Metabolic, humoral, and cellular responses in adult volunteers immunized with the genetically inactivated pertussis toxin mutant PT-9K/129G

Cellular pertussis vaccine containing a Bordetella pertussis strain that produces a nontoxic pertussis toxin molecule

Bordetella pertussis 165-9K/129G, which produces a nontoxic form of pertussis toxin (PT), was used to prepare a whole-cell diphtheria-tetanus-pertussis (DTP) vaccine. The in vivo potency and the serological response induced by this vaccine were comparable to those of the conventional DTP vaccine which contains active PT. The toxic activities induced by PT such as leukocytosis, histamine sensitivity, and potentiation of anaphylactic reactions, which are present in the conventional DTP vaccine, were absent in the new vaccine. These results suggest that the introduction of a whole-cell vaccine containing B. pertussis 165-9K/129G would induce the same immunity as the conventional vaccine and would avoid the administration of a harmful toxin to children.

Generation of human monoclonal antibodies that confer protection against pertussis toxin

A panel of human monoclonal antibodies reactive with pertussis toxin has been generated by means of Epstein-Barr virus infection. One of these, the 3F11 monoclonal antibody, showed the ability to neutralize in vitro and in vivo the toxic effects of the toxin. Western blot (immunoblot) analysis located the 3F11 epitope on the S3 subunit.

Development and clinical testing of an acellular pertussis vaccine containing genetically detoxified pertussis toxin

In 1924 Ramon described the inactivation of diphtheria toxin by formaldehyde treatment. This method allowed the introduction of mass vaccination against diphtheria and tetanus and opened the way to the inactivation of viruses by chemical treatment. In this review we describe the use of genetic manipulations for the inactivation of pertussis toxin. The toxin inactivated by this new method is an antigen superior to those obtained by chemical treatment and has been used to develop a new vaccine against whooping cough.

Progress towards the development of new vaccines against whooping cough

Acellular vaccines against whooping cough are in the final stage of clinical testing and are likely to become available for mass immunization in the near future. Over a dozen vaccines of similar composition have been developed by vaccine companies and research laboratories; all of them contain a detoxified form of pertussis toxin (PT) that may be present alone or combined with one or more other non-toxic proteins, such as filamentous haemagglutinin (FHA), pertactin (69 kDa), and the agglutinogens (AGG). Most of the vaccines contain a PT that has been inactivated by chemical treatment, a process that reduces the immunogenicity of the molecule and may not completely eliminate the risk of reversion to toxicity. To avoid these problems, we have constructed by genetic manipulation a mutant of Bordetella pertussis that produces a non-toxic form of PT. This molecule (PT-9K/129G) contains two amino acid substitutions in the S1 subunit (Arg9-->Lys and Glu129-->Gly) which abolish the enzymatic activity of the S1 subunit and all the toxic properties of PT, without changing the immunological properties of the wild-type toxin. Following extensive preclinical studies, which have shown that PT-9K/129G is safe and more antigenic than the toxin treated with chemical agents, this molecule was tested for safety and immunogenicity in adult volunteers, 18-month-old children and 2-month-old infants. The molecule has been tested alone, combined with FHA and pertactin and also combined with diphtheria and tetanus toxoids.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial vaccines: old and new, veterinary and medical

Developments in veterinary and medical bacterial vaccines are outlined. In the former case, economic considerations are paramount, and cruder, less purified products of proven efficacy continue to be employed. For human use, however, safety and absence of side effects are increasingly demanded. Various examples of human and veterinary vaccines are discussed, and interaction between the two fields is illustrated by reference to the pig-bel disease in New Guinea and the possible aetiology of Sudden Infant Death Syndrome.

Properties of the B oligomer of pertussis toxin

The B oligomer of pertussis toxin was purified from culture supernatants of Bordetella pertussis strains which do not secrete the S1 subunit. The purified B oligomer is devoid of toxicity for CHO cells and other in vivo properties of the toxin, such as leukocytosis and histamine sensitization, but it retains the abilities to agglutinate erythrocytes and to induce the proliferation of T lymphocytes. The B oligomer is also able to induce protective immunity in mice but is less potent than molecules containing the S1 subunit also.

Lymphokine secretion and cytotoxic activity of human CD4+ T-cell clones against Bordetella pertussis

Human CD4+ T-cell clones specific for pertussis toxin and other Bordetella pertussis antigens have been tested for their cytotoxic activity, lymphokine production, and capacity to induce immunoglobulin synthesis. Clones specific for the S1 subunit of pertussis toxin were cytotoxic for autologous Epstein-Barr virus-transformed B cells, which had been pulsed with the native antigen, the recombinant S1 subunit of pertussis toxin, or synthetic peptides derived from the S1 amino acid sequence. The killing of antigen-pulsed target cells was class II restricted. All of the T-cell clones produced mostly interleukin-2 and gamma interferon and assisted allogeneic B cells in the production of immunoglobulins M and G but not immunoglobulin E. The potential in vivo role of the cytotoxic activity of these clones is discussed.

The cell mediated and humoral immune response to vaccination with acellular and whole cell pertussis vaccine in adult humans

The cell mediated immune response (CMI) against pertussis antigens following vaccination with the traditional Danish whole cell pertussis vaccine (WC-P) and the Japanese acellular pertussis vaccine (A-PV) JNIH-3 was studied in four adult human volunteers. Vaccination with the A-PV induced an in vitro proliferative response of peripheral blood lymphocytes to pertussis toxin (PT) subunits S2-S4, S3-S4 and S5 and the filamentous hemagglutinin (FHA), and a better serological response to native PT, detoxified PT (dPT) and FHA than the WC-PV. The induced CMI and serological response were followed over a period of 17 weeks, and were not seen to decline during this period. Further, an in vitro proliferative response to Bordetella pertussis agglutinogen 2 and 3 were demonstrated using lymphocytes from recently and not-so-recently pertussis-vaccinated adults.

Phase I clinical trial of an acellular pertussis vaccine composed of genetically detoxified pertussis toxin combined with FHA and 69 kDa

An acellular pertussis vaccine composed of genetically detoxified pertussis toxin (PT-9K/129G), filamentous haemagglutinin (FHA) and pertactin (69 kDa protein) was evaluated in adult volunteers, in double blind, versus placebo. No fever was reported in either group. Mild local reactions were reported after injection of both vaccine and placebo. After the first dose a marked increase in antibodies to PT, FHA and 69 kDa protein was seen in vaccinated subjects with the exception of one who responded well to PT and FHA but did not show a humoral response to the 69 kDa protein. All vaccinees acquired cellular immunity against the three antigens. No significant variation was observed in the humoral or cellular responses after the second dose.

Properties of pertussis toxin mutant PT-9K/129G after formaldehyde treatment

Formaldehyde treatment is a method routinely used to detoxify diphtheria, tetanus, and pertussis toxins as well as other molecules suitable for vaccine production. To investigate whether chemical detoxification alters the immunological properties of vaccine components, we have treated the pertussis toxin mutant PT-9K/129G with formaldehyde and tested the properties of the resulting molecules. Very low concentrations of formaldehyde stabilize the molecule without affecting the physicochemical and immunological parameters. Increasing doses of formaldehyde abolish the mitogenic and hemagglutinating activities of PT-9K/129G. At the same time, the molecule loses the ability to be recognized by a monoclonal antibody specific for a major protective epitope on the S1 subunit of pertussis toxin and its affinity for anti-pertussis toxin polyclonal antibodies is also reduced. In marked contrast, the ability of PT-9K/129G to be recognized by human T-cell clones is not affected by Formalin treatment. In vivo, the formaldehyde-treated molecules induce amounts of specific antibodies comparable with those of untreated molecules but significantly lower levels of toxin-neutralizing antibodies. Furthermore, the formaldehyde-treated molecules also show a reduced protective activity in the intracerebral challenge assay.