Recombinant Staphylococcal Antigen-F (r-ScaF), a novel vaccine candidate against methicillin resistant Staphylococcus aureus infection: Potency and efficacy studies

Abstract Staphylococcus aureus is a human commensal and pathogen, its clinical importance is exacerbated by the spread of multi-drug resistant strains. The potential future failure of antibiotic therapy necessitates the development of novel control regimes, including new immunotherapeutic approaches. S. aureus has a large repertoire of surface components with potential for immunological targeting. The aim of this study was to evaluate the efficacy of a novel member of staphylococcal conserved antigen family (ScaF) as a factor to elicit cellular and humoral immunity. To determine the ScaF potential as a vaccine candidate, experimental groups of mice were immunized with recombinant Scaf (r-ScaF) formulated in Freund's and alum adjuvants or PBS and subsequently challenged in the sepsis model of S. aureus disease. The vaccine formulations induced robust cellular cytokines responses, including IFN-γ and IL-17, as well as increased production of IgG2a rather than other subclass of IgGs. Active immunization with r-ScaF with adjuvants led to decreased mortality of infected mice and a lower associated bacterial burden in the internal organs in comparison to the control group. Taken together, our Results indicate to the possibility of the r-ScaF protein to be considered as an important component of a multivalent prophylactic vaccine candidate.