Pathogenesis and natural history of the Bundibugyo species of Orthoebolavirus in nonhuman primates

The current outbreak of Bundibugyo virus (BDBV) in Africa is a global public health concern particularly as there are no licensed medical countermeasures (MCM). Well characterized animal models that accurately replicate human BDBV infection are needed to develop effective MCM. We exposed 21 cynomolgus monkeys (CM) to BDBV to examine the progression and natural history of BDBV disease (BVD). BVD was more protracted than reported for Ebola and Sudan infection in CM with a lower lethality rate of 67% consistent with lower human BVD mortality rates. IHC and spatial proteomics identified CD209+, CD68+, and/or HLA-DR+ macrophages and dendritic cells as early targets of BDBV. These infected cells frequently colocalized with fibrin and infiltrating MPO+ neutrophils and S100A9+ myeloid-derived suppressor cells, consistent with the development of an active inflammatory response and early coagulopathy. Transcriptomic and proteomic analyses of the circulating immune response correspondingly reflected a cytokine-driven hyperinflammatory state in CM that succumbed to disease. Surviving animals resolved systemic inflammation by the study endpoint; however, BDBV antigen was identified in immune privileged tissues with lesion-associated inflammation aligning with known post-Ebola sequela in humans. This data should assist in identifying weaknesses in the disease course that can be exploited to develop new MCM.