Project description:The H5N1 avian influenza virus clade 2.3.4.4b outbreak represents a major pandemic threat for humans. Although most human cases to date have been mild, several severe cases of respiratory illness have been reported. A key unanswered question is the pathogenesis of H5N1 infection in primates following respiratory infection. In this study, we observed severe clinical disease in cynomolgus and rhesus macaques following respiratory infection with the H5N1 isolate A/Texas/37/2024 (hu-TX37-H5N1). Cynomolgus macaques inoculated with a high dose of hu-TX37-H5N1 developed severe consolidative necrotizing pneumonia with extrapulmonary spread. Clinical disease was rapidly progressive and lethal in 100% (9 of 9) of macaques by day 5-9 following challenge. Rhesus macaques inoculated with varying doses of hu-TX37-H5N1 demonstrated dose-dependent mortality, and surviving animals showed robust natural protective immunity against high dose re-challenge. H5N1 infection in both cynomolgus and rhesus macaques was characterized by upregulation of proinflammatory cytokine, innate immune cell, complement and coagulation, apoptosis, and immune exhaustion pathways and downregulation of NK, T, and B cell activation and differentiation pathways. Taken together, our data demonstrate severe respiratory disease with H5N1 clade 2.3.4.4b in nonhuman primates and suggest that acute inflammation and immune dysregulation are key contributors to disease pathogenesis.
Project description:The 2024 outbreak of highly pathogenic avian influenza virus (HPAIV) H5N1 in U.S. dairy cattle presented an unprecedented scenario where the virus infected bovine mammary glands and was detected in milk, raising serious concerns for public health and the dairy industry. Unlike previously described subclinical influenza A virus (IAV) infections in cattle, H5N1 infection induced severe clinical symptoms, including respiratory distress, mastitis, and abnormal milk production. To understand the host immune responses and changes particularly in the mammary gland, we performed scRNA-seq analysis on bovine milk somatic cells (bMSC) in-vitro infected with H5N1 isolate from dairy farm. We identified ten distinct cell clusters and observed a shift toward type-2 immune responses, characterized by T-cells expressing IL13 and GATA3, and three different subtypes of epithelial cells based on expression of genes associated with milk production. Our study revealed temporal dynamics in cytokine expression, with a rapid decline in luminal epithelial cells and an increase in macrophages and dendritic cells, suggesting a role in increased antigen presentation. These findings indicate that bovine H5N1 infection triggers complex immune responses involving both pro-inflammatory and regulatory pathways. This research fills a critical gap in understanding the immune responses of bovine mammary glands to H5N1 infection and highlights the need for further investigation into therapeutic strategies for managing such outbreaks.
Project description:Experimental spillover of H5N1 clade 2.3.4.4b high pathogenicity avian influenza virus from gulls to minks reveals mammalian adaptation without spillback potential
| PRJEB95805 | ENA
Project description:Highly Pathogenic Avian Influenza A virus subtype H5N1 (clade 2.3.4.4b) Isolated from a natural protected area in Peru
Project description:The 2022 North American outbreak of 2.3.4.4b H5N1 avian influenza virus revealed significant mammalian adaptation and pathogenicity, yet mechanisms remain unclear. To address this knowledge gap, we investigated the North American H5N1 strain (GA/W22-145E/22), which demonstrated unique immune cell-mediated systemic dissemination, neuroinvasion, and 100% mortality in ferrets, unlike the non-lethal Eurasian strain (KR/W811/21). Genomic and reverse genetics studies identified PB2478I and NP450N mutations as key determinants of enhanced polymerase activity, immune cell tropism, and pathogenicity. Mutant GA/W22-145E/22 virus carrying PB2478V/NP450S showed complete survival without systemic dissemination. Furthermore, GA/W22-145E/22 demonstrated robust replication in human PBMCs and bovine mammary gland organoids, raising concerns about zoonotic spillover. These findings underscore PB2478I and NP450N as pivotal markers of pathogenicity, emphasizing the urgent need for enhanced surveillance and targeted interventions