Submitted to: American Society of Parasitologists
Publication Type: Abstract Only
Publication Acceptance Date: April 30, 2004
Publication Date: July 10, 2004
Citation: Jenkins, M.C., Tuo, W., Dubey, J.P. 2004. Progress on developing a native recombinant vaccine against bovine neosporosis. Annual Meeting of American Society of Parasitologists, p. 84. Technical Abstract: Neosporosis is recognized worldwide as a major cause of reproductive failure in dairy cattle. Vaccination against neosporosis is being pursued because cattle that have been exposed to Neospora caninum prior to pregnancy exhibit lower abortion rates compared to naïve cattle. In our research, a mouse model of congenital neosporosis is being used to evaluate the vaccine efficacy of native and recombinant N. caninum antigens. In this model, complete protection against experimental tachyzoite infection of the fetus was achieved by vaccination of dams prior to pregnancy with whole N. caninum tachyzoite protein. Also, in recent studies only 40% of pups born from dams that were immunized with plasmid DNA (pCMV) coding for NcGRA7 antigen contained detectable N. caninum in brain and lung tissue. This level of protection was increased two-fold (20% positive) by the addition of CpG adjuvant to the pCMV-NcGRA7 preparation. Plasmid DNA injection appears to be necessary for protection because immunization with recombinant protein failed to prevent in utero tachyzoite transfer. Studies in sheep, as a ruminant model for dairy cattle, showed that while immunization with whole N. caninum had only a slight effect on congenital transmission, complete protection against fetal loss was achieved. Studies underway include the testing of multiple recombinant N. caninum antigens delivered by plasmid DNA injection with CpG adjuvant, the evaluation of this vaccination approach in sheep, and eventually in dairy cattle.