Submitted to: American Association of Veterinary Parasitologists
Publication Type: Abstract only
Publication Acceptance Date: 4/30/2007
Publication Date: 7/14/2007
Citation: Higgins, J.A., Obrien, C.N., Abrahante, J., Abrahamsen, M., Fayer, R., Kniel, K., Jenkins, M.C. 2007. Intracellular levels of the viral symbiont CPV in Cryptosporidium parvum correlate with fecundity of the parasite in dairy calves. American Association of Veterinary Parasitologists, July 14-18, 2007, Washington, D.C. Interpretive Summary:
Technical Abstract: Previous reports have cited differences in clinical signs and oocyst output among strains of Cryptosporidium parvum. The purpose of this study was to determine if levels of the C. parvum intracellular viral symbiont CPV correlated with observed clinical and parasitological differences. Calves infected with C. parvum Beltsville strain oocysts produced ten-fold total greater numbers of oocysts than calves infected with C. parvum Iowa strain oocysts (P = 0.05). At each day post-infection (days 4-10) mean oocyst production was greater in C. parvum Beltsville-infected calves compared to C. parvum Iowa-infected calves. This increased fecundity was correlated with levels of CPV as measured by real-time RT-PCR using CPV RNA-specific primers. In 5 replicates, the CPV:rRNA RT-PCR ratio in C. parvum Beltsville oocysts was 3-4 fold greater than in C. parvum Iowa oocysts. The greater CPV signal in C. parvum Beltsville relative to C. parvum Iowa was corroborated with fluorescence intensity of sporozoites from each strain labeled with antibodies to CPV 40 kDa capsid protein. These findings suggest that the viral symbiont CPV has an effect on oocyst fecundity and consequently might affect the severity of infection.