Different Host-Endogenous Retrovirus Relationships between Mammals and Birds Reflected in Genome-Wide Evolutionary...

Area of Science:

• Evolutionary biology
• Genomics
• Molecular biology

Background:

• Mammals and birds exhibit significant differences in endogenous retrovirus (ERV) loads.
• Host-ERVs interactions, including conflict and co-option, are proposed causes for these differences.
• Long-term genomic evolutionary signals of host-ERV interactions and their impact on ERV loads remain understudied.

Purpose of the Study:

• To investigate the long-term genomic evolutionary signals of host-ERV interactions.
• To determine how these interactions contribute to the observed differences in ERV loads between mammals and birds.
• To identify specific genes and evolutionary mechanisms associated with ERV load variation.

Main Methods:

• Phylogeny-controlled correlation analysis was performed on approximately 5,000 genes.
• The study compared the dN/dS ratio of each gene with the ERV load in 12 mammals and 21 bird species.
• Gene set enrichment analysis was employed to identify biological processes involved in host-ERV associations.

Main Results:

• Birds showed a higher proportion of genes with a strong correlation between dN/dS ratio and ERV load than mammals.
• A significant association was found between the dN/dS of the leucine-rich repeat-containing protein 23 gene and ERV load in birds.
• Gene silencing, rather than immunity or DNA recombination, was identified as a major contributor to the dN/dS-ERV load association in both groups.

Conclusions:

• Distinct evolutionary patterns in bird and mammal genes partially explain lower ERV loads in birds.
• Gene silencing is a universal mechanism significantly involved in the long-term evolutionary interaction between hosts and ERVs.
• Host genes may have either driven or responded to changes in ERV loads throughout evolution.