pertactin

Pertactin is a surface-exposed, outer membrane protein produced by Bordetella pertussis, the bacterium that causes pertussis. It is encoded by the prn gene and is also found in some related Bordetella species such as B. parapertussis. Pertactin functions as an adhesin that promotes attachment of the bacterium to the ciliated cells of the human respiratory tract, aiding colonization.

Biochemically, pertactin is classified as an autotransporter protein. It has a secreted N-terminal passenger domain that mediates adhesion and a C-terminal beta-barrel domain that anchors the protein in the outer membrane. The passenger domain can be released from the cell surface by proteolysis, and the protein is displayed on the bacterial surface in multiple conformations.

Pertactin contributes to virulence by facilitating adherence to host tissues and may interact with components of the extracellular matrix, supporting stable colonization of the airways. Its role as an adhesin makes it a target for the host immune response.

Immunologically, pertactin is one of the antigens included in acellular pertussis vaccines, typically formulated with other proteins such as pertussis toxin derivatives, filamentous hemagglutinin, and fimbrial proteins. Vaccine-induced antibodies against pertactin contribute to protection against disease and transmission.

In circulating B. pertussis populations, pertactin-deficient strains have been reported in multiple regions since the early 2010s, reflecting vaccine-driven selection in some contexts. The public health significance is under study; nonetheless, acellular vaccines with multiple antigens aim to provide broad protection against pertussis.

Pertactin is also used in laboratory serology and research as an antigen to monitor immune responses following vaccination or infection.