Virus {Psi}M2 enters a non-lytic lifecycle alternative to lysogeny during infection of Methanothermobacter marburgensis
- 1Leipzig University
Abstract
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 exclusively follow the classic lytic lifecycle but can also enter an alternative, chronic infection-like state. Growth experiments showed that infected cultures in minimal medium, optimized for the methanogen host (MS medium) did not exhibit complete lysis but continuously released infective virions. In contrast, in a suboptimal complex medium (SAB medium), the {Psi}M2-infected culture released virions in the exponential growth phase and eventually lysed after 14 hours post infection. Although the genome of {Psi}M2 encodes a putative integrase, a prerequisite for lysogeny, whole genome sequencing of {Psi}M2-infected M. marburgensis cultures revealed that the viral DNA remained extrachromosomal rather than integrating into the host genome, likely due to a mutation in the integrase gene. These findings suggest that {Psi}M2 enters a non-lytic lifecycle alternative to lysogeny under suboptimal host growth conditions. Sequencing further identified a heterogeneous viral population including previously undescribed variants. A high density of non-synonymous mutations and frameshift-inducing insertions was observed within ORFs predicted to encode a capsid protein and a major spike protein, suggesting these viral variants to differ in host recognition and infectivity. Overall, our results show more complex viral behavior and greater genetic variability than previously described.
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BibTeX
@misc{schlaich2026virus,
title = {{Virus PsiM2 enters a non-lytic lifecycle alternative to lysogeny during infection of Methanothermobacter marburgensis}},
author = {S. M. Schlaich and J. Herbert and D. Crippa and B. R. Kercin and M. C. Schoelmerich and B. Molitor},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.07.757236},
url = {https://www.biorxiv.org/content/10.64898/2026.10.07.757236v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Virus {Psi}M2 enters a non-lytic lifecycle alternative to lysogeny during infection of Methanothermobacter marburgensis
AU - S. M. Schlaich
AU - J. Herbert
AU - D. Crippa
AU - B. R. Kercin
AU - M. C. Schoelmerich
AU - B. Molitor
PY - 2026
DA - 2026/10/07
PB - bioRxiv
DO - 10.64898/2026.10.07.757236
UR - https://www.biorxiv.org/content/10.64898/2026.10.07.757236v1
AB - 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 exclusively follow the classic lytic lifecycle but can also enter an alternative, chronic infection-like state. Growth experiments showed that infected cultures in minimal medium, optimized for the methanogen host (MS medium) did not exhibit complete lysis but continuously released infective virions. In contrast, in a suboptimal complex medium (SAB medium), the {Psi}M2-infected culture released virions in the exponential growth phase and eventually lysed after 14 hours post infection. Although the genome of {Psi}M2 encodes a putative integrase, a prerequisite for lysogeny, whole genome sequencing of {Psi}M2-infected M. marburgensis cultures revealed that the viral DNA remained extrachromosomal rather than integrating into the host genome, likely due to a mutation in the integrase gene. These findings suggest that {Psi}M2 enters a non-lytic lifecycle alternative to lysogeny under suboptimal host growth conditions. Sequencing further identified a heterogeneous viral population including previously undescribed variants. A high density of non-synonymous mutations and frameshift-inducing insertions was observed within ORFs predicted to encode a capsid protein and a major spike protein, suggesting these viral variants to differ in host recognition and infectivity. Overall, our results show more complex viral behavior and greater genetic variability than previously described.
ER -