A dense granule protein (NCDG1) gene from Neospora caninum

Neosporosis is a parasitic disease caused by the protozoan Neospora caninum which appears responsible for almost half of bovine abortions in the US dairy industry. At present, the complete life cycle of N. caninum is unknown primarily because the definitive host (i.e. host in which sexual development of the parasite occurs) has yet to be identified. Given the close relationship of N. caninum to Toxoplasma gondii, many investigators have postulated a carnivore to be the definitive host. It is clear that effective control of neosporosis will require the prevention of horizontal N. caninum transmission to cows by either removing sources of the parasite or vaccinating susceptible animals against infection. Vertical transmission of the parasite to neonates (i.e. congenital infection) may be minimized by first identifying and then removing infected cows from the breeding population. Although several serological methods are available to diagnose the disease, each technique requires preparation of antigen from cultured tachyzoites. Our research group has identified two cDNA clones from N. caninum tachyzoites which express recombinant antigens in Escherichia coli that can be used to detect antibodies (Ab) by enzyme-linked immunosorbent assay to N. caninum in infected cows. The present study was conducted to investigate the expression of one of these cDNAs and examine the distribution of the encoded native protein in tachyzoites.