THE VACA AND THE CAGA OF HELICOBACTER PYLORI : TWO MULTITASKING PROTEINS OF A MULTITASKING BACTERIUM

Helicobacter pylori infects 50% of the population and 10-20% of the infected individuals develop various gastroduodenal illness, which include gastritis, duodenal ulcer, gastric ulcer, distal gastric adenocarcinoma and gastric mucosa-associated lymphoid tissue lymphoma. The bacterium was classified as type I carcinogen by WHO in 1994. Most of the pathogenic potentials of H. pylori have been attributed to two virulence factors, namely the vacuolating cytotoxin (vacA) and the cytotoxin-associated gene A (cagA). For some geographical regions, however, carrying the virulence specific genes and expressing them may not correlate with the H. pylori associated clinical manifestations. Moreover, most of the H. pylori infections are benign and eradication of the bacterium may increase the probability of having other diseases, like esophageal cancer. The reason for these extreme variations in clinical outcomes in relation to H. pylori infection is unknown, which underscores the need for studying the mechanism of developing these diseases by multidisciplinary approach.