EXPERIMENTAL TRANSMISSION OF INFLUENZA VIRUS INFECTION IN MICE : III. DIFFERING EFFECTS OF IMMUNITY INDUCED BY INFECTION AND BY INACTIVATED INFLUENZA VIRUS VACCINE ON TRANSMISSION ON INFECTION

Immunization of mice by infection or intraperitoneal injection with homotypic A(2), heterotypic A(0), or recombinant A(0)A(2) virus have differing effects on transmission of influenza A(2) virus infection. Immunization by infection with A(2) virus resulted in refractoriness to reinfection either by artificial aerosols or by exposure to infected cage-mates. Immunization by inoculation with inactivated A(2) virus vaccine resulted in a decreased susceptibility to transmitted infection in immunized contacts, but following A(2) virus challenge, transmission of infection by immunized infectors was not altered. Immunization by infection with influenza A(0) virus or recombinant A(0)A(2) virus resulted in a decreased susceptibility to transmitted A(2) virus infection in immunized contacts, and to decreased transmission after A(2) virus infection in immunized infector mice. These differing effects on transmission of infection are attributed to differences in specific local immunologic responses following the various immunization procedures.