Susceptibility of chickens to avian encephalomyelitis virus. V. Behavior of a field strain in laying hens.

Some 12-month-old laying hens were inoculated orally or subcutaneously with 10(4.7) EID50 of a field strain of avian encephalomyelitis virus. They were examined for propagation of the virus in the body at regular intervals of time. When two hens were sacrificed daily in the group of oral inoculation, the virus was found in liver, pancreas, and esophagus in both hens 1 day, in brain, lumbar part of the spinal cord, heart, spleen, pharynx, larynx, glandular stomach, muscle, and blood in one of the two hens 1 day, and in various parts of the body 3 approximately 9 days after inoculation. After that, the virus was detected almost continually from the central nervous system and abdominal parenchymatous organs in nearly all the hens examined up to the end of the observation period, or 21 days after inoculation. Virus detection from the digestive tract and ovarian follicle, however, decreased in frequency and virus titer was reduced remarkably with the lapse of time after inoculation. When the largest amount of virus was determined in each organ, it was the largest, or 10(6.5) EID50/0.1 g, in the liver and about 10(5.0) EID50/0.1 g in spleen, pancreas, kidney, and ovarian follicle. There was little difference in virus propagation and its course between the group of subcutaneous inoculation and that of oral administration.