Assessing circovirus gene flow in multiple spill-over events.

Area of Science:

• Virology
• Evolutionary Biology
• Genomics

Background:

• Viral spillover events necessitate host and pathogen adaptation, yet the evolutionary mechanisms remain unclear.
• Host-adapted viral phylogenies can obscure ancient cross-species transmission, complicating evolutionary analyses.
• Understanding these dynamics is crucial for managing viral diseases in vulnerable populations.

Purpose of the Study:

• To investigate the interplay between virus-host co-divergence and cross-species transmission.
• To examine the role of viral structural constraints in host-jumping events.
• To identify evolutionary signatures of cryptic host adaptation in Beak and feather disease virus (BFDV).

Main Methods:

• Analysis of structural constraints in the capsid protein of Beak and feather disease virus (BFDV) populations.
• Assessment of reservoir-based genotype stratification during known spillover events.
• Phylogenetic analysis to identify co-divergence defying signatures.

Main Results:

• Identified evolutionary signatures in BFDV that contradict simple co-divergence models.
• Demonstrated that capsid protein structural constraints permit host switching, even in host-adapted viral populations.
• Highlighted competing evolutionary forces of host co-divergence and cross-species transmission.

Conclusions:

• BFDV evolution exhibits cryptic host adaptation, challenging traditional co-divergence paradigms.
• Capsid protein structure plays a key role in enabling opportunistic host switching.
• Endangered psittacine species face complex infection risks from viruses with seemingly co-diverging genotypes.