DISCRIMINATION OF NEOSPORA-CANINUM FROM TOXOPLASMA-GONDII AND OTHER APICOMPLEXAN PARASITES BY HYBRIDIZATION AND PCR

Neospora caninum is a protozoan parasite which causes neurological pro blems in dogs and abortion in cattle. As N. caninum is difficult to di stinguish morphologically from Toxoplasma gondii, we developed a molec ular tool capable of discriminating between the two parasites. Genomic DNA was isolated from in vitro cultured N. caninum tachyzoites and cl oned into a plasmid vector. Resulting colonies were subsequently scree ned by differential hybridization using N. caninum and T. gondii DNA. Two clones were characterized in detail: one clone, termed pNc5, was f ound to be specific for N. caninum whereas the second clone, pNc1, hyb ridized with DNA from both parasites. The sequence of pNc5 was determi ned and different oligonucleotide primers were designed for use in the polymerase chain reaction (PCR). A 944 bp fragment was specifically a mplified from N. caninum DNA, but not from DNA extracted from T. gondi i or different Sarcocystis species. Positive signals in PCR were obtai ned with as little as 100 pg parasite template DNA. In addition, dual PCR with primer pairs specific for N. caninum and T. gondii allowed th e detection of either parasite in mixed samples. (C) 1996 Academic Pre ss Limited