Gerbils (Meriones unguiculatus) are highly susceptible to oral infection with Neospora caninum oocysts

Abstract

Laboratory-reared gerbils (Meriones unguiculatus) were found to be highly susceptible to oral infection with Neospora caninum (NC-Liv strain) oocysts. Gerbils fed approximately 1000 oocysts became sick or died at 6-13 days post feeding of oocysts (PFO). N. caninum was isolated in cell culture and from gamma-interferon-knockout mice inoculated with homogenates of mesenteric lymph nodes of gerbils examined as early as 1 day PFO. Numerous N. caninum tachyzoites were found in ulcerative lesions in the intestines of gerbils examined at 7-9 days PFO. In a gerbil fed 10 oocysts, N. caninum tachyzoites were found in lesions in the brain. Gerbils fed 10 oocysts developed antibodies to N. caninum by 18 days PFO as determined by the Neospora agglutination test (titers > or =1:500). All gerbils remained negative for antibodies to Toxoplasma gondii as determined by the Toxoplasma agglutination test.