New PCR primer pairs specific for Cryptococcus neoformans serotype A or B prepared on the basis of random amplified polymorphic DNA fingerprint pattern analyses

Thirty-three strains of Cryptococcus neoformans were isolated from clinical specimens, including specimens from AIDS patients in Brazil, and were clas sified into two serotypes; we detected 31 and 2 strains of serotypes A and B, respectively. Random amplified polymorphic DNA (RAPD) fingerprint patter n analyses of these strains of serotypes A and B showed that the patterns w ere similar for strains of each serotype when three 10-mer primers were use d as the RAPD primers. Comparative studies of the fingerprint patterns of t he study isolates with those of the reference strains also showed that the RAPD patterns for strains of each serotype were related and that most of th e fingerprint bands existed commonly for all strains of each serotype teste d. The common RAPD bands (an approximately 700-bp band for serotype A and a n approximately 450-bp band for serotype B) were extracted and the DNA sequ ences were determined. Using this information, we prepared two and one PCR primer pairs which were expected to be specific for C. neoformans serotypes A and B, respectively, Use of each PCR primer combination thus prepared fo r serotype A or B was 100% successful in identifying the respective C. neof ormans serotypes, including the 33 clinical isolates tested in the present study. Among these combinations, one for serotype A was found to amplify DN A from C. neoformans serotype B as well as serotype A. Serotype B-specific PCR primer pairs amplified DNA from not only serotype B strains but also fr om serotype C strains. The usefulness of other serotype-specific PCR primer s for clinical C. neoformans isolates is discussed.