Vacuolating cytotoxin of Helicobacter pylori plays a role during colonization in a mouse model of infection

Helicobacter pylori, the causative agent of gastritis and ulcer disease in humans, secretes a toxin called VacA (vacuolating cytotoxin) into culture s upernatants, VacA was initially characterized and purified on the basis of its ability to induce the formation of intracellular vacuoles in tissue cul ture cells. Ii, pylori strains possessing different alleles of vacA differ in their ability to express active toxin, Those strains expressing higher t oxin levels are correlated with more severe gastric disease. However, the s pecific role(s) played by VacA during the course of infection and disease i s not clear, We have used a mouse model of ii, pylori infection to begin to address this role. A null mutation of vacA compromises H. pylori in its ab ility to initially establish infection. If an infection by a, vacA mutant i s established, the bacterial load and degree of inflammation are similar to those associated with an isogenic wild-type strain. Thus, in this infectio n model, vacA plays a role in the initial colonization of the host, suggest ing that strains of H.ylori expressing active alleles of vacA may be better adapted for host-to host transmission.