ETIDIOH - NEW

Abstract Although influenza A viruses (IAV) are notorious respiratory pathogens, some IAV strains can reach and replicate in the central nervous system (CNS) in vivo. In particular, highly pathogenic avian influenza viruses (HPAIV) pose a threat for future pandemics and are linked to greater neurotropic potential . Moreover, neurotropic IAV strains have shown a more significant impact on the onset and pathogenesis of neurodegenerative diseases (NDD). However, despite its clinical relevance , the dynamics and cellular tropism of IAV infection in the CNS are not well understood. In this study, we analyzed the replication of HPAIV H7N7 in vitro using a primary murine triple co-culture system comprising neurons, astrocytes, and microglia . We found that microglia become highly infected early on and induce a strong pro-inflammatory response before undergoing apoptosis . Using fluorescence microscopy with automated single-cell profiling, we found that, in contrast to non-neurotropic H3N2, th...

Abstract Yakutia, the largest breeding ground for wild migratory birds in Northeastern Siberia , plays a big role in the global ecology of avian influenza viruses (AIVs). In this study, we present the results of virological surveillance conducted between 2018 and 2023, analyzing 1970 cloacal swab samples collected from 56 bird species . We identified 74 AIVs of H3N6, H3N8, H4N6, H5N3, H7N7, H10N3, and H11N9 subtypes in Anseriformes order. Phylogenetic analysis showed that the isolates belong to the Eurasian lineage and have genetic similarities with strains from East Asia, Europe, and North America. Cluster analysis has demonstrated the circulation of stable AIV genotypes for several years. We assume that Yakutia is an important territory for viral exchange on the migratory routes of migrating birds. In addition, several amino acid substitutions have been found to be associated with increased virulence and adaptation to mammalian hosts , highlighting the potential risk of interspecific...

Abstract High pathogenicity (HP) avian influenza viruses (AIV) generally evolve from low pathogenicity (LP) precursors after transmission from wild birds to chickens (Gallus gallus domesticus) and turkeys (Meleagris gallopavo), causing severe economic losses worldwide. Turkeys are more susceptible to AIV infection than chickens and are considered potential bridging hosts that facilitate the emergence of HPAIV . Beyond the polybasic cleavage site (pCS) in hemagglutinin (HA), little is known about other virulence determinants of HPAIV in these species. In 2015, HPAIV H7N7 and its LP ancestor were isolated from the same chicken farm, which differed by 16 nonsynonymous mutations across all eight gene segments, in addition to the pCS. Here we identify the genetic determinants, including the pCS, that contributed to the HPAIV H7N7 virulence, transmission, replication, and tissue distribution in chickens and turkeys. Notably, the non-structural (NS1) or matrix (M) proteins ’ encoding segments...

Abstract Evaluating the trade-off hypothesis for the evolution of virulence using empirical data poses significant challenges. The hypothesis suggests that pathogens evolve to maximize transmissibility, but fatality imposes limits as there are diminishing gains in transmissibility . In this study, we analyzed a secondary dataset of influenza virus infections in ferrets (Mustela putorius furo), categorized by Hemagglutinin (HA) and Neuraminidase (NA) subtypes . Subgroups defined by the H7/N9 and H7/N7 combinations exhibited fatality rates of approximately 30% and reached cumulative viral titers close to 7.5 (log10 titer/mL). These levels represent intermediate fatality rates , as the H5/N6 and H5/N1 subgroups had higher fatality rates but reached lower cumulative viral titers. Using cumulative viral titer as a proxy for potential secondary transmissions, the analysis suggests that intermediate fatality rates are associated with higher numbers of secondary transmissions . However, there ...