Avian metapneumovirus subtype B in a Northern shoveler (Spatula clypeata) wintering in Italy: implications for the domestic-wild bird interface?

Abstract

Avian metapneumovirus (aMPV) is an important pathogen in poultry, primarily affecting chickens and turkeys, and it causes acute respiratory disease or reproductive disorders. Considering previous molecular or serological evidence of aMPV in different wild bird species, the role of non-domestic hosts in the virus epidemiology has been called into question. A molecular survey was therefore performed on wild aquatic bird species sampled during the Italian Avian Influenza Surveillance plan from 2021-2023 in the Bologna province. A total of 250 oropharyngeal swabs were collected and screened for all circulating aMPV subtypes through multiplex real-time RT-PCR. An aMPV-B strain, named aMPV/B/Italy/Northern_shoveler/80/21, was detected in an adult Northern shoveler (Spatula clypeata) wintering in Italy in 2021, and it was characterized by partial amplification and sequencing of the attachment glycoprotein gene. Phylogenetic analysis showed close relationships between this strain and those circulating in Italian poultry from 2014-2019. Given the high aMPV-B burden on the Italian poultry sector and the similarity of aMPV/B/Italy/Northern_shoveler/80/21 strain to those circulating in chickens and turkeys, potential virus spillover from domestic to wild birds could have occurred at the livestock-wildlife interface. Considering that aMPV-B is well adapted to gallinaceans, this represents one of the rare molecular detections of this subtype in waterfowl species. Expanding aMPV monitoring and conducting further biological studies on wild hosts are essential for a better understanding of their role in maintaining aMPV circulation.RESEARCH HIGHLIGHTSWild birds sampled in Italy tested for aMPV detection and characterization.aMPV-B found for the first time in a wintering Northern shoveler.Close phylogenetic relationship with aMPV-B strains circulating in Italian poultry.