{
  "id": 12923336,
  "title": "Virus {Psi}M2 enters a non-lytic lifecycle alternative to lysogeny during infection of Methanothermobacter marburgensis",
  "url": "https://urgent.news/2026/10/08/virus-psi-m2-enters-a-non-lytic-lifecycle-alternative-to-lysogeny",
  "topic": "science",
  "section": "Science",
  "published": "2026-10-08T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.10.07.757236v1?rss=1"
  },
  "original_language": "en",
  "account": "Methanogens, archaea that generate methane during metabolism, often reside in oxygen-free environments where they face viral threats. Among these virus infections is {Psi}M2, a head-tailed virus that typically exhibits a destructive lytic lifecycle, killing its host Methanothermobacter marburgensis after invasion. However, researchers have discovered that {Psi}M2 can also adopt a different, persistent infection strategy. Culture experiments conducted in minimal growth medium for the host showed that infected cells did not undergo complete destruction but consistently expelled infectious viral particles. Conversely, in a growth medium less conducive to the host, {Psi}M2 released virions while the host cells continued to multiply for 14 hours post infection before finally lysing.\n\nDespite the presence of a gene that could potentially facilitate lysogeny (a form of viral integration), genetic analysis of the infected M. marburgensis cultures indicated that the viral DNA persisted outside the host genome. This likely resulted from a mutation in the integrase gene, responsible for integrating viral DNA. The findings imply that {Psi}M2 initiates a non-lytic lifecycle under suboptimal conditions for host growth rather than transitioning into lysogeny. Furthermore, genomic sequencing revealed a diverse viral population, including novel variants. An abundance of non-synonymous mutations and frame-shift-causing insertions, particularly in the genes coding for a capsid protein and a major spike protein, likely led to differences in host recognition and infectivity among these variants. In summary, the investigation uncovers a more intricate viral behavior and increased genetic variability in {Psi}M2 compared to earlier descriptions.",
  "summary": "Methanogens, a diverse group of archaea that produce methane during energy metabolism, are prevalent in anoxic habitats where they are exposed to viral infections. The head-tailed virus {Psi}M2 is one of few virus isolates that infect a methanogen host and was described as a lytic virus that lyses its host, Methanothermobacter marburgensis. Here, we present evidence that {Psi}M2 does not…",
  "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."
}