Isolation, Identification, and Pathogenicity of Neospora caninum China Yanbian strain

Background: the aim of the study was to provide a point of reference to study the neospora caninum infections in china. methods: genome dna was extracted from the brains of aborted fetuses and specific pcr was performed with n. caninum nc5-targeted specific primers. fetal bovine brain tissues were homogenized and continuously cultured in vero cells with double antibodies. the medium was replaced at 2-d intervals and the state of cells was observed. results: a 608 bp nc5 gene band was detected by pcr amplification. after sequencing, the sequence of the sample shared 99.5% homology with genbank (af061249). brain homogenates were continuously cultured in vero cells for 34 d and n. caninum was found. the results of ifat and nc5 gene-based pcr detection were n. caninum-positive, and the parasite was tentatively named n. caninum china yanbian strain. babl/c mice were inoculated with the separated parasites and showed clinical symptoms of ataxia and limb paralysis after 12 d. only 3 mice survived. the blood of dying mice and the hearts, livers, spleens, lungs, kidneys, and brains of dead mice were collected aseptically. the nc5 gene-based pcr showed that n. caninum may exist in brains, livers, and spleen. based on immunohistochemical observations, we showed that n. caninum tachyzoites existed in the brains and livers. conclusion: we have successfully isolated bovine-specific n. caninum strain from brain tissues of aborted cattle in the china yanbian region. this isolated strain has a strong infectious ability towards babl/c mice.