[Helicobacter pylori: focus on CagA and VacA major virulence factors].

After colonizing the human gastric mucosa, Helicobacter pylori can remain within the host for years and even decades, and is associated with several, highly significant gastric pathologies. In Mexico, the seroprevalence at 1 year of age is 20% and the estimated increment in seropositivity per year is 5% for children aged 1-10 years. More than 80% of adults are infected by the time they are 18-20 years old. Bacterial virulence factors have been proposed for H. pylori, such as urease, flagella, heat-shock protein, lipopolysaccharide, adhesions, vacuolating cytotoxin, cag pathogenicity island and the cytotoxin-associated protein, the latter being the most studied mechanism to date.