ISOLATION OF SPECIFIC DNA PROBES FOR DETECTION OF CRYPTOCOCCUS-NEOFORMANS

We report the construction of a genomic library and isolation of repet itive DNA probes from Cr. neoformans that are species-and variety-spec ific. The inserts of the genomic library were in a range 0.3-1.8 kb, w hich were in normal distribution in length. Among 592 clones of the ge nomic library, there were 400(67.6%) clones inserted repetitive DNA se quence and 192(32.4%) inserted single copy DNA sequence of the Cr. neo formans genome. From the library, three specific probes were identifie d. Clone pCNIIA6 was serotype A-specific, pCNIIB5 species-specific, an d pCNIIIG1 variety-specific (var. neoformans). On the basis of the hig h specificity and sensitivity of the signals observed by hybridization , we suggest that these probes provide a means for both biotyping and early diagnosis of Cr. neoformans.