Induction of Partial Specific Heterotypic Immunity in Mice by a Single Infection with Influenza A Virus

Schulman, Jerome L. (Cornell University Medical College, New York, N.Y.), and Edwin D. Kilbourne. Induction of partial specific heterotypic immunity in mice by a single infection with influenza A virus. J. Bacteriol. 89:170-174. 1965.-Mice infected 4 weeks previously with influenza A virus were found to be partially immune when challenged with influenza A2 virus. This partial immunity was demonstrated by reduced titers of pulmonary virus, decreased mortality, and less extensive lung lesions. A specific immunological basis for this protection was suggested by the absence of any protection in animals previously infected with influenza B virus when challenged with A2 virus, or in animals previously infected with influenza A virus when challenged with influenza B virus. Parenteral inoculation with inactivated influenza A virus did not induce partial immunity to A2 virus challenge. An accelerated rise of hemagglutinating-inhibiting antibody after A2 virus challenge was demonstrated in animals previously infected with influenza A virus.