DEVELOPMENT OF A POLYMERASE CHAIN-REACTION ASSAY FOR THE DIAGNOSIS OFNEOSPOROSIS USING THE NEOSPORA-CANINUM-14-3-3 GENE

Neospora caninum is a recently described apicomplexan parasite which c auses neuromuscular disease in dogs, and abortion and neonatal morbidi ty in cattle, sheep and horses. Morphological similarites and serologi cal cross-reactivity between N. caninum and the closely related parasi te Toxoplasma gondii, have resulted in the frequent misdiagnosis of ne osporosis as toxoplasmosis. This report describes the isolation and ch aracterization of an N. caninum cDNA clone encoding a 14-3-3 protein h omologue. The 14-3-3 proteins are a class of proteins which show a hig h degree of amino acid sequence conservation across several eukaryotic taxa. Using less conserved regions of the N. caninum cDNA clone, nest ed primers were designed for the amplification of a 614-bp N. caniman DNA fragment by the polymerase chain reaction (PCR). The DNA fragment was amplified from N. caninum genomic DNA, but not from T. gondii, Sar cocystis muris, Sarcocystis tenella, or Sarcocystis cruzi genomic DNA. Additionally, the fragment was amplified from DNA prepared from the b rains of N. caninum-infected mice, but not from the brain of a mouse i nfected with T. gondii. These results suggest that this PCR assay may be useful for the diagnosis of neosporosis.