ANTIBODY-RESPONSES AND PROTECTION IN MICE IMMUNIZED ORALLY AGAINST INFLUENZA-VIRUS

Antibody responses and protection were studied in BALB/c mice immunize d orally with formalin-inactivated influenza viruses (A/PR/8/34) combi ned with cholera toxin B subunit as adjuvant. Influenza virus-specific IgA as well as IgG antibody responses were induced in the mice, depen ding on the oral dosage frequency. The oral immunization by multiple d oses resulted in reduction of viral replication in the nose and preven tion of development of infection in the lung after intranasal (i.n.) c hallenge. The protective effect in the nose was thought to be related to the nasal IgA antibody response. The oral immunization was, however , less efficient for induction of the IgA antibody response and protec tion in the nose, compared with an i.n. immunization. The oral immuniz ation following subcutaneous priming led to the complete protection in the nose, accompanied by a prompt local IgA antibody response. Copyri ght (C) 1996 Elsevier Science Ltd.