What is a pathogenicity island?

A pathogenicity island is a distinct genetic region in a bacterial genome that is responsible for virulence. These islands often carry multiple genes that contribute to the ability of a bacterium to cause disease, such as those coding for toxins, adhesins, or other factors that promote infection.

Pathogenicity islands are typically acquired through horizontal gene transfer, which allows bacteria to rapidly gain the ability to cause disease. Their presence can significantly alter the characteristics of a bacterium, enhancing its pathogenic potential compared to strains that do not possess these islands. The unique organization and composition of a pathogenicity island can be identified through genetic analysis, distinguishing them from the core genome of the bacterial species. This concept helps researchers understand how certain bacteria evolve to become more virulent and contributes to the development of targeted therapies and vaccines.