Submitted to: International Journal for Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/25/2005
Publication Date: 10/1/2005
Citation: Haldorson, G.J., Mathison, B.A., Wenberg, K., Conrad, P.A., Dubey, J.P., Trees, A.J., Yamane, I., Baszler, T.V. 2005. Immunization with native surface protein ncsrs2 induces a th2 immune response and reduces congenital neospora caninum transmission in mice. International Journal for Parasitology. 35:1407-1415. Interpretive Summary: Neospora caninum is a single-celled parasite. It causes abortion in cattle and paralysis in companion animals. It is the most important cause of abortion in dairy cattle. Dogs and coyotes are its definitive hosts and main reservoirs of infection. This parasite is transmitted efficiently from the cow to the calf transplacentally. Scientists at the Beltsville Agricultural Research Center and Washington State Univ. describe vaccination experiments in mice using a recombinant protein.The results will be of interest to biologists, parasitologists, and veterinarians.
Technical Abstract: NcSRS2, a tachyzoite surface protein of Neospora caninum, is an immunodominant protein with respect to induction of antibody production and has a role in attachment and invasion of host cells. Native NcSRS2 was isolated from whole tachyzoite lysate antigen by affinity chromatography using NcSRS2 specific monoclonal antibody and used to immunize BALB/c mice in a congenital transmission study. NcSRS2 was a highly conserved protein as indicated by comparison of deduced amino acid sequence obtained from NcSRS2 gene sequences of ten geographically distinct N. caninum isolates. Mice immunized with purified native NcSRS2 produced antigen-specific antibody, primarily of IgG 1 subtype. Following challenge during gestation with 107 tachyzoites, immunized mice had a statistically significant decreased frequency of congenital transmission compared to non-immunized mice (P < 0.05) or mice inoculated with adjuvant alone (P < 0.01). Decreased congenital transmission among immunized mice correlated with a predominately Th2 immune response compared to non-immunized mice as indicated by an increased ratio of interleukin 4 (IL-4) to interferon gamma (IFN-gamma) secretion from antigen- stimulated splenocytes. The results provide a rationale for NcSRS2 as a candidate subunit vaccine antigen for reduction of N. caninum congenital transmission. Furthermore, the studies suggest that a Th2 immune response, if directed against an appropriate antigen, may induce protection against N. caninum congenital infection in mice.