Characterisation of a monoclonal antibody and its use to purify the cytotoxin of Helicobacter pylori.

The vacuolating cytotoxin (VacA) is a major virulence factor of Helicobacter pylori which is not yet well characterised and is difficult to obtain in large quantities. Here we describe the production of a monoclonal antibody that recognises the native but not the denatured form of VacA. The antibody can be efficiently used in affinity chromatography for one-step purification of large quantities of VacA from culture supernatants. Elution at acidic pH dissociates the oligomeric molecule into monomers that reanneal in a time-dependent fashion. The purified cytotoxin is able to bind, and to intoxicate HeLa cells.