Submitted to: Journal of Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/12/1999
Publication Date: N/A
Citation: Interpretive Summary: Neosporosis is a parasitic disease that appears to be a major cause of abortion and neonatal morbidity in dairy cattle in the U.S.A. and worldwide. Congenital transmission of the causative organism, Neospora caninum, to the fetus most commonly results in abortion. Infected calves are also born which may appear clinically normal or display a range of neurological defects from mild to complete paralysis and death. 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. Thus, prevention of congenital transmission is crucial to limiting economic losses in cattle incurred through neosporosis. Vaccination with native or recombinant N. caninum antigens may be one approach to prevent the spread infection in bovines and other hosts. The present study was conducted to develop a small animal model for neosporosis that can be used to conduct vaccine efficacy trials prior to testing in bovines. As an integral part of this process we have also evaluated and applied a sensitive molecular technique for detecting Neospora in animal tissues.
Technical Abstract: Aspects of neosporosis, including congenital transmission, have been shown to occur in mice. In this report we confirm vertical transmission in BALB/c mice. A Neospora-specific PCR assay was evaluated a means of detecting N. caninum transmission to offspring. BALB/c mice were infected with the NC-1 isolate of N. caninum during pregnancy (days 8- 15 gestation). Transmission nof parasite, detected by PCR, was determined in offspring from 2 days to 2 days old. The tissue locations of parasites in congenitally infected pups of different ages was also determined. Reproducible N. caninum infections were achieved and measured in offspring using the PCR technique. We report a high rate of successful pregnancies accompanied by a higher rate of parasite transfer to offspring than previously reported. The protocol of infection of dams and detection of parasite in offspring described may be useful in the evaluation of candidate vaccines against N. caninum infection nand/or congenital transmission.