Bioengineering of Bordetella pertussis Adenylate Cyclase Toxin for Antigen-Delivery and Immunotherapy

Abstract

The adenylate cyclase toxin (CyaA) is one of the major virulence factors of Bordetella pertussis, the causative agent of whooping cough. CyaA is able to invade eukaryotic cells where, upon activation by endogenous calmodulin, it synthesizes massive amounts of cAMP that alters cellular physiology. The CyaA toxin is a 1706 residues-long bifunctional protein: the catalytic domain is located in the 400 amino-proximal residues, whereas the carboxy-terminal 1306 residues are implicated in toxin binding to the cellular receptor, the αMβ2 (CD11b/CD18) integrin, and subsequently in the translocation of the catalytic domain across the cytoplasmic membrane of the target cells. Indeed, this protein is endowed with the unique capability of delivering its N-terminal catalytic domain directly across the plasma membrane of eukaryotic target cells. These properties have been exploited to engineer the CyaA toxin as a potent non-replicating vector able to deliver antigens into antigen presenting cells and elicit specific cell-mediated immune responses. Antigens of interest can be inserted into the CyaA protein to yield recombinant molecules that are targeted in vivo to dendritic cells, where the antigens are processed and presented by the major class I and class II histocompatibility complexes (MHC-I and II). CyaA turned out to be a remarkably effective and versatile vaccine vector capable of inducing all the components of the immune response (T-CD4, T-CD8, and antibody). In this chapter, we summarize the basic knowledge on the adenylate cyclase toxin and then describe the application of CyaA in vaccinology, including some recent results of clinical trials of immunotherapy using a recombinant CyaA vaccine.

Functional and structural consequences of epithelial cell invasion byBordetella pertussisadenylate cyclase toxin

“…While the infection by CyaA of myeloid cells such as macrophages, neutrophils, dendritic cells, 276 natural killer cells, has been extensively studied [4,[39][40][41], much less is known about the 277 intoxication of non-inflammatory cells lacking the CD11b/CD18 receptor. In these cells, CyaA 278 is able to directly interact with the plasma membrane and translocate its catalytic domain across 279 the lipid bilayer although the precise molecular mechanism of intoxication remains 280 elusive [1,8,42,43]. 281 We previously showed and we confirm here that CyaA can efficiently invade A549 alveolar 282 Effect of CyaA on the cytoskeleton stiffness of A549 cells.…”

Innovative Immunization Strategies for Antivenom Development

“…A last approach to be mentioned here is the use of the adenylate cyclase toxin, CyaA, from Bordetella pertussis , which mediates translocation of its genetically engineerable N-terminus into the cytoplasmic site of eukaryotic cells with which it is in close proximity [ 180 ]. The CyaA toxin has further been engineered to deliver antigens into APCs in vivo, after which epitopes of the antigen have been reported to be confirmed displayed on the MHC I and II complexes of the targeted APCs [ 180 ].…”

A high-affinity calmodulin-binding site in the CyaA toxin translocation domain is essential for invasion into eukaryotic cells

“…Invasion of target cells occurs via a unique process among known bacterial toxins. First, RD binds with high affinity to a cell receptor, the CD11b/CD18 integrin that is expressed by a subset of leukocytes (neutrophils, dendritic cells (DC) and macrophages) [42][43][44][45][46][47][48][49][50] . CyaA can also intoxicate cells lacking CD11b/CD18 by directly interacting with the target cell membrane, although with a reduced efficiency 12,[51][52][53][54] .…”