Vaccination with gamma-irradiated Neospora caninum tachyzoites protects mice against acute challenge with N. caninum.
Neospora caninum, an apicomplexan parasite, is a leading cause of bovine abortions worldwide. The efficacy of gamma-irradiated N. caninum strain NC-1 tachyzoites as a vaccine for neosporosis was assessed in C57BL6 mice. A dose of 528 Gy of gamma irradiation was sufficient to arrest replication but not host cell penetration by tachyzoites. Female C57BL6 mice were vaccinated with two intraperitoneal inoculations of 1 x 10(6) irradiated tachyzoites at 4-wk intervals. When stimulated with N. caninum tachyzoite lysates, splenocytes of vaccinated mice, cultured 5 and 10 wk after vaccination, secreted significant (P<0.05) levels of interferon gamma, interleukin (IL)-10, and small amounts of IL-4. Antibody isotype-specific ELISA of sera from vaccinated mice exhibited both IgG1 and IgG2a isotypes of antibodies. Vaccinated mice were challenged intraperitoneally with 2 x 10(7)N. caninum tachyzoites. All vaccinated mice remained healthy and showed no obvious signs of neosporosis up to the 25th day post-challenge when the study was terminated. All unvaccinated control mice died within 1 wk of infection. Gamma-irradiated N. caninum tachyzoites can serve as an effective, attenuated vaccine for N. caninum.
Ramamoorthy
S
S
Department of Biomedical Sciences and Pathobiology, Virginia Tech, 1410 Prices Fork Road, Blacksburg, Virginia 24061-0342, USA.
Lindsay
D S
DS
Schurig
G G
GG
Boyle
S M
SM
Duncan
R B
RB
Vemulapalli
R
R
Sriranganathan
N
N
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D002417:Cattle; D003048:Coccidiosis / Q000469:parasitology / Q000473:pathology / Q000517:prevention & control*; D016207:Cytokines / Q000378:metabolism; D005260:Female; D005720:Gamma Rays; D051379:Mice; D008810:Mice, Inbred C57BL; D018688:Neospora / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity / Q000528:radiation effects; D016052:Protozoan Vaccines / Q000008:administration & dosage / Q000528:radiation effects; D013154:Spleen / Q000276:immunology; D014611:Vaccination; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000528:radiation effects
D000913:Antibodies, Protozoan; D016207:Cytokines; D016052:Protozoan Vaccines; D014613:Vaccines, Attenuated