Applications: ImmunityReactive species: Bordetella pertussis
"Abstract: The use of a cationic lipid nanoparticle based triple adjuvant complex (L-TriAdj) was previously demonstrated to provide great utility in enhancing local intranasal immunity against pertussis. However, the role of lipid composition as a critical product parameter has not been fully elucidated. The aim of this study was to optimize the lipid composition of L-TriAdj using design-of-experiments methodology, and to define the role of lipid composition on the physicochemical properties and in vitro behavior (cellular viability, uptake and cytokine expression) of L-TriAdj pertussis vaccine formulations applied to antigen presenting cells. L-TriAdj formulations were prepared using a thin-film hydration and extrusion method, with admixing of the adjuvant components and antigens. In-vitro experiments were conducted using the MTT assay, confocal imaging and flow cytometry. The DoE approach was used to optimize L-TriAdj vaccine formulations to particle sizes less than 200 nm. Results indicated that increasing the alkyl chain length of phosphatidylcholine (PC) lipids was associated with significant changes in cellular viability, enhancement of cellular uptake and induction of IL-12 and IFN-γ. Varying the ratio between phosphoethanolamine and phosphatidylcholine lipids was associated with significant changes in cellular viability and uptake; however, no significant effects in dendritic cell maturation were noted."Article snippet: Bordetella pertussis toxin mutant was purchased from Creative Diagnostics (Shirley, NY, USA).
Figure 1. Effect of different formulations and varying lipid composition on the cellular viability of JAWS II dendritic cells after treatment for 24 h.
Background
B. pertussis toxin is a protein-based exotoxin produced by the bacterium Bordetella pertussis, which causes whooping cough. It is a complex protein composed of multiple subunits, each contributing to its overall function. It belongs to the family of AB toxins, characterized by an A subunit responsible for enzymatic activity and a B subunit involved in receptor binding and cellular entry. The A subunit of the B. pertussis Toxin possesses ADP-ribosyltransferase activity, which enables it to modify specific target proteins within host cells. By adding ADP-ribose moieties to these target proteins, the toxin disrupts their normal function, leading to a range of pathophysiological effects. These include interference with cellular signaling pathways, modulation of immune responses, and impairment of host defenses against B. pertussis.
Figure 1. Schematic depiction of the cellular uptake and mode of action of pertussis toxin. (Source: Ernst, K., 2022)
The Pertussis Toxin Mutant is a modified version of the pertussis toxin, where specific genetic changes have been made to reduce its virulence. This mutant variant contains a modified sequence encoding the enzyme subunit. Through site-directed mutagenesis, two amino acid residues, arginine-9 and glutamic acid-129, have been replaced with lysine (R9K) and alanine (E129A), respectively. The pertussis toxin typically interferes with host immune responses by modifying target proteins through ADP-ribosylation. However, the B. pertussis Toxin (Mutant) exhibits reduced enzymatic activity, leading to a decreased ability to disrupt cellular signaling pathways and impair immune defenses. This modified toxin retains its antigenic properties, making it an ideal candidate for stimulating an immune response or serving as a carrier to enhance immune reactions against other antigens. The B. pertussis Toxin (Mutant) holds great promise in pertussis research and vaccine development. Its reduced virulence makes it a safer candidate for studying the host-pathogen interactions and immune response during pertussis infection. Researchers can utilize this modified toxin to gain insights into the molecular mechanisms underlying pertussis pathogenesis and evaluate the efficacy of potential therapeutic interventions. Moreover, its diminished pathogenicity and antigenic nature make it an attractive component for designing safer and more effective pertussis vaccines. By incorporating this mutant toxin into vaccine formulations, researchers can elicit a targeted immune response against B. pertussis while minimizing the risks associated with the wild-type toxin.
Q: I noticed the material is shipped at 4 °C. Can I freeze it after receiving it? Will repeated freeze–thaw cycles cause stability issues?
A: Yes, it can be frozen, but repeated freeze–thaw cycles should be avoided. It is recommended to aliquot the material upon arrival before freezing.
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References
Mutants of pertussis toxin suitable for vaccine development
Immunization with chemically detoxified pertussis toxin can prevent severe whooping cough with an efficacy similar to that of the cellular pertussis vaccine, which normally gives unwanted side effects. To avoid the reversion to toxicity and the loss of immunogenicity that may follow chemical treatment of pertussis toxin, inactive toxins were constructed by genetic manipulation. A number of genetically engineered alleles of the pertussis toxin genes, constructed by replacing either one or two key amino acids within the enzymatically active S1 subunit, were introduced into the chromosome of strains of Bordetella pertussis, B. parapertussis, and B. bronchiseptica. These strains produce mutant pertussis toxin molecules that are nontoxic and immunogenic and that protect mice from the intracerebral challenge with virulent Bordetella pertussis. Such molecules are ideal for the development of new and safer vaccines against whooping cough.
Investigating pertussis toxin and its impact on vaccination
Whooping cough, caused by Bordetella pertussis, remains a major global health problem. Each year around 40 million of pertussis cases resulting in 200,000–400,000 annual deaths occur worldwide. Pertussis toxin is a major virulence factor of B. pertussis. Murine studies have shown its importance in bacterial colonization and in immunomodulation to evade innate or adaptive immunity. The toxin is composed of an A protomer expressing ADP-ribosyltransferase activity and a B oligomer, responsible for toxin binding to target cells. The toxin is also a major protective antigen in all currently available vaccines. However, vaccine escape mutants with altered toxin expression have recently been isolated in countries with high vaccination coverage illustrating the need for improved pertussis vaccines.
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Figure 1. Effect of different formulations and varying lipid composition on the cellular viability of JAWS II dendritic cells after treatment for 24 h. 
Figure 1. Schematic depiction of the cellular uptake and mode of action of pertussis toxin.
