#Zoonotic #infections and genomic #evolution of novel #reassortant swine #influenza A viruses in #Spain

 

Abstract

Influenza A virus (IAV) circulates widely in European pig populations and continues to diversify through frequent introductions from humans, followed by reassortment within swine. Spain represents a particularly dynamic ecological setting due to the coexistence of intensive white-pig production, extensive Iberian-pig systems, and abundant wild boar populations. This study provides an integrated analysis of IAV evolution and genomic diversity in swine in Spain between 2019 and 2022, expanding on previous surveillance from 2016 to 2019. Sampling across 24 provinces yielded 66 new whole-genome sequences from Iberian and white pigs. We identified 18 genotypes, including 11 novel reassortants not detected in our previous survey. Several genotypes, such as H1N2 G21 and G22, H3N2 G23, and the unusual H3N1 G12, were exclusive to the country. Some genotypes were detected across white pigs, Iberian pigs, and wild boar in Toledo and Badajoz, suggesting viral flow among swine populations. Phylogenetic analyses revealed ongoing introductions of H1N1pdm09 from humans into pigs, generating at least five reassortant genotypes (G10, G16–G19). These lineages incorporated pandemic internal cassettes and, in some cases, human-seasonal N2 segments, highlighting the continued role of humans as a source of viral incursions. Conversely, four zoonotic infections (H1N1v) detected in Spain between 2022 and 2026 were linked to genotypes circulating in white pigs, underscoring the bidirectional nature of IAV transmission at the human swine interface. Overall, this study demonstrates that Spain provides ecological conditions conducive to IAV diversification, reassortment, and zoonotic risk. The findings reinforce the need for sustained One Health surveillance.

Source: Virus Evolution Journal, https://doi.org/10.1093/ve/veag067

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#H9N2 avian #influenza virus in #Bangladesh: three genetically distinct co-circulating subgroups retain a largely conserved #antigenic phenotype

 

Abstract

Low pathogenic avian influenza (LPAI) H9N2 viruses are endemic in poultry across Bangladesh, causing substantial economic losses and posing a persistent zoonotic risk. Although genetic surveillance has documented ongoing viral evolution, the relationship between genetic diversification and antigenic change remains poorly understood. This study investigated the genetic diversity, reassortment, and antigenic characteristics of contemporary H9N2 viruses circulating in Bangladesh. Phylogenetic analysis of 219 sampled sequences revealed three genetically distinct monophyletic haemagglutinin (HA) G-lineage sub-groups, each characterised by unique amino acid substitutions. In contrast, neuraminidase (NA) displayed similar genetic diversity without distinct phylogenetic clusters. A dual-metric analysis of paired HA and NA phylogenies identified 20 putative reassortant H9N2 viruses. Further analysis showed that genetic diversity was geographically structured; however, all three HA subgroups co-circulated across multiple regions, and some live bird markets contained representatives of all three groups simultaneously, suggesting that live bird markets may facilitate mixing between genetically distinct viruses, and create opportunities for reassortment among otherwise geographically separated strains. Despite substantial genetic diversity and reassortment, all viruses remained antigenically similar based on haemagglutination inhibition and virus neutralisation assays. However, a representative strain from one subgroup induced significantly lower homologous and heterologous antibody titres, suggesting reduced immunogenicity. Our findings demonstrate a notable disconnect between genetic evolution and antigenic change in Bangladeshi H9N2 viruses. While reassortment and genetic diversification continue to shape viral populations, antigenic properties remain largely conserved, supporting the continued relevance of current vaccine strategies while highlighting the importance of ongoing genetic and antigenic surveillance.

Source: BioRxIV, https://doi.org/10.64898/2026.11.13.766375

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Linden Tree on a Bastion, Albrecht Durer (1494)

 

{Click on Image to Enlarge}

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Public Domain.

Source: WikiArt, https://www.wikiart.org/en/albrecht-durer/linden-tree-on-a-bastion-1494

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