Failure of maternal antibodies to protect young turkey poults against challenge with turkey rhinotracheitis virus.

Groups of turkey poults with high levels of maternal antibodies (MA+) to turkey rhinotracheitis virus (TRTV) were challenged with virulent TRTV at 1, 5, and 10 days of age. A maternal antibody-free group (MA-) was also challenged at 1 day of age. Before each challenge, levels of maternal antibodies to TRTV were measured by enzyme-linked immunosorbent assay. Clinical signs were scored for each group. Unchallenged poults showed no signs. Respiratory signs in poults infected at 10 days of age resembled those seen in MA- birds infected at 1 day of age but both were more severe than in MA+ birds infected at 1 day of age, when the maternal antibodies were highest. However, overall, the presence of high levels of maternal antibodies did not prevent the development of clinical disease.