Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 12, 2004
Publication Date: March 8, 2004
Citation: Jenkins, M.C., Soares, R., Murphy, C.A., Hemphill, A., O'Handley, R., Dubey, J.P. 2004. Localization of a 56 kda antigen that is present in multiple developmental stages of neospora caninum. Journal of Parasitology. 90:660-663.
Interpretive Summary: Neosporosis is a parasitic disease of many species of domestic animals caused by the protozoan Neospora caninum. In cows, the parasite can be transmitted to the fetus via the placenta and cause a variety of clinical effects including abortion. Calves born from Neospora-infected cows may exhibit neurological symptoms and die within one week after birth or may be infected with the parasite and show no clinical signs of disease. There is an urgent need control transmission of the Neospora to offspring by either identifying cows infected with the parasite and/or treating infected cows by vaccination or drug therapy. The present study describes a protein associated with internal structures of N. caninum tachyzoites. The recombinant form of the protein was produced by cloning the gene in Escherichia coli. Antiserum was then prepared against the recombinant protein and was used to localize the protein by electron microscopy. The protein appears to be excreted by the parasite during cell invasion and thus may be a candidate antigen for a vaccine against neosporosis.
The purpose of the present study was to characterize the intracellular distribution of a native Neospora caninum 56 kDa protein that is recognized by sera from
N. caninum-infected dairy cattle. The cDNA coding for this protein was expressed in Escherichia coli as a polyHis fusion protein, to which antiserum was prepared and used to localize the antigen in N. caninum tachyzoites and bradyzoites. By SDS-PAGE/
immunoblotting, anti-recombinant Nc56 serum recognized a major 56 kDa protein and 2 minor (43, 39 kDa) proteins of N. caninum tachyzoites. Antiserum to recombinant 56 kDa protein showed this antigen to be present in both N. caninum tachyzoites and bradyzoites/cysts as detected by immunofluorescence staining. Immunoelectron microscopy revealed the 56 kDa antigen to be present in the apical end of both tachyzoites and bradyzoites, and possibly extracellularly secreted by tachyzoites