PRE-AIDS ERA ISOLATES OF PNEUMOCYSTIS-CARINII F SP. HOMINIS - HIGH GENOTYPIC SIMILARITY WITH CONTEMPORARY ISOLATES

Isolates of Pneumocystis carinii f. sp, hominis were examined from six individuals who died of P. carinii pneumonia between 1968 and 1981 an d who had underlying immunodeficiencies which were not due to human im munodeficiency virus infection. DNA sequence variation was analyzed in the genes encoding the mitochondrial large subunit rRNA (mt LSU rRNA) , the internal transcribed spacer (ITS) regions of the nuclear rRNA, t he arom locus, and the mitochondrial small subunit rRNA, No major vari ations were observed when these isolates were compared to isolates fro m HIV-infected individuals. A small number of minor differences were d etected, A new position at which variation occurred in the mt LSU rRNA was observed in one sample. Three new ITS sequence types were identif ied, A total of nine different ITS sequence types were found in the si x samples. Mixed infection with different ITS sequence types of P. car inii f. sp. hominis was observed in four of the six samples. The ITS l ocus was the most informative of the four loci for distinguishing amon g the isolates of P. carinii f. sp. hominis, The data suggest that iso lates of P. carinii f. sp. hominis from before the AIDS pandemic are g enetically very similar to those currently found in HN-infected indivi duals.