Evidence for metaviromic islands in marine phages

Area of Science:

• Microbiology
• Genomics
• Virology

Background:

• Metagenomic islands (MGIs) are genomic regions in prokaryotes that under-recruit in metagenomes.
• The Constant-Diversity (C-D) model links MGIs to phage predation and maintenance of prokaryotic population diversity.
• This study extends the MGI concept to phage genomes within a metavirome.

Purpose of the Study:

• To investigate under-recruiting regions in phage genomes (metaviromic islands, MVIs).
• To assess the relevance of the Constant-Diversity (C-D) model to phage biology.
• To identify phage genes associated with MVIs and their potential functions.

Main Methods:

• Metagenomic analysis of a metavirome sample.
• Recruitment analysis of phage genomes against the metavirome.
• Identification and characterization of under-recruiting regions (MVIs) in phage genomes.

Main Results:

• Under-recruiting regions were identified in phage genomes, termed metaviromic islands (MVIs).
• Genes involved in host recognition showed under-recruitment, supporting the C-D model.
• Terminases and other packaging-related genes also exhibited significant under-recruitment.
• Some highly related phage genomes lacked MVIs, suggesting generalist strategies.

Conclusions:

• The C-D model may extend to phage genomes, with MVIs playing a role in phage-host interactions.
• MVIs are not solely related to host recognition but also to phage genome packaging.
• The absence of MVIs in some phages might indicate a broad host range and generalist lifestyle.