Avian Metapneumovirus circulation in Italian broiler farms

Avian Metapneumovirus (aMPV) is the casual agent of Turkey Rhinotracheitis (TRT), and also causes a respiratory infection in chickens, which can result in Swollen Head Syndrome (SHS). The current information on prevalence of aMPV in broiler in Italy is fragmentary and the impact on production remains unknown. In order to draw an epidemiological picture of aMPV in broiler flocks, starting from 2014, a survey has been performed mainly in the highly poultry populated areas in the North of Italy. Swabs collected during one-off and longitudinal studies were tested using A and B subtype specific Real Time RT-PCR. Samples were also tested for Infectious Bronchitis Virus (IBV) using PCRs followed by sequencing. When possible, production data and respiratory diseases were recorded. Results confirmed the high prevalence of aMPV in broiler older than 30 days in absence of field IBV. All viruses detected were of B subtype. To evaluate the genetic variability in Italian aMPV strains, the fusion (F) and attachment (G) gene nucleotide sequences of selected isolates were determined. These were compared with sequences obtained from turkeys sampled in the same area and in the same period and with previously published aMPV sequences.