The Story behind the Science: The discovery of Helicobacter pylori CagA, the first tumorigenic bacterial protein.

In this article, we reconstruct the history of the science that led to the discovery of CagA, the protein that causes gastric cancer, where teams in the United States and Italy made independent observations that ultimately merged. We also honor the memory of Antonello Covacci, who played an important role in this discovery and passed away prematurely in 2023.