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

Vaccine. 2010 Aug 23;28(37):6076-85. doi: 10.1016/j.vaccine.2010.06.086. Epub 2010 Jul 7.


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 microg). 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 > or =50 microg with the highest IgG ASC, Invaplex 50 (100%) and S. flexneri 2a LPS (71%), as well as, serologic responses (43%) occurring with the 240 microg dose. Fecal IgA responses, Invaplex 50 (38.5%) and LPS (30.8%), were observed at doses > or =240 microg. 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.

Trial registration: NCT00082069.

Publication types

  • Clinical Trial, Phase I
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Administration, Intranasal
  • Adult
  • Animals
  • Antibody Formation
  • Antibody-Producing Cells / immunology
  • Dysentery, Bacillary / immunology
  • Dysentery, Bacillary / prevention & control*
  • Female
  • Guinea Pigs
  • Humans
  • Immunity, Mucosal*
  • Immunization Schedule
  • Immunoglobulin A / blood
  • Immunoglobulin A / immunology
  • Immunoglobulin G / blood
  • Immunoglobulin G / immunology
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Shigella Vaccines / adverse effects
  • Shigella Vaccines / immunology*
  • Shigella flexneri / immunology
  • Young Adult


  • Immunoglobulin A
  • Immunoglobulin G
  • Shigella Vaccines

Associated data