My laboratory is interested in the biology and molecular biology of medically important fungi. The fungus that we spend the most time studying is Cryptococcus neoformans, a basidiomycetous yeast that is closely related to mushrooms and a number of plant pathogens. C. neoformans is ubiquitous in the environment and is found globally. Infections typically occur via a pulmonary route after spores or yeast cells are inhaled. Once the lung is colonized, the fungus can remain there or disseminate to other parts of the body. A wide variety of mammals are susceptible to C. neoformans infections. In humans, the most frequent manifestation of infection is meningitis. Typically, immunosuppressed individuals are at the highest risk for infection although the fungus can infect healthy individuals. AIDS patients are at greatest risk for cryptococcosis, with 5-10% infected at the peak of the epidemic. In undeveloped countries, the number can be as high as 30%. If untreated, cryptococcosis is almost 100% fatal.
Our major interest in C. neoformans concerns the role that mating plays in virulence. The fungus is heterothallic with a bipolar mating system containing two mating types, MATα and MATalpha. In nature, MATalpha cells significantly out number MATα cells in population surveys. This bias is also reflected in clinical isolates where MATα cells are rarely isolated from patients. Studies in our laboratory have shown that MATalpha cells are more virulent than MATα cells. In addition, we and others, have found that a number of genes that are required for fertility are also required for virulence of the organism. More importantly, a number of genes that are involved in mating also control certain aspects of fungal morphology. Since it still remains unclear as to what morphology is responsible for infections researchers will continue to dissect the mating pathway and other pathways that regulate fertility and development.
A second fungus that we work with in our laboratory is Candida albicans. C. albicans is an ascomycete, which is closely related to the model yeast, Saccharomyces cerevisiae. This fungus is the most important and most frequently isolated human fungal pathogen. It is capable of infecting virtually every site in the body and although C. albicans is a normal commensal of humans and other mammals, infections can be life threatening. Our specific interests in C. albicans concern its ability to form biofilms. C. albicans can form biofilms on virtually any implantable device. Similar to bacterial biofilms, once a C. albicans biofilm is formed, it is virtually impossible to treat with antibiotics, consequently the device must be removed, sometimes at great expense or risk. We are interested in the mechanisms that underlie biofilm formation and are presently using microarrays to search for genes required for biofilm formation. We are also interested in the genetic basis for the increased drug resistance of cells that are growing in the biofilm phenotype. The use of microarrays to study C. albicans biofilms has allowed us to identify a number of genes that are only expressed when cells grow as a biofilm. The genes are currently being disrupted in order to study their effect on the ability of the strain to form a biofilm as well as any change in antifungal susceptibility.
A third fungus that we work with is Aspergillus fumigatus. A. fumigatus is a ubiquitous fungus that grows exclusively in a mold-like or filamentous morphology. The fungus is classified as an ascomycete and is related to Aspergillus nidulans and Neurospora crassa, two model filamentous fungi. Although A. fumigatus is one of the most common fungi that humans encounter, it poses little problems for healthy people. However, for certain types of immunosuppressed patients, infections can be fatal. In fact, we perform a number of epidemiological studies on A. fumigatus because it is a frequent cause of outbreaks in hospitals. The fungus is particularly dangerous for patients undergoing bone marrow transplantations since infections have a very low cure rate and can be uniformly fatal. We perform studies to determine the relatedness of populations of strains recovered from outbreaks using a variety of fingerprinting techniques.
Lastly, we have recently begun to collaborate on a regular basis with the Fungus Testing Laboratory in the Dept. of Pathology here at UTHSCSA. Our interactions with the FTL are through Deanna Suttton, Annette Fothergill, and Mike Rinaldi, and concern the molecular identification and epidemiology of unknown isolates that come into the FTL. We use rDNA sequencing to help identify unknown organisms and use a variety of techniques to study the relatedness of isolates that may be involved in outbreaks.
2. Kwon-Chung, K.J., B.L. Wickes, and W.L. Whelan. 1987. Ploidy and DNA content of Candida stellatoidea.
Infect. Immun. 55:3207-3208.
3. Kwon-Chung, K.J., B.L. Wickes, and W.G. Merz. 1988. Association of electrophoretic karyotype of Candida stellatoidea with virulence for mice. Infect. Immun. 56:1814-1819.
4. Kwon-Chung, K.J., W.S. Riggsby, R.A. Uphoff, J.B. Hicks, W.L. Whelan, E. Reiss, B.B. Magee, and B.L.
Wickes . 1989. Genetic differences between Type I and Type II Candida stellatoidea.
Infect. Immun. 57:527-532.
5. Kwon-Chung, K.J., B.L. Wickes, and J. Plaskowitz. 1989. Taxonomic clarification of Cladosporium trichoides Emmons and its subsequent synonyms. J. Med. Vet. Mycol. 27:413-426.
6. Kwon-Chung, K.J., B.L. Wickes, I.F. Salkin, H.L. Kotz, and J.D. Sobel. 1990. Is Candida stellatoidea disappearing from the vaginal mucosa? J. Clin. Mic. 28:600-601.
7. Wickes, B.L., J.E. Golin, and K.J. Kwon-Chung. 1991. Chromosomal rearrangement inCandida stellatoidea results in a positive effect on phenotype. Infect. Immun. 56:1762-1771.
8. Wickes, B.L., J. Staudinger, B.B. Magee, K.J. Kwon-Chung, P.T. Magee, and S. Scherer. 1991. Candida albicans: Several genes previously assigned to chromosome 1 map to chromosome R, the rDNA-containing linkage group. Infect. Immun. 59:2480-2484.
9. Kwon-Chung, K.J., J.C. Edman, and B.L. Wickes. 1992. Genetic association of mating types and virulence in Cryptococcus neoformans. Infect. Immun. 60:602-605.
10. Kwon-Chung, K.J., B.L. Wickes, L. Stockman, G.D. Roberts, D. Ellis, and D.H. Howard. 1992. Virulence, serotype, and molecular characteristics of environmental strains of Cryptococcus neoformans var. gattii. Infect. Immun. 60:1869-1874.
11. Wickes, B.L., J.B. Hicks, W.G. Merz, and K.J. Kwon-Chung. 1992. The molecular analysis of synonymy within the genus Candida. J. Gen. Mic. 138:901-907.
12. Lehmann, P.F., U. Khazan, L.C. Wu, B.L. Wickes, and K.J. Kwon-Chung. 1992. Karyotype and isozyme profiles do not correlate in Kluyveromyces marxianus var. marxianus. Mycol. Res. 96:637-642.
13. Wickes, B.L., T.D.E. Moore, and K.J. Kwon-Chung. 1994. Comparison of the electrophoretic
karyotypes and chromosomal location of ten genes in the two varieties of Cryptococcus
neoformans. Microbiol. 140:543-550.
14. Wickes, B.L., and J.C. Edman. 1995. The Cryptococcus neoformans GAL7 gene and its use as an inducible promoter. Molec. Microbiol. 16:1099-1109.
15. Chang, Y.C., B.L. Wickes, and K.J. Kwon-Chung. 1995. Further analysis of the CAP59 locus of Cryptococcus neoformans: structure defined by forced expression and the description of a new ribosomal protein gene. Gene 167:179-183.
16. Wickes, B.L., U. Edman, M.E. Mayorga, and J.C. Edman. 1996. Dimorphism in Cryptococcus neoformans: Association with the a - mating type. Proc. Natl. Acad. Sci. USA 93:7327-7331.
17. Wickes, B.L., U. Edman, and J.C. Edman. 1997. The Cryptococcus neoformans STE12 a gene: A
putative SaccharomycescerevisiaeSTE12 homolog that is mating-type specific.
Molec. Microbiol. 26:951-960.
18. Chang, Y.C., B.L. Wickes, G.F. Miller, L. Penoyer, and K.J. Kwon-Chung. 2000 . A MAT a specific gene of
C. neoformans , STE1 2 a , regulates virulence and is essential for monokaryotic fruiting.
J. Exp. Med. 91:871-881.
19. Chaturvedi, S., B. Rodeghier, J. Fan, C.M. McClelland, B.L. Wickes, and V. Chaturvedi. 2000. Direct PCR
of Cryptococcus neoformans MAT a and MATa pheromones to determine mating type, ploidy, and variety: a
tool for epidemiological and molecular pathogenesis studies. J. Clin. Mic. 38:2007-2009.
20. Karos, M., Y.C. Chang, C.M. McClelland, D.L. Clarke, Fu, J.M., B.L. Wickes, and K.J. Kwon-Chung.
2000 . Mapping of the Cryptococcus neoformans MAT a locus: Presence of a cluster of mating type
specific pheromone response MAP kinase cascade homologs. J. Bact. 182:6222-227
21. Clarke, D.L., G.L. Woodlee, C.M. McClelland, T.S. Seymour, and B.L. Wickes. 2001. The
Cryptococcus neoformans STE11 a gene is alpha-specific and required for mating. Molec. Microbiol.
22. Ramage, G., Vande Walle, K., Wickes, B.L, and J.L. López-Ribot. 2001. A standardized method for
invitro antifungal susceptibility testing of Candida albicans biofilms. Ant. Ag. Chem. 45:2475-2479.
23. Ramage, G., Vande Walle, K., Wickes, B.L, and J.L. López-Ribot. 2001. Biofilm Formation by Candida dubliniensis. J. Clin. Mic. 39:3234-3240.
24. Viviani, M.A., Esposto, M.C., Cogliati, M., Montagna, M.T., and B.L. Wickes. 2001. Isolation of a
Cryptococcus neoformans serotype A MATa strain from the Italian environment.
J. Med. Mycol. 39:383-386.
25. Cogliati, M., Esposto, M.C., Clarke, D.L., Wickes, B.L., Viviani, M.A. 2001. Origin of Cryptococcus
neoformans var. neoformans diploid strains. J. Clin. Mic. 39:3889-3894.
26. Ramage, G., VandeWalle, K., Wickes, B.L., and J. L. López-Ribot. 2001. Characteristics of biofilm formation by Candida albicans. Rev. Iber. Mic. 18:163-170.
27. McClelland, C.M., Woodlee, G.L., Seymour, T. S., and B.L. Wickes. 2002. Isolation and characterization
of the Cryptococcus neoformans MATa pheromone gene. Genetics 160:935-947.
28. Perea, S., Lopez-Ribot, J.L., Wickes, B.L., Kirkpatrick, W.R., Dib, O., Bachman, S.P., Keller, S.M.,
Martinez , M., Patterson, T.F. 2002. Molecular mechanisms of fluconazole resistance in Candida
Dublinienisis isolates from HIV-infected patients with oropharyngeal candidiasis.
Ant. Ag. Chemother. 46:1695-1703.
29. Nucci, M., Akiti, T., Barreiros, G., Silveira, F., Revankar, S.G., Wickes, B.L., Sutton, D.A., and T.F.
Patterson. 2002. Nosocomial outbreak of Exophiala jeanselmei fungemia associated with contamination
Of hospital water. Clin. Infect. Dis. 34:1475-1480.
30. Ramage, G., S. P. Bachmann, B. L. Wickes, Patterson, T.F., and J. L. López-Ribot. 2002. Investigation of
multidrug efflux pumps in relation to fluconazole resistance in Candida albicans biofilms.
J. Antimicrob. Chemother. 49:973-980.
31. Chung, S., M. Karos, Y.C. Chang, J. Lukszo, B.L. Wickes, K.J. Kwon-Chung. 2002 . Molecular
analysis of CPR a , a MAT a specific pheromone receptor gene of Cryptococcus neoformans.
Euk. Cell 1:432-439.
32. Chatuverdi, V., J. Fan, B. Stein, M.J. Behr, B.L. Wickes, W.A. Samsonoff, and S. Chaturvedi. 2002. Characterization of Cryptococcus neoformans mating pheromones reveals divergent MF a 1 sequences among three varieties (five serotypes) and a conserved MATa sequence in serotype D (var. neoformans), and diploid A/D strains. Infect. Immun. 70:5225-5235.
33. Ramage, G., K. Vande Walle, S. P. Bachmann, B.L. Wickes and J. L. López-Ribot. 2002. In vitro
pharmacodynamic properties of three antifungal agents against preformed C. albicans biofilms determined by time kill studies. Ant. Mic. Ag. Chemo. 46:3634-3636.
34. Bachmann, S.P., K. Vande Walle, G. Ramage, T.F. Patterson, B.L. Wickes, J.R. Graybill, and J.L.
López Ribot. 2002. In Vitro interactions between Caspofungin and Candida albicans biofilms.
Ant. Mic. Ag. Chem. 46:3591-3596.
35. Ramage, G., K. Vande Wall, J.L. López-Ribot, and B.L. Wickes. 2002. The filamentation pathway controlled by the Efg1 regulator protein is required for biofilm formation and development in Candida albicans. FEMS Microbiol. Letts 214:95-100.
36. Ramage, G., S.P. Saville, B.L. Wickes, and J. L. López-Ribot. 2002. Inhibition of Candida albicans
biofilm formation by farnesol, a quorum sensing molecule. Appl. Environ. Mic. 68:5459-63.
37. Wickes, B.L. 2002. The role of mating type and morphology in Cryptococcus neoformans
Pathogenesis. Int. J. Med. Microbiol. 292:313-329.
38. Keller, S.M., M.A. Viviani, M.C. Esposto, M. Cogliati, and B.L. Wickes. 2003. Characterization of a Cryptococcus neoformans serotype A MATa strain. Microbiol. 149: 131-142.
39.Tscharke, T.L., M. Lazera, B.L. Wickes, and K. J. Kwon-Chung. 2003. . Haploid fruiting in Cryptococcus neoformans is not mating type alpha-specific. Fung. Genet. Biol. 39:230-237
40. Lutz, B.D., M.E. Tannehill, M.G. Rinaldi, J. Jin, B.L. Wickes, and M.M. Huycke. 2003. Outbreak of invasive Aspergillus infections in surgical patients due to a contaminated air-handling system. Clin. Infect. Dis. Clin. Infect. Dis 37:786-793.
41. Bachmann, S.P., G. Ramage, K. VandeWall, T.F. Patterson, B.L. Wickes, and J.L. Lopez-Ribot. 2003. Combination of Antifungal Agents Against Biofilms of Candida albicansIn Vitro. Ant. Ag. Chemo. 47 3657-3659.
42. Saracli, M.A., K. Sener, A. Gonlum, S.T. Yildiran, and B.L. Wickes. 2003. Genotyping of clinical Rhodotorula rubra isolates by pulsed field gel electrophoresis. Mycoses 46:487-491.
43. Ramage, G., K. Tomsett, B.L. Wickes, J.L. Lopez-Ribot, and S.W. Redding. 2004. Denture
stomatitis: a role for Candida biofilms. Oral Surg. Oral Med. Oral Surg. Oral Radiol. Endod. 98:53-59.
44. Jin, J., Lee, Y-K., and B.L. Wickes. 2004. A simple chemical extraction method for DNA isolation
from Aspergillus fumigatus and other Aspergillus Species. J. Clin. Mic. 42: 4293-4296
45. Revankar, S.G., J. Fu, M.G. Rinaldi, S.L. Kelly, D.E. Kelly, D.C. Lamb, S.M. Keller, and B.L. Wickes. 2004. Cloning and characterization of the lanosterol 14 a -demethylase ( ERG11 ) gene in Cryptococcus neoformans. Biochem. Biophys. Res. Commun. 324:719-28.
46. Moylett, E.H., J. Chinen, B.L. Wickes, Y.R. Shea, K.J. Kwon-Chung, and S.M. Holland. 2004.
Limitations of the Vitek Yeast Biochemical Card for the Identification of Basidiomycetous Yeasts. J. Allergy Clin. Immunol. 114:206.
47. Barchiesi F., M. Cogliati, A.M. Schimizzi, M.C. Esposto, B.L. Wickes, G. Scalise, and M.A. Viviani. 2005. Relationship between pathogenicity and mating type in Cryptococcus neoformans serotypes A, D and AD. J. Infection. (In Press)
48. Saracli M.A., S.T. Yildiran S.T., K. Sener, A. Gonlum, L. Doganci, S.M. Keller, and B.L. Wickes. 2005. Karyotyping of Turkish environmental Cryptococcus neoformans variety neoformans isolates by pulsed field gel electrophoresis. Mycopath. (In Press).
49. Liu, L., J. Ramos, J. Panepinto, X. Zhu, S. Elski, J. Fu, B.L. Wickes, and P. R. Williamson. 2005. Multiple virulence-associated genes are dependent on VAD1 in the human fungal pathogen, Cryptococcus neoformans. J. Clin. Invest. (In Press)
50. Loftus, B., et al . . 2005. The genome and transcriptome of Cryptococcus neoformans, a basidiomycete fungal pathogen of humans. Science (In Press)
C. RESEARCH SUPPORT (Current)
1R01AI54946-01 Period: 2/03-1/06
National Institute of Allergy and Infectious Disease
“Congenic strains from serotype A Cryptococcus neoformans”.
The major goal of this study is to prepare congenic strains of Cryptococcus neoformans and compare their virulence.
Role: Principle Investigator
R21 DE15079-01 Period: 8/1/03-7/31/05 (PI, Lopez-Ribot)
Agency: National Institute of Dental Research
“Analysis of the Candida albicans proteome”
The major goal of this study is to identify biofilm-specific proteins in Candida albicans
N01-AI-30041 Period: 9/03-8/10 (PI Patterson)
Agency: National Institute of Allergy and Infectious Diseases
“New animal models of invasive aspergillosis”
The major goal of this study is to develop and standardize multiple animal models of aspergillosis
RESEARCH SUPPORT (Completed last 3 years)
1R29 5R29AI43522-05 6/98-6/04
National Institute of Allergy and Infectious Disease
“Mating Type and Virulence in Cryptococcus neoformans”
Role: Principle Investigator
Identification of Mating Type Associated Antifungal Targets in Cryptococcus neoformans
Role: Principle Investigator