MOUSE MODEL FOR CENTRAL-NERVOUS-SYSTEM NEOSPORA-CANINUM INFECTIONS

Neospora caninum is a protozoan parasite that causes severe disease in transplacentally infected dogs and abortions in domestic ruminants. R odent models of neosporosis rely on treatment of hosts with methylpred nisolone acetate (MPA) to enhance infections. The present study report s the development of an inbred BALB/c mouse model that results in cent ral nervous system neosporosis in the absence of MPA treatment. Seven of 12 BALB/c mice died 26-70 days after subcutaneous (s.c.) inoculatio n with tachyzoites of the NC-1 strain of N. caninum, and none of 12 BA LB/c mice died after s.c. inoculation with tachyzoites of the NC-3 str ain. None of 8 HSD:ICR mice (4 mice, NC-1 strain; 4 mice, NC-3 strain) developed clinical neosporosis or died after s.c. inoculation with ta chyzoites. Control BALB/c (2) and HSD:ICR (2) mice s.c. inoculated wit h Hanks' balanced salt solution did not develop clinical signs of dise ase. Some mice in all N. caninum-inoculated groups had brain lesions, but significantly (P < 0.05) more BALB/c mice inoculated with the NC-1 strain had brain lesions.