Immunomodulatory and Anti-Viral Activities of Pertussis Toxin and of Its Non-Toxic Derivatives

The innate immune system represents the fastest defense to microbial invasion although many pathogens can modulate the host response either in favor of or against their survival and propagation. In this regard, some bacterial toxins possess immunostimulating properties that have been exploited in terms of vaccine adjuvancy and induction of specific cytotoxic T lymphocytes. Among these, Bordetella pertussis toxin (PTX) possesses the ability of modulating the immune responses in in vivo, ex-vivo and in vitro experimental systems. In addition, PTX, as well its nontoxic B-oligomer PTX-B and the genetically inactivated PT-9K/129G molecule, have been recently shown to inhibit infection of CD4+ T lymphocytes and macrophages by the human immunodeficiency virus, the etiological agent of the acquired immunodeficiency syndrome. This article focuses on the regulation of the immune response and on the anti-viral properties of PTX and of its nontoxic related molecules and as an example of exploitation of a natural bacterial product to combat viral infections.