Development of a vaccine-challenge model for avian metapneumovirus subtype C in turkeys

The objective of this study was to evaluate different preparations of avian metapneumovirus (aMPV) subtype C as vaccine challenge in turkeys. Two aMPV isolates and their respective nasal turbinate homogenates after propagation in turkeys were used in the study. Significantly higher clinical sign scores were recorded in birds inoculated with 20 or 2% turbinate homogenate of recent isolate. Birds in the above groups showed more pronounced histopathological lesions, and a higher percentage of birds showed viral RNA and antigen in tissues. The data demonstrated that nasal turbinate homogenate of recent isolate produced severe clinical signs and lesions in turkeys and could be an ideal candidate for vaccine-challenge studies.