Analysis of adjuvant action Escherichia coli enterotoxin

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A mutant of Escherichia coli enterotoxin (mLT) has mucosal adjuvant action to humoral immuno-response for various antigens like influenza vaccine or measles virus and induced high titers of anti-antigen. However, for a live varicella vaccine (the Oka strain), it induced cellular immunity, which is important for host defense for VZV infection. A commercially available live Oka vaccine virus and toxin were administered once simultaneously via the nasal route, in mice. Ten or 12 months later, a delayed-type hypersensitivity to the vaccine virus was detected by footpad test, but an antibody neutralizing the varicella-zoster virus was not. When spleen cells from mice immunized with the vaccine and toxin were re-stimulated by live vaccine in vitro, their thymidine uptake and IL-2 production were higher than those from mice immunized with the vaccine alone, but lower than those of spleen cells prepared from mice 2 months after nasal administration. Production of IL-4 in these cells, however, was not induced by re-stimulation in vitro. These results suggest that cellular immunity is induced and maintained over 1 year, though it declines with age. The nasal administration of the vaccine and mLT might be effective for maintaining cellular immunity to the varicella-zoster virus long term