ETIDIOH - NEW

Abstract The structural instability of influenza hemagglutinin (HA) is related to its function in low pH-mediated membrane fusion , which requires prior cleavage of the premature HA0 by a host protease . The precise determinants underlying the stability and cleavability of HA remain to be fully understood and have implications for risk assessment of zoonotic influenza A viruses (IAV), viral transmissibility and vaccine production. To address this, we conducted random mutagenesis on early 2009 pandemic H1 HA, followed by selection of acid-stable viruses and detailed profiling of the mutant HAs. This resulted in identification of four mutations , which increase the acid-stability and decrease the fusion-promoting activity of H1 HA, without compromising viral entry and replication in cells. The newly recognized mutations are situated in the globular head , vestigial esterase and membrane-proximal part of H1 HA, in regions involved in the refolding of HA at low pH. A fifth mutation, D346N,...

Abstract As a rare subtype of avian influenza virus, H16 viruses are predominant in gulls but rarely found in domestic birds . The low prevalence of H16 viruses has limited our understanding of their epidemiology and evolutionary dynamics . In this study, we isolated three novel H16N3 viruses from migratory gulls in East Asian–Australasian Flyway in eastern China in 2023, which are significantly different from previously identified isolates. To fully understand the epidemiology and genetics characteristics of the global H16 viruses, we compared the host divergence of several rare subtypes and determined that the H13 and H16 subtypes were predominantly pooled into different species of gulls by sharing their internal genes, whereas the waterfowl of Anatidae served as the primary natural reservoirs of the H8, H11, H12, H14, and H15 subtypes. Detailed phylogenetic analysis revealed the evolutionary divergence of globally circulating H16 viruses and their frequent gene reassortment . Furthe...