In-vitro cellular tropism and immunomodulatory response to rVSV?G-ZEBOV-GP in human cells derived from tissues associated with adverse events

The recombinant vesicular stomatitis virus–vectored Zaire Ebola virus glycoprotein (rVSV?G-ZEBOV-GP) vaccine, while effective and well-tolerated, exhibits notable reactogenicity, manifesting in expected adverse events (AEs) such as fever, headache, and pain, along with rare, unexpected AEs like skin lesions, cutaneous vasculitis, and transient arthritis. The presence or absence of AEs following rVSV?G-ZEBOV-GP vaccination is associated with a specific innate plasma signature. This study aims to elucidate in-vitro the tropism of the vaccine for different cell types derived from tissues previously reported to be involved in the unexpected AEs. Upon in-vitro infection with rVSV?G-ZEBOV-GP, various cell types such as synoviocytes, fibroblast, keratinocytes and endothelial cells (except chondrocytes) demonstrate productive infection, which in dermal fibroblast triggered the release of many innate plasma signature markers, including keratinocytes' proinflammatory and proapoptotic cytokines such as OSM and TRAIL. Infected monocytes from buffy coats, activated by infection, produce most innate plasma signature markers. In co-culture, rVSV?G-ZEBOV-GP-infected monocytes serve as a source to synoviocytes infection, resulting in a distinct kinetics modulation in innate biomarkers (transcription and secretion) and upregulation of specific genes such as NEDD8 and SIGLEC-1, which have been associated with inflammatory arthritis in animal models. Altogether, our work based on in-vitro studies provide insights into the possible mechanisms of rVSV?G-ZEBOV-GP observed reactogenicity by showing tropism of the vaccine for off target cells derived from AE affected compartments (skin, joints, vessels). Furthermore, in-vitro interaction with infected monocytes modulates the innate response of synoviocytes. Overall design: Transcriptomic analysis was used to outline the response after rVSV?G-ZEBOV-GP infection of Monocytes, Synoviocytes and co-culture of these two. Monocytes (CD14+) were isolated from fresh Peripheral Blood Mononucleate Cells (PBMCs) from healthy donors and synoviocytes isolated from a primary cell culture were used to set up different cell cultures: two mono-cultures and a co-culture. In the co-culture, monocytes were infected with rVSV?G-ZEBOV-GP for 1h, extensively washed and plated together with the synoviocytes in fresh growth medium. Cells were infected with rVSV?G-ZEBOV-GP MOI 1 or mock stimulated.