[Testing the immunity to orthopoxviruses in the white mouse with vaccinia virus]

An infection model was developed, which allows the study of humoral and cellular immune response mechanisms induced by Orthopox viruses in mice. The optimal infection route for neurovirulent vaccinia virus strains was investigated and resulted in well-defined clinical symptoms in non-immunized susceptible mice. Signs of disease were taken as a basis for comparison. Challenge infections by intracutaneous (i.c.) and intraperitoneal (i.p.) application of vaccinia strain Munich 1 (M1) appeared to be most suited to testing immunities of different status in vivo. Mice passively immunized with an anti-vaccinia immune serum survived intraperitoneal challenge infection with 4LD50/mouse. After an intracutaneous challenge infection with 10(4) TCID50/animal, however, they were fully susceptible. Mice immunized with live vaccinia virus showed a solid immunity to both intracutaneous and intraperitoneal challenge.