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

D. Tribble*, R. Kaminski, J. Cantrell, M. Nelson, C. Porter, S. Baqar, C. Williams, R. Arora, J. Saunders, M. Ananthakrishnan, J. Sanders, G. Zaucha, R. Turbyfill, E. Oaks

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


Shigellosis is a leading cause of diarrhea worldwide prompting vaccine development. The Shigella flexneri Invaplex 50 is a macromolecular complex containing IpaB, IpaC, 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. μg). 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 ≥50. μg with the highest IgG ASC, Invaplex 50 (100%) and S. flexneri 2a LPS (71%), as well as, serologic responses (43%) occurring with the 240. μg dose. Fecal IgA responses, Invaplex 50 (38.5%) and LPS (30.8%), were observed at doses ≥240. μg. The Invaplex 50 nasal vaccine was safe with encouraging mucosal immune responses. Follow-on studies will optimize dose, delivery mechanism and assess efficacy in a S. flexneri 2a challenge study.

Original languageEnglish
Pages (from-to)6076-6085
Number of pages10
Issue number37
StatePublished - Aug 2010


  • Invaplex
  • Nasal vaccine
  • Shigella flexneri


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