Role of interferon in murine lactic dehydrogenase virus infection, in vivo and in vitro

The induction of interferon (IF) by lactic dehydrogenase virus (LDV) and the action of exogenous IF on LDV multiplication have been studied in vivo and in vitro. In vivo the induction of serum IF by LDV was shown to correspond with the virus challenge dose. In vitro LDV-infected macrophages did not produce detectable IF. As to the action of IF in vivo, the prophylactic or therapeutic administration of IF to mice reduced the LDV serum titers only temporarily. In vitro, (i) the sensitivity of LDV to IF in macrophage culture was 30 times less than that of vesicular stomatitis virus, and 5 times less than that of Sendai virus, and (ii) prolonged exposure of LDV-infected macrophages to high IF concentrations did not cure the chronic infection, but only decreased the virus titer. The probable role of IF in the establishment of the early phase of a persistent but reduced viremia in mice is discussed.