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Safety and Immunogenicity of a Shigella flexneri 2a Invaplex 50 Intranasal Vaccine in Adult Volunteers
NAVAL MEDICAL RESEARCH CENTER SILVER SPRING MD
Pagination or Media Count:
Shigellosis is a leading cause of diarrhea worldwide prompting vaccine development The Shigella flexneri lnvaplex 50 is a macromolecular complex containing lpaB, lpaC, and LPS, formulated from an aqueous extract of virulent Shigella delivered via nasal administration. Preclinical vaccine testing demonstrated safety, immunogenicity and efficacy. An open-label dose-escalating phase 1 study evaluated a 3-dose 2-week intervals regimen via nasal pipette delivery. Thirty-two subjects were enrolled into one of four vaccine dose groups 10, 50, 240, or 480 micrograms. The vaccine was well tolerated with minor short-lived nasal symptoms without evidence of dose effect. Antibody-secreting cell ASC responses were elicited at doses equal 50 micrograms with the highest lgG ASC, Invaplex 50 100 and S.flexneri 2a LPS 71, as well as. serologic responses 43 occurring with the 240 micrograms dose. FecallgA responses, Invaplex 50 38.5 and LPS 30.8 were observed at doses 240 micrograms. The lnvaplex 50 nasal vaccine was safe with encouraging mucosal immune responses. Follow-on studies will optimize dose, delivery mechanism and assess efficacy in aS. flexneri 2a challenge study.
APPROVED FOR PUBLIC RELEASE