GENOTYPIC AND PHENOTYPIC CHARACTERIZATION OF CRYPTOSPORIDIUM-PARVUM ISOLATES FROM PEOPLE WITH AIDS

Genotypic analysis of Cryptosporidiun parvum has demonstrated the pres ence of two subgroups within the species, whereas biochemical and anti genic characterization have shown more heterogeneity. The clinical rel evance of these observations is unknown. C. parvum isolates from peopl e with AIDS were studied with respect to parasite genotypes and virule nce in cell monolayers and laboratory animals. Ten elf 13 oocyst sampl es had a characteristic human-associated (H) genotype; 3 had a genotyp e typic;il of calf-excreted oocysts (C), Virulence in cell culture was mildly or markedly lower in the 5 isolate:; tested (4 H and 1 C) comp ared with the GCH1 reference isolate, H isolates did not infect newbor n ICR mice, whereas 1 of the 2 C isolates tested did. These findings r einforce the concept of C. parvum genetic subgroupings that correlate to some extent with infectivity and suggest that additional heterogene ity is present within the subgroups.