An enzyme-linked immunosorbent assay for detection of the antigens of avian encephalomyelitis viruses (AEVs) was developed, using an antigen capture method with affinity-purified anti-AEV immunoglobulins prepared in rabbits. Both the Van Roekel strain and a field strain of AEV could be detected at concentrations of 4 x 10(3) ng/g tissue in the presence or absence of an uninfected chicken embryo extract. The procedure was used to determine the distribution of antigens to the Van Roekel strain after inoculation of 6-day-old chicken embryos. Antigen concentrations were highest in the embryo brain and lower in the heart and other tissues. When the same strain was inoculated intramuscularly into day-old chickens, highest levels of antigen were noted in the pancreas, gizzard, and brain. Patterns of fecal antigen excretion and antibody production were studied after inoculation of the field strain by the intramuscular, intracerebral, and oral routes. Excretion was most prolonged following oral inoculation (4-10 days), although antigen could be detected by 2 days after intracerebral inoculation. Detectable antibody was present by 10 days following infection by each route.