Immunogenicity of the hookworm Na-ASP-2 vaccine candidate: characterization of humoral and cellular responses after vaccination in the Sprague Dawley rat.

The recombinant larval protein Na-ASP-2 from the human helminth parasiteNecator americanus is a lead candidate for a human hookworm vaccine. We havecharacterized the humoral and cellular immune responses elicited by the Na-ASP-2formulated with the aluminum-based adjuvant Alhydrogel® in the Sprague Dawley rat.We demonstrated that Na-ASP-2 vaccine induced a strong antibody response at alldoses tested, as evidenced by high specific IgG1, IgG2a and IgM titers. High IgGantibody titers were maintained up to three months post vaccination and were boostedby an additional vaccine dose. Specific cell proliferation and a Th2 cytokine profilewere also observed in peripheral blood of all rats immunized with the formulatedvaccine. Host IL-6 levels were also significantly elevated. These data provideevidence that the immune response of the Na-ASP-2 vaccine is robust and durableand therefore suitable for the further clinical development of the Na-ASP-2 vaccine.