Avian Metapneumovirus 2024 North American Outbreak: Genomics Direct Future Plans

Avian metapneumovirus (aMPV) is a highly contagious pathogen that has caused enormous economic losses worldwide and recently to the U.S. poultry industry. It results in upper respiratory disease, which worsens with secondary bacterial infection. The infection may also spread to the reproductive tract, impacting both egg quality and quantity. Based on the genetic heterogeneity of the G gene, four subtypes, A, B, C, and D, have been identified for aMPVs, with two new, unclassified subtypes detected in North America. Genetic structure and molecular characterization are crucial for understanding genetic diversity, viral epidemics, host range, geographical distribution, and the determinants of pathogenicity and virulence. Additionally, genetic data guide infection control, such as the selection of vaccine strains. This review article provides valuable insights into the genomic characterization of aMPVs, particularly considering the recent introduction and rapid spread of subtypes A and B in the United States. The review highlights the outlines for future control plans based on the molecular characterization of recently emerging aMPVs in U.S. poultry.