ARS | Publication request: DEVELOPMENT OF A VACCINE AGAINST NEOSPOROSIS: TESTING OF NEOSPORA CANINUM ANTIGENS IN A CONGENITAL MOUSE MODEL

Submitted to: American Association of Veterinary Parasitologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 1999
Publication Date: N/A

Technical Abstract: Neospora caninum (Nc) is a cyst-forming coccidian that was first identified as causing neurologic disease in canines and now appears to be a significant cause of reproductive failure in dairy cattle worldwide. The goal of our research is to develop a vaccine for preventing neontal death and abortion by blocking vertical and horizontal transmission of the parasite to susceptible animals. A mouse model of congenital bovine neosporosis was developed such that pregnant dams inoculated with Nc tachyzoites produce offspring infected with Nc as demonstrated by a quantitative-competitive PCR (QC-PCR) assay. Our research showed that infection of pregnant BALB/c mice with Nc tachyzoites at gestation days 11-13 resulted in a highly reproducible infection rate of pups. This mouse model was used to assess the vaccine efficacy of native and recombinant (NCDG1 & NCDG2) Neospora tachyzoite antigens. Dissimilar to adjuvant-immunized controls, neonates born of mothers immunized with nativ tachyzoite antigen 4-6 wks prior to Nc tachyzoite challenge showed no discernable Nc DNA as measured by QC-PCR. Only partial protection against congenital transfer was observed in offspring of dams immunized with recombinant NCDG1& NCDG2 antigens. The protection results in the dams was inconclusive. These results suggest that immunization with native Nc tachyzoite antigen can protect against vertical transmission of the parasite and provide a basis for developing a vaccine derived from recombinant DNA-expressed proteins.