Submitted to: Systematic Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/10/2000
Publication Date: N/A
Citation: Interpretive Summary: Neospora hughesi is a recently discovered single-celled parasite. It can cause a neurological disease in horses. Little is known of the biology of this organism. Scientists at the Beltsville Agricultural Research Center and the Oregon State University report characteristics of an isolate of Neospora hughesi recovered from the spinal cord of a horse with neurologic signs. Results will be of interest to biologists, parasitologist and pathologists.
Technical Abstract: Neospora organisms were isolate in cell cultures inoculated with homogenate of spinal cord from a horse in Oregon. Tachyzoites of this Oregon isolate of Neospora were maintained continuously by cell culture passage and tachyzoites were infective to immunosuppressed mice. Gamma interferon gene knockout (KO) mice injected with tachyzoites developed fatal myocarditis and numerous tachyzoites were seen in lesions. Gerbils (Meriones unguiculatus) inoculated with tachyzoites developed antibodies (>1:500) as indicated by the N. caninum aggultination test, but did not develop clinical signs and Neospora was not demonstrable in their tissues. Tissue cysts were not found in gerbils, nude mice, KO mice, cortisonized outbred Swiss Webster mice, or BALB/c mice injected with the Oregon equine isolate of Neospora. Ultrastructurally, tachyzoites of the Oregon isolate from the myocardium of infected KO mice and from cell culture were similar to N. caninum tachyzoites. Western blot analysis using SAG1 and SRS2 polyclonal and monoclonal antibodies, and characterization of the internal transcribed spacer 1(ITS1) sequences from the equine isolates and different isolates of Neospora from dogs and cattle, indicated that the equine isolates of Neospora, including the Oregon isolate, are distinct from N. caninum isolates from cattle and dogs.