Characterisation of the first Australian isolate of Neospora caninum from cattle

Miller, C.M.D., Quinn, H.W., Windsor, P.A., and Ellis, J.T. (2002) Characterisation of the first Australian isolate of Neospora caninum from cattle. Australian Veterinary Journal, 80 (10). pp. 620-625.

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Objective: To isolate Neospora caninum from a congenitally infected calf.

Procedure: A calf was obtained from a N caninum infected dam maintained in a dairy herd of Holstein-Friesian cattle located on the south coast of NSW near Nowra. The calf was euthanased and samples collected for serology and pathology. Samples of brain and spinal cord of the calf were homogenised and injected into immunocompromised mice in an attempt to recover protozoa by in vivo culture. Sequential passage of brain homogenate through IFNgR KO mice was performed and tissue culture flasks were inoculated with brain homogenate. Parasites were identified by electron microscopy and DNA sequencing. The antigen profile of the isolate was analysed using Western blotting. Pathogenicity was examined in BALB/c mice and transmission of the parasite during pregnancy was examined in Qs mice.

Results: The calf was seropositive for N caninum and histopathological examination of sections of cerebrum identified lesions consistent with a very mild infection with N caninum. The parasites isolated using tissue culture were identified as N caninum, based on the sequence of the ribosomal DNA and electron microscopy. The antigen profile of the new isolate was similar to that of the NC-Liverpool isolate, but quite different from that of Toxoplasma gondii. In BALB/c mice inoculated with the new isolate, severe clinical signs developed in only three of ten infected mice, compared with six of ten mice infected with NC-Liverpool. Mild to moderate nonsuppurative encephalitis was observed in BALB/c mice infected with the new isolate, compared with mice infected with NC-Liverpool, that developed severe nonsuppurative encephalitis. Transplacental transmission of the isolate arising from an acute infection during pregnancy occurred in about 87% of pups.

Conclusion: This is the first isolation of bovine Neospora caninum in Australia. This isolate, called NC-Nowra, appears to be a less virulent form and may prove to be a suitable candidate for vaccine development.

Item ID: 34600
Item Type: Article (Research - C1)
ISSN: 1751-0813
Keywords: Neospora caninum; cattle; isolate
Funders: University of Technology, Sydney, NSW Agriculture
Date Deposited: 26 Aug 2014 05:17
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0702 Animal Production > 070205 Animal Protection (Pests and Pathogens) @ 70%
07 AGRICULTURAL AND VETERINARY SCIENCES > 0707 Veterinary Sciences > 070708 Veterinary Parasitology @ 30%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8303 Livestock Raising > 830302 Dairy Cattle @ 50%
97 EXPANDING KNOWLEDGE > 970107 Expanding Knowledge in the Agricultural and Veterinary Sciences @ 25%
97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 25%
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