Submitted to: International Journal for Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2007
Publication Date: 8/1/2008
Citation: Jenkins, M.C., Higgins, J.A., Brahante, J., Kniel, K., Obrien, C.N., Trout, J.M., Lancto, C., Abrahamsen, M., Fayer, R. 2008. Fecundity of Cryptosporidium parvum is Correlated with Intracellular Levels of the Viral Symbiont CPV. International Journal for Parasitology. 38:1051-1055. Interpretive Summary: Cryptosporidiosis is an intestinal parasitic disease of humans and calves caused by species of Cryptosporidium. The parasite is spread through a fecal-oral route of infection. Studies in humans and animals have shown differences in the virulence of strains of C. parvum. It remains unknown what factor is responsible for virulence of the parasite. In this study, it was shown that a strain of C. parvum which produces 5-fold greater numbers of parasites during an infection also possesses higher levels of an intracellular virus than another C. parvum strain that produces fewer oocysts. These findings suggest that the viral symbiont CPV affects the virulence of C. parvum oocysts.
Technical Abstract: Differences in the virulence and fecundity of Cryptosporidium parvum isolates have been observed by several researchers studying cryptosporidiosis. The purpose of the present study was to determine if there was a correlation between intracellular levels of the viral symbiont CPV in C. parvum and fecundity of two strains of the parasite, namely C. parvum Beltsville (B) and C. parvum Iowa (I). Dairy calves infected with 106 C. parvum-B secreted five-fold greater numbers of oocysts compared with calves infected with the same number of C. parvum-I oocysts. The increased fecundity of the former strain was corroborated by semi-quantitative PCR assay of DNA isolated from cell cultures infected with either C. parvum-B or C. parvum-I. Real-time RT-PCR analysis of viral RNA revealed a three-fold greater number of CPV in C. parvum-B compared to C. parvum-I oocysts. These findings may indicate a role for CPV in fecundity and possibly virulence of C. parvum.