1 x 10⁷cells/fiask). The cells were then scraped from the flasks with rubber spatulas, the contents of multiple flasks combined, and the cells resuspended in PBS for use. Initial experiments assessed the time required to saturate the receptors on the HVEC for TSST-I, with time-points including 0, 5, 15, 30, and 60 min. At each time point, the cells were incubated with TSST-I, washed 3 times by centrifugation at 4⁰C, and both the cells and supernates counted for radioactivity with use of a scintillation counter. Scatchard analysis was performed to determine receptor numbers per HVEC.

Bacterial virulence factor assays in KSFM

TSST-I was quantified by a sandwich ELISA procedure [Yarwood et al. (2000) J. Clin. Microbiol. 38:1797-1803]. δ hemolysin levels were assessed by a competition ELISA procedure. Briefly, intact δ hemolysin was synthesized by the University of Minnesota Microchemical Facility; chromatographically purified, and verified to have hemolytic activity. A rabbit was hyperimmunized against the hemolysin. Serum was collected from the rabbit and shown to contain antibodies that bound to δ hemolysin. The immunoglobulins in the rabbit serum were collected by 33% ammonium sulfate precipitation and resolubilization in PBS. A competition ELISA was set up in which microtiter plate wells were coated with δ hemolysin, different concentrations of δ hemolysin (or culture fluids) plus a predetermined dilution of anti-δ antibodies were added, and the plates were developed with an anti-rabbit-horseradish peroxidase second antibody conjugate [Yarwood et al. (2000)]. a hemolysin, lipase (glycerol ester hydrolase), and protease were measured in bioassays comparing the activities of in test samples to the activities of known concentrations of purified control proteins [Schlievert et al. (2000) Ann. Intern, Med. 96:937-940]. Briefly, rabbit erythrocytes (α hemolysin), tributyrin (lipase), or casein (protease) were added to 45⁰C agarose (0.75% in PBS), and 4 ml of homogeneous mixtures were applied to microscope slides. After solidifying, 4 mm wells were punched in the agarose, and 20 ul volumes of culture fluids or control purified proteins were added to the wells. Finally, the slides were incubated humidified at 37⁰C for 8 h. The areas of the zones of clearing were determined to be proportional to protein concentrations.

Microarray experiments with S. aureus infected epithelial cells

V428 HVEC were grown to confluence in 250 ml Falcon tissue culture flasks (BD Biosciences) (approximately 3 x 10⁷ cells/flask) in KSFM. The medium was removed and replaced with new medium the day before experimentation. On the day of assay, S. aureus MN8 or S. aureus MNSM bacteria were added to epithelial cells at a bacterial concentration of 10⁹/ml KSFM added, i.e., 10¹⁰ bacteria in a total volume of 10 ml KSFM (approximately 100 bacteria per epithelial cell) and cultured for 6 h (S. aureus MN8) or for 3 h and 6 h (S. aureus MNSM). Separate flasks were then incubated for 3 and 6 hours. AU incubations were stationary, at 37^°C, and in an atmosphere of 7% CO₂. At the end of the incubation, flasks were removed from the incubator and culture supernatants were removed and stored at -2O⁰C for later cytokine and chemokine analysis (see below.). Trypsin-EDTA solution (10 ml; Ix trypsin-EDTA; 0.25% trypsin, 0.1% EDTA; Mediatech, Inc.) was added to the flasks, and after 5 minutes detached epithelial cells were removed from the flasks. The epithelial cells were washed once and RNA was isolated from them using the Qiagen RNeasy Mini™ kit. Fragmented biotin-labeled cRNA was prepared from this RNA and used for microarray analysis using methods described in the GeneChip® Expression Analysis Technical Manual (Affymetrix, Santa Clara, CA; April, 2003). In brief, single-stranded cDNA was prepared from the RNA, double-stranded cDNA was prepared from the single-stranded cDNA, and biotin-labeled cRNA was prepared from the double-stranded cDNA. Finally, the biotin-labeled cRNA was fragmented by metal-induced hydrolysis and allowed to hybridize to an Affymetrix Ul 33 A Human GeneChip® (Affymetrix). Data were analyzed by software provided by The Institute for Genome Research (Microarray Software Suite; Rockville, MD) and Affymetrix Microarray Suite Software.

Assays for chemokines and cytokines ELISA (Enzyme-linked Immunosorbent Assays) were performed on the supernatants from the cultures peformed for microarray analysis (see above). Representative chemokines and cytokines were chosen. Assay kits, which were purchased from R and D Systems, Minneapolis, MN, included assays for chemokine ligand 20 (macrophage inflammatory protein-3ce [MIP-3α]), IL-1/3, IL-6, IL-8, TNF-α, and interferon-7. All assays including standard curve generation were performed according to the manufacturer's instructions. Absorbance values and calculated concentrations of chemokines and cytokines in the supernatants were derived from the linear parts of the standard curves, hi addition, supernatants from HVEC incubated for 6 h with two other SAG, SEB (100 ug/ml) and SPE A (100 ug/ml), and ovalbumin (100 ug/ml, Sigma, as an irrelevant protein control) were assayed for MIP-3o; and IL- 8 for confirmation of TSST-I activation of HVEC.

Studies were conducted to confirm the identity of the receptor to which TSST- 1 binds. These studies involved testing the ability of a dodecapeptide (corresponding to a region of TSST-I previously shown to bind to epithelial cells) (see below) to inhibit competitively the ability of TSST-I to bind to the HVEC receptor and induce chemokine and cytokine release. Briefly, TSST-I (100 ug/ml) alone or with the dodecapeptide [Tyr-Asn-Lys-Lys-Lys-Ala-Thr-Val-Gm-Glu-Leu-Asp] (SEQ ID NO:1; 1000 ug/ml), synthesized, purified, and verified to have the correct sequence by the University of Minnesota Microchemical Facility, were incubated with HVEC for 6 h, and then chemokines and cytokines were assayed by ELISA. The dodecapeptide, which was used by others to inhibit both SAG activity and transport of SAG across mucosal surfaces [Arad et al. (2000) Nat. Med. 6:414-421; Shupp et al. (2002) Infect. Immun. 70: 2178-2186], lies outside the region of TSST-I that interacts either with MHC class II or TCR [Arad et al. (2000)]. Measurement of porcine vaginal tissue permeability to TSST-I ex-vivo

Specimens of normal, porcine vaginal mucosa were excised from animals at slaughter, transported to the inventors' laboratory in sealed plastic bags, and utilized within 3 h of harvest. Tissue discs (8-10 mm diameter) were mounted in continuous- flow perfusion chambers (5 mm diameter orifice) that were maintained at 37⁰C on water-jacketed blocks. An epithelial surface of 0.20 cm² was exposed to the donor compartment. PBS (pH 7.4) was pumped through the receiving chamber at 1.8 ml/h as collection fluid. The chambers were incorporated into an automated continuous flow system to permit regular sampling over a 12 h period. Seven to nine replicates were prepared for each sample application.

Permeability to ³⁵S labeled TSST-I was assessed as previously described [Davis et al. (2003)]. Viable (1.6 x 10⁹/ml) or heat-killed TSS S. aureus MN8 (both approximately 100 bacteria/ epithelial cell) together with ³⁵S TSST-I were applied to the epithelial surface in KSFM without antibiotics. Perfusate was collected into scintillation vials at 1 h intervals for up to 12 h. The mean of three 100 ul aliquots of the labeled material in the donor chamber was used to determine total applied radio label. Flux was calculated for each sampling interval from the relationship: Flux = Q/ At, where Q is the quantity of radiolabel traversing the tissue (dpm) in time t (min) and A is the area of epithelial surface exposed in cm². Units of flux are dprn/cm²/min.

Biopsies of intact porcine mucosa were incubated at 37⁰C with either PBS or with topically-applied S. aureus MN8 in KSFM for up to 12 h. Following experimentation, the biopsies were fixed in formalin, wax embedded, cross-sectioned, and stained with hematoxylin and eosin (H&E) for histological examination.

Example 2. Characterization of Secreted Virulence Factors of S. aureus MNSM and MN8

MNSM and MN8, typical TSST-I producing S. aureus strains from cases of mTSS (menstrual toxic shock syndrome), produced and secreted the following virulence factors when grown in KSFM medium over the 6 h incubation period with HVEC: TSST-I (up to 80 ug/ml in broth culture), a hemolysin, δ hemolysin, protease, and lipase. Although MNSM and MN8 were determined by PCR to have the gene for SEA, the toxin could not be detected by protein analysis.

Example 3. A Microarray Analysis of the Epithelial Cell Response to S. aureus Bacteria

In mRNA microarray analyses it was observed that the V428 HVEC responded to S. aureus MN8 (as measured after 6 h of co-culture) by up- or down- regulating the expression of a multiplicity of genes. The expression of 2,889 genes was modulated by 1.5-fold or greater, of 986 genes by 2-fold or greater, and 84 genes by 5-fold or more. Of the 84 genes whose expression was modulated by 5 -fold or more, the expression of 83 genes was up-regulated. Of these 83 genes, most are involved in signal transduction and lead to activation of the immune system. Table 1 lists some of the HVEC genes that were up-regulated by S. aureus MN8. For example, the expression of chemokine ligand 20 (macrophage inflammatory protein (MIP)- 3α) gene was upregulated by 274-fold, that of interleukin-8 (IL-8) by 64-fold, and that of tumor necrosis factor α (TNFα) by 19.7-fold. Other proinflammatory/immunregulatory genes whose expression was upregulated include chemokine ligand 2 (CXCL2; 27.9-fold), chemokine ligand 1 (CXCLl; 21.1-fold), the cytokines interleukin (IL)-Ia (7.5 -fold) and IL-I β (6.1 -fold), and the adhesion ligand ICAM-I (not shown;10.6-fold).

Table 1. Genes in HVEC whose expression was up-regulated by S. aureus (MNSM and MN8)

^aNS, No significant change from control. Up- or down-regulations of ,^-fold were significant. CXCL14 also known as BRAK/bolekine. Colony stimulating factor

(CSF) 2 also known as granulocyte-macrophage CSF. CSF 3 also known as ggrraannuullooccyte CSF. Lymphotoxin-β also known as TNF-β. ^bRelated to C-reactive protein. The effect of S. aureus strain MNSM (100 bacteria per epithelial cell) on HVEC gene expressed was determined after 3 h and 6 h of co-culture. S. aureus MNSM stimulated the up- or down-regulation of 341 genes and 410 genes by 2 fold or more compared to controls following 3 h and 6 h of incubation with HVECs, respectively (Table 1). As observed with S. aureus MN8 (above) and TSST-I 100 ug/ml (see below), S. aureus MNSM up-regulated chemokine and cytokine genes. The genes most up-regulated at 6 h were MIP-3θ! (up-regulated 478 fold), CXCLl (GRO-α; up-regulated 17 fold), CXCL2 (GRO-ft up-regulated 13 fold), and CXCL3 (GRO-γ, up-regulated 20 fold). Cytokine genes, such as TNF-α and IL-1/3 were also up-regulated at 6 h with fold changes of 11 and 4, respectively. No significant up- regulation of toll-like receptor (TLR) genes following 3 Ii and 6 h incubation of HVECs with S. aureus MNSM was observed; however, modest TLR 2 gene expression was detected with up-regulation of 1.2 and 1.5 fold at 3 h and 6 h, respectively (data not shown). Similar to TSST-I (100 ug/ml), up-regulation of MHC class I F gene expression by 1.9 and 2.3 fold was produced following incubation with S. aureus MNSM for 3 and 6 h, respectively.

TNF-Q! and IL-I proteins were detected in the supernatants from cultures of HVEC incubated with S. aureus MNSM for 6 h, at amounts of 139 pg/ml and 36 pg/ml, respectively (Fig. 1). The detection of TNF-ce and IL-1/3 in the supernatants at 6 h correlated with up-regulation of the genes encoding these cytokines by 11 and 4 fold, respectively, as measured by microarray analysis (Table 1). Chemokines MIP- 3a, IL-8 and IL-6, were also detected in supernatants from cultures of HVEC with S. aureus MNSM at 3 h and 6 h. At 6 h, the concentrations of these chemokines were MIP-30! (80 pg/ml), IL-6 (33 pg/ml), and IL-8 (88 pg/ml). The amounts generally correlated with the up-regulation of the genes encoding these chemokines at 6 h as measured by microarray analysis (Table 1). However, the correlation of fold up- regulation of the MIP3Q! gene with MJPSa protein detected by ELISA is generally in the same direction, but the protein concentration was not as high as expected based on the microarray data. The inventors have observed that proteases made by TSS S. aureus strains MNSM and MN8 degrade MD?-3Q! protein (data not shown), and this likely contributed to the lack of complete concordance between gene and ELISA data for MIP-3α! and possibly other chemokines. Interferon-γ was not detected in the supernatants from experiments of HVEC incubated with S. aureus MNSM at either time point, again consistent with the lack of up-regulation of this gene as measured by microarray analysis (Table 1). HVEC controls (without TSST-I or S. aureus MNSM) showed no detectable cytokines or chemokines at 3 h and 6 h. The lower limit of detection for all cytokines and chemokines was 4 pg/ml to 16 pg/ml, and depended on the cytokine or chemokine. Data obtained by ELISA of S. aureus strain MN8 incubated for 6 h also confirmed the same chemokine and cytokine release by the HVEC (data not shown).

Example 4. Adherence of TSST-I and S. aureus MN8 to HVEC

³⁵S- TSST-I binding experiments determined that ³⁵S-TSST-I bound to the HVEC at approximately 5 x 10⁴ receptors/epithelial cell with saturation of receptors occurring within 15 min of incubation at 4⁰C (Fig. T). S. aureus MN8, co-cultured at 1 x 10⁹ CFU/ml with HVEC in KSFM at 37⁰C for up to 6 h, was found to adhere, proliferated, and formed aggregates on the HVEC, and produced exotoxins.

Example 5. Cytokine and Chemokine Release from HVEC Following Stimulation with TSST-I and Other SAG Generation and Culture of Immortal HVEC

One of the most important physical barriers to SAG in humans is the intact epithelium. It seemed possible that SAG (and very possibly other exotoxins produced by the bacteria) induced inflammation of the epithelium and that this inflammation could serve to diminish this physical barrier. The studies described below show that the SAG TSST-I up-regulates inflammatory chemokine and cytokine gene expression in epithelial cells. Monolayers of the immortalized HVEC were prepared and characterized by use of cytokeratin-specific antibody staining and by assessing the presence of cellular tight junctions. A mixture of monoclonal antibodies (mAb) (mAb AEl and mAb AE3) specific for human cytokeratins bound, as expected, to the HVEC (data not shown), indicating that the cells were epithelial in nature. The AEl mAb is specific for the high molecular weight (mw) cytokeratins 10, 14, 15, and 16 and the low mw cytokeratin 19 and the AE3 mAb is specific for the high molecular weight cytokeratins 1-6 and the low molecular weight cytokeratins 7 and 8. The cells formed partial tight junctions, consistent with the fact that vaginal epithelial cells, like oral epithelial cells but in contrast to epithelial cells of the intestinal tract, do not form tight junctions but form a permeability barrier by piling on top of one another and secreting water insoluble compounds such as ceramides, glucosyl ceramides, and cholesterol. The HVEC also had morphology typical of non-stratified squamous epithelial cells when grown in KSFM at 37^°C in 7% CO₂.

Effect of S. aureus Exotoxin TSST-I on the Cellular Morphology of HVEC

HVEC were examined for gross morphological effects by confocal microscopy following treatment with purified TSST-I . HVEC lost cell-to-cell contact and contracted following 6 hours of exposure to TSST-I (100 μg/ml).

TSST-I concentrations of 100 μg/ml are physiologically relevant to TSS S. aureus strains since, when cultured as thin films on tampons placed in dialysis tubing and then submerged beneath Todd Hewitt soft agar, TSS S. aureus produced 1.0-1.5 mg/ml of TSST-I. In addition, recent studies of TSST-I production by methicillin resistant Staphylococcus aureus (MRSA) isolates from TSS patients indicated that 100 to 1000 μg/ml of TSST-I is produced by these strains when grown as thin films on polyethylene mesh. Thus, it is probable that TSS S. aureus growing on mucosal surfaces as thin films in vivo produce TSST-I in excess of 100 μg/ml.

S. aureus Exotoxin TSST-I Enhances the Levels of Cytokine and Chemokine Expression in HVEC

The studies described below demonstrate that bacterial exotoxins up-regulate the expression of cytokines and chemokines in HVEC. The global responses (in terms of mRNA transcript production) of HVEC to TSST-I (at 10 μg/ml and 100 μg/ml) and untreated control HVEC following culture for 3 and 6 hours were determined using the Affymetrix Human GeneChip^® U133A by a modification of the method described in Example 1.

TSST-I at lOug/ml caused only 60 genes and 61 genes of HVEC to be up- or 5 down-regulated by 2 fold or more at 3 h and 6 h, respectively (data not shown). On the other hand, treatment of HVEC for 3 and 6 hours with TSST-I (100 μg/ml) caused significant up- and down-regulation (by two fold or greater) of the expression of 1472 genes and 2386 genes, respectively. As shown in Table 2, chemokine genes whose transcript levels were significantly up-regulated by 6 hours included, for example, o CCL20 (encoding MIP-3Q;; 169-fold), CXCLl (encoding GRO-α; 84 fold), CXCL2 (encoding GRO-/3; 13 fold), and CXCL3 (encoding GRO-γ, 32 fold). In addition, genes encoding cytokines whose transcript levels were also significantly up-regulated included, for example, those encoding TNF-o; and IL- 1 _/S, with changes of 2.5-fold and 2.0-fold, respectively. Moreover, mRNA expression of major histocompatibility 5 complex (MHC) class I classical genes (A, B, C) and non-classical genes (F and G) was significantly up-regulated in response to TSST-I . There were also large numbers of hypothetical proteins and cell regulatory genes affected by TSST-I at 100 ug/ml (data not shown). Finally, the gene for toll-like receptor (TLR) 3 was up- regulated by 4 fold at 3 h (data not shown); no other TLR genes were significantly up- 0 or down-regulated by TSST-I (100 ug/ml).

Table 2. Genes in HVEC whose expression was up-regulated after exposure to TSST- 1 for 3 or 6 hours.

^aNS, No significant change from control

Representative cytokine and chemokine genes whose expression was determined by the above-described microarray analysis to be up-regulated following exposure of HVEC to TSST-I (100 μg/ml) were analyzed in terms of encoded protein production using Enzyme-Linked Immunosorbent Assays (ELISA). Specifically, cytokine (IL-1/3, TNF-α, and interferon-^) and chemokine (MIP-3α, IL-6, and IL-8) concentrations were determined in the supernatants of cultured HVEC incubated with TSST-I (100 μg/ml) for 3 or 6 hours (Fig. 3). Ovalbumin (100 μg/ml) (rather than TSST-I) was added to control cultures and was found to cause only minimal production of cytokines and chemokines from the HVEC after the 6 hours of culture (see Table 3), thereby indicating that the effects seen with TSST-I (100 μg/ml) were caused by the exotoxin itself and were not non-specific effects that would be elicited by any exogenous protein.

Significant levels of both IL- 1/3 and TNF-α were detected in culture supernatants following incubation of HVEC with TSST-I (100 μg/ml) for 6 hours (12 pg/ml and 68 pg/ml, respectively) (Fig. 3). As shown in Table 2, the levels of IL-IjS and TNF-α proteins were consistent with the measured transcriptional induction of these genes (2.0 and 2.5-fold, respectively) by TSST-I. In contrast, but consistent with the inability to detect interferon-γ transcripts, interferon-7 protein was not detected in culture supernatants following incubation of HVEC with TSST-I (100 μg/ml).

The chemokines MIP-3α! (240 pg/ml), IL-6 (15 pg/ml), and IL-8 (475 pg/ml) were detected in culture supernatants following incubation of HVEC with TSST-I

(100 μg/ml) for 6 hours. Control HVEC (without TSST-I) did not produce detectable levels of the cytokines or chemokines tested for after 3 and 6 hours of incubation.

Additionally, HVEC were cultured for 6 h with TSST-I (100 ug/ml), a control protein (ovalbumin; 100 ug/ml), two other SAG, i.e., SEB (100 ug/ml), and SPE A (100 ug/ml. ELISA for MIP-3α and IL-8 were performed on supernatants from all cultures (Table 3). TSST-I (100 ug/ml) induced similar production of the two chemokines as was observed to be produced by HVEC incubated for 6 h with TSST-I (100 ug/ml) in the microarray studies. Ovalbumin (100 ug/ml) did not stimulate production of MIP-3α! and IL-8 above background, suggesting the TSST-I effect was not the result simply of exposure to any exogenous foreign protein (Table 3). The other two SAG at 100 ug/ml (SEB and SPE A) induced production of MIP-3Q: and IL- 8 similar to TSST-I (100 ug/ml). Table 3. Chemokine and cytokine secretion by HVEC in response to TSST-I and others SAG.

^aDodecapeptide concentration was 1,000 μg/ml.

Confirmation of receptor on HVEC to which TSST-I binds

Studies were performed to further characterize the TSST-I receptor on the HVEC that was involved in stimulation of the production of chemokines and cytokines. In these studies, ten-fold excess amounts (ug/ug) of the dodecapeptide Tyr- Asn-Lys-Lys-Lys- Ala-Thr- Val-Gln-Glu-Leu- Asp (SEQ ID NO : 1 ), which previously had been shown to inhibit both superantigenicity and mucosal transport by a TCR and MHC II independent mechanism [Arad et al. (2000); Shupp et al. (2002)], were incubated with HVEC for 6 h and TSST-I (100 ug/ml) and ELISA were performed on supernatants from the relevant cultures to detect MIP-3o; and IL-8. The dodecapeptide competitively inhibited TSST-I induced release of both MIP-3α and IL-8 (Table 3). Example 6. TSST-I Penetration of Porcine Vaginal Tissue ex-vivo in the Presence of TSS S. sureus MN8

Previous research has demonstrated that porcine vaginal tissue is an excellent model of human vaginal tissue in that the cellular architecture and permeability barriers are very similar [Davis et al (2003)]. The present studies indicate that TSST- 1 penetrated normal intact porcine vaginal mucosa poorly, suggesting that other factors, such as inflammation, may facilitate TSST-I penetration (Table 4). The total amount of ³⁵S labeled TSST-I penetrating across porcine vaginal tissue was increased significantly in the presence of viable TSS S. aureus MN8 (200 ng) over the 12 h period compared to untreated control tissue (36 ng). Killed MN 8 cells also facilitated significant penetration of radiolabeled TSST-I across the porcine vaginal tissue (115 ng) compared to untreated control tissue, but not to the same extent as viable S. aureus MN 8 (Table 4). These data suggested that secreted factors from the viable organisms contributed significantly to the increased radiolabeled TSST-I penetration.

Table 4. Penetration Of³⁵S TSST-I across intact porcine vaginal mucosa in the presence of TSS S. aureus.

^aMaximum flux was defined as the greatest amount of radiolabeled TSST-I penetrating across the entire porcine vaginal mucosa per cm² of tissue per min. Histological examination of the tissue incubated with viable TSS S. aureus indicated desquamation of superficial epithelial cells and separation of the upper epithelium from the basement membrane region so as to create subepithelial blistering. This was accompanied by a marked sub-epithelial lymphocytic infiltrate, which was surprising in an ex vivo specimen isolated from vascular perfusion.

A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

Claims

What is claimed is:

1. A method of enhancing an immune response, the method comprising: administering to a vertebrate subject an isolated immune-enhancing bacterial exotoxin or an isolated functional fragment of the bacterial exotoxin; and administering to the vertebrate subject an immunogenic stimulus.

2. The method of claiml , wherein the bacterial exotoxin is a bacterial superantigen (SAG).

3. The method of claim 1 , wherein the bacterial SAG is toxic shock syndrome toxin 1 (TSST-I).

4. The method of claim 2, wherein the bacterial SAG is a staphylococcal enterotoxin (SE).

5. The method of claim 2, wherein the bacterial SAG is a streptococcal pyrogenic exotoxin (SPE).

6. The method of claim 1, wherein the bacterial exotoxin is a bacterial pore-forming protein.

7. The method of claim 1, wherein the immunogenic stimulus is a cancer- specific immunogenic stimulus.

8. The method of claim 1, wherein the immunogenic stimulus is an infectious microorganism-specific immunogenic stimulus.

9. A method of enhancing expression of a major histocompatibility complex (MHC) class I molecule on the surface of a cell, the method comprising: contacting a cell with an isolated bacterial exotoxin or a functional fragment thereof, wherein the contacting results in an increase in expression of a MHC class I molecule on the surface of the cell or a second cell; and confirming that there is an increase of expression on the surface of the cell or the second cell.

10. The method of claim 9, wherein the contacting is in vitro, the method comprising: providing a plurality of cells from a vertebrate subject; contacting the cells with the bacterial exotoxin, or the functional fragment thereof, in vitro; and assessing the level of expression of the MHC class I molecule on the surfaces of the cells.

11. The method of claim 10, further comprising, after the contacting, administering the cells, or the progeny of the cells, to the vertebrate subject.

12. The method of claim 10, wherein the method comprises: administering the bacterial exotoxin to a vertebrate subject; and assessing the level of expression of the MHC class I molecule on the surfaces of a plurality of cells obtained from the vertebrate subject.

13. The method of claim 9, wherein bacterial exotoxin is a bacterial SAG.

14. The method of claim 13, wherein the bacterial SAG is TSST-I.

15. The method of claim 13, wherein the bacterial SAG is a SE.

16. The method of claim 13, wherein the bacterial SAG is a SPE.

17. A method of delivering a polypeptide antigen to the cytoplasm of a cell, the method comprising contacting a vertebrate cell with an isolated bacterial pore-forming protein, or a functional fragment thereof, and an isolated polypeptide antigen.

18. The method of claim 17, wherein the cell is an antigen presenting cell

(APC).

19. The method of claim 17, wherein the contacting is in vitro, the method comprising: providing a cell from a vertebrate subject; and contacting the cell with the bacterial pore-forming protein, or the functional fragment thereof, in vitro.

20. The method of claim 19, further comprising contacting the cell in vitro with the isolated polypeptide antigen.

21. The method of claim 20, further comprising, after contacting the cell in vitro, administering the cell to the vertebrate subject.

22. The method of claim 19, further comprising: administering the cell to the vertebrate subject; and administering the polypeptide antigen to the vertebrate subject.

23. The method of claim 18, wherein the method comprises administering the bacterial pore-forming protein and the polypeptide antigen to a vertebrate subject.

24. The method of claim 18, wherein the bacterial pore-forming protein is α-hemolysin.