Cryptosporidium parvum is an important, poorly-understood protozoan parasite that causes refractory intestinal infection in HIV-infected persons. The clinical spectrum of cryptosporidiosis is broad, ranging from asymptomatic carriage to life-threatening diarrhea. Several small studies have suggested that clinical diversity is accompanied by genetic heterogeneity among different C. parvum isolates. The investigator will examine the correlation between the genotype and pathogenicity of C. parvum isolates using molecular genetic techniques. Isolates from a collection of stool samples and intestinal biopsies that have been previously collected will be studied. Genotypic data will be correlated with clinical information obtained from the infected patients.
The specific aims of this proposal are to: (1) identify genetic polymorphism of the C. parvum elongation factor-2 and actin genes in human isolates. DNA sequence variation of these genes will be detected by restriction fragment length polymorphism (RFLP) analysis of PCR-generated gene fragments. (2) characterize the ribosomal RNA genes from C. parvum. The small subunit (18s) ribosomal RNA genes from the AUCp-1 isolate of C. parvum will be cloned, sequenced and used to identify genetic polymorphism within rRNA genes from the C. parvum isolates. (3) correlate the genotype of C. parvum isolates with their clinical behavior and histology. (4) identify genotype-specific C. parvum oocyst mRNAs.
