Pithoviruses Are Invaded by Repeats That Contribute to Their Evolution and Divergence from Cedratviruses
Abstract Pithoviridae are amoeba-infecting giant viruses possessing the largest viral particles known so far. Since the discovery of Pithovirus sibericum, recovered from a 30,000-yr-old permafrost sample, other pithoviruses, and related cedratviruses, were isolated from various terrestrial and aquat...
Published in: | Molecular Biology and Evolution |
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Main Authors: | , , , , , , , |
Other Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Oxford University Press (OUP)
2023
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Subjects: | |
Online Access: | http://dx.doi.org/10.1093/molbev/msad244 https://academic.oup.com/mbe/advance-article-pdf/doi/10.1093/molbev/msad244/53253432/msad244.pdf https://academic.oup.com/mbe/article-pdf/40/11/msad244/53676949/msad244.pdf |
Summary: | Abstract Pithoviridae are amoeba-infecting giant viruses possessing the largest viral particles known so far. Since the discovery of Pithovirus sibericum, recovered from a 30,000-yr-old permafrost sample, other pithoviruses, and related cedratviruses, were isolated from various terrestrial and aquatic samples. Here, we report the isolation and genome sequencing of 2 Pithoviridae from soil samples, in addition to 3 other recent isolates. Using the 12 available genome sequences, we conducted a thorough comparative genomic study of the Pithoviridae family to decipher the organization and evolution of their genomes. Our study reveals a nonuniform genome organization in 2 main regions: 1 concentrating core genes and another gene duplications. We also found that Pithoviridae genomes are more conservative than other families of giant viruses, with a low and stable proportion (5% to 7%) of genes originating from horizontal transfers. Genome size variation within the family is mainly due to variations in gene duplication rates (from 14% to 28%) and massive invasion by inverted repeats. While these repeated elements are absent from cedratviruses, repeat-rich regions cover as much as a quarter of the pithoviruses genomes. These regions, identified using a dedicated pipeline, are hotspots of mutations, gene capture events, and genomic rearrangements that contribute to their evolution. |
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