Submitted to: Coccidiosis International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/30/1997
Publication Date: N/A
Technical Abstract: Neospora caninum is a recently described protozoan parasite which infects a wide range of mammals. Originally identified as a cause of death and paralysis in dogs, the parasite has been identified as an important cause of abortion and neonatal mortality in dairy cattle worldwide. The only known route of infection is via congenital transmission to the foetus. We are developing a mouse model for congenital N. caninum infection so that candidate antigens can be evaluated as vaccines against neosporosis and vertical transmission of the parasite in cattle. In order to measure the effect of vaccine candidates or drugs on the transfer of the parasite to the offspring of N. caninum-infected mice, we have developed two N. caninum-specific, quantitative-PCR methods. The first of these was based on a cDNA clone, Nc4/Nc2, which was isolated by immunoscreening an N. caninum cDNA library with infected bovine sera (Lally et al 1996, Clin. Diag. Lab. Immunol. 3:275-279). The second PCR assay was based on an N. caninum- specific DNA sequence, Nc5, isolated in different screen from naturally infected dogs. Groups of female mice were infected at 10 days of gestation with N. caninum tachyzoites (NC-1 strain). Tissues from 1-2 day old pups were examined by PCR assay for the presence of parasite DNA. N. caninum was detected in lungs, brain and liver from pups born to infected mothers. The results from our initial studies demonstrate that congenital transfer of N. caninum can be achieved by innoculation of pregnant BALB/c mice with N. caninum tachyzoites, and that the PCR assays we have developed can be used to follow infection and quantify relative levels of the parasite in this system.