Engineering Skin Bacteria for Needle-Free Topical Vaccination

The ubiquitous skin colonist Staphylococcus epidermidis elicits a CD8+ T cell response pre-emptively, in the absence of infection, but the scope and purpose of this program remain unclear. Here, we show that this colonist also induces a potent, durable, and specific antibody response. Colonizing mice with S. epidermidis engineered to display tetanus toxin fragment C elicits neutralizing antibodies that protect against lethal challenge. A related strain expressing a SpyCatcher moiety can be conjugated to recombinant immunogens, and the resulting commensal elicits long-lasting, high antibody titers, including robust nasal IgA. An enzymatic approach to display immunogens on gram-positive bacteria extends this strategy to genetically intractable commensals: Cutibacterium acnes labeled with immunogens elicits strong T and B cell responses. Thus, immunity to common skin colonists involves a coordinated T and B cell response, which can be redirected against pathogens as a novel form of topical vaccination.

Speaker: Djente Bousbaine, Stanford University