Global dissemination of H5N1 influenza viruses bearing the clade 2.3.4.4b HA gene and biologic analysis of the ones detected in China

Abstract

H5N1 avian influenza viruses bearing the clade 2.3.4.4b hemagglutinin gene have been widely circulating in wild birds and are responsible for the loss of over 70 million domestic poultry in Europe, Africa, Asia, and North America since October 2020. During our routine surveillance, 13 H5N1 viruses were isolated from 26,767 wild bird and poultry samples that were collected between September 2021 and March 2022 in China. To investigate the origin of these Chinese isolates and understand their genetic relationship with the globally circulating H5N1 viruses, we performed a detailed phylogenic analysis of 233 representative H5N1 strains that were isolated from 28 countries. We found that, after they emerged in the Netherlands, the H5N1 viruses encountered complicated gene exchange with different viruses circulating in wild birds and formed 16 genotypes. Genotype one (G1) was predominant, being detected in 22 countries, whereas all other genotypes were only detected in one or two continents. H5N1 viruses of four genotypes (G1, G7, G9, and G10) were detected in China; three of these genotypes have been previously reported in other countries. The H5N1 viruses detected in China replicated in mice, with pathogenicity varying among strains; the G1 virus was highly lethal in mice. Moreover, we found that these viruses were antigenically similar to and well matched with the H5-Re14 vaccine strain currently used in China. Our study reveals the overall picture of H5N1 virus evolution and provides insights for the control of these viruses.

Avian influenza overview June – September 2022

“…Since then, it has been persistently circulating in this geographic area, and in West Africa it reassorted with the A(H9N2) subtype of the zoonotic G1 lineage (Ouoba et al, 2022). Starting from October 2021, different A(H5N1) genotypes, some of them previously identified in Europe, have been detected in South and East Asia, including China (Cui et al, 2022). In December 2021, North America announced the first detection of an A(H5N1) virus strongly related to the A(H5N1) identified in Northern Europe during the 2020-2021 epidemic season (Bevins et al, 2022;Caliendo et al, 2022b).…”

Detection of New H5N1 High Pathogenicity Avian Influenza Viruses in Winter 2021–2022 in the Far East, Which Are Genetically Close to Those in Europe

“…It was confirmed that two types of H5 viruses with different hemagglutinin (HA) in the genetic pool were already circulating in autumn 2021; one had been continuously present with genetic drift among the European bird population since autumn 2020, and the other, which originated in African countries but could be widely spread throughout European countries [ 8 ] had been detected since October 2021. Under such a circumstance, many gene-reassorted viruses, including H5N1, were generated, and dominant H5N1 reassorted viruses were further transferred from Europe to African, North American, or Asian countries in winter 2021–2022 [ 9 , 10 , 11 , 12 ]. Phylogenetic analyses have already revealed that two types of H5 HPAIVs invaded southern Japan at the end of 2021.…”

TREX (transcription/export)-NP complex exerts a dual effect on regulating polymerase activity and replication of influenza A virus

“…The global spread of viral pathogens, such as IAV and SARS-CoV-2, led to major economic and health challenges worldwide [42][43][44]. Revealing host genes essential for infection by IAV can provide insights into the virus pathogenesis, and facilitate the development of novel therapeutics.…”