Characterization of murine Caraparu Bunyavirus liver infection and immunomodulator-mediated antiviral protection.

A rapid, peripheral disease model utilizing the Bunyavirus, Caraparu, was established in mice for the evaluation of antiviral therapy with immunomodulators. 4-6-week-old B6C3F1 female mice, inoculated intraperitoneally with virus, developed coagulative liver necrosis and died between 4-6 days after infection. This Caraparu disease model was relatively resistant to treatment with immunomodulators, such as ABMP, Ampligen, alpha-interferon (IFN-alpha) or beta-interferon (IFN-beta). However, a significant increase in median survival time (MST) was consistently observed upon treatment with gamma-interferon (IFN-gamma). The nucleoside analog--ribavirin--was highly effective against Caraparu virus in repeated treatment schedules begun on either day -1, day 0, or day +1 of infection. Ribavirin gave little protection when initiation of treatment was delayed until day +2. However, combined treatment with IFN-gamma, starting on day 0 and ribavirin starting on day +2, significantly reduced mortality.