Dados do Trabalho

Título

Genomic characterization of highly pathogenic avian influenza A virus H5N1 after 2020

Introdução

Avian influenza A viruses (AIV) infect bird populations worldwide, and their sporadic transmission to humans and other non-human mammals has raised concerns about the pandemic potential of these viruses. While most AIVs cause only mild-to-asymptomatic infection in avian hosts, highly pathogenic (HP) avian influenza (HPAI), restricted to H5 and H7 AIV subtypes, causes extremely high mortality (up to 100%) in domestic bird populations. HPAI viruses can also cause severe disease in humans following spillover via avian-to-human transmission, with case fatality around 60%. The spatial spread of H5N1 avian influenza and the long-term persistence of the virus in some regions present a serious threat to the health of humans and migratory birds.

Objetivo (s)

We aimed to characterize the population sizes of H5N1 detected in human and non-human mammals since 2020 and describe its genomic characteristics and global epidemiology.

Material e Métodos

Full-length genome sequences of the 8 segments of HPAI virus H5N1 collected from 1996 to 2022 were obtained from the GenBank database (http://www.flu.lanl.gov). Sequences were aligned and sequences divergence over time was determined using temporal and nucleotide distance analysis in IQTree 2 and BEAST v1.10. P-distance was used to analyze the similarities among sequences, and single nucleotide polymorphisms were detected using Geneious Prime.

Resultados e Conclusão

A total of approximately 400 sequences per segment was downloaded from GenBank, including sequences from different hosts such as avian, swine, mink, geese, and humans, among others. The recent human samples from the 2018-2022 outbreak grouped within the clade 2.3.4.4b, which has been the predominant strain in wild birds and poultry populations since 2021. Even though mink samples present the alanine (A) at position 271 of polymerase gene (PB2) (T271A), which enhances the polymerase activity of influenza A viruses in mammalian host cells, we did not observe the same mutation in recent H5N1 sequences from humans. The severity of human cases and the potential for limited human-to-human transmission highlights the need for continued surveillance and research to enhance preparedness to respond effectively to future outbreaks and mitigate the risk of a major public health crisis.

Palavras-chave

influenza viruses, avian, H5N1