Local immunity in the respiratory tract of the chicken. I. Transudation of circulating antibody in normal and virus-infected birds.

Three-week-old chickens were given sheep erythrocytes or bovine serum albumin intravenously. Seven days later their tears and saliva possessed low levels of antibody to those antigens. Concurrent infection with lentogenic Newcastle disease virus (NDV) caused a significant increase in transuded antibody in those fluids. In chickens with circulating antibody to NDV, induced by parenterally administered inactivated vaccine, respiratory infection with heterologous infectious bronchitis virus resulted in limited transudation of anti-NDV. In contrast, the tears, saliva and tracheal fluid of non-vaccinated chickens undergoing primary infection with NDV acquired considerable levels of specific anti-NDV. The difference between the two groups is attributed to locally synthesized antibody.