{
  "id": 4341916,
  "title": "Influenza A virus H5N1 genotypes B3.13 and D1.1 show temperature-dependent restriction of replication in primary human respiratory epithelial cell cultures derived from the upper and lower respiratory tract.",
  "url": "https://urgent.news/2026/08/29/influenza-a-virus-h5n1-genotypes-b3-13-and-d1-1-show-temperature",
  "topic": "health",
  "section": "Health & Medicine",
  "published": "2026-08-29T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.08.27.747488v1?rss=1"
  },
  "original_language": "en",
  "account": "The H5N1 clade 2.3.4.4b avian influenza A viruses, responsible for significant threats to wildlife and potential human infection, require mutations enabling improved interaction with mammalian cells and enhanced replication at lower respiratory tract temperatures. Researchers compared a human H1N1pdm09-like virus to H5N1 genotypes B3.13 and D1.1 for replication at temperatures mimicking the upper and lower human respiratory tract, as well as temperature conditions found in dairy cow udder tissue. All H5N1 viruses exhibited larger plaque sizes on MDCK cells at 37°C and 39°C compared to the H1N1pdm09 virus. When tested in primary, differentiated human nasal and bronchial epithelial cultures, H5N1 viruses displayed restricted infectious virus production compared to H1N1 at 33°C. While H5N1 genotype D1.1 also exhibited reduced replication at 37°C and 39°C, H5N1 genotype B3.13 replicated nearly at equivalent titers to H1N1pdm09. Regardless of temperature, all H5N1 viruses showed similar cell tropism in respiratory tract cells, infecting more ciliated cells than non-ciliated cells. The infection of nasal epithelial cells by H1N1, H5N1 B3.13, and D1.1 viruses induced higher levels of innate immune factors than infection of bronchial epithelial cells. These findings suggest that H5N1 genotypes B3.13 and D1.1 viruses demonstrate distinct temperature-dependent replication patterns compared to the H1N1pdm09 virus.",
  "summary": "H5N1 clade 2.3.4.4b avian influenza A viruses pose a significant threat to wild animal populations, domesticated animals, and potentially, the human population. For H5N1s to infect and transmit among mammalian species, mutations for improved utilization of mammalian receptors and enhanced replication at the lower temperatures of the upper respiratory tract need to be acquired. A human…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}