Transcriptional signatures of rapid protection from Sudan virus infection by a single dose of a vesicular stomatitis virus-based vaccine

Sudan virus (SUDV) has caused multiple outbreaks of human disease with case fatality rates ranging from 41 to 100%. We have previously shown that a single vaccination with a recombinant vesicular stomatitis virus-based vaccine expressing the SUDV-Gulu glycoprotein (VSV-SUDV) prevented clinical and fatal disease from lethal SUDV challenge in cynomolgus macaques. With the high probability of future outbreaks, it is critical to determine the molecular mechanisms of VSV-SUDV-mediated protection and the ability to impart rapid protection against SUDV infection. In this study, RNA from whole blood samples obtained from nine cynomolgus macaques that were challenged with SUDV-Gulu post-vaccination with either VSV-EBOV (28 days before challenge, n = 3) or VSV-SUDV (28 or 7 days before challenge, n = 3/group) was subjected to bulk RNA sequencing. EdgeR, STEM, MaSigPro, and CIBERSORTx were used to assess longitudinal transcriptional changes elicited by vaccination and challenge. Our analysis revealed that VSV-SUDV and VSV-EBOV elicited distinct transcriptional responses. Moreover, NHPs vaccinated with VSV-EBOV (non-protective) generated a transcriptional response following SUDV challenge indicative of dysregulated inflammation. In contrast, NHPs that received VSV-SUDV vaccine generated a transcriptional response indicative of a recall adaptive immune response. Finally, in-silico deconvolution methods indicated changes in immune cell frequency consistent with immune response and resolution in the VSV-SUDV-vaccinated NHPs that are not observed with VSV-EBOV-vaccinated NHPs. These data indicate that VSV-SUDV vaccination results in a protective humoral response as late as 7 days before challenge despite transcriptional evidence of subclinical features of infection.