Biological activity of an intravenous preparation of human vaccinia immune globulin in mouse models of vaccinia virus infection.

The biological activity of a new intravenous (i.v.) preparation of human vaccinia immune globulin (VIGIV) was evaluated in two mouse models of vaccinia virus (VV) infection. In a mouse tail lesion model, female CD-1 mice were inoculated i.v. with 7 x 10(4) PFU of VV to produce >10 lesions per tail 8 days later. In a mouse lethality model, female severe combined immunodeficient (SCID) mice were inoculated i.v. with 3 x 10(4) PFU of VV to produce 100% mortality within 45 days. The ability of VIGIV to reduce tail lesion formation in CD-1 mice and mortality in SCID mice was determined by (i) pretreatment of a lethal VV dose with VIGIV prior to i.v. inoculation into SCID mice and (ii) i.v. administration of VIGIV to CD-1 and SCID mice the day before and up to 8 days after VV infection. VIGIV reduced the proportion of CD-1 mice with >10 tail lesions in a dose-related manner when VIGIV was given 1 day before and up to 1 day after VV inoculation. The pretreatment of VV with VIGIV prolonged survival and decreased mortality. VIGIV (100 and 400 mg/kg) prolonged survival when given up to 4 days after VV inoculation, and the 400-mg/kg dose reduced the mortality rate by 80% when given the day before or immediately after VV inoculation. The biological activity of VIGIV was demonstrated in both the immunocompetent and immunocompromised murine models. The timing of treatment relative to VV inoculation appeared to be important for the demonstration of VIGIV's biological activity.