Intranasal immunization with recombinant Vaccinia virus Tiantan harboring Zaire Ebola virus gp elicited systemic and mucosal neutralizing antibody in mice.

Accumulating literature revealed that human mucosa was likely one of the important routes for EBOV attachment and further infection. Therefore inducing effective mucosal immune responses play key role in preventing the virus infection. Vaccinia virus Tiantan strain (VV) was a remarkably attenuated poxvirus, which has been broadly exploited as a multifunctional vector during the development of genetically recombinant vaccine and cancer therapeutic agent. In this study, we generated a recombinant VV harboring EBOV gp (VV-Egp) that was used to immunize mice, followed by assessing immune responses, particularly the mucosal immune responses to EBOV GP. A stable and further attenuated VV-Egp, in which the VV ha gene was replaced with the EBOV gp, was generated. In BALB/c mouse model, intranasal immunization with VV-Egp elicited robust humoral and cellular immune responses, including high level of neutralizing serum IgG and IgA against EBOV, and a large amount of GP-specific IFN-γ secreting lymphocytes. More importantly, EBOV GP-specific neutralizing secreted IgA (sIgA) in nasal wash and both sIgA and IgG in vaginal wash were induced. In summary, immunization with a safe and stable recombinant VV carrying a single EBOV gp conferred robust systemic immune response and mucosal neutralizing antibodies, indicating that the recombinant virus could be utilized as a viral vector for plug-and-play universal platform in mucosal vaccine development.