Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/1999
Publication Date: N/A
Interpretive Summary: Neospora caninum is a parasite which was first identified as causing neuromuscular paralysis and death in dogs. Neospora-like organisms have also been found in naturally infected cattle, goats, horses, deer and sheep. Neosporosis has become a widely recognized disease of cattle and appears to be a significant cause of abortion and neonatal morbidity in dairy cattle in the United States and world-wide. Transfer of the parasite to the fetus may result in abortion, stillbirth, delivery of a diseased calf that dies a few days after birth, or birth of an apparently normal, but infected calf. Infected dams and their congenitally infected offspring can transmit the parasite during subsequent pregnancies and vertical transmission appears to be a major route of infection within a herd. Another route of infection may be via foodstuffs contaminated by infective organisms found in fecal material of canids, the recently identified definitive host of the parasite. Prevention of parasite transmission is crucial to limiting economic losses in cattle incurred through neosporosis. Vaccination may be one approach to prevent the spread infection in bovines, canines and other hosts. The present study was conducted to investigate the effect of immunization with a complex mixture of N. caninum tachyzoite antigens on transmission of the parasite from experimentally infected mouse dams to their offspring. A sensitive molecular technique for detecting Neospora parasite DNA was utilized to detect the presence of N. caninum in the tissues of the offspring and the dams.
Technical Abstract: Neosporosis is a significant cause of abortion and neonatal morbidity in dairy cattle. The disease is caused by Neospora caninum, an intracellular protozoan parasite. Vertical transmission to the fetus is currently the only proven route of infection, although horizontal infection via the oocyst stage has been demonstrated experimentally. Vaccination may be one approach to prevent the spread infection in bovines, canines and other hosts. In this report, we describe the use of a mouse model of vertical N. caninum infection to evaluate candidate antigens as vaccines. Parasites present in the tissues of dams and offspring were detected using a Neospora caninum-specific PCR assay. Immunization of dams with a single inoculation of a crude lysate of tachyzoite antigens appeared to induce complete protection against infection of the offspring. The adults did not appear to be similarly protected against the challenge infection of N. caninum tachyzoites.