Research Note: Detection of Avian metapneumovirus subgroup C specific antibodies in a mallard flock in Italy

Abstract

Avian metapneumovirus ( aMPV ) is a viral pathogen that causes respiratory signs and drops in egg production most notably in turkeys but also affects chickens, ducks and other species. Four subgroups (aMPV-A, -B, -C and -D) have been characterized to date, which differ genetically, antigenically and in terms of geographic distribution and host range. Despite the rising awareness towards aMPV, many aspects of its epidemiology are still poorly understood. In this pilot study, a serological survey was carried out to assess the possible circulation of subgroups A, B, and C in intensively raised ducks in Northern Italy. A total of 220 sera from 10 Pekin duck flocks and one mallard flock were collected at slaughter and tested by subgroup-specific aMPV-A, B, and C indirect ELISA assays. None of the tested birds had been vaccinated against aMPV and no symptoms had been reported. No aMPV-A, B or C antibodies were detected in any bird of the Pekin duck flocks, whereas the entire mallard flock tested positive for aMPV-C antibodies. This is the first report of aMPV-C antibodies in ducks in Italy, where only aMPV-B has been reported to circulate in recent years. Further research efforts will be targeted towards the screening of a larger panel of samples, in the hope of obtaining positive samples from which full length genome sequences and infectious viruses can be isolated for virus characterization. Finally, the demonstration of aMPV-C specific antibodies in the serum of all sampled mallards indirectly suggests that this species is readily infected by aMPV-C and supports a possible role of wild anatids as a transmission vector of the virus.

Establishment and application of a quadruple real-time RT-PCR for detecting avian metapneumovirus

“…aMPV was first discovered in South Africa in 1970, spread throughout Europe in the 1980s and was found in the United States in 1996. In recent years, the detection of aMPV has been reported in many countries or regions, especially in Europe [6][7][8][9][10][11][12].…”

Molecular Survey on A, B, C and New Avian Metapneumovirus (aMPV) Subtypes in Wild Birds of Northern-Central Italy

“…On the other hand, a recent study [ 39 ] reported the seropositivity for aMPV-C of an entire mallard flock reared in Lombardy (Northern Italy) during a serological survey on ducks and mallards at slaughter. Our direct identification further supports the susceptibility of this species and suggests that there is a precise connection between wild and domestic populations, especially since migrating birds may have frequent contact with resident urban birds in peri-urban and farming areas [ 40 ].…”

Molecular characterization of avian metapneumovirus subtype C detected in wild mallards ( Anas platyrhynchos ) in The Netherlands

“…Duck species are natural reservoir hosts for many viruses that pose a threat to other wild and domestic avian species, mammals, and humans. These include influenza A virus (species Alphainfluenzavirus influenza ) (Poen et al., 2018), West Nile virus (species West Nile virus ) (Cox et al., 2015), Newcastle disease virus (species Avian orthoavulavirus 1 ) (Franca et al., 2014), and avian metapneumovirus (AMPV, species Avian metapneumovirus ) (Jardine et al., 2018; Legnardi et al., 2021). In particular, wild mallards ( Anas platyrhynchos ) migrate annually over large areas, with a geographical range encompassing wetlands of the northern hemisphere, with populations present in all continents (Guillemain et al., 2020).…”

“…Nile virus (species West Nile virus) (Cox et al, 2015), Newcastle disease virus (species Avian orthoavulavirus 1) (Franca et al, 2014), and avian metapneumovirus (AMPV, species Avian metapneumovirus) (Jardine et al, 2018;Legnardi et al, 2021). In particular, wild mallards (Anas platyrhynchos) migrate annually over large areas, with a geographical range encompassing wetlands of the northern hemisphere, with populations present in all continents (Guillemain et al, 2020).…”

“…However, this strain cannot confidently be placed within these lineages due to a lack of published sequence information (Wei et al, 2013). Further confirmation of the presence of AMPV-C in Europe was provided by two studies from Italy in which AMPV-C antibodies were detected in commercial mallards (Legnardi et al, 2021), and AMPV-C infection was detected in an oropharyngeal swab collected from a Eurasian wigeon (Mareca penelope) in 2007 (Graziosi et al, 2022). In this study, we have identified seven cases of AMPV-C in a collection of oropharyngeal-and cloacal swabs obtained from wild mallards in the Netherlands between 2017 and 2019 and have characterized the full-length genome sequence of two strains with a particular focus on sequence variation observed in the G protein.…”