Influence of interferon in natural resistance of mice to Sendai virus pneumonia.

The influence of interferon (IFN) on the natural resistance to Sendai virus was investigated in resistant (C57BL/6NCr) and susceptible (DBA/2NCr) mouse strains. After inoculation with strain 52 Sendai virus, the pulmonary titers of Sendai virus were similar in both mice strains, indicating that the quantity of virus in the lungs may not be a major factor in determination of resistance. The pulmonary IFN titers were higher in DBA/2 mice, indicating that increased susceptibility of DBA/2 mice is not a result of inadequate production of IFN. Treatment of both strains with exogenous IFN before and during viral infection induced an increased survival time in C57BL/6 mice, but eventual mortality was the same in both mouse strains. Administration of anti-IFN antibodies to both mouse strains during Sendai infection decreased mortality equally in both strains, compared with mortality in control mice. Seemingly, the difference in resistance to Sendai virus in DBA/2 and C57BL/6 mice was probably not a result of the beneficial effects of IFN. On the contrary, administration of anti-IFN antibodies decreased the susceptibility of both mouse strains.