PCR-restriction fragment length polymorphism (RFLP) analyses reveal both extensive clonality and local genetic differences in Candida albicans

Using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method to obtain genotypes for the diploid pathogenic yeast, Can dida albicans, we analysed 204 C. albicans isolates from three populations of the Duke University community: two from clinical sources [one from patie nts infected with human immunodeficiency virus (HIV) and the other from pat ients without HIV infection], and the third from healthy student volunteers . The results indicated: (i) extensive evidence for clonality within and be tween populations of C. albicans; and (ii) greater genotypic and gene diver sities in the nonclinical population than those derived from clinical speci mens, regardless of HIV status. The two clinical populations were genetical ly more similar to each other than either was to the population consisting of isolates from healthy people. Within each population sample there was a general lack of heterozygotes, and random associations of alleles within an d between loci were found in less than 50% of the loci or pairs of loci. Th ese findings were consistent between the two sets of samples analysed: thos e including all isolates and those including only clone-corrected isolates. Possible mechanisms are presented to explain the observed patterns of gene tic variation within and between C. albicans populations.