Submitted to: Experimental Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/1/1999
Publication Date: N/A
Citation: Interpretive Summary: Neospora caninum is a single-celled parasite of livestock and companion animals. It is a major cause of abortion in dairy cattle in many countries, including the U.S. The parasite is transmitted from the mother to the fetus and cows can become infected by the resistant stage (oocyst) of the parasite excreted in the feces of dogs. Little is known of immunity yto N. caninum in cattle and there is no vaccine or drugs to control neosporosis in cattle. Scientists at the Beltsville Agricultural Research Center and the Institute for Epidemiology and Virology in Wusterhausen, Germany have characterized monoclonal antibodies against selected proteins of N. caninum. These results will be useful to parasitologists and immunologists studying the biology of N. caninum.
Technical Abstract: Neospora caninum, a coccidian parasite closely related to Toxoplasma gondii, can infect broad host range and is regarded as an important cause of bovine abortion worldwide. In the present study four antigens of Neospora caninum were partially characterized using monoclonal antibodies. Immunofluorescence of viable tachyzoites as well as the immunoprecipitation nof antigens extracted from tachyzoites previously labeled by surface biotinylation revealed that three of these antigens with apparent molecular weights of 40, 38 and 19 kDa are located in the outer surface membrane of this parasite stage. Further evidence for the surface localization of the 38-kDa antigen was obtained by immunoelectron microscopy. In addition to the surface molecules, an antigen located in dense granules and the tubular network of the parasitophorous vacuole was detected by another monoclonal antibody. When tachyzoite antigens separated under non-reducing conditions swere probed on Western blots, this antibody reacted mainly with a 33-kDa antigen. Immunohistochemical analysis of infected tissue sections indicated that the 33-kDa dense granule antigen is present in both tachyzoites and bradyzoites while the 38-kDa surface antigen from tachyzoites seems to be absent in bradyzoites.