Age-associated changes in fecal excretion patterns of strain 93 chick embryo lethal orphan virus in chicks

Oral incoulation of chickens with strain 93 (chick embryo lethal orphan) virus produced a subclinical infection of the gastrointestinal tract. The pattern of fecal virus excretion in birds infected at 4 or more weeks of age (adult pattern) differed from that in chicks infected when newly hatched (juvenile pattern). By comparison with the juvenile pattern, the adult pattern was characterized by lower peak titers of fecal virus, earlier decline in virus titer, and shorter duration of excretion. Quantitative studies on hatchmates infected at various ages showed that these characteristics are established sequentially with age: lower peak titers were observed in birds infected at 2 to 4 days of age; early decline in titer was first observed in birds infected at 14 days of age; and curtailed excretion was observed in birds infected at 21 days of age. Possible mechanisms operative in the autosterilization process are discussed.