Table of Contents
ISRN Molecular Biology
Volume 2012, Article ID 170676, 9 pages
Research Article

Receptor Binding by Cholera Toxin B-Subunit and Amino Acid Modification Improves Minimal Peptide Immunogenicity

1Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, 171 82 Stockholm, Sweden
2Division of Education and Research administration, Mälardalen University, P.O. Box 883, 721 23 Västerås, Sweden
3Etvax AB, Gunnar Asplunds Alle 16, 171 63 Solna, Sweden
4Institution of Clinical and Experimental Medicine, Linköping University, 581 83 Linköping, Sweden

Received 12 April 2012; Accepted 20 May 2012

Academic Editors: H. Hashimoto and I. Kim

Copyright © 2012 Andreas Boberg et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We increase our understanding of augmenting a cellular immune response, by using an HIV-1 protease-derived epitope (PR75–84), and variants thereof, coupled to the C-terminal, of the B subunit of cholera toxin (CTB). Fusion proteins were used for immunizations of HLA-A0201 transgenic C57BL/6 mice. We observed different capacities to elicit a cellular immune response by peptides with additions of five to ten amino acids to the PR epitope. There was a positive correlation between the magnitude of the elicited cellular immune response and the capacity of the fusion protein to bind GM-1. This binding capacity is affected by its ability to form natural pentamers of CTB. Our results suggest that functional CTB pentamers containing a foreign amino acid-modified epitope is a novel way to overcome the limited cellular immunogenicity of minimal peptide antigens. This way of using a functional assay as readout for improved cellular immunogenicity might become highly valuable for difficult immunogens such as short peptides (epitopes).