Avian metapneumovirus infections in poultry flocks in Poland – molecular evidence for emerging divergence from vaccine strains

A gap of over 30 years separates the first European aMPV-B strains (1980s–1990s) from Polish strains from 2022–2023. Analysis of amino acid sequences revealed numerous substitutions in the surface G and SH proteins, including changes in regions implicated in antigenicity, receptor binding, and immune recognition. These alterations may modify viral epitopes, potentially contributing to immune escape and reducing the efficacy of current vaccines.

Overall, the presented study underscores the importance of continuous genomic surveillance of circulating strains, particularly given the limited availability of complete European aMPV genomes, to better inform vaccine design and disease control measures.</p> <p></p><p>Despite use of aMPV vaccines, clinical signs of disease caused by aMPV infection with field strains were widely reported in poultry production in Poland.</p><p>The strains detected formed a distinct cluster of “Polish field strains”.</p><p>Two complete aMPV-B genomes revealed several non-synonymous mutations, especially in G and SH genes, that may account for the poor protection provided by the vaccines.</p><p>Phylogenetic analysis of two Polish complete genomes revealed a significant genetic distance from available aMPV-B strains.</p><p></p> <p>Despite use of aMPV vaccines, clinical signs of disease caused by aMPV infection with field strains were widely reported in poultry production in Poland.</p> <p>The strains detected formed a distinct cluster of “Polish field strains”.</p> <p>Two complete aMPV-B genomes revealed several non-synonymous mutations, especially in G and SH genes, that may account for the poor protection provided by the vaccines.</p> <p>Phylogenetic analysis of two Polish complete genomes revealed a significant genetic distance from available aMPV-B strains.</p>