Systemic and Mucosal Immune Responses From Serotype‐Switched Viral‐Vectored Ebola Vaccines

ABSTRACT

Ebola virus is a highly virulent pathogen causing severe hemorrhagic fever with 25%–90% mortality. The 2014 outbreak infected over 28,000 people, causing 11,325 deaths. Although there is one FDA‐approved vaccine available for limited use, additional vaccines are needed. We developed adenoviral‐vectored vaccines expressing the ebolavirus glycoprotein (GP), the sole viral surface protein and primary immunogen. Vaccine constructs spanned three species and five human adenovirus subtypes, including low‐seroprevalent serotypes to minimize pre‐existing immunity. We compared single‐dose and prime‐boost regimens, intramuscular versus needle‐free intranasal delivery, and serotype‐switching strategies. Immunogenicity was assessed by quantifying GP‐specific antibodies and T cell responses in BALB/c mice. Species C vectors (Ad5 and Ad6) elicited strong antibody responses and promoted rapid class switching to IgG compared to species B and D vectors. Serotype‐switched regimens further enhanced antibody levels via intramuscular or intranasal routes and generated robust T cell responses when delivered intramuscularly. Intranasal vaccination induced detectable IgA but no measurable T cell responses, indicating route‐dependent immune compartmentalization. Sera partially inhibited viral entry in a dose‐dependent manner, with the greatest reduction observed in the Ad5/Ad6 regimen. Collectively, adenoviral species selection, serotype switching, and route of administration significantly influence GP‐specific immunity and warrant further evaluation in protective challenge models.