Safety and Immunogenicity of CVD 1208S, a Live, Oral DeltaguaBA Deltasen Deltaset Shigella Flexneri 2a Vaccine Grown on Animal-free Media

A previous Phase 1 trial demonstrated that Shigella flexneri 2a deleted in guaBA, sen and set (strain CVD 1208) is well-tolerated and immunogenic after a single oral dose of 10(8) or 10(9) CFU. To facilitate further clinical development, the strain was reconstructed using animal-free media to conform to regulatory guidelines, and designated CVD1208S. Healthy inpatient volunteers were randomized (double-blind) to receive a single oral dose of either CVD 1208S (10(8) [n = 7] or 10(9) [n = 7] CFU) or placebo (n = 2). Both vaccine dosage levels were generally well-tolerated. Anti-lipopolysaccharide responses, measured as IgA antibody secreting cells, serum IgG, or fecal IgA levels, occurred in 7 (100%), three (43%) and two (29%) subjects following inoculation with 10(9) CFU, respectively. Interferon gamma production in response to Shigella antigens was observed in 1 of 4 (25%) and 4 of 7 (57%) subjects, following inoculation with 10(8) and 10(9) CFU. We conclude that CVD 1208S retains a favorable safety and immunogenicity profile after reconstruction on animal-free media, comparable to that seen with CVD 1208, which was constructed on media containing animal products, and shows promise as a live, oral Shigella vaccine.