| Abstract: | Susceptibility to pseudorabies virus (PRV) infection in mice, which were continuously depleted of natural killer (NK) cell activity by injection of anti-asialo GM1, was examined. Effects of serum thymic factor (FTS) on susceptibility of mice to PRV were also investigated. In mice with depleted NK cell activity, the mortality of PRV-infected mice was markedly high, whereas that of FTS-pretreated mice was significantly lower than the controls. Reduced susceptibility to PRV was demonstrated in mice treated with anti-asialo GM1 antisera before the PRV infection. Such a reduced susceptibility was not observed in mice inoculated with the antisera on day 1 post-infection (PI). To analyze the FTS-induced resistance to PRV infection, NK cell activity, macrophage activity, and interferon (IFN) productions were studied. Interferon production and NK cell activity were enhanced in the FTS-pretreated mice, suggesting that interferon may play an important role in this FTS-induced resistance to PRV infection. |
