Submitted to: Infection and Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/1994
Publication Date: N/A
Interpretive Summary: Babesiosis, is a serious tick transmitted disease of cattle. The disease is caused by a protozoal (one-celled animal) parasite that invades red blood cells, where it divides at the expense of the blood cell. The disease occurs primarily in the subtropical regions of the world. The disease occurs in Mexico, remains a threat to reintroduction into the southern U.S., and plays a significant economic role in the U.S./Mexico cooperative cattle industry. One of the goals is to develop a safe vaccine that can be administered to cattle before they are shipped into an endemic area. Research efforts have focused, over the past 10 years, or so, on identifying proteins associated with the parasite that, when used as a vaccine, would result in the formation of specific antibodies in cattle that would prevent the parasite from invading the red blood cells. Several proteins have been identified that induce a good antibody response, and one eof them was used, in this study, as a vaccine. Antibody specific for this protein was shown to slow the invasion process in cultures grown in the laboratory. However, when inoculated into cattle, the animals were not protected against infection with the Babesia organisms despite their antibody response to the protein. The study suggests that protection does not necessarily correlate with the production of antibody, at least with specificity for this particular protein.
Technical Abstract: Cattle immunized with a recombinant merozoite surface antigen-1 molecule (MSA-1) produced high-titered antibody that reacted with the surface of the parasite and neutralized merozoite infectivity in vitro. However, recombinant MSA-1 immunization did not confer protection against challenge with virulent Babesia bovis. These results indicate that antibody-mediated dneutralization of merozoite infectivity in vitro, at least for MSA-1 specific antibody, does not reflect in vivo protective immunity to babesiosis.