Abstract: Neospora caninum is the causal agent of bovine neosporosis which results in high levels of abortion. The protective efficacy of two Neospora antigens: Neospora cyclophilin (NcCyP) and NcSRS2 was evaluated. Mice vaccinated with recombinant (r) NcCyP, rNcSRS2, and the combination rNcCyP plus rNcSRS2, formulated with adjuvant ImmuMax-SR® and CpG were challenge-infected 3 weeks following the booster immunization and necropsied 3 weeks after the challenge infection. Mice vaccinated with rNcCyP, rNcSRS2, or the combination of rNcCyP and rNcSRS2 responded with high levels of NcCyP- or NcSRS2- specific antibodies. Mice which received vaccines formulated with either rNcCyP or the combination rNcCyP and rNcSRS2 had a higher (p<0.01) percent protection when compared to the mock- or non-vaccinated mice. Groups immunized with rNcSRS2 alone exhibited slightly lower levels of protection. Results indicate that NcCyP is a highly efficacious vaccine candidate useful in protection against Neospora infection.

Abstract: Neospora caninum is the causal agent of bovine neosporosis which results in high levels of abortion. The present study determined the protective efficacy of two Neospora antigens—Neospora cyclophilin (NcCyP) and NcSRS2. The ability of native NcCyP to upregulate mouse IFN? was also confirmed in this study. Recombinant NcCyP or NcSRS2 were tested either alone or in combination and formulated with adjuvant ImmuMax-SR and CpG. Female BALB/c mice (n=15) of 10-12 weeks of age were immunized s.c. twice in a 2-week interval with vaccines containing either NcCyP alone, NcSRS2 alone, NcCyP plus NcSRS2, or non-recombinant bacterial antigen (NR) in 2 separate trials. All mice were challenge-infected 3 weeks following the booster immunization and necropsied 3 weeks after the challenge infection. Brain and serum were collected and Nc-specific DNA sequence in brain tissue and antibodies in serum were analyzed by PCR or ELISA/Western blotting.