Oral immunization against respiratory viruses in mice

The results presented here extend our previous observations regarding oral immunization against respiratory viruses in three areas. First, from an experiment comparing Sendai virus with influenza virus it appears that the nature of the antigen as well as host-parasite interactions may play an important role in efficiency of oral immunization. Second, oral immunization with an inactivated virus can apparently induce a cell-mediated immune response. Preliminary evidence (not shown) indicated that the magnitude of effector cell killing versus virus-infected target cells was positively influenced by including cholera toxin in the oral immunization regimen. This is consistent with a recent report that cholera toxin could enhance T cell proliferative response to co-fed KLH. Finally, we have shown that oral immunization with inactivated virus plus cholera toxin combined with intranasal inactivated virus boosting, can protect mice from infection for nearly two years--their normal life span.