CA2274984A1 - Candida albicans gene (csa1) encoding a mycelial surface antigen, and uses thereof - Google Patents

Abstract

The present invention relates to a Candida albicans gene (CSA1) encoding a surface protein. The present invention also relates to the surface protein and methods for using the protein or the gene for the detection, prophylaxis or treatment of candidal infection. The protein encoded is a surface antigen of Candida albicans yeast and mycelial forms, respectively. The mycelial surface antigen was shown to be present predominantly in the terminal third of the hyphal structures. CSA1 is a gene coding for a unique surface antigen.

Description

Candida albicans crene (CSAI) encoding a mycelial surface antigen, and uses thereof BACKGROUND OF THE INVENTION
(a) Field of the Invention The invention relates to Candida albicans gene (CSA1) encoding a mycelial surface antigen, and uses thereof for the treatment or prophylaxis of candidal infections.
~(b) Description of Prior Art Candida albicans is of major medical importance, being the most commonly isolated fungal species from various mucosal surfaces in healthy individuals and from infectious sites in patients with candidiasis. Most frequently, it causes superficial, irritating infections of the oral and urogenital tracts. However, serious deep-seated or systemic infections can develop, particularly in immunocompromised subjects.
The performance of Candida albicans as an opportunistic pathogen is associated with a number of factors that include the morphological and functional modifications resulting from switching between the yeast and the hyphal forms. Mycelium formation is believed to contribute to fungal adhesion to host cell surfaces and to facilitate invasion of a variety of host tissues through the expression of specialized surface proteins and enzymes (Staab, J. F., et al., Science 283: 1535-1538, 1999). On the basis that the dimorphic process is likely to be associated with differential expression of mycelial cell-specific molecules, biochemical and immunological approaches have been used for their identification.
The success of immunological approaches largely depends on the nature and specificity of the antibody preparation but recently the use of monoclonal antibodies (MAbs) has proven invaluable in the screening of yeast versus mycelial antigens. As summarized by Ponton et al., (Ponton, J., et al., Infect. Immun., 61: 4842-4847, 1993), different types of germ tube surface antigens have been described but true hyphal antigens (type I antigens) appear to be scarce because most hyphae-specific MAbs also react with either DTT-treated (stripped) yeast cells '(type II antigens) or both yeast cells and germ tubes (type I,V antigens).
It would be highly desirable to be provided with a Candida albicans surface antigen for the detection, treatment or prophylaxis of candidal infections.
SiTL~IARY OF THE INVENTION
One aim of the present invention is to provide a nucleic acid sequence encoding a Candida albicans surface antigen for the detection, treatment or prophylaxis of candidal infections.
Another aim of the present invention is to provide a detection kit for candidal infection.
In accordance with the present invention there is provided a nucleic acid sequence having a sequence as follows:
gtcgacacaa taagctaaat agagtgcagt aagatgtgat tgtcatcttt agtagatgct cctataggta attgtataag gttattgcgg agttaacgct ggtattgggt ttcgcttggt agtttctagt attggcacta aaattttttt tttcttgttt gtcgcacaca cagttgattg gctagaatta aagctcaact ttgcacaatt taaaaacaat gcattaggcg atttatcgcg 3 0 taaattaatt accacaacaa agaacaactt attttccgat tgtccaatca atgtcatagg tgttctcggg tttgttacaa tgtctggaaa tatcgaaaac ttacgataat ttaaatgttg gtttgtggat tttagaaggg ataatacaat gattggatag cactaagtcc cgtatagttc gacaacggtt tatttgggtt actacttata gagccctggt ccccagaatt tgaaaatgta gttggttgtg aaacactcag ggatatactc aacaatgctt ccatccattg ttatttcaat cgttttagca tcctttgtga gtgcagaatc atctattaca gaagcaccaa caacaaccgc tgaagataat ccatatacta tctacccaag tgttgccaag actgcttcta tcaatggttt tgctgacaga atttatgatc aattgccaga gtgtgccaag ccatgtatgt tccaaaacac tggtgtgacc ccatgtccat actgggatac tgggtgtttg tgtattatgc caacatttgc tggtgccatt ggttcttgta ttgctgagaa gtgtaaaggc caagacgttg tttctgctac aagtttggga acttccattt gttccgttgc tggtgtgtgg gatccatact ggatggtgcc tgcaaatgtc cagagcagtt taagtgctgc tgccactgct gttgcatcgt cttctgaaca accagttgaa acatcttctg aaccagctgg atcttctcag tctgttgaat cttctcaacc tgctgaaacctcatcatctgaacctgctgagacttcatcatctgaacctgctg~gacttc ~tcggaaacatcatccgaacaacctgcttcatctgaacctgctgaaacttcatcagaaga i atcttctacaatcacttcagccccatcaactcctgaagataacccatacaccatctaccc aagtgttgccaagactgcttctatcaatggttttgctgacagaatctacgaccaattgcc agagtgtgccaagccatgtatgttccaaaacactggtgtgaccccatgtccatactggga tactgggtgcttgtgtattatgccaacatttgctggtgccattgggtcttgtattgctga gaagtgtaaaggccaagacgttgttgctgctacaagtttgggaacttccatttgttccgt tgctggtgtgtgggatccatactggatggtgcctgcaaatgtccagagcagtttaagtgc tgctgccactgctgttccatcatcctccgaacaatcagttgaaacatcttctgaatcagc tgaatcttctcagtctgttgaatcttctcaacctgctgaaacctcatctgaacaaccatc tgagacttcatctgaaacttcttcccaacaactttcaagtatcacttcagcaccagactc ctccgctacaagcagctcctcaaccacatctacttttattagaactgcttccattaatgg 2 ttttgctgataaactttacgaccaattaccagaatgtgctaaaccatgtatgttccaaaa tactggcataacaccatgtccatactgggatgccggttgtttatgtgtcatgccacaatt tgcaggtgctattggttcatgtgttgccgatagttgtaaaggtcaagatattgtttctgt caccagcttgggtacttctgtttgttctgttgccggtgttaatgcaccttattggatgct tccagctagtgttaaaagtagcttaagtgttgctgctactgcagtaccaacctccgacag 2 tgcatctgaaactgcttcccaagaaccatctgaaacttcatctgaacagccatcagaaac tgcttcacaacaacctgctgaaacttcatcagaagaatcttctacaatcacttcagcccc atcaactcctgaagataacccatacaccatctacccaagtgttgccaagactgcttctat caatggttttgctgacagaatctacgaccaattgccagagtgtgccaagccatgtatgtt ccaaaacactggtgtgaccccatgtccatactgggatactgggtgcttgtgtattatgcc 3 aacatttgctggtgccattgggtcttgtattgctgagaagtgtaaaggccaagacgttgt ttctgctacaagtttgggaacttccatttgttccgtcgctggtgtatgggatccatattg gatgattccagctaatgcacaaagcagtttgaatgctgctgccactgctgttgcatcatc ttctgaacaaccagttgaaacatcttctgaagctgctgaatcttctcaaaatcctgctga atcttcttctcaacaaccatctgaaactgcttctcaagaaccatctgaaacttcttccca 3 5 agaaccatca gaaagctcat cagagcaacc tgctgagact tcatcagaag aatcttctac catcacttca gctccatcaa ctcctgaaga taatccatac accatctacc caagtgttgc caagactgct tctatcaatg gttttgctga cagaatttat gatcaattgc cagagtgtgc caagccatgt atgttccaaa acactggtgt gaccccatgt ccatactggg atactgggtg cttgtgtatt atgccaacat ttgctggtgc cattgggtct tgtattgctg agaaatgtaa aggacaagag gttgtttctg ttacaagttt gggtagctct atttgttccg ttgctggtgt atgggatcca tactggatgc ttccagctaa cgtgcaaagc agtttgaatg ccgctgccac tgctgttgca acttctgata gtgcatctga ggttgcttct gcttccgaat ccgcatctca agttccacaa gaaacttctg ctgcttcatc acaatcagcc aacaactcag ttg~ttctgc tgctccatct aactcgtctg tttcagctgc tccatctagc aactcatctg gtgttccagc tgcgccatct aacaattcat ctggtgcttc agttgttcca tcacaatcag ccaacaattc atctgcttca gctgctccat ctaacaactc atctagtgct atttctggaa gtgttgcacc atcaagctac ggaaactctaccattgcacaaccatctacttctacaaaatccgatgctgc atcaattact ggtccaattactacagacaaggttataaccaatgagtctggcattgtctt tacatctaca gtaatcattacacatgtttctgaatattgtgaccagacttctgctgctgc tgttcaatca tcagcatgtgaagaacagtcaagtgctaaatcagaacaagcttctgcttc atcagaacaa gttaaggtcattactagtgtggtttggtgtgagtcatctattcaatctat tgaatctgtc aaaacaagtgcagaagctgctcataagactgaggttattgctagttgtgc aagtgaatta agctctttgagttctgctaaatctgaagctatgaagactgtttctagttt agttgaagtt caaaaatctgcagttgccaaacaaacctcgttggctgctgtacaatcatc 2 tgctgcttct gtacaattaagtgctgctcacgcccaaaagtcgtctgaggcagttgaagt tgcccaaact gctgttgctgaagcttctaaagctggtgatgaaatttcgactgaaattgt taacatcacc aagacagtttcttctggtaaggagactggtgtttcccaagctactgttgc tgctaacaca cattcagttgctattgctaatatggcaaataccaagtttgccagcacaat gtcgttgttg gtcgctagtttcgtgtttgttggtctctttatttaagaggtataataagt 2 tcttataatt ttcttgataaattttatttttttctgttttcggttactatatgtataaag ttttgttaat actataatttttttgttagcctcggtatttcttaaaatagttgtaaattc acccaaatag gaagacagaaaaaagtctag (SEQ ID N0:1) a 4291 pb Also in cordance ac with the present invention, there is provided from the a probe above derived 30 nucleic cid sequence. probe hybridizable a The is with a sample of a nuc leic acid sequence of a pat ient for detecting CSA1 ge ne or its correspo nding mRNA.
The CSA1 gene , or its corresponding when det ected mRNA, in the sampl e is indicative the patient infected of being 35 with Cand ida albicans.

_ 5 _ Also in accordance with the present invention, there is provided a primer pair derived the above from nucleic acid sequence amplifyingCSA1 gene for or its corresponding mRNA.

Further in accordance present with the invention, there is provided a protein encoded by the above nucleic a cid sequence. The pro tein has preferably a sequence llows:
as fo imlpsivisiv lasfvsaessiteaptttaednpytiypsvaktasingfadriydqlpec akpcmfqntg vtpcpywdtgclcimptfagaigsciaekckgqdwsatslgtsicsvag vwdpywmvpa nvqsslsaaatavassseqpvetssepagssqsvessqpaetsssepaet sssepaetss etsseqpassepaetsseesstitsapstpednpytiypsvaktasingf adriydqlpe cakpcmfqntgvtpcpywdtgclcimptfagaigsciaekckgqdwaat slgtsicsva gvwdpywmvpanvqsslsaaatavpssseqsvetssesaessqsvessqp aetsseqpse tssetssqqlssitsapdssatssssttstfirtasingfadklydqlpe cakpcmfqnt gitpcpywdagclcvmpqfagaigscvadsckgqdivsvtslgtsvcsva gvnapywmlp asvksslsvaatavptsdsasetasqepsetsseqpsetasqqpaetsse esstitsaps tpednpytiypsvaktasingfadriydqlpecakpcmfqntgvtpcpyw dtgclcimpt fagaigsciaekckgqdwsatslgtsicsvagvwdpywmipanaqssln 2 aaatavasss eqpvetsseaaessqnpaesssqqpsetasqepsetssqepsessseqpa etsseessti tsapstpednpytiypsvaktasingfadriydqlpecakpcmfqntgvt pcpywdtgcl cimptfagaigsciaekckgqewsvtslg ssicsvagvwdpywmlpanv qsslnaaata vatsdsasevasasesasqvpqetsaassqsannsvasaapsnssvsaap ssnssgvpaa psnnssgasvvpsqsannssasaapsnnsssaisgsvapssygnstiaqp 2 ststksdaas itgpittdkvitnesgivftstviithvseycdqtsaaavqssaceeqss akseqasass eqvkvitswwcessiqsiesvktsaeaahkteviascaselsslssaks eamktvsslv evqksavakqtslaavqssaasvqlsaahaqksseavevaqtavaeaska gdeisteivn itktvssgketgvsqatvaanthsvaianmantkfastmsllvasfvfvg lfi 1203 as (SEQ ID N0:2) .

30 More preferably, surface the protein is a antigen of Candida albicans .

From the protein, invention the present further provides a vacci ne against Candida albicans.
The vaccine comprises the protein as described above, or an immunizing fragments thereof, in combination uiith a pharmaceutically acceptable excipient.
In accordance with the present invention there is also provide the use of a protein as defined above for the manufacture of a vaccine for the treatment or prophylaxis of Candida albicans infection.
Still in accordance with the present invention, there is provided a diagnostic kit for detecting Candida albicans infection in a sample of a nucleic acid sequence of a patient. The kit comprises the nucleic acid sequence as described above, or a fragment thereof capable of hybridizing with CSA1 gene of Candida albicans, or its corresponding mRNA.
The present invention further provides a diagnostic kit for detecting Candida albicans infection in a nucleic acid sample of a patient. The kit comprises the probe or the primer pair as defined above.
In accordance with the present invention, there is also provided the use of the diagnostic kit as described above, for detecting Candida albicans infection in a nucleic acid sample from a patient.
The present invention also provides the use of the nucleic acid sequence as described above for detecting upon hybridization with a sample of nucleic acid sequence the presence of CSAI gene of Candida albicans, or its corresponding mRNA, in the sample.
The present invention also contemplate the use of the probe as defined above for detecting upon hybridization with a sample of a nucleic acid sequence the presence of CSA1 gene of Candida albicans in the sample.
Further in accordance with the present invention, there is provided the use of a primer pair as defined above for detecting by polymerase chain reaction (PCR) CSA1 gene from Candida albicans, or its corresponding mRNA, in a sample, wherein detection of an amplified fragment with the primer is indicative of the sample being infected with Candida albicans.
Also in accordance with the present invention, there is provided an antibody directed against the protein as defined above for treating Candidal infection, wherein the antibody binds to the protein for masking same and thereby reducing virulency of the Candidal infection. The antibody is preferably a polyclonal antibody. Alternatively, and more preferably, the antibody is a monoclonal antibody.
Most preferably, the monoclonal antibody is MAb 4E1 monoclonal antibody. The antibody is preferably used for treating a Candidal infection, wherein the antibody binds to the protein for masking same and thereby reducing virulency of the Candidal infection.
The antibody can therefore be used for the manufacture of a medicament for treating a Candidal infection, wherein said antibody binds to the protein for masking same and thereby reducing virulency of the Candidal infection.
The present invention has many applications.
Candida albicans is a fungal human pathogen that infects the mucosal tissues and can elicit systemic infections in human. The major commercial applications of the present invention therefore concern the diagnostic, the prevention and the treatment of candidal infections.
As for the diagnostic, in a preferred embodiment of the invention, the presence of Candida albicans at sites of infection could be easily detected by polymerase chain reaction (PCR) with oligonucleotide primers derived from SEQ ID NO:1. The Candida albicans CSA1 gene encodes an abundant _ g mycelial surface antigen. Expression of CSA1, or part thereof, in either bacteria or yeast and purification of the corresponding polypeptides can therefore, in combination with monoclonal antibodies such as MAb 4E1 directed against the CSA1 protein, can be used in ELISA assays to detect the presence of anti-CSA1 in sera of infected individuals.
As for the prevention of Candidal infections, ~urified proteins or peptides derived from expression Qf CSA1 in bacteria or yeast could also be used to immunize individuals against candidal infections. The CSA1 gene itself could be used in genetic vaccination against C. albicans through single or repeated injections of an eukaryotic expression vector carrying SEQ ID NO: 1. Passive immunization, either through topical or systemic applications of the monoclonal antibodies directed against the CSA1 protein is also a potential commercial application.
As now for the treatment of Candidal infections, vaginal infections occur in immuno competent patients and result from an inappropriate response of the immunity system. It has been demonstrated that vaginal allergic responses against C. albicans can predispose to recurrent candidal infection. Since CSA1 protein is a surface antigen that is shown to stimulate the production of IgG
antibodies, single or repeated administrations of the purified CSA1 protein on the mucosal surface of the vagina may modulate the immune response and is effective in the treatment of recurrent vaginitis associated to C. albicans.
BRIEF DESCRIPTION OF THE DRAWINGS
Figs. lA to 1C illustrate the sorting of S.
cerevisiae transformants by uncoated, MAb A2C7- and MAb 4E1-coated magnetic beads;

_ g _ Fig. 2A illustrates a schematic representation of the genomic DNA fragments carried by the indicated plasmids and the ability of the corresponding yeast transformants to be sorted out by MAb 4E1-coated magnetic beads, (+) sorting and (-) no sorting;
Fig. 2B illustrates the deduced amino acid sequence of CSA1 using the single letter code;
Fig. 3 illustrates an alignment of the Cs~lp CH
domain with peptide sequences derived form the C.
immitis Ag2 and M. grisea Pthll proteins;
Fig. 4 illustrates a northern hybridization of total RNA extracted from the yeast and mycelial form of C. albicans with probes derived from CSA1 and the S. cerevisiae ACT1 gene;
Figs. 5A and 5B illustrate an indirect immunofluorescence microscopy of C. albicans yeast cells with MAb 4E1;
Fig. 6A illustrates a schematic representation of the CSAI locus from strains ATCC 32354 and CAI4;
Fig. 6B illustrates a southern analysis of the genomic DNA extracted from the C. albicans strains ATCC 32354 and CAI4;
Fig. 7A illustrates a schematic representation of the wild type, CAT:: URA:: CAT- and CAT-disrupted alleles of CSA1 from strain CAI4;
Fig. 7B illustrates the disruption of the CSA1 gene from C. albicans; and Figs. 8A to 8F illustrate the indirect immunofluorescence microscopy of the C. albicans csal0 mutant strains with MAb 4E1.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, there is provided an IgG MAb which strongly reacts with the terminal third of the growing filaments, but not with the parent blastospore, in C. albicans mycelial cultures. In immunoblots, the MAb 4E1 detected two species of 117 and 104 kDa from DTT-extracts prepared from the mycelial cells but not from yeast cells suggesting that the 4E1 antigen defines a true type I
antigen.
To further characterize this surface antigen and also to confirm its differential expressibn in feast versus hyphae, the corresponding gene was cloned. The inventors of the present invention reasoned that functional surface expression of this major mycelial antigen in the yeast S. cerevisiae might provide a simple and rapid approach to clone the corresponding gene. Using magnetic beads coated with MAb 4E1, S. cerevisiae transformants expressing a Candida genomic library were immunocaptured and Candida Surface Antigen 1 (CSA1) gene was cloned.
Experimental procedures Strains and media Candida albicans ATCC 32354 was used for the production of monoclonal antibodies and throughout this study. Yeast cells were cultured in Iscove's modified Dulbecco medium at 25°C and mycelium formation was induced at 37°C, as described before.
Disruption of CSA1 was performed in the C. albicans strain CAI4 (Fonzi, W. A., and Irwin, M. Y., Genetics 134: 717-728, 1993). The S. cerevisiae strain used was W303-lb (Thomas, B. J., and Rothstein, R., Cell 56: 619-630, 1989) (MATa ade2-1 canl-100 his3-11,15 leu2-3,112 trpl-1 ura3-1) which was grown at 30°C in either YPD or SC -ura broth as described (Kaiser, C., et al., Laboratory Course Manual for Methods in Yeast Genetics. Cold Spring Harbor Laboratory, New York:
Cold Spring Harbor Laboratory Press, 1994) for untransformed or transformed yeast, respectively. The E. coli strain used for plasmid purification and subcloning experiments was MC1061 and was cultured in 2 X YT medium supplemented with 1% glucose and 50 ~.g/mL ampicillin.
DNA manipulations and transformations All DNA manipulations were carried out according to standard procedures. All restriction enzymes and other DNA modifying enzymes were purchased from New England Biolabs (Mississauga, Ont.).
Purification of total RNA was performed according to the procedure described by Kohrer and Domdey (Kohrer, K., and Domdey, H., Methods Enzymol. 194: 398-405, 1991). For the construction of the library and for Southern analysis, purification of genomic DNA from 40 mL yeast culture was carried out as described by Kaiser et al. (Kaiser, C., et al., Laboratory Course Manual for Methods in Yeast Genetics. Cold Spring Harbor Laboratory, New York: Cold Spring Harbor Laboratory Press, 1994). Standard procedures were used for Southern and Northern analyses. Nucleic acids were transferred onto nylon membranes in all cases (Hybond-NT""; Amersham Life Science; Oakville, Ont.) and the radioactive probe was prepared with the RediprimeT"' kit (Amersham Life Science) using [32P] dCTP
(ICN) according to the manufacturer's instructions.
Automatic DNA sequencing reactions were performed by the dye terminator cycle protocol with dsDNA on a GeneAmp PCR system 9600 and a 373 DNA Sequencer (Applied Biosystems, Perkin Elmer; Mississauga, Ont.).
Complete sequencing of CSA1 using universal primers was achieved by the construction of overlapping subclones in pTZl8R (Pharmacia Biotech; Baie d'Urfe, Que.). The CSA1 nucleotide sequence has been deposited in the GenBank database under the accession number AF080221.

Transformation of yeast using lithium acetate salt was performed according to the rapid procedure described by (Kaiser, C., et al., Laboratory Course Manual for Methods in Yeast Genetics. Cold Spring Harbor Laboratory, New York: Cold Spring Harbor Laboratory Press, 1994). The CaCl2 protocol for transformation of E. coli was used for all subcloning experiments and recovery of the p4E1 plasmid~ from yeast whereas electroporation was used to construct the genomic library.
Construction of the Candida albicans genomic library High molecular weight genomic DNA prepared as described above was partially digested with Sau3A I
and size-selected on a discontinuous potassium acetate gradient (5-25 0). Fractions containing DNA fragments > 5 kb were pooled and ligated to the BamHI cut, dephosphorylated yeast 2 ~, plasmid YEP24. The ligation mixtures were then used to transform E. coli by electroporation. Approximately 15 000 total independent transformants were obtained, pooled into two aliquots of - 8 000 and 7 000 clones, and restriction digests performed on randomly selected plasmid DNA clones indicated that ~ 90% had an insert of an. average size of 8 kb. Plasmid DNA prepared from pool I (~ 8 000 clones) was introduced into S.
cerevisiae cells and the resulting transforrnants were selected onto SC -ura plates (~ 15) . A total of -. 30 000 colonies, were scraped from the selective solid medium, pooled into 10 mL of SC -ura and 1 mL aliquots were frozen at - 80°C.
Screening of S. cerevisiae transformants with MAb-coated microspheres Immunocapture of yeast transformants was performed with Sheep anti-mouse IgG-linked magnetic microspheres (DynabeadsT"' M-280, Dynal; Lake Success, NY) coated with MAb 4E1 and a particle concentrator (Dynal). Coating of the microspheres (1 mg) with MAb 4E1 (1 mL of hybridoma supernatant; - 50 ~g/mL of IgG) was done by a 2 h incubation at room temperature in a rotary shaker. Coated-beads were then washed four times in phosphate-buffered saline supplemented with 0,1°s bovine serum albumin (PBS-BSA) for 10 min each on a rotary shaker. As a negative control, the magnetic beads either uncoated or coated with MAb A2C7 (anti-e,nolase) were incubated under the same conditions.
For immunoscreening, yeast transformants exponentially growing into SC -ura medium were harvested by low speed centrifugation and suspended into 1 mL of PBS-BSA at a final concentration of 1.5 O.D.600/mL.
Coated beads (100 ~,1; 6 X106 beads) were then added and the suspension was rotated for 16 h at 4°C. At the end of the incubation, the microspheres were maintained on the wall of the tube by a lateral magnet and the supernatant was discarded. The beads were washed four times with PBS-BSA as described above.
Free and cell-bound beads were finally recovered into 110 ~L of PBS-BSA for plating onto SC -ura plates (100 ~L) and microscopic examination (10 ~.L) .
Magnetic bead sorting from homogenous cultures of S. cerevisiae carrying either YEP24 or p4E1 was performed essentially as described above with the following modifications. Exponentially growing cultures (O.D.600/mL between 1 - 1.5) were adjusted to a final cell density of 105 cells/mL in PBS-BSA before the addition of the coated- (MAb 4E1) or uncoated beads (106/mL). The incubation was also done at room temperature for 2 h rather than overnight at 4°C.
Finally, serial dilutions (10-fold) of the free- and cell-bound beads were plated onto selective SC -ura solid medium.

Competition experiments were conducted by first incubating the yeast transformant (105 - 106 cells) harvested from exponential cultures, and washed once with PBS-BSA, with either 1 mL of PBS-BSA or the MAb 4E1 supernatant for 1 h at room temperature before sorting with the coated microspheres.
Indirect immunofluorescence microscopy Indirect immunofluorescence microscopy ' was ~arried out essentially as described by Pringle et al., (Pringle, ,T. R., et al., Methods Enzymol. 194:
565-602, 1991) using undiluted MAb 4E1 hybridoma supernatant as primary antibody and fluorescein conjugated goat anti-mouse IgG antibodies (Bio/Can Scientific; Mississauga, Ont.) at 1/500. final dilution.
Disruption of CSA1 The 3.5 kb CAT::URA3::CAT cassette from plasmid pCUC (Fonzi, W. A., and Irwin, M. Y., Genetics 134:
717-728, 1993) was isolated by digestion with Bam HI
and inserted at the Bam HI site of plasmid p4E10S to create p4El~S::CUC. The 4.6 kb fragment released from p4E10S::CUC by digestion with Hpa I was used to transform C. albicans CAI4. Early logarithmic cells (O.D.600 0.3) were transformed with approximately 5-10 ~,g of DNA. Cells were plated onto SC -ura medium.
Approximately 3 transformants per ~g of DNA were visible after 3 days of incubation at 30°C. Primary transformants were replated onto SC -ura medium containing uridine (50 ~g/ml) and 5'-fluoorotic acid (FOA) (1 mg/ml) and FOA resistant colonies were subjected to further rounds of transformation. At each stage of this process, integration of the disrupting cassette at the CSA1 locus was confirmed by Southern analysis.

Results Expression cloning of the C. albicans gene encoding the 4E1 antigen In Fig. lA, exponentially growing cultures of S. cerevisiae transformed with the indicated plasmids were sorted out with uncoated, MAb A2C7- and MAb 4E1 coated microspheres as described above. The results are expressed as the average number of colonies recovered per 105 cells +/- SD from an experiment harried out in triplicate.
Experiments showed that S. cerevisiae cells transformed with the yeast multicopy plasmid YEP24 did not attach to either uncoated or MAb 4E1-coated magnetic beads (Fig, lA). This indicated that there is no non-specific adherence of the cells to the beads and that the epitope recognized by MAb 4E1 is either not expressed or not exposed at the cell surface in this organism. S. cerevisiae was thus transformed with a C. albicans genomic library, and the pooled transformants were screened with the magnetic beads coated with MAb 4E1 during a 16 h incubation period at 4°C. Following extensive washes with PBS-BSA, the free and cell-bound microspheres were finally resuspended into the same buffer and spreaded onto selective agar plates (SC -ura). After an incubation of 3 days at 30°C three colonies grew up on this medium. However, of the three plasmids recovered only one, designated p4El, conferred the ability of freshly transformed S. cerevisiae cells to be sorted out by the coated beads. As assessed by colony formation on SC -ura plates, approximately 0.68 % of the cells (676 +/- 111 per 100 000 cells) from exponentially growing cultures of the p4E1-transformant could be recovered with the coated beads (Fig. lA). That this low level of sorting resulted from a specific interaction between the candidal antigen exposed at the surface of S. cerevisiae transformants and MAb 4E1 was first suggested by the dramatic reduction observed in the sorting efficiency (0.01 %; 13 +/- 8 and 0.02 0: 18 + - 7 per 100 000 cells) when sorting was performed with uncoated and MAb A2C7-coated (anti-enolase) beads, respectively (Fig. lA). This was confirmed by competition experiments where an excess of MAb 4E1 was incubated with exponentially growing 'p4E1 ~ransformants prior to sorting with the coated microspheres (Fig. 1B).
In Fig. 1B, either 105 cells (Exp. 1) or 106 cells (Exp. 2) from an exponentially growing culture of the S. cerevisiae transformed with p4E1 were first incubated with either MAb 4E1 or PBS-BSA prior to sorting with the MAb 4E1-coated microspheres. The results are expressed as the percentage of inhibition on the sorting resulting from a preincubation with MAb 4E1 as calculated from the number of colonies recovered with the coated beads.
In the two parallel experiments (Exp. 1 and Exp. 2), competition with MAb 4E1 led to 90 % and 82 inhibition in sorting, respectively. Therefore it is concluded that plasmid p4E1 carries the C. albicans gene coding for the 4E1 surface antigen. The low sorting efficiency of the yeast transformants also suggested a much reduced expression or surface exposure of this mycelial antigen in S. cerevisiae yeast cells compared to mycelial cultures of C.
albicans. Microscopic examination of the MAb 4E1-sorted cells revealed that the microspheres were not randomly distributed over the cell surface but preferentially attached to the growing bud or at the mother-daughter neck junction (Fig. 1C). Fig. 1C
illustrates representative differential interference contrast micrograph (100X) of the S. cerevisiae p4E1-transformant recovered with the MAb 4E1-coated magnetic beads.
The deduced amino acid sequence of CSA1 reveals the presence of repeated domains with sequence similarity to the C. immitis antigen 2 and M. grisea Pthll protein Partial restriction mapping of plasmid p4E1 indicated that it carries a 7.4 kb genomic fragment (Fig. 2A). In Fig. 2A, the hatched box represents the ~SA1 coding region and the arrow represents the direction of transcription. Subcloning experiments and immunocapture of the corresponding transformants showed that the gene encoding the 4E1 surface antigen (thereafter referred to as Candida Surface Antigen 1;
CSA1) lies on the 4.2 kb Sal I-Xba I fragment (Fig.
2A). This genomic fragment was then entirely sequenced on both strands and found to contain a single, uninterrupted, open reading frame (ORF) of - 3609 bp. In Fig. 2B, the predicted signal peptide (aa 1-17) and the hydrophobic stretch predicted to serve as GPI-anchoring determinant (aa 1184-1203) are in bold italics. The repeated hydrophilic sequences TSAP
(SEQ ID N0:3) and P(A/S/V)ETS(E/Q) (SEQ ID N0:4) are underlined and twice underlined, respectively. The five CH domains are black boxed. The putative N-glycosylation sites located in the C-terminus of Csalp are denoted by asterisks.
The deduced amino acid sequence of the ORF
(1203 aa) revealed several important features (Fig.
2B) . First, both the N- and C-termini contain a core of hydrophobic residues which may function as a signal sequence and a GPI-anchoring determinant, respectively. Anchoring to membranes through a GPI
moiety is a common feature of many cell wall-associated proteins in fungi, including C. albicans and S. cerevisiae. That this putative GPI-anchoring determinant is important for the corxect assembly of the 4E1 antigen into the cell wall is suggested by the observation that yeast expressing a C-terminal 164-as truncated version of the protein cannot be sorted by the coated microspheres (Fig. 2A). A striking feature of the protein is a 102 residues cysteine-rich hydrophobic domain (CH domain) that is repeated 5 times in the sequence. The sequence identity between each domain exceeds 95 %, except for the central repeat (aa 403-504 in Csalp) which diverges slightly from the other repeats (84 % sequence identity, -. 94 sequence similarity). These CH domains are interspersed by segments of variable length (60 to 89 aa) almost exclusively composed (89 %) of the residues P, E, T, S, A and Q, with an overall net charge of -54. Within these acidic- proline rich domains at least two motifs, TSAP (SEQ ID N0:3) and P(A/S/V)ETSS(E/Q)(SEQ ID N0:4), can be distinguished.
A copy of the TSAP motif is always found upstream (15-16 aa) of a CH domain whereas the longer motif is repeated several times within the segments separating the CH domains. Finally, the 333-as domain located between the last CH domain and the putative GPI-anchoring determinant (aa 852-1184), is also enriched in the residues P, E, T, S, A and Q (66 0) with a net negative charge of -13. This domain contains all the putative N-glycosylation sites (10).
A search for sequence similarity in the S.
cerevisiae protein database revealed that there is no homologue of Csalp in this organism. However, a significant similarity was noticed between the CH
domains of Csalp, the immunoreactive antigen 2 (Ag2) of Coccidioides immitis and the Pthll protein of Magnaporthe grisea (Fig. 3). In Fig. 3, alignment was performed with the CLUSTALW software available on the ExPASy molecular biology WWW server of the Swiss Institute of Bioinformatics. The sequence of Ag 2 was taken from bugger et al. (bugger, K. O., et al., Biochem. Biophys. Res. Commun. 218: 485-489, 1996).
C. immitis is an important fungal human pathogen whereas M. grisea is a plant fungal pathogen responsible for the infection of the rice blast. The C. immitis Ag2 is a 194-as protein that is expressed in the mycelium- and spherule-phase cell walls (bugger, K. O., et al., Biochem. Biophys. Res. Commun.
218: 485-489, 1996). Pthllp is a 628- as protein that acts as an upstream component of pathogenicity signaling in M. grisea. Amino acids 19-88 of Ag2 and 34-104 of Pthllp show 35 % and 29 % sequence identity (56 % and 50 % sequence similarity), respectively, with a 66-as motif internal to the Csalp CH domains.
Remarkably, all the cysteine residues, with an insertion of a single amino acid in Ag2 align with those found in the Csalp CH domains. In addition to the similarity in the primary amino acid sequence, the content of hydrophobic residues within this motif is similar (~ 26 %) in all three proteins.
The 4E1 surface antigen can be detected in the growing buds of C. albicans yeast cells In the present invention, it was demonstrated above that the 4E1 surface antigen is exposed on the hyphal extensions in the mycelial form of C. albicans (Deslauriers, N., et al., Microbiology 142: 1239-1248, 1996). The antigen could not be detected either in the parent blastospore from mycelial cells or in the yeast form of C. albicans. Northern analysis confirmed the presence of an abundant CSA1 transcript (-- 4.0 kb) with total RNA extracted from C. albicans mycelial cultures (Fig. 4). In Fig. 4, Total RNA was prepared from C. albicans cultures growing in IMDM

medium either at 25°C (predominantly yeast cells; Y) or at 37°C (mycelial cells; M). Identical amounts of total RNA (20 ~.g) were fractionated by agarose-formaldehyde gel and transferred onto nylon membrane.
The RNA blot was then hybridized with the CSA1 3.9 kb Hpa I fragment and a probe derived from the S.
cerevisiae ACT1 gene (actin). The top panel illustrates the autoradiogram of the Northern ~iybridization, whereas the bottom panel illustrates the ethidium Bromide staining of the agarose-formaldehyde gel. A low level of mRNA could however also be detected in the RNA sample prepared from C.
albicans blastospores harvested during the early exponential growth phase. This, and the low level of expression of the surface antigen in S. cerevisiae yeast cells, therefore prompted the inventors to reexamine the presence of Csalp by .indirect immunofluorescence microscopy in C. albicans yeast cells (Figs. 5A and 5B). Fig. 5A illustrates a bright field illumination micrograph (40X) of C. albicans yeast cells incubated with MAb 4E1 and the fluorescein-conjugated anti-mouse IgG secondary antibody, whereas Fig. 5B illustrates the epifluorescence micrograph of Fig. 5A. The arrows point to the cellular structures (Fig. 5A) reacting with the primary and secondary antibodies (Fig. 5B).
As for the Northern analysis, the culture was grown to the early exponential phase to increase the proportion of budding yeast. Under these conditions MAb 4E1 reacted with a fraction of the cell population. As observed previously with the S. cerevisiae transformants, the antigen was detected predominantly, if not exclusively, in the growing buds. Control experiment where only the secondary fluorescein-conjugated antibody was added confirmed the specificity of the immunofluorescence profile. Hence, either a sub population of C. albicans yeast cells express Csalp or the blastospores may transiently express the surface antigen during the budding process.
Disruption of CSA1 indicates that this gene is not essential for viability of either the yeast or mycelial form of C. albicans As a first step toward assessing the functional dole of CSA1, a strain with disrupted alleles of this gene was constructed. As evidenced by Southern analysis (Fig. 6B), the parental strain (strain CAI4) used for the targeted disruption carries shorter alleles of CSAI than that observed in the ATCC 32354 strain. The Hpa I fragment, which contains most of the CSAI coding region and part of the 5' flanking sequence, is -. 3.4 kb long in CAI4 compared to 3.9 kb in ATCC 32354. As predicted from the sequence of the gene five fragments, including a doublet of ~ 0.5 kb, should light up when the genomic DNA digested with Bam HI is probed with the Hpa I fragment (Fig. 6A). In Fig. 6A, grey and black boxes correspond respectively to the N- and C-terminal sequences of the CSAI coding region. The hatched and open boxes represent the repeated CH domains the hydrophilic sequences, respectively. The relevant restriction sites are shown . B; Bam HI, H; Hpa I, P; Pst I. In Fig. 6B, the genomic DNA (10 fig) prepared from strains ATCC 32354 (A) and CAI4 (C) was digested with the indicated restriction enzymes, fractionated on agarose gel, transferred onto nylon membranes and probed with the CSA1 3.9 kb HpaI-fragment. The DNA size markers (lkb ladder; Gibco-BRL) are indicated on the left.
Fragments of identical sizes were observed in genomic DNA prepared from both strains. However, the signal intensity ratio of the 0.5 kb over the 1.0 kb fragment was significantly reduced for strain CAI4 compared to ATCC 32354. This strongly suggests that the alleles of CSA1 from CAI4 are missing one of the two 0.5 kb Bam HI fragments . To confirm this and to locate more precisely the deletion site, genomic DNA was digested with Pst I and again probed with the Hpa I fragment.
In contrast to the ~ 1.8 kb predicted from the sequence, this revealed that the internal pst I
fragment of CSA1 is -.1.3 kb in size in strain CAI4.
Collectively therefore, these results indicate that the alleles of CSA1 found in strain CAI4 lack the --0.5 kb Bam HI fragment located toward the 3' end of the gene in strain ATCC 32354. Based on the nucleotide sequence, deletion of this Bam HI fragment predicts a protein composed of four instead of five CH
domains.
The Ura-blaster technique was used to disrupt the CSA1 gene. The coding region of CSA1 internal to the Bam HI sites was replaced by the disrupting cassette composed of the CAT and URA3 sequences (Fig.
7A). The DNA was then restricted with Hpa I and the linear DNA fragment was used to transform strain CAI4.
Integration of the disrupting cassette at the CSA1 locus was monitored, after each round of transformation, by Southern analysis of the genomic DNA prepared from the Ura+ transformants and digested with Eco RV and Xba I (Fig. 7B). In Fig. 7A, the grey boxes correspond to the CSA1 coding region. The size of the corresponding Eco RV - Xba I fragment is indicated on the right. The relevant restriction sites are shown . B; Bam HI, E; Eco RV, H; Hpa I, X ;
Xba I. In Fig. 7B, lane 1 represents the genomic DNA
(10 fig) prepared from the parental strain CAI4, lane 2 represents a first-round Ura3+ transformant, lane 3 represents a first-round FOA-resistant segregant, lane 4 represents a second-round Ura3+ transformant, lane 5 represents a second-round FOA-resistant segregant, and lane 6 represents a third-round Ura3+ transformant digested with Eco RV and Xba I. The resulting Southern blot was probed with the CSA1 Hpa I - Bam HI
fragments. The DNA size markers (lkb ladder; Gibco-BRL) are indicated on the left.
Following the second round of transformation, three bands of 6.0 kb, 3.9 kb and 3.2 kb corresponding to csal : : CAT-URA3 -CAT, CSA1 and csal : : CAT
respectively, were revealed by Southern analysis (Fig.

7.B, lane 4). Hence, strain CAI4 is triploid at the CSA1 locus and a third round of transformation was required to get a strain lacking all functional alleles of this gene (Fig. 7B, lane 6).
The construction and selection of the csal mutants was carried out with the yeast form of C.
albicans CAI4. Since Csalp is weakly expressed in that form the viability of the knockout strain was therefore anticipated. However, all the mutant strains (single, double and triple deletions) showed the same viability when grown under conditions that elicit the transition from the yeast to the mycelial form (Figs. 8A to 8F). Furthermore, the number and size of the hyphal extensions were similar in all three cultures. Hence, CSAI is not essential for cell growth in either morphological phases and its absence does not preclude the emergence and elongation of the hyphal structures. Indirect immunofluorescence microscopy performed on the mycelial cells with MAb 4E1 indicated that the relative abundance of the surface antigen was subjected to a gene dosage effect (Figs. 8A to 8F compare the relative fluorescence intensity between the single and double mutant). Most importantly, the antigen could not be detected in the triple mutant indicating that Csalp .is the only C.
albicans surface antigen containing the 4E1 epitope.
Differential interference contrast (Figs. 8A to 8C) and epifluorescence (Figs. 8D to 8F) micrographs (40X) of the single (Figs. 8A and 8D), double (Figs. 8B and 8E) and triple (Figs. 8C and 8F csal0 deletant constructed in strain CAI4 are illustrated. The mycelial form was induced as described in Fig. '4 and ~he indirect immunofluorescence with MAb 4E1 was performed as in Figs. 5A and 5B..
Discussion The composition of the Candida albicans cell wall has been thoroughly studied and antigenic variations in cell wall mannoproteins as a function of dimorphism were investigated with polyclonal and monoclonal antibodies. These antibodies were most frequently directed toward carbohydrates carried by the cell wall proteins. In the present invention MAbs directed against C. albicans cell wall proteins have been produced and it is showed that MAb 4E1 recognizes proteinaceous antigens on the surface of mycelial cells. In the present invention, the inventors have cloned the corresponding gene as a first step toward understanding the role of this mycelial cell wall protein.
A number of expression cloning systems have been developed to isolate cDNA clones corresponding to cell surface molecules, and immunological screening by antibody capture after panning, FRCS, or magnetic bead sorting was successfully used in mammalian cells.
Here an adaptation of this approach for isolating C.
albicans genes encoding cell surface molecules has been described. From ~ 1,5 X 10~ yeast cells derived from 8 X 103 independent transformants, three were sorted out by the MAb 4E1-coated magnetic beads and one carried the C. albicans gene CSAI (p4E1 transformant) illustrating the exquisite selectivity of the technique. Since expression or surface exposure of this antigen appears to be restricted to a particular phase of the cell cycle and at a low level in budding yeast (see below), the method is also very sensitive. Immunocapture of S. cerevisiae transformants thus offers an attractive alternative for the identification of C. albicans genes encoding surface antigens. In both C. albicans and. S.
cerevisiae yeast cells the low level of expression of Csalp was not randomly distributed over the cell surface, but localized predominantly in the growing buds. The strong induction of the CSAI transcript observed upon transition from the yeast to the mycelial form and the absence of Csalp from the parent blastospore suggest that the distribution of the antigen may be restricted to sites of cell surface elongation.
The primary amino acid sequence of Csalp reveals the presence of repeated, nearly identical, cysteine-rich hydrophobic domains that are separated by acidic proline-rich hydrophilic domains composed of two repetitive units: TSAP and P(S/A/V)ETSS(E/Q).
Interestingly, the number of repeats within CSAI was found to be different from strains CAI4 and ATCC 32354 (Fig. 7A), as well as from various laboratory strains and clinical isolates. Tandem repeats have been found in surface proteins from a variety of organisms, including the C. albicans Alsl, Hwpl and Hyrl cell wall proteins, and are frequently involved in host cell attachment, evasion of phagocytosis, invasion of host cells or act as neutralization epitopes. The role of these repeats is currently unknown. However, the presence of domains with sequence similarity to the Csalp CH domains in surface proteins from two distantly related fungi, C. immitis and M. gr.isea, suggests a common function.
Cell surface hydrophobicity (CSH) in C.
albicans and M. grisea has been linked to a plethora of host interactions and fungal functions, and several surface proteins are thought to be involved in CSH in C. albicans. Given the hydrophobic character of the CH domain and the preferential expression of Csalp during the mycelial growth phase, its potential function may be to increase the overall hydrophobicity of the fungal cell wall associated with the transition from the yeast to the mycelial form. In support of this hypothesis the CH domains of Csalp, and the analogous domains found in Ag2 and Pthllp, present similitude to a class of small secreted fungal proteins (96-125 aa) called hydrophobins.
Hydrophobins from different species have now been identified. They present a weak sequence identity (4 %) but they all possess 8 cysteine residues dispersed throughout a sequence rich in proline and hydrophobic amino acids. Despite their weak sequence identity they appear to be functionally interchangeable (Kershaw, M. J., et al., EMBO J. 17: 3838-3849, 1998).
In response to environmental stimuli, these molecules self-assemble into polymeric structures to form a coat that increases dramatically the hydrophobic character of the fungal cell walls.
Morphogenesis in C. albicans is more than a change in cell shape and entails the expression of physiological attributes linked to its performance as a successful commensal and opportunistic pathogen.
Until now molecular genetic approaches have identified a few genes encoding hyphae-specific surface proteins that may contribute to differences in cell wall structure and functions. In the present invention, it is now reported that C. albicans Csalp is a non-essential protein differentially expressed in blastospores and mycelia. Its accessibility to external ligands, its dynamic expression and hydrophobic character together with its sequence similarity to domains found in the immunogenic Ag2 protein (C. immitis) and Pthllp (M. grisea) suggest that this protein may be involved in surface interactions with its changing molecular and cellular environment.
While the invention has been described in con-nection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any varia-tions, uses, or adaptations of the invention follow-ing, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as follows in the scope of the appended claims.

SEQUENCE LISTING
(1) GENERAL INFORMATION:
(i) APPLICANT:
(A) NAME: Universite Laval (B) STREET: Cite Universitaire (C) CITY: Quebec (D) STATE: Quebec (E) COUNTRY: Canada (F) POSTAL CODE (ZIP): G1K 7P4 (ii) TITLE OF INVENTION: CANDIDA ALBICANS GENE (CSA1) ENCODING A
MYCELIAL SURFACE ANTIGEN, AND USES THEREOF
(iii) NUMBER OF SEQUENCES: 4 (iv) CORRESPONDENCE ADDRESS
(A) ADDRESSEE: SWABEY OGILVY RENAULT
(B) STREET: 1981 McGill College Avenue - Suite 1600 (C) CITY: Montreal (D) STATE: QC
(E) COUNTRY: Canada (F) ZIP : H3A 2Y3 (v) COMPUTER READABLE FORM:
(A) MEDIUM TYPE: Floppy disk (B) COMPUTER: IBM PC compatible (C) OPERATING SYSTEM: PC-DOS/MS-DOS
(D) SOFTWARE: PatentIn Release #1.0, Version #1.30 (EPO) (vi) CURRENT APPLICATION:
(A) APPLICATION NUMBER:
(B) FILING DATE:
(vii) PRIOR APPLICATION DATA:
(A) APPLICATION NUMBER: CA 2,237,134 (B) FILING DATE: 10-JUL-1998 (viii) ATTORNEY/AGENT INFORMATION:
(A) NAME: Kevin P. Murphy (B) REGISTRATION NUMBER: 4166 (C) REFERENCE/DOCKET NUMBER: 6013-71"CA" FC/CC/LM
(ix) TELECOMMUNICATION INFORMATION:
(A) TELEPHONE: 514 845-7126 (B) TELEFAX: 514 288-8389 (2) INFORMATION FOR SEQ ID NO: 1:
(i) SEQUENCE CHARACTERISTICS:
(A) LENGTH: 4291 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: DNA (genomic) (iii) HYPOTHETICAL: NO
(iv) ANTI-SENSE: NO
(xi) SEQUENCE DESCRIPTION: SEQ ID NO: 1:

(2) INFORMATION FOR SEQ ID NO: 2:
(i) SEQUENCE CHARACTERISTICS:
(A) LENGTH: 1203 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi)SEQUENCE DESCRIPTION: N0:2:
SEQ
ID

MetLeu ProSerIle ValIleSer IleValLeu AlaSer PheValSer AlaGlu SerSerIle ThrGluAla ProThrThr ThrAla GluAspAsn ProTyr ThrIleTyr ProSerVal AlaLysThr AlaSer IleAsnGly PheAla AspArgIle TyrAspGln LeuProGlu CysAla LysProCys MetPhe GlnAsnThr GlyValThr ProCysPro TyrTrp AspThrGly CysLeu CysIleMet ProThrPhe AlaGlyAla IleGly SerCysIle AlaGlu LysCysLys GlyGlnAsp ValValSer AlaThr SerLeuGly ThrSer IleCysSer ValAlaGly ValTrpAsp ProTyr TrpMetVal ProAla AsnValGln SerSerLeu SerAlaAla AlaThr AlaValAla SerSer SerGluGln ProValGlu ThrSerSer GluPro AlaGlySer SerGln SerValGlu SerSerGln ProAlaGlu ThrSer SerSerGlu ProAla GluThrSer SerSerGlu ProAlaGlu ThrSer SerGluThr SerSer GluGlnPro AlaSerSer GluProAla GluThr SerSerGlu GluSer SerThrIle ThrSerAla ProSerThr ProGlu AspAsnPro TyrThr IleTyrPro SerValAla LysThrAla SerIle AsnGlyPhe AlaAsp ArgIleTyr AspGlnLeu ProGluCys AlaLys ProCysMet Phe Gln Asn Thr Gly Val Thr Pro Cys Pro Tyr Trp Asp Thr Gly Cys Leu Cys Ile Met Pro Thr Phe Ala Gly Ala Ile Gly Ser Cys Ile Ala Glu Lys Cys Lys Gly Gln Asp Val Val Ala Ala Thr Ser Leu Gly Thr Ser Ile Cys Ser Val Ala Gly Val Trp Asp Pro Tyr Trp Met Val Pro Ala Asn Val Gln Ser Ser Leu Ser Ala Ala Ala Thr Ala Val Pro Ser Ser Ser Glu Gln Ser Val Glu Thr Ser Ser Glu Ser Ala Glu Ser Ser Gln Ser Val Glu Ser Ser Gln Pro Ala Glu Thr Ser Ser Glu Gln Pro Ser Glu Thr Ser Ser Glu Thr Ser Ser Gln Gln Leu Ser Ser Ile Thr Ser Ala Pro Asp Ser Ser Ala Thr Ser Ser Ser Ser Thr Thr Ser Thr Phe Ile Arg Thr Ala Ser Ile Asn Gly Phe Ala Asp Lys Leu Tyr Asp Gln Leu Pro Glu Cys Ala Lys Pro Cys Met Phe Gln Asn Thr Gly Ile Thr Pro Cys Pro Tyr Trp Asp Ala Gly Cys Leu Cys Val Met Pro Gln Phe Ala Gly Ala Ile Gly Ser Cys Val Ala Asp Ser Cys Lys Gly Gln Asp Ile Val Ser Val Thr Ser Leu Gly Thr Ser Val Cys Ser Val Ala Gly Val Asn Ala Pro Tyr Trp Met Leu Pro Ala Ser Val Lys Ser Ser Leu Ser Val Ala Ala Thr Ala Val Pro Thr Ser Asp Ser Ala Ser Glu Thr Ala Ser Gln Glu Pro Ser Glu Thr Ser Ser Glu Gln Pro Ser Glu Thr Ala Ser Gln Gln Pro Ala Glu Thr Ser Ser Glu Glu Ser Ser Thr Ile Thr Ser Ala Pro Ser Thr Pro Glu Asp Asn Pro Tyr Thr Ile Tyr Pro Ser Val Ala Lys Thr Ala Ser Ile Asn Gly Phe Ala Asp Arg Ile Tyr Asp Gln Leu Pro Glu Cys Ala Lys Pro Cys Met Phe Gln Asn Thr Gly Val Thr Pro Cys Pro Tyr Trp Asp Thr Gly Cys Leu Cys Ile Met Pro Thr Phe Ala Gly Ala Ile Gly Ser Cys Ile Ala Glu Lys Cys Lys Gly Gln Asp Val Val Ser Ala Thr Ser Leu Gly Thr Ser Ile Cys Ser Val Ala Gly Val Trp Asp Pro Tyr Trp Met Ile Pro Ala Asn Ala Gln Ser Ser Leu Asn Ala Ala Ala Thr Ala Val Ala Ser Ser Ser Glu Gln Pro Val Glu Thr Ser Ser Glu Ala Ala Glu Ser Ser Gln Asn Pro Ala Glu Ser Ser Ser Gln Gln Pro Ser Glu Thr Ala Ser Gln Glu Pro Ser Glu Thr Ser Ser Gln Glu Pro Ser Glu Ser Ser Ser Glu Gln Pro Ala Glu Thr Ser Ser Glu Glu Ser Ser Thr Ile Thr Ser Ala Pro Ser Thr Pro Glu Asp Asn Pro Tyr Thr Ile Tyr Pro Ser Val Ala Lys Thr Ala Ser Ile Asn Gly Phe Ala Asp Arg Ile Tyr Asp Gln Leu Pro Glu Cys Ala Lys Pro Cys Met Phe Gln Asn Thr Gly Val Thr Pro Cys Pro Tyr Trp Asp Thr Gly Cys Leu Cys Ile Met Pro Thr Phe Ala Gly Ala Ile Gly Ser Cys Ile Ala Glu Lys Cys Lys Gly Gln Glu Val Val Ser Val Thr Ser Leu Gly Ser Ser Ile Cys Ser Val Ala Gly Val Trp Asp Pro Tyr Trp Met Leu Pro Ala Asn Val Gln Ser Ser Leu Asn Ala Ala Ala Thr Ala Val Ala Thr Ser Asp Ser Ala Ser Glu Val Ala Ser Ala Ser Glu Ser Ala Ser Gln Val Pro Gln Glu Thr Ser Ala Ala Ser Ser Gln Ser Ala Asn Asn Ser Val Ala Ser Ala Ala Pro Ser Asn Ser Ser Val Ser Ala Ala Pro Ser Ser Asn Ser Ser Gly Val Pro Ala Ala Pro Ser Asn Asn Ser Ser Gly Ala Ser Val Val Pro Ser Gln Ser Ala Asn Asn Ser Ser Ala Ser Ala Ala Pro Ser Asn Asn Ser Ser Ser Ala Ile Ser Gly Ser Val Ala Pro Ser Ser Tyr Gly Asn Ser Thr Ile Ala Gln Pro Ser Thr Ser Thr Lys Ser Asp Ala Ala Ser Ile Thr Gly Pro Ile Thr Thr Asp Lys Val Ile Thr Asn Glu Ser Gly Ile Val Phe Thr Ser Thr Val Ile Ile Thr His Val Ser Glu Tyr Cys Asp Gln Thr Ser Ala Ala Ala Val Gln Ser Ser Ala Cys Glu Glu Gln Ser Ser Ala Lys Ser Glu Gln Ala Ser Ala Ser Ser Glu Gln Val Lys Val Ile Thr Ser Val Val Trp Cys Glu Ser Ser Ile Gln Ser Ile Glu Ser Val Lys Thr Ser Ala Glu Ala Ala His Lys Thr Glu Val Ile Ala Ser Cys Ala Ser Glu Leu Ser Ser Leu Ser Ser Ala Lys Ser Glu Ala Met Lys Thr Val Ser Ser Leu Val Glu Val Gln Lys Ser Ala Val Ala Lys Gln Thr Ser Leu Ala Ala Val Gln Ser Ser Ala Ala Ser Val Gln Leu Ser Ala Ala His Ala Gln Lys Ser Ser Glu Ala Val Glu Val Ala Gln Thr Ala Val Ala Glu Ala Ser Lys Ala Gly Asp Glu Ile Ser Thr Glu Ile Val Asn Ile Thr Lys Thr Val Ser Ser Gly Lys Glu Thr Gly Val Ser Gln Ala Thr Val Ala Ala Asn Thr His Ser Val Ala Ile Ala Asn Met Ala Asn Thr Lys Phe Ala Ser Thr Met Ser Leu Leu Val Ala Ser Phe Val Phe Val Gly Leu Phe Ile (2) INFORMATION FOR SEQ ID NO: 3:
(i) SEQUENCE CHARACTERISTICS:
(A) LENGTH: 4 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: peptide (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 3:
Thr Ser Ala Pro (2) INFORMATION FOR SEQ ID N0: 4:
(i) SEQUENCE CHARACTERISTICS:
(A) LENGTH: 6 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: peptide (ix) FEATURE:
(A) NAME/KEY: Modified-site (B) LOCATION:2 (D) OTHER INFORMATION:/note= "Xaa can either be Ala, Ser or Val"
(ix) FEATURE:
(A) NAME/KEY: Modified-site (B) LOCATION:6 (D) OTHER INFORMATION:/note= "Xaa can either be Glu or Gln"
(xi) SEQUENCE DESCRIPTION: SEQ ID NO: 4:

Pro Xaa Glu Thr Ser Xaa

Claims (20)

1. A nucleic acid sequence as set forth in SEQ ID
NO: 1.

2. A probe derived from the nucleic acid sequence of claim 1, said probe being hybridizable with a sample of a nucleic acid sequence of a patient for detecting CSA1 gene or its corresponding mRNA, said CSA1 gene, or its corresponding mRNA, when detected in said sample is indicative of said patient being infected with Candida albicans.

3. A primer pair derived from the nucleic acid sequence of claim 1 for amplifying CSA1 gene or its corresponding mRNA.

4. A protein encoded by the nucleic acid sequence of claim 1.

5. The protein of claim 4 having a sequence as set forth in SEQ ID NO:2.

6. The protein of claim 4 or 5, wherein said protein is a surface antigen of Candida albicans.

7. A vaccine against Candida albicans, said vaccine comprising the protein of claim 4, 5 or 6, or an immunizing fragments thereof, in combination with a pharmaceutically acceptable excipient.

8. Use of a protein as defined in claim 4, 5 or 6 for the manufacture of a vaccine for the treatment or prophylaxis of Candida albicans infection.

9. A diagnostic kit for detecting Candida albicans infection in a sample of a nucleic acid sequence of a patient, said kit comprising the nucleic acid sequence of claim 1, or a fragment thereof capable of hybridizing with CSA1 gene of Candida albicans, or its corresponding mRNA.

10. A diagnostic kit for detecting Candida albicans infection in a nucleic acid sample of a patient, said kit comprising the probe of claim 2 or the primer pair of claim 3.

11. Use of the diagnostic kit of claim 9 or 10, for detecting Candida albicans infection in a nucleic acid sample from a patient.

12. Use of the nucleic acid sequence of claim 1 for detecting upon hybridization with a sample of nucleic acid sequence the presence of CSA1 gene of Candida albicans, or its corresponding mRNA, in the sample.

13. Use of the probe of claim 2 for detecting upon hybridization with a sample of a nucleic acid sequence the presence of CSA1 gene of Candida albicans in said sample.

14. Use of a primer pair as defined in claim 3 for detecting by polymerase chain reaction (PCR) CSA1 gene from Candida albicans, or its corresponding mRNA, in a sample, wherein detection of an amplified fragment with said primer is indicative of said sample being infected with Candida albicans.

15. An antibody directed against the protein of claim 4, 5 or 6 for treating a Candidal infection, wherein said antibody binds to the protein for masking same and thereby reducing virulency of the Candidal infection.

16. The antibody of claim 15, wherein said antibody is a polyclonal antibody.

17. The antibody of claim 15, wherein said antibody is a monoclonal antibody.

18. The antibody of claim 17, wherein said antibody is MAb 4E1 monoclonal antibody.

19. Use of an antibody as defined in claim 15, 16, 17 or 18 for treating a Candidal infection, wherein said antibody binds to the protein for masking same and thereby reducing virulency of the Candidal infection.

20. Use of an antibody as defined in claim 15, 16, 17 or 18 for the manufacture of a medicament for treating a Candidal infection, wherein said antibody binds to the protein for masking same and thereby reducing virulency of the Candidal infection.