WO2009155665A1

WO2009155665A1 - Methods and compositions for treating pathological infections

Info

Publication number: WO2009155665A1
Application number: PCT/AU2009/000830
Authority: WO
Inventors: Lor Wai Tan
Original assignee: Central Northern Adelaide Health Service; The Queen Elizabeth Hospital Research Foundation Inc.
Priority date: 2008-06-26
Filing date: 2009-06-26
Publication date: 2009-12-30

Abstract

The present invention relates to methods for treating or preventing infection of a subject by a pathogen. More particularly, the present invention contemplates methods and compositions relating to administering to the subject an agent which inhibits sialic acid mediated adhesion of the pathogen to a surface of the subject.

Description

METHODS AND COMPOSITIONS FOR TREATING PATHOLOGICAL

INFECTIONS

PRIORITY CLAIM

This application claims priority to Australian provisional patent application 2008903259 filed 26 June 2008, the contents of which are hereby incorporated by reference.

FIELD

The present invention relates to methods and compositions for treating or preventing infection of a subject by a pathogen.

BACKGROUND

Pathogen infection is a leading cause of illness in humans and animals, which in some instances can lead to death. Pathogen infection can have significant economic effects, in particular in relation to high treatment costs, loss of work time, and poor health of livestock.

Antibiotics are commonly used to treat microbial infections. However, a number of microorganisms are inherently resistant to conventional antibiotics. Furthermore, some microorganisms, which would otherwise be susceptible to conventional antibiotic therapy, are able to adopt a state which is resistant to conventional antibiotics. Such a state is commonly found in biofilms.

Biofilms are a structured population or community of microbial cells enclosed in a self- produced polymeric matrix and adherent to an inert or living surface. Biofilm formation may occur in a series of sequential steps; firstly microorganisms bind to a surface. Once a foothold is established, the microorganisms may rapidly multiply whilst simultaneously secreting a protective polysaccharide matrix. The colonization process is completed when the microflora switch to a sessile phenotype that cannot be easily dislodged.

Biofilms may form on a range of different surfaces. Typically, the surfaces are solid surfaces exposed to or submerged in an aqueous solution. Biofilms are particularly important in mammalian health, including human health.

Biofilms that are associated with human health include biofilms that form on mucosa of the respiratory, urogenital and alimentary tracts. An example of a human disease that is often associated with the presence or formation of a biofilm on a mucosal surface is chronic rhinosinusitis (CRS). CRS is a disease which results in chronic inflammation of the paranasal sinuses, and may further include inflammation of part of the nose.

In Australia chronic rhinosinusitis (CRS) is classified as a prevalent condition within the major chronic respiratory diseases group. Between 2000-01 the collective cost of treatment for CRS and asthma exceeded $693 million, 50 % of which was spent on pharmaceuticals. In the US, CRS results in 11.5 million physician visits per year with an estimated US$ 2 billion spent annually on medications. There clearly is a significant economic cost in terms of reduced productivity, work days lost, and increased expenditure on elective surgery.

Recent advances in microscopy have improved the ability to detect bacterial biofilms in situ. Using scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM) techniques, clear evidence now exists for bacterial biofilms on sinus mucosa of CRS patients. Increasingly, bacterial biofilms have been implicated as aetiological agents in the development of CRS. As bacterial communities in biofilms adopt a phenotype that do not require functional growth and cell wall synthesis gene expression, conventional systemic antibiotic treatments that specifically target metabolically active bacteria undergoing replication or cell wall synthesis are of reduced efficacy.

Surgery is often performed to remove infected mucosa on a mucosal surface. However, incomplete removal of the infected mucosa often leads to the regeneration of the biofilm and associated disease.

Biofilms can also be resistant to conventional antibiotic treatments and their propensity for regeneration following incomplete surgical removal may explain the refractory and often recalcitrant nature of chronic rhinosinusitis (CRS).

In many forms of pathogen infection (including viral and bacterial infections), attachment to a surface of a subject is an important step for effective infection. In light of the above, a method for treating or preventing pathogen infection, by inhibiting pathogen attachment would be desirable. Given the recalcitrant nature of biofilms comprising pathogens, a method for treating or preventing biofilm formation would also be desirable.

Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.

SUMMARY

The present invention relates to methods for treating or preventing infection of a subject by a pathogen.

In particular, the present invention provides a method for treating or preventing infection of a subject by a pathogen, the method comprising administering to the - A -

subject an agent which inhibits sialic acid mediated adhesion of the pathogen to a surface of the subject.

In some embodiments of the invention, the infection comprises a biofilm on a surface of the subject.

In some embodiments, the agent inhibits sialic acid mediated adhesion of the pathogen to a surface of the subject by one or more of: i) inhibiting cleavage of a sialic acid residue on a surface of the subject by a pathogen; and/or ii) binding to a sialic acid binding molecule of the pathogen.

The present invention also provides a pharmaceutical composition comprising an agent which inhibits sialic acid mediated adhesion of a pathogen to a surface of a subject together with a pharmaceutically acceptable carrier or diluent.

The present invention also provides a use of an agent which inhibits sialic acid mediated adhesion of a pathogen to a surface of a subject in the manufacture of a medicament for the treatment or prevention of infection of a subject by a pathogen.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

It is to be understood that the following description is for the purpose of describing particular embodiments only and is not intended to be limiting with respect to the above description.

The present invention provides a method for treating or preventing infection of a subject by a pathogen, the method comprising administering to the subject an agent which inhibits sialic acid mediated adhesion of the pathogen to a surface of the subject. Sialic acid mediated adhesion of pathogens to a surface may involve binding of the pathogen to a sialic acid residue on the surface. Accordingly, the presence of a sialic acid residue on the surface can promote pathogen adhesion to the surface, which can result in infection.

Sialic acids are N- or O-substituted derivatives of neuraminic acid. Sialic acids are widely distributed in humans and animals, and may be components of glycoproteins or glycolipids.

Glycoproteins and glycolipids are molecules comprising oligosaccharide chains. The oligosaccharide may be linked to one or more sialic acid residues. Oligosaccharides include, for example, galactose, glucose, mannose, N-acetylneuraminic acid, fucose, N- acetylgalactosamine, N-acetylglucosamine and xylose. The sialic acid residue may be linked to the oligosaccharide by an α2-6 or an α2-3 linkage.

Glycoproteins and glycolipids may be membrane bound compounds, and may comprise one or more sialic acid residues on the extracellular portion of the compound. Accordingly, cells expressing glycoproteins or glycolipids, and tissues or organs comprising such cells, are potential targets for pathogen adherence and infection. Glycoproteins include, for example, mucins and collagens.

Mucin glycoproteins may be expressed on the surface of cells, including those of the mucosa. Oligosaccharides can make up to 80% of the molecular weight of mucin glycoproteins. The most common sugar groups associated with mucin glycoproteins are sialic acid, N-Acetyl galactosamine, N-Acetyl glucosamine, galactose and fructose. Sialic acid residues are commonly linked to other sugar groups including, for example, galactose. Sialic acids with α2-3Gal and α2-6Gal linkages are present in ciliated and non-ciliated, goblet and basal cells of the respiratory epithelium. A number of pathogens including, for example, viruses and bacteria may interact with and/or adhere to sialic acid molecules on surfaces of subjects to promote infection of the subject. The pathogen may bind to the sialic acid residue and/or cleave a sialic acid residue to expose oligosaccharide residues to enable adherence of the pathogen.

For example, some viral and bacterial pathogens target terminal sialic acids as potential receptors during the pathogen-to-host mucosa adhesion step. The pathogen may either bind directly to the sialic acid.

In some embodiments, the pathogen binds to sialic acid present on the surface via a sialic acid binding molecule of the pathogen.

For example, a sialic acid binding molecule expressed on the surface of a number of pathogens, including many viruses and bacteria, is haemagglutinin or M protein. The amino acid sequences of haemagglutinin, M protein and sialidase in bacteria and viruses can exhibit significant variation between different strains as they evolve. Details of haemagglutinin, M protein and sialidase of different pathogens may readily be accessed by searching online databases including, for example, GenBank.

For example, binding of Streptococcus pyogenes to α2-6 linked sialic acid groups on the host's pharyngeal epithelium occurs via its streptococcal wall M protein. Similarly, influenza viruses use their surface haemagglutinin to bind the host sialic acid groups.

As can be appreciated by the person skilled in the art, other pathogens may have different sialic acid binding molecules and such other sialic acid binding molecules would be readily ascertained by a person skilled in the art. Accordingly, the present invention should not be considered limited to the interaction of M protein and/or haemagglutinin with sialic acid. In some embodiments, the agent inhibits binding between the pathogen, or a sialic acid binding molecule thereof, and a sialic acid residue on a surface of the subject.

In some embodiments, the binding affinity of the agent to the pathogen, or a sialic acid binding molecule thereof, may be higher than the binding affinity of the pathogen, or a sialic acid binding molecule thereof, to a sialic acid present on the surface of the subject. In this regard, the agent may outcompete the sialic acid residues expressed on the surface of the subject with respect to binding to the pathogen, thereby inhibiting sialic acid mediated adhesion of the pathogen to the surface of the subject.

In other embodiments, while the agent may not have a higher binding affinity to the pathogen or a sialic acid binding molecule thereof, than to the sialic acid residues expressed on the surface of the subject, the amount of agent administered may be sufficient to reduce or prevent sialic acid mediated adhesion of the pathogen to the surface of the subject.

In some embodiments, the cleavage of a sialic acid residue on a surface of a subject can augment adhesion and/or infection by pathogens on the surface. In some embodiments, this occurs via exposure of a penultimate sugar after cleavage of a sialic acid residue, and this sugar may then be targeted or bound to by the pathogen.

For example, in the case of some viruses, after binding to sialic acid groups via haemagglutinin, a viral neuraminidase may then cleave the sialic groups to expose the penultimate Gal residue that serves as the attachment point for viral particles to invade host cells.

Streptococcus pneumoniae is also an example of a bacterium whose adherence is dependent on neuraminidases cleaving sialic acid residues located on host epithelium. In some embodiments, the agent inhibits cleavage of a sialic acid residue on a surface of the subject by the pathogen.

In some embodiments, the agent may inhibit cleavage of a sialic acid residue by a pathogen by masking the sialic acid residue on the surface of the subject, thereby preventing the pathogen from accessing the sialic acid residue. In some embodiments, the agent may bind to the pathogen or an enzyme or receptor thereof to inhibit cleavage of the sialic acid residue by the pathogen.

As can be appreciated, in some embodiments, the agent may inhibit cleavage of multiple sialic acid residues. In some embodiments, the agent may also inhibit cleavage of sialic acid residues with different linkage patterns. For example, the agent may inhibit the cleavage of more than one of α2-3, α2-6 and α2-8 linked sialic acid residues.

Cleavage of a sialic acid residue by a pathogen may involve a sialidase. A "sialidase" should be understood as any enzyme that catalyses the hydrolysis of terminal acylneuraminic residues from oligosaccharides, glycolipids and/or glycoproteins. The term "sialidase" as used herein should also be understood to encompass a neuraminidase.

Bacteria, protists, fungi and viruses may comprise one or more sialidases. Bacterial and viral sialidases share amino acid similarity at the active site of the enzyme. A particular characteristic of bacterial sialidases is the presence of non-sialidase related domains in the protein. These domains have other activities or functions which are beneficial to the bacteria. Viral sialidases are present on viral protein coats. Similarly, many bacterial sialidases are membrane anchored enzymes.

Methods for identifying the nucleic acid or amino acid sequences for bacterial and viral sialidases are known in the art and may include, for example, database searching or homology searching (i.e. BLAST search) against a known sequence. - ci -

In some embodiments, the sialidase is neuraminidase A. As an example, the Gene ID for neuraminidase A from Streptococcus pneumoniae is 933902 (NCBI database). In a further example, the Gene ID for neuraminidase A, also known as N- acetylneuraminate lyase, from Staphylococcus aureus is 1123083.

Accordingly, in some embodiments, the agent inhibits cleavage of a sialic acid residue by a sialidase. Inhibition of cleavage of a sialic acid residue may inhibit sialic acid mediated adhesion of the pathogen to the surface of the subject.

In some embodiments, the binding affinity of the agent to the sialidase of the pathogen may be higher than the binding affinity of the sialidase to a sialic acid present on the surface of the subject.

In other embodiments, while the agent may not have a higher binding affinity to the sialidase of the pathogen than the sialic acid expressed on the surface of the subject, the amount of agent administered may be sufficient to reduce or prevent sialic acid mediated adhesion of the pathogen to the surface of the subject.

As set out above, the present invention contemplates an "agent" which inhibits sialic acid mediated adhesion of a pathogen to a surface of a subject.

The agent may include, for example, a peptide, a drug, a small molecule, an antibody or an aptamer. The agent may be a molecule from a chemical or peptide library, a molecule selected by rational drug design, an antibody or an aptamer.

In some embodiments, the agent comprises a sialic acid analogue. The sialic acid analogue may comprise a sialic acid molecule or a fragment thereof. In some embodiments, the sialic acid analogue may comprise a sialic acid linked to a carrier molecule. For example, the sialic acid analogue may be a sialylated glycan. The sialylated glycan may comprise linkage of a sialic acid, or fragment thereof, to an oligosaccharide including, for example, lactose, galactose, glucose, mannose, N- acetylneuraminic acid, fucose, N-acetylgalactosamine, N-acetylglucosamine or xylose. Sialylated glycans are available from commercial sources including, for example, Sigma Aldrich, or may be synthesized.

In some embodiments, the sialylated glycan comprises sialyllactose. Sialyllactose has a molecular formula of C23H39NO19 and may be composed as a salt, for example, sialyllactose sodium salt with a molecular formula of C23H3sNOi9Na, which is available from Sigma Aldrich (catalogue number A0828). Examples of different forms of sialyllactose include 3'-sialyllactose and 6'-sialyllactose.

In some embodiments, the agent may comprise an antibody.

In the case of an antibody for inhibiting sialic acid mediated adhesion to a surface of a subject, the antibody may be a polyclonal antibody, a monoclonal antibody, a chimeric antibody, a single chain antibody, a Fab fragment, or fragments produced by a Fab expression library.

In some embodiments, the antibody may bind to a sialic acid binding molecule or a sialidase of a pathogen.

For the production of antibodies, various hosts including goats, rabbits, rats, mice, humans, and others, may be immunized by injection with the polypeptide or any fragment or oligopeptide thereof that has immunogenic properties. Depending on the host species, various adjuvants may be used to increase immunological response. Such adjuvants include, but are not limited to, Freund's, mineral gels such as aluminium hydroxide, and surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, keyhole limpet hemocyanin, and dinitrophenol.

Monoclonal antibodies may be prepared using any technique which provides for the production of antibody molecules by continuous cell lines in culture. These include, but are not limited to, the hybridoma technique, the human B-cell hybridoma technique, and the EBV-hybridoma technique (for example as described by Kohler et al, Nature 256: 495-497, 1975; Kozbor et al, J. Immunol. Methods 81: 31-42, 1985; Cote et al, Proc. Natl. Acad. ScL 80: 2026-2030, 1983; and Cole et al, MoI. Cell Biol. 62: 109-120, 1984).

Antibody fragments which contain specific binding sites may also be generated. For example, such fragments include F(ab')2 fragments which can be produced by pepsin digestion of the antibody molecule and the Fab fragments which can be generated by reducing the disulfide bridges of the F(ab')2 fragments. Alternatively, Fab expression libraries may be constructed to allow rapid and easy identification of monoclonal Fab fragments with the desired specificity (for example as described by Huse et al, Science 254: 1275-1281, 1989).

As set out above, the present invention contemplates inhibition of sialic acid mediated adhesion of a pathogen to a "surface" of a subject.

The surface of the subject may be any surface on which a pathogen may adhere by sialic acid mediated adhesion. In this regard, the surface may be a surface of a cell, tissue, organ or extracellular matrix of the subject. In some embodiments, the surface may comprise a mucosal surface, urinary tract surface, reproductive surface, alimentary surface, skin (in particular follicle) surface, tooth surface, ear canal surface or a corneal surface. The surface may comprise the surface of a cell making up a tissue or a migratory cell including, for example, a lymphocyte or erythrocyte. In some embodiments, the surface is a mucosal respiratory surface. Mucosal respiratory surfaces include surfaces of the lungs, nostrils, nasal cavity, oropharynx, laryngopharynx, larynx, glottis, trachea, mouth and sinuses.

In some embodiments, the mucosal respiratory surface is a paranasal sinus surface. Paranasal sinuses include the maxillary sinuses, the frontal sinuses, the ethmoid sinuses and the sphenoid sinuses.

In some embodiments, the surface is an artificial surface. Such artificial surfaces may be present as a result of a surgical procedure. Examples of artificial surfaces include tubing and other medical devices, such as catheters, pacemakers, prosthetic heart valves, prosthetic joints, voice prostheses, contact lenses, intrauterine devices. Medical devices include disposable or permanent catheters, (e.g. central venous catheters, dialysis catheters, long-term tunnelled central venous catheters, short-term central venous catheters, peripherally inserted central catheters, peripheral venous catheters, pulmonary artery Swan-Ganz catheters, urinary catheters, and peritoneal catheters), long-term urinary devices, tissue bonding urinary devices, vascular grafts, vascular catheter ports, wound drain tubes, ventricular catheters, hydrocephalus shunts, heart valves, heart assist devices (e.g. left ventricular assist devices), pacemaker capsules, incontinence devices, penile implants, small or temporary joint replacements, urinary dilator, cannulas, elastomers, hydrogels, surgical instruments, dental instruments, tubing, such as intravenous tubes, breathing tubes, dental water lines, dental drain tubes, and feeding tubes, fabrics, paper, indicator strips (e.g. paper indicator strips or plastic indicator strips), adhesives (e.g. hydrogel adhesives, hot-melt adhesives, or solvent-based adhesives), bandages, orthopedic implants, and any other device used in the medical field.

As indicated, in some embodiments, the artificial surface is a prosthetic surface. The prosthetic surface may include, for example, a catheter, pacemaker, prosthetic heart valve, prosthetic joint, voice prostheses, contact lens, intrauterine device, urinary catheter or a peritoneal catheter.

In some embodiments, the prosthetic surface is an implant, catheter or stent. The catheter may for example be a central venous catheter, a peripheral intravenous catheter, an arterial catheter, a haemodialysis catheter, an umbilical catheter, precutaneous nontunneled silicone catheter, a cuffed tunnelled central venous catheter or a subcutaneous central venous port.

In some embodiments, the agent is coated onto the artificial surface. Accordingly, the present invention provides an artificial surface, as hereinbefore described, coated with the agent.

In some embodiments, the present invention also contemplates other artificial surfaces which need not be implanted into a subject, which are coated with the agent. For example, the agent may be incorporated into filters or filter media for the entrapment of pathogens. Examples of such filters or filter media include air filters such as respirator filters or surgical masks or water filters. In further embodiments, the agent may also be incorporated into protective clothing such as surgical scrubs, gloves and the like, for the entrapment of pathogens.

Methods for coating artificial surfaces with agents are known in the art and include methods disclosed in Yaszemski and Lewandrowski (Biomaterials in Orthopedics, Marcel Dekker, Inc., New York, 2004). Methods may also include, for example, soaking or dipping the artificial surface in a bath of liquid agent. The liquid bath may be agitated and may include the application of heat and/or ultrasonic energy. Alternatively, the artificial surface may be coated with the agent by spraying the agent, for example, by way of pressurized nozzles. The artificial surface may be coated with the agent alone or in conjunction with one or more coating materials. Coating materials may include any liquid or semi-liquid material including, for example, polymers and thin films. The coating materials which can be used in conjunction with an agent of the present invention are any desired, suitable substances. In some embodiments, the coating materials comprise solvents in which the agent is at least partially soluble or dispersible or emulsified, and/or in combination with polymeric materials as solutions, dispersions, suspensions, lattices, etc.

Coating materials may include, for example, polymeric materials, sugars, waxes, and fats and monomers that are cross-linked or polymerized. Such coating materials are applied in the form of, for example, powders, solutions, dispersions, suspensions, and/or emulsions of one or more polymers, optionally in aqueous and/or organic solvents and combinations thereof or optionally as liquid melts including no solvents. When used with an agent, the polymeric materials are optionally applied simultaneously with, or in sequence to (either before or after), the agent. Such polymeric materials employed as, for example, primer layers for enhancing subsequent coating applications (e.g., application of alkanethiols or sulfhydryl-group containing coating solutions to gold-plated devices to enhance adhesion of subsequent layers), layers to control the release of the agent (e.g., barrier diffusion polymers to sustain the release of the agent, such as hydrophobic polymers; thermal responsive polymers; pH- responsive polymers such as cellulose acetate phthalate or acrylate-based polymers, hydroxypropyl methylcellulose phthalate, and polyvinyl acetate phthalate), protective layers for an underlying agent layer (e.g., impermeable sealant polymers such as ethylcellulose), biodegradable layers, biocompatible layers (e.g., layers comprising albumin or heparin as blood compatible biopolymers, with or without other hydrophilic biocompatible materials of synthetic or natural origin such as dextrans, cyclodextrins, polyethylene oxide, and polyvinyl pyrrolidone), layers to facilitate delivery of the artificial surface (e.g., hydrophilic polymers, such as polyvinyl pyrrolidone, polyvinyl alcohol, polyalkylene gylcol (i.e., for example, polyethylene glycol), or acrylate-based polymer/copolymer compositions to provide lubricious hydrophilic surfaces), drug matrix layers (i.e., layers that adhere to the medical device and have an agent incorporated therein or thereon for subsequent release into the body), and epoxies. When used as a drug matrix layer for localized agent delivery, the polymer coatings may comprise any material capable of absorbing, adsorbing, entrapping, or otherwise holding the agent to be delivered. The material is, for example, hydrophilic, hydrophobic, and/or biodegradable, and may be selected from the group consisting of polycarboxylic acids, cellulosic polymers, gelatin, polyvinylpyrrolidone, maleic anhydride polymers, polyamides, polyvinyl alcohols, polyethylene oxides, glycosaminoglycans, polysaccharides, polyesters, polyurethanes, silicones, polyurea, polyacrylate, polyacrylic acid and copolymers, polyorthoesters, polyanhydrides such as maleic anhydride, polycarbonates, polyethylene, polypropylenes, polylatic acids, polystyrene, natural and synthetic rubbers and elastomers such as polyisobutylene, polyisoprene, polybutadiene, including elastomeric copolymers, such as Kraton®, styrene-isobutylene-styrene (SIBS) copolymers; polyglycolic acids, polycaprolactones, polyhydroxybutyrate valerates, polyacrylamides, polyethers, polysaccharides such as cellulose, starch, dextran and alginates; polypeptides and proteins including gelatin, collagen, albumin, fibrin; copolymers of vinyl monomers such as ethylene vinyl acetate (EVA), polyvinyl ethers, polyvinyl aromatics; other materials such as cyclodextrins, hyaluronic acid and phosphorylcholines; and mixtures and copolymers thereof. Coatings from polymer dispersions such as polyurethane dispersions (BAYHDROL, etc.) and acrylic latex dispersions may also be used. Polymers may include polyurethanes; polyacrylic acid, and aqueous coating compositions comprising an aqueous dispersion or emulsion of a polymer having organic acid functional groups and a polyfunctional crosslinking agent having functional groups capable of reacting with organic acid groups. The release rate of an agent from drug matrix layers may be largely controlled, for example, by variations in the polymer structure and formulation, the diffusion coefficient of the matrix, the solvent composition, the ratio of agent to polymer, potential chemical reactions and interactions between agent and polymer, the thickness of the agent adhesion layers and any barrier layers, and the process parameters, e.g., drying, etc. The coating(s) applied may allow for a controlled release rate of a coating substance with the controlled release rate including both long-term and/or sustained release. Additionally, a coating substance may include suspension particles, e.g., a powder comprising the agent. For example, the suspension particles may be fused to the surface of the prosthesis by a coating solution.

The coatings may be applied such that they result in a suitable thickness, depending on the coating material and the purpose for which the coating(s) is applied. As an example, coatings applied for localized agent delivery are typically applied to a thickness of 1 to 30 microns, or 2 to 20 microns. Very thin coatings, e.g., of about 100 angstroms, and much thicker coatings, e.g., more than 30 microns, are also possible. It is also within the scope of the present invention to apply multiple layers of the same or different coating materials, which may perform identical or different functions (e.g., to provide for biocompatibility, to control agent release, etc.).

In some embodiments, the coating may be such that once a pathogen binds to the agent on the artificial surface, the agent dissociates from the artificial surface, thus preventing chronic or permanent attachment of the pathogen to the artificial surface.

As set out above, the present invention contemplates inhibition of sialic acid mediated adhesion of a "pathogen" to a surface of a subject.

The pathogen contemplated may be any pathogen which may adhere to a surface of a subject via sialic acid mediated adhesion. In some embodiments, the pathogen may be a bacterium, fungus, protist or virus.

In some embodiments, the bacterium may include a bacterium from a Helicobacter species including Helicobacter pylori, Helicobacter hepaticus, Helicobacter raγγini, Helicobacter muridarum, Helicobacter bills; Haemophilus species including Haemophilus influenzae; Streptococcus species including Streptococcus mutans, Streptococcus pyogenes, Streptococcus pnuemoniae; Enterococci species including Enterococcus faecalis; Bacteroides species; Bifidobacterium species; Peptococcus species; Peptostreptococcus species; Pseudomonas species including Pseudomonas aeruginosa; Ruminococcus species; Clostridia species including Clostridium difficile; Lactobacillus species including Lactobacillus acidophilus; Neisseria species including Neisseria gonorrhea, Neisseria meningitides; Escherichia coli; Vibrio cholerae; Shigella species including Shigella dysenteriae, Shigella flexneri, and Shigella Sonnei, Yersinia species including Yersinia enterocolitica; Pseudomonas aeruginosa; Bordetella pertussis; Campylobacter species including Campylobacter jejuni; Haemophilus influenzae; Staphyloccus species including Staphyloccus epidermis, Staphyloccus aureus; or Helicobacter species including Helicobacter pylori.

In some embodiments, the bacterium is a Streptococcus species, including, for example, Streptococcus mutans, Streptococcus gordonii or Streptococcus pneumoniae.

In some embodiments the bacterium is a Staphylococcus species, including, for example, Staphylococcus aureus.

In some embodiments the bacterium is a Helicobacter species, including, for example,

Helicobacter pylori.

In some embodiments the bacterium is a Haemophilus species, including, for example,

Haemophilus influenza.

In some embodiments, the fungus may include a fungus from a Alternaria species; Aspergillus species, including Aspergillus fumigates, Blastomyces dermatitidis; Candida species; Cladophialophora bantiana, Coccidioides immitis; Cryptococcus species, including Cryptococcus neoformans (var. neoformans, var. gattii), Emmonsia parva var. parva, Emmonsia parva var. crescens, Epidermophyton floccosum, Fonsecaea compacta, Fonsecaea pedrosoi, Histoplasma capsulatum var. Capsulatum; Histoplasma species including Histoplasma capsulatum var. duboisii, Histoplasma capsulatum var. farcinimosum, Madurella grisea, Madurella mycetomatis, Microsporum species, Neotestudina rosatii, Paracoccidioides brasiliensis, Penicillium marneffei; Phycomycetes including Mucor, Phizopus and Absidia species, Scedosporium apiospermum (Pseudallescheria boydii), Scedosporium proliferans (inflatum), Sporothrix schenckii, or Trichophyton species.

A "protist" may include any of the numerous generally unicellular eukaryotic organisms of the kingdom Protista. However, it will be appreciated that some protists are multicellular. The protist may be a protozoan. Some forms of Protista are responsible for causing disease, especially in humans. For example, protists may include protists selected from a group consisting of: Chlorophyta (Green Algae); Phaeophyta (Brown Algae); Pyrrophyta (Dinoflagellates); Chrysophyta (Diatoms); Rhodophyta (Red Algae); Charophyta (Stoneworts); and Euglenophyta (Euglena). Further examples of protists include organisms within the Phylum Apicomplexa, such as any one of the organisms selected from a group consisting of: Coccidia; Hemogregarina spp.; Eimeria; Isospora; Sarcocystis cruzi; Toxoplasma spp.; Cryptosporidium spp.; Plasmodium spp.; and Cyclospora cayetanensis.

In some embodiments, the virus may include a virus selected from one or more of the group consisting of Adenoviridae including Mastadenovirus such as Human Adenovirus and Atadenovirus such as Ovine Adenovirus; Herpesviridae; Poxviridae including vaccinia, fowlpox, swinepox and sheeppox; Papovaviridae; Orthohepadnavirus; Parvoviridae including adeno-associated virus; Birnaviridae; Reoviridae; Flaviviridae; Picornaviridae including poliovirus; Togaviridae including Sindbis virus and Semliki Forest virus; Filoviridae; Hepadnaviridae; Paramyxoviridae; Picornaviridae; Rhabdoviridae; Arenaviridae; Bunyaviridae; Or thorny xoviridae; Reoviridae; Retroviridae including Lenti virus.

In some embodiments, the virus may be an Influenza virus. The term "Influenza virus" should be understood to include an RNA virus in one of three genera, Influenzavirus A, Influenzavirus B and Influenzavirus C, of the family Orthomyxoviridae. The Influenzavirus A genus has one species, namely influenza A virus. Wild aquatic birds are the natural hosts for a large variety of influenza A. Occasionally, viruses are transmitted to other species and may then cause outbreaks in domestic poultry or give rise to human influenza pandemics. The type A viruses are the most virulent human pathogens among the three influenza types and cause the most severe disease. The influenza A virus can be subdivided into different serotypes based on the antibody response to these viruses. Examples of influenza A virus serotypes that have been confirmed in humans include: HlNl, H2N2, H3N2, H5N1, H7N7, H1N2, H9N2, H7N2, H7N3 and H10N7.

The Influenzavirus B genus has one species, namely influenza B virus. Influenza B almost exclusively infects humans and is less common than influenza A. The only other animals known to be susceptible to influenza B infection are the seal and the ferret. This type of influenza mutates at a rate 2-3 times lower than type A and consequently is less genetically diverse, with only one influenza B serotype. As a result of this lack of antigenic diversity, a degree of immunity to influenza B is usually acquired at an early age. However, influenza B mutates enough that lasting immunity is not possible. This reduced rate of antigenic change, combined with its limited host range (inhibiting cross species antigenic shift), ensures that pandemics of influenza B do not occur.

The Influenzavirus C genus also has only one species, namely the influenza C virus, which infects humans, dogs and pigs, sometimes causing both severe illness and local epidemics. However, influenza C is less common than the other types and usually only causes mild disease in children.

The term "influenza virus" as used herein may also encompass human parainfluenza viruses, which are RNA viruses belonging to the paramyxovirus family. Such viruses are a common cause of respiratory infections in children such as croup but can also cause a disease similar to influenza in adults. As set out above, the present invention contemplates treating or preventing infection of a subject by a pathogen.

As referred to herein, the term "infection" may be manifest as, for example, the attachment of a pathogen to a surface of a subject, multiplication and/or reproduction of a pathogen in or on a subject, one or more symptoms caused by a pathogen in a subject and/or one or more host responses to a pathogen. Thus, treatment or prevention of an infection in a subject may include modulation of any of the above- mentioned manifestations of infection in a subject.

In some embodiments, the infection comprises a biofilm on a surface of the subject.

The term "biofilm" as used herein may be understood as a structured population or community of microbial cells enclosed in a self-produced polymeric matrix and adherent to an inert or living surface. Biofilm formation may occur in a series of sequential steps; firstly microorganisms recognise and bind to target receptors, which may include, for example, terminal sugars of glycoproteins that are expressed on a host mucosa. Once a foothold is established, the microorganisms may rapidly multiply whilst simultaneously secreting a protective polysaccharide matrix. The colonization process is completed when the microflora switch to a sessile phenotype that cannot be easily dislodged from the mucosa.

Biofilms may be produced by and/or colonised by diverse microflora. For example, in some embodiments, the biofilm comprises a bacterial cell. The bacterial cell may be any bacterial cell that is able to make up part of biofilm.

In addition to bacteria, the biofilms contemplated in the present invention include biofilms comprising other types of microflora such as actinobacteria, fungi, protists and the like. Accordingly, in some embodiments, administration of the agent to the subject is used to treat or prevent a biofilm on a surface of the subject.

In some embodiments, a disease state may be associated with the infection and/or biofilm. The disease state may be any disease state associated with any of the aforementioned pathogens. The disease state may comprise an acute or chronic disease.

Disease states may include, for example, Anthrax infection, Bacterial Meningitis, Botulism, Brucellosis, Campylobacteriosis, Cat Scratch Disease, Cholera, Diphtheria, Epidemic Typhus, Gonorrhea, Impetigo, Legionellosis, Leprosy (Hansen's Disease), Leptospirosis, Listeriosis, Lyme disease, Melioidosis, Rheumatic Fever, MRSA infection, Nocardiosis, Pertussis (Whooping Cough), Plague, Pneumococcal pneumonia, Psittacosis, Q fever, Rocky Mountain Spotted Fever (RMSF), Salmonellosis, Scarlet Fever, Sinusitis, Shigellosis, Syphilis, Tetanus, Trachoma, Tuberculosis, Tularemia, Typhoid Fever, Typhus, Urinary Tract Infections, AIDS, AIDS Related Complex, Chickenpox (Varicella), Common cold, Cytomegalovirus Infection, Colorado tick fever, Dengue fever, Ebola hemorrhagic fever, Hand, foot and mouth disease, Hepatitis, Herpes simplex, Herpes zoster, HPV, Influenza (Flu), Lassa fever, Measles, Marburg hemorrhagic fever, Infectious mononucleosis, Mumps, Norovirus, Poliomyelitis, Progressive multifocal leukencephalopathy, Rabies, Rubella, SARS, Smallpox (Variola), Viral encephalitis, Viral gastroenteritis, Viral meningitis, Viral pneumonia, West Nile disease, Yellow fever, Aspergillosis, blastomycosis, candidiasis, coccidiodomycosis, cryptococcosis, histoplasmosis, sporotrichosis, chromoblastomycosis, lobomycosis, dermatophytosis, dermatomycosis, onychomycosis, piedra, mycetoma, fusariosis, pityriasis versicolor, tinea barbae, tinea capitis, tinea corporis, tinea cruris, tinea favosa, tinea nigra, tinea pedis, phaeohyphomycosis, rhinosporidiosis, aspergillosis, mycotic keratitis, candidiasis, giardiasis and other gastrointestinal disorders including amoebic dysentery and diarrhoea, cutaneous and visceral leishmaniasis, Chagas¹ disease, coccidiosis, ick, trichomoniasis, African sleeping sickness, red tides, toxoplasmosis, malaria, and microbial keratitis, including Acanthamoeba keratitis.

In some embodiments, the disease state may be a respiratory disease.

In some embodiments, the disease state comprises a biofilm-mediated disease. A biofilm mediated disease is a disease characterised by the presence or formation of a biofilm on a surface of the subject as hereinbefore described. In some embodiments, the presence of a biofilm on a surface of the subject may be associated with a disease state in the subject. For example, several human disease states may be associated with biofilm formation on a surface of the subject. Such disease states include, for example: biofilm-mediated sub-types of chronic rhinosinusitis, cystic fibrosis, dental caries and related gum diseases, otitis media with effusion, sepsis and complications arising from bacterial biofilm colonization of artificial surfaces, such as prosthetic implants or cardiac stents and chronic eye infections, including chronic eye infections from continuous use of contact lenses.

In particular embodiments, the disease state is a biofilm-mediated respiratory disease. The biofilm-mediated respiratory disease may be a chronic respiratory disease including, for example, chronic rhinosinusitis.

Rhinosinusitis may be described as an inflammation of the nasal cavity and/or paranasal sinuses and involves the nasal mucosa. Chronic rhinosinusitis (CRS) may be diagnosed when signs or symptoms of inflammation persist for 8-12 weeks or longer. Symptoms of CRS include nasal obstruction, loss of sense of smell, nasal or postnasal discharge, nasal congestion, and facial pain/pressure (typically over the affected sinus area). The method of the present invention may be used to treat or prevent infection by a pathogen, of a surface of any suitable subject. Typically, the subject is an animal subject. Suitable subjects include, for example, mammalian subjects such as humans, primates, livestock animals such as horses, cattle, sheep, pigs, goats or the like, companion animals such as dogs or cats, laboratory test animals such as mice, rats, guinea pigs or birds, or animals of veterinary significance, or animals of economic significance. The subject may also include non-mammalian animal subjects such as birds including poultry birds such as chickens; reptilian subjects including companion reptiles such as turtles, tortoises and snakes; fish including wild-caught fish and fish in aquaculture.

In some embodiments, the subject may have an increased susceptibility to a pathogen infection. A subject with an increased susceptibility to a pathogen infection may include, for example, an immunocompromised subject, or a subject with a wound or defect in a surface of the subject.

An immunocompromised subject may be a subject with primary immunodeficiency resulting from a genetic immune defect or an acquired immunodeficiency, for example, AIDS. Alternatively, an immunocompromised subject may be a subject treated with immunomodulatory drugs including, for example, immunosuppressive drugs, chemotherapy, or disease-modifying antirheumatic drugs. Immunocompromised subjects have an increase risk of pathogen infection and are also prone to opportunistic infection from pathogens which would typically not result in infection of an immunocompetent subject.

A subject with a wound or a defect in a surface may have an increased likelihood of pathogen infection as the wound or defect removes the innate protection of the intact surface. This is particularly the case for wounds including, for example, burns or cuts, in which pathogens are able to obtain direct access to the underlying tissues. Wounds or defects can be particularly prevalent in the epithelium. The epithelium includes skin (epidermis), the outer surface of the cornea, the lining inside of the lungs, the gastrointestinal tract, the reproductive and urinary tracts, mucous membranes such as the mouth, the oesophagus, and part of the rectum. The epithelium also includes the endothelium, which is the inner lining of blood vessels, the heart, and lymphatic vessels and the mesothelium which forms the walls of the pericardium, pleurae, and peritoneum.

In some embodiments, the method for treating or preventing infection of a subject by a pathogen further comprises an antibiotic or antiviral treatment. Antibiotic and antiviral treatments are known in the art.

In some embodiments, administration of the agent improves responsiveness to antibiotic therapies for treating the microbial infection including, for example, a biofilm. In this regard, the agent may prevent or breakdown biofilms comprising microbes which may otherwise be resistant to antibiotic therapies.

In some embodiments, administration of the agent reduces the risk of recurrent pathogen infection including, for example, biofilm formation.

In some embodiments, the agent may be administered to the subject before, during or after a surgery. The surgery may be to treat or prevent an infection and/or biofilm, with the administration of the agent used to augment the treatment.

Sinus surgery may be used to treat sinusitis, including chronic rhinosinusitis, due to the resistance of the pathogens, often associated with a biofilm, to conventional drug therapies. Accordingly, in some embodiments, the surgery is sinus surgery. Administration of the agent before sinus surgery may assist in the removal of the biofilm. Furthermore, administration of the agent during or after sinus surgery, may prevent or reduce the incidence of biofilm recurrence or pathogen infection. Accordingly, in some embodiments, the agent is administered to prevent recurrence of an infection after surgery or treatment with an antibiotic or antiviral treatment.

In some embodiments, the agent is administered to prevent or treat an infection incident to a surgery. For example, the infection or potential infection may result from the presence of a pathogen on surgical instruments or in the air (e.g. as an aerosol) during surgery.

In some embodiments, the surgery may be associated with the implantation of a prosthetic implant, catheter or stent. In these embodiments, the method may comprise administering the agent to the prosthetic implant before, during or after implantation of the prosthetic implant.

In light of the above, administration of the agent may be used to improve a surgical prognosis. The prognosis may be improved as a result of preventing or treating an infection incident to the surgery or may be improved by preventing or reducing the incidence of recurrent pathogen infection, which may also include preventing recurrent biofilm formation.

In some embodiments, administering the agent to the subject in the various embodiments of the present invention may comprise administration by any suitable method. For example, the agent may be administered orally, parenterally, topically, endoscopically, by injection, systemically or by any other suitable means. In some embodiments, the agent is delivered to a mucosal surface and/or a mucosal respiratory surface as hereinbefore described.

In some embodiments, administration may involve pre-coating an artificial surface, such as a prosthetic, with the agent. Examples of artificial surfaces, including prosthetics are as previously described herein. The agent may be coated onto an artificial surface in multiple layers, such that individual molecules of the agent or layers disengage from the artificial surface once pathogen binding occurs. Coating an artificial surface with the agent may be used to prevent adhesion of the pathogen to the artificial surface and/or prevent adhesion of the pathogen to a surface of the subject proximal or distal to the artificial surface when implanted into the subject. In this regard, coating an artificial surface with the agent may also prevent the formation of a biofilm on the artificial surface and/or prevent the formation of a biofilm on a surface of the subject proximal or distal to the artificial surface when implanted into the subject. Administration of the agent to the subject encompasses the coating an artificial surface with the agent, as the artificial surface is implanted in the subject.

In the case of a wound or defect in a surface of the subject, the agent may, for example, be administered directly to the wound or defect and/or to a region(s) near and/or surrounding the wound or defect.

The agent may be delivered to the site of infection or potential infection or administered to a subject so as to reach the site of infection or potential infection. For example, the agent may be administered systemically.

The administration of the agent in the various embodiments of the present invention may be administration of the agent alone, or administration of the agent formulated into a suitable pharmaceutical composition.

Accordingly, the present invention also provides a pharmaceutical composition comprising an agent which inhibits sialic acid mediated adhesion of a pathogen to a surface of a subject together with a pharmaceutically acceptable carrier or diluent.

In some embodiments, the agent may be an agent as hereinbefore described.

The pharmaceutical composition may also include one or more pharmaceutically acceptable additives, including pharmaceutically acceptable salts, amino acids, polypeptides, polymers, solvents, buffers, excipients and bulking agents, taking into consideration the particular physical and chemical characteristics of the agent to be administered.

The preparation of such pharmaceutical compositions is known in the art, for example as described in Remington's Pharmaceutical Sciences (18th ed., Mack Publishing Co., Easton, Pa., 1990) and LI. S. Pharmacopeia: National Formulary (Mack Publishing Company, Easton, Pa., 1984).

For example, the agent can be prepared into a variety of pharmaceutical compositions in the form of, e.g., an aqueous solution, an oily preparation, a fatty emulsion, an emulsion, a gel, etc., and these preparations can be administered as intramuscular or subcutaneous injection or as injection to an organ, or as an embedded preparation or as a transmucosal preparation through nasal cavity, rectum, uterus, vagina, lung, etc. The composition may be administered in the form of oral preparations (for example solid preparations such as tablets, capsules, granules or powders; liquid preparations such as syrup, emulsions or suspensions). Compositions containing the agent may also contain a preservative, stabiliser, dispersing agent, pH controller or isotonic agent. Examples of suitable preservatives are glycerin, propylene glycol, phenol or benzyl alcohol. Examples of suitable stabilisers are dextran, gelatin, a-tocopherol acetate or alpha-thioglycerin. Examples of suitable dispersing agents include polyoxyethylene (20), sorbitan mono-oleate (Tween 80), sorbitan sesquioleate (Span 30), polyoxyethylene (160) polyoxypropylene (30) glycol (Pluronic F68) or polyoxyethylene hydrogenated castor oil 60. Examples of suitable pH controllers include hydrochloric acid, sodium hydroxide and the like. Examples of suitable isotonic agents are glucose, D-sorbitol or D-mannitol.

The composition may also contain other constituents or additives such as a pharmaceutically acceptable carrier, diluent, excipient, suspending agent, lubricating agent, adjuvant, vehicle, delivery system, emulsifier, disintegrant, absorbent, preservative, surfactant, colorant, flavorant or sweetener, taking into account the physical and chemical properties of the agent being administered.

The composition may be administered orally, parenterally, by inhalation spray, adsorption, absorption, topically, rectally, nasally, bucally, vaginally, intraventricularly, via an implanted reservoir in dosage formulations containing conventional non-toxic pharmaceutically-acceptable carriers, or by any other convenient dosage form. The term parenteral as used herein includes subcutaneous, intravenous, intramuscular, intraperitoneal, intrathecal, intraventricular, intrasternal, and intracranial injection or infusion techniques.

When administered parenterally, the composition may be in a unit dosage, sterile injectable form (solution, suspension or emulsion) which is preferably isotonic with the blood of the recipient with a pharmaceutically acceptable carrier. Examples of such sterile injectable forms are sterile injectable aqueous or oleaginous suspensions. These suspensions may be formulated according to techniques known in the art using suitable dispersing or wetting agents and suspending agents. The sterile injectable forms may also be sterile injectable solutions or suspensions in non-toxic parenterally- acceptable diluents or solvents, for example, as solutions in 1,3-butanediol. Among the acceptable vehicles and solvents that may be employed are water, saline, Ringer's solution, dextrose solution, isotonic sodium chloride solution, and Hanks' solution. In addition, sterile, fixed oils are conventionally employed as solvents or suspending mediums. For this purpose, any bland fixed oil may be employed including synthetic mono- or di-glycerides, corn, cottonseed, peanut, and sesame oil. Fatty acids such as ethyl oleate, isopropyl myristate, and oleic acid and its glyceride derivatives, including olive oil and castor oil, especially in their polyoxyethylated versions, are useful in the preparation of injectables. These oil solutions or suspensions may also contain long- chain alcohol diluents or dispersants. The carrier may contain minor amounts of additives, such as substances that enhance solubility, isotonicity, and chemical stability, for example anti-oxidants, buffers and preservatives.

When administered orally, the agent may be formulated into unit dosage forms such as tablets, cachets, powder, granules, beads, chewable lozenges, capsules, liquids, aqueous suspensions or solutions, or similar dosage forms, using conventional equipment and techniques known in the art. Such formulations typically include a solid, semisolid, or liquid carrier. Exemplary carriers include lactose, dextrose, sucrose, sorbitol, mannitol, starches, gum acacia, calcium phosphate, mineral oil, cocoa butter, oil of theobroma, alginates, tragacanth, gelatin, syrup, methyl cellulose, polyoxyethylene sorbitan monolaurate, methyl hydroxybenzoate, propyl hydroxybenzoate, talc, magnesium stearate, and the like.

A tablet may be made by compressing or moulding the agent optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing, in a suitable machine, the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, surface active, or dispersing agent. Moulded tablets may be made by moulding in a suitable machine, a mixture of the powdered active ingredient and a suitable carrier moistened with an inert liquid diluent.

The administration of the agent in the various embodiments of the present invention may also utilize controlled release technology. The agent may also be administered as a sustained-release pharmaceutical. To further increase the sustained release effect, the agent may be formulated with additional components such as vegetable oil (for example soybean oil, sesame oil, camellia oil, castor oil, peanut oil, rape seed oil); middle fatty acid triglycerides; fatty acid esters such as ethyl oleate; polysiloxane derivatives; alternatively, water-soluble high molecular weight compounds such as hyaluronic acid or salts thereof (weight average molecular weight: ca. 80,000 to 2,000,000), carboxymethylcellulose sodium (weight average molecular weight: ca. 20,000 to 400,000), hydroxypropylcellulose (viscosity in 2% aqueous solution: 3 to 4,000 cps), atherocollagen (weight average molecular weight: ca. 300,000), polyethylene glycol (weight average molecular weight: ca. 400 to 20,000), polyethylene oxide (weight average molecular weight: ca. 100,000 to 9,000,000), hydroxypropylmethylcellulose (viscosity in 1% aqueous solution: 4 to 100,000 cSt), methylcellulose (viscosity in 2% aqueous solution: 15 to 8,000 cSt), polyvinyl alcohol (viscosity: 2 to 100 cSt), polyvinylpyrrolidone (weight average molecular weight: 25,000 to 1,200,000).

Alternatively, the agent may be incorporated into a hydrophobic polymer matrix for controlled release over a period of days. The agent may then be moulded into a solid implant, or externally applied patch, suitable for providing efficacious concentrations of the agent over a prolonged period of time without the need for frequent re-dosing. Such controlled release films are well known to the art. Other examples of polymers commonly employed for this purpose that may be used include nondegradable ethylene-vinyl acetate copolymer a degradable lactic acid-glycolic acid copolymers which may be used externally or internally. Certain hydrogels such as poly(hydroxyethylmethacrylate) or poly(vinylalcohol) also may be useful, but for shorter release cycles than the other polymer release systems, such as those mentioned above.

The carrier may also be a solid biodegradable polymer or mixture of biodegradable polymers with appropriate time release characteristics and release kinetics. The agent may then be moulded into a solid implant suitable for providing efficacious concentrations of the agent over a prolonged period of time without the need for frequent re-dosing. The agent can be incorporated into the biodegradable polymer or polymer mixture in any suitable manner known to one of ordinary skill in the art and may form a homogeneous matrix with the biodegradable polymer, or may be encapsulated in some way within the polymer, or may be moulded into a solid implant. For topical administration, the composition of the present invention may be in the form of a solution, spray, lotion, cream (for example a non-ionic cream), gel, paste, ointment or lozenge. Alternatively, the composition may be delivered via a liposome, nanosome, or nutri-diffuser vehicle.

In some embodiments, the topical composition is adapted for administration to a mucosal surface of a subject. In some embodiments, the topical composition is adapted for administration to a mucosal respiratory surface of a subject.

A cream is a formulation that contains water and oil and is stabilized with an emulsifier. Lipophilic creams are called water-in-oil emulsions, and hydrophilic creams oil-in-water emulsions. The cream base for water-in-oil emulsions are normally absorption bases such as vaseline, ceresin or lanolin. The bases for oil-in-water emulsions are mono-, di- and triglycerides of fatty acids or fatty alcohols with soaps, alkyl sulphates or alkyl poly glycol ethers as emulsifiers.

A lotion is an opaque, thin, non-greasy emulsion liquid dosage form for external application to the skin, which generally contains a water-based vehicle with greater than 50% of volatiles and sufficiently low viscosity that it may be delivered by pouring. Lotions are usually hydrophilic, and contain greater than 50% of volatiles as measured by LOD (loss on drying). A lotion tends to evaporate rapidly with a cooling sensation when rubbed onto the skin.

A paste is an opaque or translucent, viscous, greasy emulsion or suspension semisolid dosage form for external application to the skin, which generally contains greater than 50% of hydrocarbon-based or a polyethylene glycol-based vehicle and less than 20% of volatiles. A paste contains a large proportion (20-50%) of dispersed solids in a fatty or aqueous vehicle. An ointment tends not to evaporate or be absorbed when rubbed onto the skin. An ointment is an opaque or translucent, viscous, greasy emulsion or suspension semisolid dosage form for external application to the skin, which generally contains greater than 50% of hydrocarbon-based or a polyethylene glycol-based vehicle and less than 20% of volatiles. An ointment is usually lipophilic, and contains > 50% of hydrocarbons or polyethylene glycols as the vehicle and < 20% of volatiles as measured by LOD. An ointment tends not to evaporate or be absorbed when rubbed onto the skin.

A gel is usually a translucent, non-greasy emulsion or suspension semisolid dosage form for external application to the skin, which contains a gelling agent in quantities sufficient to impart a three-dimensional, cross-linked matrix. A gel is usually hydrophilic, and contains sufficient quantities of a gelling agent such as starch, cellulose derivatives, carbomers, magnesium-aluminum silicates, xanthan gum, colloidal silica, aluminium or zinc soaps.

The composition for topical administration may further include drying agents, anti- foaming agents; buffers, neutralizing agents, agents to adjust pH; colouring agents and decolouring agents; emollients; emulsifying agents, emulsion stabilizers and viscosity builders; humectants; odorants; preservatives, antioxidants, and chemical stabilizers; solvents; and thickening, stiffening, and suspending agents, and a balance of water or solvent. In some embodiments, the topical formulation may be in the form of a spray. Examples of suitable spray formulations include nasal sprays, mouth or throat sprays and skin sprays.

An aspect of the present invention also provides a composition, as previously described herein, when used according to any of the methods described herein for treating or preventing infection of a subject by a pathogen.

Another aspect of the invention provides for use of an agent which inhibits sialic acid mediated adhesion of a pathogen to a surface of a subject in the manufacture of a medicament for the treatment or prevention of an infection in a subject

In some embodiments, the agent, pathogen, infection and/or surface contemplated may be as hereinbefore described.

The present invention is further described by the following non-limiting examples:

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a plot graph of Neuraminidase A activity from bacteria isolated from biofilm positive chronic rhinosinusitis patients and from bacteria isolated from chronic rhinosinusitis patients with no biofilm present on their mucosa.

Figure 2 shows a graph of the percentage inhibition of biofilm formation in three clinical strains of S. aureus (denoted as stains 1, 15 and 19) and reference strain ATCC 25923 by treatment with different concentrations of 3'-Sialyllactose.

Figure 3 shows a table of StaphPlex pathogen gene targets used in the StaphPlex Panel and target symbols used in Figure 6.

Figure 4 shows representative photographs of the frontal sinuses from Sheep 7 with induced S. aureus biofilm formation that have been treated with 3'-Sialyllactose (A - left frontal sinus) or PBS (B - right frontal sinus).

Figure 5 shows representative photographs of the frontal sinuses from Sheep 8 with induced S. aureus biofilm formation that have been treated with 3'-Sialyllactose (A - left frontal sinus) or PBS (B - right frontal sinus). Figure 6 shows a table of the StaphPlex Panel results for enumeration of the biofilms in sheep 7 and 8 as well as the appropriate controls. The values in the table are Mean Fluorescent Intensity (MFI) values.

Figure 7 shows a graph of IFNγ protein levels from sinus mucosa treated with 3'- Sialyllactose compared with control treated sinus mucosa.

Figure 8 shows a graph of ILl [3 protein levels from sinus mucosa treated with 3'- Sialyllactose compared with control treated sinus mucosa.

EXAMPLE 1

Bacteria cultured from biofilm positive CRS patients exhibit higher Neuraminidase A activity

Bacteria isolated from biofilm positive CRS patients have higher NanA activity compared with CRS patients with no biofilm present on their mucosa (Figure 1), implicating NanA as a virulence factor in biofilm formation in CRS.

Materials and Methods Sinonasal biopsies were harvested from CRS patients undergoing endoscopic sinus surgery and immediately placed in Dulbecco's Modified Eagles' Media without antibiotics or amphotericin B and a subsample was stained for bacterial biofilm using BacLight Dead/Live kit (Invitrogen, Australia) on a Zeiss Apotome Confocal Scanning Microscope.

Tissue was also incubated overnight at 37°C, 5% CO2 and 80% relative humidity after which 100-200 μL of media in which the tissue had been placed was used to inoculate 2 mL of bovine CSF broth (Oxoid, Australia) in 5 mL conical flasks. Bacteria were grown overnight at 37°C on a shaking platform. Bacteria were then harvested by centrifugation and the pellet prepared for total protein extractions using Qproteome Bacterial Protein Preparation Kit (Qiagen, Australia) according to the manufacturer's instructions.

A mini Bradford assay was performed to determine total protein concentration. 50 μg of total protein was used to determine Neuraminidase A activity (Aplex Red Neuraminidase or Sialidase Assay Kit, Invitrogen).

Statistical analysis was carried out by GraphPad Prism v4 (San Diego USA).

EXAMPLE 2 3'-Sialyllactose inhibits biofilm formation in vitro

3'-Sialyllactose (250, 125, 62.5 μM) inhibited biofilm formation in clinical isolates (S. aureus strains 1, 15 and 19), as shown in Figure 2.

Materials and Methods

Clinical isolates of S. aureus were obtained from the Dept of Microbiology The Queen Elizabeth Hospital and streaked onto blood agar plates and allowed to grow overnight at 37°C. A single colony was removed and resuspended in 0.9% sodium chloride and adjusted to 0.5 McFarland Units on a turbidity meter (equivalent to IxIO⁵ Colony Forming Units).

Bacteria were then seeded in a 96 well plate at 10 μL per well and 190 μL of CSF broth was added. Bacteria were allowed to grow for 8 days. In previous pilot experiments, an 8 day growth period was required for biofilm formation in vitro.

Media was removed and fresh CSF in which 3'-Sialyllactose (3.13, 62.5, 125, 250 or 500 μM) was resuspended was added and incubated for 24 h. Excess media was removed and the wells washed with Ix PBS twice and fixed in methanol for 15 min. Plates were then air dried at room temperature. 200 μL of 0.1 % (w/v) of crystal violet was added for 5 min on a rocking platform.

Excess crystal violet was removed and the wells rinsed with water. 200 μL of 95 % ethanol was added and allowed to mix for 30 min to dissolve crystal violet.

Absorbance was read at 595 nm. Percentage inhibition of biofilm formation was calculated as:

1-Abs 595 test x 100%

Abs 595 untreated control

The percentage inhibition of the S. aureus strains at each concentration of sialyllactose was plotted on a graph as shown in Figure 2. Sialyllactose inhibited biofilm formation of S. aureus strains 1, 15 and 19.

EXAMPLE 3 3'-Sialyllactose inhibits biofilm formation in vivo

3'-Sialyllactose inhibited biofilm formation in an in vivo sheep model, as shown in Figures 3 to 8.

Materials and Methods

In vivo Staphylococcus aureus biofilm model

An in vivo sheep model of biofilm formation in the frontal sinuses was used as previously described in Ha et al. (Am J Rhinol 21: 339-345, 2007). Briefly, biofilm-mediated CRS was created in the frontal sinuses of Merino cross whethers. The frontal sinuses were chosen due to their consistent and superficial location, accessible by both mini-trephination and endoscopic approach. Following a middle turbinectomy and anterior ethmoidectomy, the position of the frontal sinus ostium was confirmed by fluorescein instillation, and then obstructed endoscopically with vaseline gauze strips. 1 x 10⁵ Colony Forming Units/mL of biofilm forming S. aureus clinical strain #1 was injected via mini-trephines into the obstructed sinuses. Previous work determined that a 7 day incubation was suitable to allow a biofilm to be established in the frontal sinuses. Each sheep was its own control.

The following treatment regime was used:

The left frontal sinus of each sheep received a daily treatment of 100 μM 3'- Sialyllactose (Sigma, USA) reconstituted in 100 mL of phosphate buffered saline (PBS) pH 7.4 that was applied using a syringe via trephines daily. The right frontal sinus, designated as the no treatment control received only 100 mL of PBS pH7.4 daily. Treatment was carried out for either 3 or 7 consecutive days. Sheep were sacrificed and their frontal sinus mucosa harvested intact and transported in sterile specimen pots in Dulbecco's Modified Eagles Media (DMEM) (Invitrogen, USA) without antibiotics or amphotericin B for immediate analysis.

Gross morphology

The intact frontal sinus was bisected with a sterile scalpel blade to expose the mucosal lining and washed in 3 consecutive changes of sterile deionised water. This was carried out to remove any planktonic bacteria present in the sinus cavities. By definition, bacterial biofilms are attached to their substrate and would remain on the mucosa after this wash step. The tissue was positioned flat on a petri dish and digital images of the gross morphology recorded. Staphylococcus aureus biofilm enumeration using Staphplex Panel (Qiagen, Germany)

The Staphplex kit is designed to simultaneously detect 18 gene targets of Staphylococcus species by PCR amplification using species specific primers (Figure 3). Detection and enumeration of this suspension array is dependent on the polystyrene bead based xMAP technology. For each Staphylococcus species, target specific capture probes are covalently linked to a specific set of colour coded beads. In the Liquichip 200 Workstation (Luminex USA), labelled PCR products are captured by the bead bound capture probes in a hybridisation suspension. This suspension is delivered to a dual laser detection device. A red laser identifies each bead (i.e., Staphylococcus species) by its colour coding, whilst a green laser detects the hybridisation signal associated with each bead. Data is collected and reported using the QIAplex MDD software. Mean Fluorescence Intensity values (MFI) are directly proportional to the quantity of each Staphylococcus species.

Three randomly selected 1 xl cm pieces of tissue were dissected from the mucosa and placed into individual 50 mL centrifuge tubes in 15 mL of 0.05% trypsin/ 0.02% EDTA (Invitrogen). The tissues were incubated at 37°C for approximately 24 h on a rotary shaker (6000 rpm) to dislodge the biofilm. After incubation, the tissue pieces were carefully removed using disposable sterile 1 mL plastic pipettes and placed in PBS for confocal scanning electron microscopy.

The bacterial biofilms were pelleted by centrifugation at 1 000 x g for 15 min, washed in 15 mL PBS and centrifugation was repeated.

The bacterial pellets were subjected to lysostaphin (Sigma) and proteinase K (Sigma) pre-treatment before DNA purification using the QIAamp DNA Mini and Blood Mini kits (Qiagen) by following the manufacturer's instructions. A 5 μL aliquot of eluted DNA was used as the template for the Staphylococcus species PCR amplification step. Multiple cytokine detection using Bioplex Multiarray Panels (Biorad USA)

The Bioplex Multiarray Panel system also adopts the xMAP technology of using up to 100 uniquely dyed fluorescent beads to simultaneously detect up to 100 cytokines. However, in this instance, the kit uses magnetic instead of polystyrene beads. A red and green laser measure the different cytokines bound to the surface of the beads. A high speed digital signal processor and associated software acquires and presents the data. Cytokine detection follows the traditional sandwich or capture immunoassay methods.

Protein lysate extraction any analysis

A 100 mg (wet weight) of sinus mucosa was flash frozen and ground in a mortar and pestle to which cell lysis buffer with protease inhibitors were added. A Bradford assay was used to determine the total protein concentrations of the lysates. 50 and 100 μg of total protein was used in the Bioplex assays. A custom panel consisting of Interleukin- 1[3, and IFNγ was selected to determine the effectiveness of 3'-Sialyllactose treatment in reducing the expression of these pro-inflammatory cytokines.

Results

3 'Sialyllactose reduces inflammation in the mucosal of the frontal sinuses

Figures 4 and 5 are representative photographs of the frontal sinus from Sheep 7 and Sheep 8, respectively. Figures 4A and 5A are the left frontal sinuses from the respective sheep which have been treated with 3'-Sialyllactose. Figures 4B and 5B are the right frontal sinuses (i.e. control sinuses).

Frontal sinuses treated with 3'-Sialyllactose were healthy with very little apparent inflammation. In contrast, control sinuses displayed characteristics of mucosal inflammation. Specifically, odema within the sinus mucosa is clearly evident in Figure 4B (see arrow). Frank puss was clearly evident in Figure 5B (see arrow).

3'-Sialyllactose reduces biofilm load in the mucosal of the frontal sinuses

Figure 6 shows the results of the biofilm enumeration using the Staphplex Panel system.

S. aureus clinical isolate #1, which was used to inoculate the frontal sinuses and cause biofilm formation was used as a positive control (SA Positive Control). DNA was extracted from 50 x 10³ cells. As shown in Figure 6, the SA Positive Control was positive for the S. aureus specific nuc gene. In addition, the ermA gene was also detected which indicated that this clinical isolate carried the erythromycin A resistance gene. Ampcheck, which comprised human DNA and was supplied with the Staphplex kit was used to confirm Taq polymerase enzyme activity.

The Mean Fluorescence Intensity (MFI) values of the nuc gene from biofilm bacteria harvested from the right sinus mucosal (PBS flush) were 2508, 2451, 2605 and 2473 (average MFI 2509.25). The corresponding MFI values from the left sinus mucosa (3 SL treatment) were 362, 343, 1440 and 1544 (average MFI 922.25) indicating that there was an approximate 2.7 fold decrease in bacterial biofilm of the 3'-Sialyllactose treated sinus.

The MFI values of the ermA gene from biofilm bacteria harvested from the right sinus mucosal (PBS flush) were 3014, 2908, 3169 and 3007 (average MFI 3024.5). The corresponding MFI values from the left sinus mucosa (3 SL treatment) were 849, 836, 2226 and 2351 (average MFI 1565.5), indicating that there was an approximate 1.9 fold decrease in bacterial biofilm of the 3'-Sialyllactose treated sinus. 3'-Sialyllactose downregulates the expression oflFNχin S. aureus infected sinus mucosa

Figure 7 shows the IFNγ results of the Bioplex assays using protein extracted from 3'- Sialyllactose treated and control sinus mucosa.

IFNγ expression is commonly associated with S. aureus colonization. Sinus mucosa treated with 3'-Sialyllactose expressed lower levels of IFNγ compared with sinus mucosa treated only with PBS, indicating that 3'-Sialyllactose reduced the level of S. aureus colonization.

3'Sialyllactose treatment attenuates the expression of the pro inflammatory cytokine ILl β

ILl [3 is a pro inflammatory cytokine whose expression in the host is triggered by microbial pathogens. As shown in Figure 7, expression of ILl [3 is 3 fold higher in the right sinus of Sheep 7 when compared to the left sinus which was treated with 3'- Sialyllactose. A similar profile is observed for Sheep 8 but at a relatively lower expression level. These results further indicate that 3'-Sialyllactose is effective in reducing S. aureus colonization.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to, or indicated in this specification, individually or collectively, and any and all combinations of any two or more of the steps or features.

Also, it must be noted that, as used herein, the singular forms "a", "an" and "the" include plural aspects unless the context already dictates otherwise.

Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or integer or group of elements or integers but not the exclusion of any other element or integer or group of elements or integers.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A method for treating or preventing infection of a subject by a pathogen, the method comprising administering to the subject an agent which inhibits sialic acid mediated adhesion of the pathogen to a surface of the subject.

2. The method of claim 1 wherein the agent inhibits binding between the pathogen, or a sialic acid binding molecule thereof, and a sialic acid residue on a surface of the subject.

3. The method of claim 1 or 2, wherein the agent inhibits cleavage of a sialic acid residue on a surface of the subject by the pathogen.

4. The method of claim 3, wherein the agent inhibits cleavage of a sialic acid residue by a sialidase.

5. The method of any one of claims 1 to 4, wherein the agent binds to a sialic acid binding molecule of the pathogen.

6. The method of claim 5, wherein the sialic acid binding molecule of the pathogen is a haemagglutinin.

7. The method of any one of claims 1 to 6, wherein the agent comprises a sialic acid analogue.

8. The method of claim 7, wherein the sialic acid analogue comprises a sialylated glycan.

9. The method of claim 8, wherein the sialylated glycan comprises sialyllactose.

10. The method of any one of claims 1 to 9, wherein the pathogen is a bacterium, fungus, protist or virus.

11. The method of claim 10, wherein the bacterium is a Streptococcus, Staphylococcus, Helicobacter or Haemophilus species.

12. The method of any one of claims 1 to 11, wherein the infection comprises a biofilm on a surface of the subject.

13. The method of any one of claims 1 to 12, wherein the surface is a surface of a cell, tissue, organ or extracellular matrix of the subject.

14. The method of any one of claims 1 to 13, wherein the surface is a mucosal surface.

15. The method of claim 14, wherein the mucosal surface is a mucosal respiratory surface.

16. The method of claim 15, wherein the mucosal respiratory surface is a paranasal sinus surface.

17. The method of any one of claims 1 to 16, wherein a disease state is associated with the infection.

18. The method of claim 17, wherein the disease state comprises a biofilm-mediated disease.

19. The method of claim 17 or 18, wherein the disease state comprises a respiratory disease.

20. The method of any one of claims 17 to 19, wherein the disease state comprises chronic rhinosinusitis.

21. The method of any one of claims 1 to 20, wherein the subject is mammalian.

22. The method of any one of claims 1 to 21, wherein the method is used before, during or after a surgery.

23. The method of claim 22, wherein the surgery is sinus surgery.

24. A pharmaceutical composition comprising an agent which inhibits sialic acid mediated adhesion of a pathogen to a surface of a subject together with a pharmaceutically acceptable carrier or diluent.

25. The composition of claim 24, wherein the agent comprises a sialic acid analogue.

26. The composition of claim 25, wherein the sialic acid analogue comprises a sialylated glycan.

27. The composition of claim 26, wherein the sialylated glycan comprises sialyllactose.

28. The composition of any one of claims 24 to 27 wherein the composition comprises a topical composition.

29. The composition of any one of claims 24 to 28 wherein the composition is adapted for administration to a mucosal surface of a subject.

30. The composition of claim 29 wherein the mucosal surface is a mucosal respiratory surface.

31. The composition of claim 29 wherein the mucosal respiratory surface is a paranasal sinus surface.

32. The composition of any one of claim 24 to 31, when used according to the method of any one of claims 1 to 23.

33. Use of an agent which inhibits sialic acid mediated adhesion of a pathogen to a surface of a subject in the manufacture of a medicament for the treatment or prevention of infection of a subject by a pathogen.