Endogenization of a Prosimian Retrovirus during Lemur Evolution

Area of Science:

• Virology
• Evolutionary Biology
• Genomics

Background:

• Endogenous retroviruses (ERVs) serve as genetic fossils, revealing past viral infections and host evolutionary history.
• Studying viruses that coevolved with lemurs can illuminate basal traits of primate viruses and host-virus interactions.

Purpose of the Study:

• To discover and characterize novel endogenous retroviruses in lemur genomes.
• To understand the evolutionary origins and significance of ERVs in primate evolution.

Main Methods:

• Next-generation sequencing was employed to identify and sequence the complete genome of a novel retrovirus.
• Phylogenetic analyses were conducted to determine the evolutionary relationships of the newly discovered retrovirus.
• Molecular clock analysis of long terminal repeat (LTR) sequences was used to estimate the timing of endogenization.

Main Results:

• A novel gamma-type betaretrovirus, named prosimian retrovirus 1 (PSRV1), was identified in the genome of Coquerel's sifaka (Propithecus coquereli).
• Phylogenetic analysis places PSRV1 as basal to other primate betaretroviruses, with close relation to simian retroviruses.
• Molecular clock analysis estimated PSRV1 endogenization at approximately 4.56 million years ago, post-dating the divergence of Propithecus species.

Conclusions:

• PSRV1 represents a significant milestone in lemur evolution, particularly during the radiation of the Propithecus genus.
• The discovery of PSRV1 provides insights into ancient retroviral lineages and their integration into host genomes.
• The presence of a gamma-type env gene in PSRV1 may have implications for cross-species transmission events and vertebrate host health.