Studies on the antigenic relationship between an isolate (127) from the egg drop syndrome 1976 and a fowl adenovirus

Birds infected with fowl adenovirus type 1 (FAV-1) developed precipitating antibody to FAV-1 but not to haemagglutinating virus 127 isolated from flocks with a depressed egg production syndrome. Once the precipitating antibody to FAV-1 was no longer detectable, the birds were then infected with 127 virus. They developed precipitating and haemagglutination-inhibiting antibody to 127 virus. They also developed precipitating antibody to the adenovirus group antigen. Birds infected only with 127 virus did not develop adenovirus group antibody. Birds which had been infected with FAV-1, and subsequently infected with infectious bronchitis virus, when without detectable FAV-1 antibody, did not show a recall of adenovirus group antibody. It is concluded that 127 and FAV-1 must share an antigen. This is further evidence that 127 is an avian adenovirus.