Safety and immunogenicity of a Shigella flexneri 2a Invaplex 50 intranasal vaccine in adult volunteers

Safety and immunogenicity of an intranasal Shigella flexneri 2a Invaplex 50 vaccine

“…The cGMP Invaplex 50 vaccine was prepared from virulent S. flexneri 2a, strain 2457T as previously described [14,16] with the following modifications. The 300 l culture was incubated at 37 • C with an agitation speed of 200 rpm and air flow of 150 l/min, in animal product-free modified Antibiotic Medium 3 with 0.003% antifoam.…”

“…1 (Oxoid/Remel, Lenexa, KS), 5 g; Bacto Dextrose (Difco/BD, Sparks, MD) 1 g; sodium chloride (molecular-biology tested, Sigma-Aldrich, St. Louis, MO), 3.5 g; potassium phosphate, dibasic (Sigma-Aldrich), 3.68 g; and, potassium phosphate, monobasic (Sigma-Aldrich), 1.32 g. After 18 h of growth, the culture was harvested by centrifugation (Sharples AS-26 continuous feed centrifuge) and an aliquot of the final culture was used for determination of bacterial colony forming units (cfu), gram stain, purity, colony uniformity, percent Congo red positive colonies and organism identity. The collected cells were extracted with water and the resulting extract was applied to an anion-exchange column (Q Sepharose High Performance, GE Healthcare) for isolation of the Invaplex 50 product in an elution step consisting of 500 mM NaCl in 20 mM Tris, pH 9.0 as previously described [16]. The final Invaplex 50 product was adjusted to 250 mM NaCl in 20 mM Tris, pH 8.8 and a final protein concentration of 3.46 mg protein/ml, sterilized by filtration (0.22 m Millipak-20 filter unit) and dispensed in 1.0 ml volumes into sterile, depyrogenated 2 ml glass vials without preservative.…”

“…The amount of IpaB and IpaC in Invaplex 50 was determined using a modified ELISA procedure [19]. The LAL (Limulus amebocyte lysate) gel clot method (Pryotell, Associates of Cape Cod, Inc.) was used to measure the quantity of lipopolysaccharide [16]. For the various analyses, the animal product free-derived Invaplex 50 lot 1307 was compared to previous cGMP lots 0994 and 0808 that were prepared from S. flexneri 2a grown in Antibiotic Medium 3 containing animal derived products [16].…”

“…Mucosal immune responses can also be achieved with intranasal immunization, although it is not clear if this is an effective route for stimulating intestinal immune responses in humans. The Shigella Invaplex 50 vaccine, currently under clinical investigation, is a macromolecular complex isolated from wild-type S. flexneri 2a that included both serotype specific (LPS) and conserved antigens (IpaB, IpaC and IpaD) and upon intranasal immunization stimulates robust intestinal and pulmonary immune responses [14][15][16].…”

“…An initial phase 1 dose-escalation study evaluating the safety and immunogenicity of the S. flexneri Invaplex 50 vaccine produced under current Good Manufacturing Practices (cGMP) was recently conducted using a pipette to deliver the vaccine intranasally [16]. The Invaplex 50 vaccine was well tolerated and resulted in antigen-specific humoral and mucosal immune responses at doses ≥ 240 g. In the current study, the S. flexneri 2a Invaplex 50 vaccine was evaluated using a new lot of cGMP Invaplex 50 to expand the dose range and safety monitoring.…”