The #bat #influenza A virus subtype #H18N11 induces nanoscale MHCII clustering upon host #cell attachment

Abstract

Prior to the discovery of bat influenza A virus (IAV) subtypes H17N10 and H18N11, all IAVs were thought to bind sialic acid residues via hemagglutinin (HA) to mediate attachment and subsequent viral entry. However, H17 and H18 engage a proteinaceous receptor: the major histocompatibility complex class II (MHCII). The mechanistic details of this hitherto unknown protein-mediated entry are not understood. Given that conventional IAVs rely on multivalent binding to sialylated glycans, we hypothesized that bat HA similarly interacts with multiple MHCII molecules. Using photoactivated localization microscopy (PALM) on fixed and live cells, we demonstrate that bat IAV particles attach to pre-existing MHCII clusters and induce a further increase in cluster size upon binding. To measure the impact of viral attachment on the dynamics of MHCII, we employ an “inverse attachment” approach, immobilizing viral particles on coverslips before seeding live MHCII-expressing cells on top. Single-molecule tracking reveals that the mobility of MHCII is indeed slowed down in viral proximity leading to a local enrichment of MHCII molecules beneath the viral particle. These findings suggest that viral attachment induces MHCII clustering, a process similar to the MHCII dynamics observed during the formation of an immunological synapse.

Source: Nature Communications, https://www.nature.com/articles/s41467-025-58834-y

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#Genomics of novel #influenza A virus (#H18N12) in #bats, Caribe #Colombia

Abstract

Influenza viruses are highly capable of mutating and adapting in mammalian hosts. While these viruses have been extensively studied in birds, research on their presence in bats has been limited. However, influenza viruses circulating in bats have shown notable molecular divergence. The present study aimed to characterize the phylogenetic, evolutionary, and antigenic relationships of an influenza A virus detected in the fishing bat Noctilio albiventris. As part of a pathogen surveillance study of public health interest, 159 rectal samples were collected from bats in the Colombian Caribbean. The samples were sequenced using RNA-Seq. A genome (eight viral contigs) associated with the Orthomyxoviridae family was identified in a pool. Most segments showed approximately 90% similarity with H18N11, except for the neuraminidase. Analysis of the N protein shows that occupies a basal position relative to the N11 subtype, with its divergence date estimated to be approximately 50 years earlier than the earliest reported N11 sequence. 3D modeling identified three mutations (K363R, T242K, and I139V), which may enhance interaction with the HLA-DR of bats. The analyses and antigenic divergence observed in the N protein of N. albiventris suggests the existence of a new subtype (H18N12) with unknown pathogenicity, which requires further investigation.

Source: Scientific Reports, https://www.nature.com/articles/s41598-025-91026-8

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