Submitted to: Molecular and Cellular Probes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 13, 1995
Publication Date: N/A
Interpretive Summary: Neospora caninum is a recently discovered single-celled parasite of livestock and companion animals. It causes abortion and neonatal mortality in cattle and other animals. Its life cycle and sources of infection are unknown. Diagnosis of neosporosis is sometimes difficult because of close similarities to another parasite, Toxoplasma gondii. Scientists at the Beltsville Agricultural Research Center and the University of Berne, Switzerland report a Neospora specific gene clone pNc5 that should be useful for the development of a PCR (polymerase chain reaction) - based diagnostic test for neosporosis. The results will be of use to veterinary pathologists and diagnosticians.
Neospora caninum is a protozoan parasite which causes neurological problems in dogs and abortion in cattle. As N. caninum is difficult to distinguish morphologically from Toxoplasma gondii, we developed a molecular tool capable of discriminating between the two parasites. Genomic DNA was isolated from in vitro cultured N. caninum tachyzoites and cloned into a plasmid vector. Resulting colonies were subsequently screened by differential hybridization using N. caninum and T. gondii DNA. Two clones were characterized in detail: one clone, termed pNc5, was found to be specific for N. caninum whereas the second clone, pNc1, hybridized with DNA from both parasites. The sequence of pNc5 was determined and different oligonucleotide primers were designed for use in the polymerase chain reaction (PCR). A 944 bp primer were designed for use in the polymerase chain reaction (PCR). A 944 bp fragment was specifically amplified from N. caninum DNA, but not from DNA extracted from T. gondii or different Sarcocystis species. Positive signals in PCR were obtained with a little as 100 pg parasite template DNA. In addition, dual PCR with primer pairs specific for N. caninum and T. gondii allowed the detection of either parasite in mixed samples.