Mutation mapping and evolutionary dynamics of Bundibugyo Ebolavirus (BDBV-2026) genomes reported from Uganda

The ongoing outbreak of Ebola Virus Disease (EVD), caused by the Bundibugyo virus (BDBV) 2026, is evolving rapidly with an increasing number of cases, geographical spread, and cross-border transmission between the Democratic Republic of the Congo (DRC) and Uganda. To identify novel mutations, annotate, and understand the evolutionary dynamics of BDBV-2026, we analysed a total of 19 genomes isolated from Ugandan cases during the ongoing BDBV-2026 outbreak using a comparative genomics approach. We observed a substantial number of amino acid substitutions with lower single nucleotide polymorphisms and complete deletion of 3' leader sequences (61 nucleotides and truncation of 5' trailer sequences (73 nucleotides) in all queried BDBV-2026 genomes. Furthermore, hotspots for unique amino acid substitutions were observed in nucleocapsid (NP), large (L) and glycoprotein (GP) open reading frames. Molecular dynamic simulations showed that changes in the NP protein had a stabilizing effect when compared with older wild-type BDBV NPs. Phylogenetic analysis demonstrated diversity within the BDBV-2026 genomes and the emergence of two sub-groups, I and II, of BDBV-2026 viruses. These findings suggest that the ongoing BDBV-2026 outbreak might have originated from a novel zoonotic spillover. This study provides a high-resolution genomic perspective on BDBV-2026 and highlights key features useful to designing vaccine and anti-viral therapeutics.