Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2003
Publication Date: 8/3/2003
Citation: Liddell, S., Parker, C.C., Vinyard, B.T., Jenkins, M.C., Dubey, J.P. 2003. Immunization of mice with plasmid dna coding for ncgra7 or ncshsp33 confers partial protection against vertical transmission of neospora caninum. Journal of Parasitology. 89:496-500. Interpretive Summary: Neosporosis is a major cause of abortion in dairy cattle caused by the protozoan parasite Neospora caninum. Abortion is a direct result of infection of the fetus by the parasite during particular stages of pregnancy. One method of preventing neosporosis is to vaccinate cows with proteins derived from the parasite. Mice have been used as a model for neosporosis because vaccination studies in cows are expensive. In the present study, mice were immunized with DNA coding for a N. caninum protein. These mice were then challenged with N. caninum during pregnancy. Unlike control mice, the offspring of vaccinated mice were found to either be free or have low levels of N. caninum. This study indicates that vaccination with a specific N. caninum protein can confer partial immunity against neosporosis. Future studies will test the vaccine in large ruminants, such as sheep or dairy cattle for similar effects.
Technical Abstract: The purpose of the present study was to use direct plasmid DNA injection to identify specific antigens that confer protection against congenital transfer of Neospora caninum. Inbred BALB/c mice were vaccinated prior to pregnancy with a recombinant plasmid containing sequences encoding N. caninum antigens NcGRA7 or NcsHSP33. The mice were challenged with N. caninum tachyzoites at 10¿12 days of gestation. Whereas 100% of pups born from dams immunized with control plasmid contained detectable levels of N. caninum DNA in a Neospora-specific PCR assay, only 46% of pups from pCMVi-NcGRA7-immunized mice and 53% of pCMVi-NcsHSP33-immunized mice were N. caninum positive, and none of the mice immunized with tachyzoite extract contained N. caninum DNA. Thus, immunization of mice with plasmid DNA expressing N. caninum antigens conferred partial protection against congenital neosporosis.