The natural history of infection with Sudan virus compared to Ebola virus in non-human primates: a rapid review.

Uganda recently declared the end of its sixth Sudan virus (SUDV) outbreak; the prior outbreak having ended just two years earlier. Efficacious vaccines are licensed for protection against Ebola virus (EBOV), but there is no evidence that these afford clinical protection against other orthoebolaviruses. While EBOV has been extensively characterized in humans and animal models, the evidence base for SUDV is more limited due to the lower frequency of outbreaks and cases to date. It is therefore valuable to consider how, and to what extent, our knowledge and evidence base on EBOV can be leveraged to support the development of countermeasures against SUDV. This rapid review aims to examine and compare the existing evidence on the natural history of EBOV and SUDV in non-human primates (NHP). Overall, 24 studies (described in 25 articles) were identified for inclusion: 19 evaluated EBOV, four evaluated SUDV, and one evaluated both. Results confirm that EBOV and SUDV infection result in very similar disease in NHP, characterized by a severe systemic inflammatory response and disseminated intravascular coagulopathy, leading to tissue and organ damage and fluid loss. Clinical presentation and progression, clinical pathology observations, and characteristics of the host immune response were consistent across viruses. There is some indication that EBOV may result in slightly faster disease progression and marginally higher mortality than SUDV, though there is substantial overlap, and minor differences are also observed with different EBOV variants. While infection of rhesus and cynomolgus macaques with SUDV or EBOV are widely accepted models of human disease, an equivalent comparison of available human data would be valuable.