Avian Pneumovirus infection in turkey and broiler farms in Italy: a virological, molecular and serological field survey

Abstract

Avian Pneumovirus (APV) is the casual agent of Turkey Rhinotracheitis (TRT), and also causes a respiratory infection in chickens, which can result in Swollen Head Syndrome. A survey of APV infection in Italian turkey and broiler farms, in a highly populated area of Northern Italy (Verona Province) is reported. Nine turkey farms and 6 broiler farms were sampled. Sixteen birds from each group were doubly swabbed from the choanal cleft for virus isolation on tracheal organ cultures (TOC) and RT nested PCR (A and B type specific) using extracted RNA. At the same time blood samples were collected for a blocking ELISA serological assay. The broiler samples for virological assays were treated with infectious bronchitis virus (IBV) antiserum raised against serotypes prevalent in the areas sampled, thus avoiding competitive growth of IBV on TOC. Ciliostasis on TOC was taken as the indicator of the presence of the virus, and confirmation was by indirect immunofluorescence. APV was isolated and detected by RT-PCR in 19 day-old turkeys, and in 34, 42 and 48 day-old broilers. All APV strains were found to be type B. All turkeys of more than 4 weeks old were APV positive by ELISA. APV infection was found to be widely spread in the area sampled and the protocol used for virus isolation was shown to be effective. Turkey rhinotracheitis first appeared in Italy in the late 1980s, and the APV isolates involved were subsequently characterised as B types. Our results confirm APV B type to be present in Italy, but the limited findings to date need to be extended by further surveys of other Italian regions.