{
  "id": 8828618,
  "title": "The La Crosse virus M segment determines virus isolate cell-to-cell spread and virulence",
  "url": "https://urgent.news/2026/09/20/the-la-crosse-virus-m-segment-determines-virus-isolate-cell-to-cell",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-20T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.17.752448v1?rss=1"
  },
  "original_language": "en",
  "account": "La Crosse virus (LACV), an orthobunyavirus transmitted by mosquitoes in North America, can lead to severe neurological disease. However, our understanding of how LACV spreads and causes disease is still incomplete. To explore this, we studied two genetically similar LACV lineage I isolates, LACV1960 and LACV1978. We discovered that LACV1960 infects and replicates more efficiently than LACV1978, while LACV1978 shows increased cell-cell spread and in vivo virulence. By creating reassortants between these isolates, we found that each genomic segment contributes to LACV pathogenesis, with the M segment being the most significant factor in vivo and plaque size and replication in vitro.\n\nFocusing on the M segment, we generated chimeric viruses using a LACV1978 background and swapped in different regions of the LACV1960 M segment. Our findings revealed that the Gc head domain of the M segment is responsible for plaque size and infectivity. Specifically, the LACV1960 Gc head chimera resulted in smaller plaques but higher infectivity compared to the wild-type LACV1978. Furthermore, our study showed that plaque size varies across and within LACV lineage isolates, suggesting that changes in the M segment may influence LACV's spread in nature.\n\nMoving forward, we plan to examine the mechanisms behind how cell-to-cell spread affects dissemination, ultimately aiming to understand how LACV genome segments influence spread, infectivity, virulence, and viral fitness.",
  "summary": "La Crosse virus (LACV) is an orthobunyavirus spread by mosquitoes in North America and can cause severe neurological disease. Despite this burden, there is a lack of LACV antiviral treatments as our fundamental understanding of how LACV spreads and causes disease remains incomplete. To investigate LACV biology, we took advantage of two genetically similar LACV lineage I isolates (LACV1960 and…",
  "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."
}