The Age Distribution in Humans of Hemagglutinating-Inhibiting Antibodies Reacting with Avian Strains of Influenza a Virus

Abstract

HI antibody against formalinized A/Duck/England/62 was found at low frequencies and low titers in the sera of persons 67 to 97 years of age in 1964. With active virus the values were lower. The same sera contained higher frequencies and higher levels of antibody against A/Equine-2/Milford/63 virus. Avian strain antibody was detectable only when the same specimen contained horse strain antibody. The HI antibody failed to neutralize active virus and reacted as heterologous antibody in the photometric test of Drescher. A low frequency of low HI antibody increases against A/Duck/England/62 was found in the sera of older persons vaccinated with Equine-2 monovalent vaccine. The present data confirm and extend information on the antigenic linkage between avian, horse and human strains of influenza A virus. HI antibody was not found in the serum collection spanning the age range from birth to 97 years of life when tested with A/Duck/England/56, A/Tern/South Africa/61 or A/Turkey/England/63, nor from birth to 66 years of age when tested with A/Duck/England/62.