Assessing circovirus gene flow in multiple spill-over events
The establishment of viral pathogens in new host environments following spillover events probably requires adaptive changes within both the new host and pathogen. After many generations, signals for ancient cross-species transmission may become lost and a strictly host-adapted phylogeny may mimic true co-divergence while the virus may retain an inherent ability to jump host species. The mechanistic basis for such processes remains poorly understood. To study the dynamics of virus–host co-divergence and the arbitrary chances of spillover in various reservoir hosts with equal ecological opportunity, we examined structural constraints of capsid protein in extant populations of Beak and feather disease virus (BFDV) during known spillover events. By assessing reservoir-based genotype stratification, we identified co-divergence defying signatures in the evolution BFDV which highlighted primordial processes of cryptic host adaptation and competing forces of host co-divergence and cross-species transmission. We demonstrate that, despite extensive surface plasticity gathered over a longer span of evolution, structural constraints of the capsid protein allow opportunistic host switching in host-adapted populations. This study provides new insights into how small populations of endangered psittacine species may face multidirectional forces of infection from reservoirs with apparently co-diverging genotypes.
KeywordsCircovirus Psittacine beak and feather disease PBFD Microbiome Viral ecology
The authors would like to thank the contributions of Peter Copley, Sheryl Hamilton, Jocelyn Hockley, Kristy Penrose, Judy Clark and Annika Everaardt of the Orange-bellied Parrot Recovery Team, and the staff of the Australian Wildlife Health Centre (Healesville Sanctuary). SD received Charles Sturt University writing up award for completion of this manuscript.
The submitting author confirms that all individual co-authors have met the criteria of authorship. SD, SS, SRR, AP, JKF contributed to the conception and design. KA, PE contributed to sample collection and data analysis. SD, SS, SRR, AP, SAG contributed to method development, data analysis and interpretation. SD, SRR, AP, drafted the manuscript. SR and AP critically revised the manuscript. SRR and JKF gave final approval and agree to be accountable for all aspects of work ensuring accuracy and integrity.
Compliance with ethical standards
Conflict of interest
The authors declare no competing financial or other conflict of interest.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. Animal sampling was obtained using guidelines set by the Australian Code of Practice for the Care and Use of Animals for Scientific Purposes (1997) and authorised by the Charles Sturt University Animal Care and Ethics Committee (permit 09/046). All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. This article does not contain any studies with human participants performed by any of the authors.
Informed consent was obtained from all individual participants included in the study.
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