Volume 6 Supplement 3

AIDS Vaccine 2009

Open Access

P12-16. Biochemical and immunological characterization of the plant-derived candidate HIV-1 mucosal vaccine CTB-MPR

  • N Matoba1,
  • I Cherni3,
  • S Kessans3,
  • J Frater3,
  • K Preston3,
  • M Bomsel2 and
  • TS Mor3
Retrovirology20096(Suppl 3):P182

DOI: 10.1186/1742-4690-6-S3-P182

Published: 22 October 2009


One of the targets of a future multi-component vaccine against HIV-1 should be one of the virus' chief mucosal penetration processes, namely epithelial transcytosis. We further reported that fusion proteins based on the membrane proximal region (MPR) of gp41, playing a key role in the transcytotic process, and the mucosal targeting subunit B of cholera toxin (CTB) are successful immunogens eliciting such transcytosis blocking immune responses and that such proteins can be produced in plants


Here, we report on the molecular characterization of CTB-MPR expressed in bacteria and transgenic plants and its immunological properties.


We show that bacterially and plant-produced CTB-MPR can be purified to homogeneity. The MPR domain could specifically and reversibly self-associate. The affinities of the mAbs 4E10 and 2F5 to CTB-MPR from either source were equivalent to their affinities toward an MPR peptide. The fusion protein's affinity to GM1-ganglioside was comparable to that of native CTB. Mice and rabbits immunized with CTB-MPR shwoed modest anti-MPR antibody response, but a prime-boost immunization with CTB-MPR and a second MPR-based immunogen elicited a stronger response. These Abs strongly blocked the epithelial transcytosis of primary clade B and D isolates in a human tight epithelial model. The Abs recognized epitopes at the N-terminal portion of the MPR peptide, away from the neutralizing epitopes and were not effective in neutralizing infection of CD4+ cells. These results indicate distinct vulnerabilities of two separate interactions of HIV-1 with human cells – Abs against the C-terminal portion of the MPR can neutralize CD4+-dependent infection, while Abs targeting the MPR's N-terminal portion can effectively block GalCer-dependent transcytosis


We conclude that Abs induced by MPR-based immunogens may provide broad protective value independent of infection neutralization and that plant-based expression can be a viable alternative for the production of subunit HIV-1 vaccine candidates.

Authors’ Affiliations

James Graham Brown Cancer Center and University of Louisville School of Medicine
Institute Cochin
Biodesign Institute and School of Life Sciences, Arizona State University


© Matoba et al; licensee BioMed Central Ltd. 2009

This article is published under license to BioMed Central Ltd.