Cytomegalovirus distribution and evolution in hominines

Area of Science:

• Virology
• Evolutionary Biology
• Primate Genetics

Background:

• Herpesviruses, including primate cytomegaloviruses (CMVs), typically exhibit co-divergence with their hosts.
• However, some herpesviruses are known to cross species barriers, complicating evolutionary histories.
• Previous limited studies suggested potential past CMV exchanges within the hominine lineage.

Purpose of the Study:

• To investigate the evolutionary history of cytomegaloviruses (CMVs) across African great apes.
• To test hypotheses of co-divergence versus host-switching events in primate CMV evolution.
• To determine the timing and directionality of potential CMV transmissions between hominine lineages.

Main Methods:

• Conducted molecular screening of 675 fecal samples from wild African great apes across nine species/subspecies.
• Generated novel CMV sequences, including the first from bonobos.
• Employed a Bayesian framework to analyze phylogenetic data, testing competing models of co-divergence and host switching, and estimating event dates.

Main Results:

• Identified CMVs in eight of nine African great ape species/subspecies sampled.
• The best-supported evolutionary model indicated a complex history of mutual CMV exchange between gorilla and panine (chimpanzee and bonobo) lineages.
• These reciprocal transmissions occurred over 800,000 years ago, prior to the divergence of chimpanzees and bonobos.

Conclusions:

• Cytomegalovirus (CMV) evolution in African great apes is characterized by significant host-switching events, challenging strict co-divergence models.
• Mutual transmissions between gorillas and panines shaped the early evolutionary trajectory of these viruses.
• These findings contribute to a broader understanding of viral genome evolution and host-jumping events in primates.