Clock-like behavior across Orthoebolavirus species suggests alternative evolution of the 2026 Bundibugyo virus outbreak
DOI:
https://doi.org/10.3855/jidc.23736Keywords:
Orthoebolavirus, Ebola, evolutionAbstract
Introduction: Recent increase in reported cases of Bundibugyo virus (species Orthoebolavirus bundibugyoense) in the Democratic Republic of the Congo and Uganda highlight the importance of understanding their evolutionary dynamics.
Methodology: We analyzed publicly available genomes obtained from the Pathoplexus database representing 3 medically relevant species of the Orthoebolavirus genus: Ebola virus (n = 3,388), Zaire virus (n = 166), and Bundibugyo virus (n = 49). We investigated whether genetic divergence is associated with sampling time utilizing root-to-tip regression analyses derived from temporally calibrated phylogenies as an indicator of molecular clock behavior.
Results: Sudan virus (R2 = 0.855) and Ebola virus (R2 = 0.709) exhibited significant temporal structures between sampling time and genetic divergence. Bundibugyo virus displayed strong clock-like behavior after exclusion of 2026 genomes (R2 = 0.983), which showed a marked substitution deficit relative to the historical molecular clock and deviated substantially from the inferred regression. Date randomization tests supported the presence of temporal signal across all datasets (p < 0.001), indicating that the temporal signals exceeded expectations under a null model without temporal structure.
Conclusions: These results provide a comparative assessment of the temporal structures across 3 medically relevant Orthoebolavirus species. While historical genomes largely conformed to molecular clock expectations, the inclusion of genomes from the ongoing 2026 Bundibugyo virus outbreak deviated from these projections, suggesting an alternative evolutionary process for 2026 Bundibugyo virus, such as viral persistence in immune-privileged anatomical sites of previously infected individuals or an independent zoonotic spillover event in an alternative species, in which the virus evolved within its natural reservoir prior to human infection.
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2026 Gustavo Sganzerla Martinez, Anuj Kumar, Mansi Dutt, Misaki Wayengera, Wilber Sabiiti, David J Kelvin, Henry Kyobe Bosa
This work is licensed under a Creative Commons Attribution 4.0 International License.
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).
