Using genomics, evolutionary biologists test several hypotheses on the origin of viruses. New evidence suggests they may have emerged more times than previously thought.

Analysis of RNA polymerase hallmark gene phylogenies supported by protein structure relationships of flaviviruses and ‘flavi-like’ viruses underpins the taxonomic expansion and reorganization of Flavi...

Epstein-Barr virus reprograms autoreactive B cells as antigen-presenting cells to promote pathogenic antinuclear T and B cell responses in lupus.

imageimageViro3D provides proteome-level, high confidence AI-protein structure predictions for >4,400 viruses, allowing mapping of form and function across the human and animal virosphere. Viro3D i...

#Ethiopia has confirmed the outbreak that has infected at least 9 people in the south of the country is of #Marburg virus disease. I commend Ethiopia’s @FMoHealth for its rapid and transparent response to the outbreak, and the work of the Ethiopia Public Health Institute and

Giant viruses, such as mimiviruses, exhibit unique characteristics, including virions visible under a light microscope, genomes larger than some unicellular organisms, and a diverse and unprecedented ...

Background: All of the major antigenic changes in influenza A(H3N2) viruses since 1968 have involved mutations at just nine amino acid positions, called cluster transition sites, surrounding the receptor binding region of the hemagglutinin surface protein. During the northern hemisphere (NH) 2024–2025 influenza season, A(H3N2) variants emerged with multiple parallel substitutions affecting cluster transition sites 135, 145, 158 and/or 189, with implications for the 2025–2026 season. Methods: Using >24,000 global A(H3) sequences between September 2024 and August 2025, we assess the nature and frequency of amino acid mutations among emerging NH and southern hemisphere (SH) A(H3N2) variants relative to the 2024–2025 subclade J and updated 2025–2026 subclade J.2 vaccine reference strains. We contextualize based upon historic amino acid variation among >210,000 global A(H3) sequences since 1968 and publicly available antigenic characterization data relative to 2024–2025 and 2025–2026 vaccine reference strains Results: Virtually all circulating A(H3N2) viruses in 2024–2025 were subclade J.2. In Europe, about one-third had cluster transition site mutations, mostly T135A with S145N. In North America, more than two-thirds had cluster transition site mutations, including T135K or S145N, with late-season increase in doubly mutated J.2.3 (N158K + K189R) and J.2.5 (S145N + N158K) subclades. The SH 2025 season showed increase in J.2.3 and emergence of J.2.4 (T135K + K189R) including a further drifted J.2.4.1 variant with additional N158D and other mutations, recently renamed subclade K. A substantial proportion of J.2.3 and J.2.4 viruses are antigenically distinct from the 2025–2026 influenza vaccine. Conclusion: Influenza A(H3N2) variants with a combination of cluster transition site mutations emerged during the NH 2024–2025 season. A further drifted and vaccine-mismatched variant now called subclade K arose during the SH 2025 season and is projected to predominate among A(H3N2) viruses for the NH 2025–2026 season. While mismatched vaccines may still provide protection, enhanced genetic, antigenic and epidemiological (eg, vaccine effectiveness) monitoring are warranted to inform risk assessment and response.

A new COP30 report finds that rising temperatures, extreme weather, evolving pathogens and climate-driven migration are reshaping disease patterns

Author summary Host recognition of viral nucleic acids is fundamental for stimulating antiviral immunity. To prevent aberrant immune activation, cells must precisely differentiate “non-self” from “sel...

Using a new method called FoldTree, the authors compare proteins on the basis of their shape to construct more accurate family trees over long evolutionary timescales and capture distant relationships...

Bats are natural reservoirs for a wide range of RNA viruses. Members of the genus Betacoronavirus , including Severe Acute Respiratory Syndrome virus 2 (SARS-CoV-2) and Middle East Respiratory Syndrome virus (MERS-CoV), have attracted particular attention due to their recent zoonotic emergence. However, much of the known diversity of betacoronaviruses is based on data from Asia, Africa, and the Middle East, with limited genomic information available from the Americas. Herein, we report the complete genome of a novel bat betacoronavirus identified from a Pteronotus parnellii bat sampled in Brazil. Phylogenetic analysis revealed that this virus is sufficiently distinct from the five recognized Betacoronavirus subgenera to represent a new subgenus. Of note, the spike protein of this novel bat coronavirus possesses a functional furin cleavage site at the S1/S2 junction with a unique amino acid sequence motif (RDAR) that differs from that found in SARS-CoV-2 (RRAR) by only one amino acid. Comparative structural analysis identified other betacoronaviruses in bats with furin cleavage sites at the S1/S2 junction, suggesting that this region is a structurally permissive “hotspot” for cleavage site incorporation. Our study provides a broader understanding of the phylogenetic and functional diversity of bat coronaviruses as well as their zoonotic potential. ### Competing Interest Statement Y.K. has received unrelated grant support from Daiichi Sankyo Co., Ltd., Fujifilm Toyama Chemical Co., Ltd., Tauns Laboratories, Inc., Shionogi & Co. Ltd., Otsuka Pharmaceutical Co., Ltd., KM Biologics Co. Ltd., Kyoritsu Seiyaku Corporation, Shinya Corporation and Fuji Rebio, Inc. Y.K. is a co-founder of FluGen. The other authors do not have any competing interests. KAKENHI Grants-in-Aid for Scientific Research on Innovative Areas, 16H06429, 16K21723, 16H06434 KAKENHI Grant-in-Aid for Scientific Research (B), JP22H02521 KAKENHI Grant-in-Aid for Early-Career Scientists, 25K18814, 22K15469 KAKENHI Grant-in-Aid for JSPS Fellows, 21J01036 AMED Research Program on Emerging and Re-emerging Infectious Diseases, JP19fk0108113, JP19fk018113 AMED, JP223fa627002, JP22am0401030, JP23fk0108659 AMED Advanced Research and Development Programs for Medical Innovation (AMED-CREST), 22gm1610010h0001 Takeda Science Foundation, https://ror.org/02y123g31 RIKAKEN HOLDINGS CO. Young Researcher Support Grant-in-aid National Health and Medical Research Council (Australia) Investigator grant, GNT2017197

Nature - Experiments suggests H9N2 has adapted to human cells but cases of person-to-person transmission haven’t been reported yet.