Local Immunity to Influenza Virus in Chicken Tracheal Organ Cultures

Abstract

Immunity to influenza A virus was demonstrated in tracheal organ cultures by parallel titration of challenge virus in replicate cultures prepared from control and virus-inoculated chickens. Five to 10 times more virus was required to infect 50% of cultures from chickens inoculated intranasally and intratracheally with active virus than from control chickens or from chickens with serum antibody induced by intramuscular and intraperitoneal inoculation of inactivated virus. Viral yield from resistant cultures was reduced. Cultures from chickens immunized with either of two antigenically distinct influenza A viruses were resistant to homotypic virus but susceptible to the heterotypic strain. Medium from such cultures contained virus-specific HAI and neutralizing activity. Cultures from some chickens inoculated up to 31 days previously were resistant. The immune state became undetectable between the first and fourth days of culturing. Results suggest that a secretory immunologic system was at least partially responsible for the immunity of the organ cultures.