IDENTIFICATION OF BOVINE NEOSPORA PARASITES BY PCR AMPLIFICATION AND SPECIFIC SMALL-SUBUNIT RIBOSOMAL-RNA SEQUENCE PROBE HYBRIDIZATION

Neospora is a newly recognized genus of pathogenic coccidia, closely r elated to Toxoplasma gondii, that can cause abortion or congenital dis ease in a variety of domestic animal hosts, On the basis of the small- subunit rRNA gene sequences of Neospora spp, and other apicomplexa coc cidia, oligonucleotide primers COC-1 and COC-2 were used for PCR ampli fication of conserved sequences of approximately 300 bp in size. A Neo spora-specific chemiluminescent probe hybridized to Southern blots of amplification products from Neospora DNA but not to Southern blots wit h amplified DNA from the other coccidian parasites tested, A Toxoplasm a-specific probe whose sequence differed from that of the probe for Ne ospora spp. by a single base pair was used to distinguish these parasi tes by specific Southern blot hybridization, The PCR system detected a s few as one Neospora tachyzoite in the culture medium or five tachyzo ites in samples of whole blood or amniotic fluid spiked with Neospora parasites. In addition, Neospora PCR products were successfully amplif ied from whole blood and amniotic fluid samples of experimentally infe cted bovine and rhesus macaque fetuses. These results indicate that th is PCR and probe hybridization system could be a valuable adjunct to s erology and immunohistochemistry for the diagnosis of Neospora infecti ons in bovine or primate fetuses.