Anthrax Research Today is a free monthly online journal that collates and summarizes the latest research about Anthrax, including details on bacillus anthracis, contagiousness, exposure, effects.

Improvement of an antibody neutralizing the anthrax toxin by simultaneous mutagenesis of its six hypervariable loops.

Laffly E, Pelat T, Cédrone F, Blésa S, Bedouelle H, Thullier P

Groupe de Biotechnologie des Anticorps, Laboratoire d'Immunobiologie, Centre de Recherches du Service de Santé des Armées, 24 Avenue des Maquis du Grésivaudan, 38702 La Tronche, France.

The enhancement of antibody affinity by mutagenesis targeting only complementarity determining regions has the advantage of respecting the framework regions, which are important for tolerance if clinical use is envisaged. Here, starting from a Fab (antigen-binding fragment; 35PA(83)) capable of neutralizing the lethal toxin of anthrax and having an affinity of 3.4 nM for its antigen, a phage-displayed library of variants where all six complementarity determining regions (73 positions) were targeted for mutagenesis was built. This library contained 5 x 10(8) variants, and each variant carried four mutations on average. The library was first panned with adsorbed antigen and washes of increasing stringency. It was then screened in parallel with either small concentrations of soluble biotinylated antigen or adsorbed antigen and long elution times in the presence of soluble antigen. The stringencies of both selections were pushed as far as possible. Compared with 35PA(83), the best selected clone had an affinity enhanced 19-fold, to 180 pM, and its 50% inhibitory concentration was decreased by 40%. The results of the two selection methods were compared, and the generality of these methods was considered.

Published 29 April 2008 in J Mol Biol, 378(5): 1094-103.
Full-text of this article is available online (may require subscription).

© 2005-2008 Anthrax Research Today. All Rights Reserved.