Mutants of Pertussis Toxin Suitable for Vaccine Development

Abstract

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.

Parenteral immunization of mice with a genetically inactivated pertussis toxin DNA vaccine induces cell-mediated immunity and protection

“…The ADP-ribosyltransferase activity of the recombinant S1 (rPTS1) encoded by pTrcHis2/pts1 and pcDNA3.1/ptS1 was inactivated by two point mutations in which Arg-13 was changed to Leu-13 and Glu-129 was changed to Gly-129 (Pizza et al, 1989). Site-directed mutagenesis was carried out using a QuikChange XL mutagenesis kit (Stratagene) according to the manufacturer's instructions.…”

“…Therefore, an important aspect in the development of our DNA vaccine was the inactivation of the S1 gene. Pizza et al (1989) showed that substitution of Glu-129 with Gly-129 in combination with either Arg-9 to Lys-9, Arg-13 to Leu-13 or Trp-26 to Ile-26 abolished the ADP-ribosylase activity but did not adversely affect immunogenicity. Nencioni et al (1990) later characterized the 9K/129G toxoid and showed that it had the same physical and immunological properties as wild-type PT.…”

“…Nencioni et al (1990) later characterized the 9K/129G toxoid and showed that it had the same physical and immunological properties as wild-type PT. For this study, we chose the 13L/129G mutation as it is reported to have marginally less leukocytosis-promoting activity and greater T-cell recognition, and mice had a higher survival rate following lethal challenge compared with the 9K/129G toxoid (Pizza et al, 1989).…”

Addition of a TLR7 agonist to an acellular pertussis vaccine enhances Th1 and Th17 responses and protective immunity in a mouse model

“…However, chemical treatment lowers to some extent immunogenicity of PT. In contrast, genetically detoxified PT mutants -including PT-9K/129G, that lacks enzymatic activity -retain the functional and immunological properties of wild-type PT [9]. PT-9K/129G was shown to be safe and immunogenic as a component of a DTaP vaccine evaluated in two large Phase III efficacy trial in infants [10,11].…”

Profile of Rino Rappuoli

“…But this time he and colleague Mariagrazia Pizza used sitedirected mutagenesis to specifically alter amino acids in the active site of the toxin. The result was a nontoxic molecule that made a potent vaccine (4).…”