Genetic resistance to lethal flaviviral encephalitis. III. Replication of Banzi virus in vitro and in vivo in tissues of congeneic susceptible and resistant mice.

The replication of Banzi virus, flavivirus, was compared in vitro and in vivo in tissues of congenic mice genetically resistant (C3H/RV) or genetically susceptible (C3H/He) to lethal infection. Ultrastructural changes in brains of resistant and susceptible adult mice following intracerebral or intraperitoneal inoculation of virus also were compared. Banzi virus replicated equally well in monolayer cultures of infant and adult brain, stimulated and non-stimulated macrophages and embryonic cells from both strains of mice. Similarly, no significant differences were found between strains in virus growth in brain, spleen or thymus of peripherally-inoculated infant mice. In intracerebrally-inoculated adult mice, virus titers in brains of resistant mice were consistently lower than in susceptible mice. Visualization of virus particles was dependent on virus concentration in tissues. The changes in brain tissues of both strains of mice were similar, differing only in the time of onset which was noted two days later in C3H/RV mice than in C3H/He mice. These results indicate that, in the case of Banzi virus, the phenotypic expression of genetically-determined resistance of lethal flavivirus infection cannot be attributed primarily to the ability of host cells to support virus replication.