Recently, we cloned the moderately repetitive sequence Ca3 of Candida albicans and demonstrated that it could be used a s probe in Southern Blot hybridization to assess the genetic relatedness of C. albicans strains. In order to compare the Southern blot hybridization patterns of large numbers of strains, we developed a computer assisted, automated DNA fingerprint analyzing system, """"""""Dendron,"""""""" which automatically scans gels, calculates similarity coefficients (SAB's) between patterns of different strains, and generated dendrograms based on SAB values. Employing this system, we found in a pilot study that 60% of asymptomatic women carried C. albicans simultaneously in the mouth and vagina, that the strains in the two locations were genetically unrelated, and that in the half of the remaining cases, the strains were highly related but nonidentical, suggesting genetic divergence of a single strain. Over 80% of vaginal commensals clustered into 3 genetically related groups while on 39% of oral commensals clustered. These, as well as earlier studies of strain relatedness in a patient with recurrent infection, are the first to demonstrate at the genetic level that there is strong strain selection in the vagina, and that vaginotropic strains indeed exist. In this proposal, we have four specific aims. 1) We will finish sequencing Ca3, complete experiments to determine hoe the Ca3 Southern blot pattern evolves in order to develop more accurate calculations of genetic relatedness between strains and finish development of the Dendron system. 2) We will perform fingerprinting studies to answer a number of basic questions related to the origin of infecting strains. These studies will determine if the clusters of genetically intrarelated vaginotropic strains carried in asymptomatic vaginas are the source of vaginotropic strains causing disease, or if vaginotropic strains represent a separate, genetically intrarelated group. These studies will also determine if single strains when separated in different anatomical locations of the same individual undergo rapid genetic divergence. 3) We will investigate the hypothesis that high frequency phenotypic witching provides the phenotypic variability in a single strain for colonizing different anatomical locations. 4) Finally, we will determine if vaginal fluid and bacterial flora contribute to strain selection as well as Candida growth and hypha formation during carriage and infection. Our ultimate goal is to determine the roles of strain selection, high frequency switching and strain evolution in vaginal candidiasis.
