ANAPHYLACTIC REACTIONS IN MICE INDUCED BY BORDETELLA PERTUSSIS LIPOPOLYSACCHARIDE

Non-primate animal models for pertussis: back to the drawing board?

Abstract

Despite considerable progress in the understanding of clinical pertussis, the contemporary emergence of antimicrobial resistance for Bordetella pertussis and an evolution of concerns with acellular component vaccination have both sparked a renewed interest. Although simian models of infection best correlate with the observed attributes of human infection, several animal models have been used for decades and have positively contributed in many ways to the related science. Nevertheless, there is yet the lack of a reliable small animal model system that mimics the combination of infection genesis, variable upper and lower respiratory infection, systemic effects, infection resolution, and vaccine responses. This narrative review examines the history and attributes of non-primate animal models for pertussis and places context with the current use and needs. Emerging from the latter is the necessity for further such study to better create the optimal model of infection and vaccination with use of current molecular tools and a broader range of animal systems.

Key points

• Currently used and past non-primate animal models of B. pertussis infection often have unique and focused applications.

• A non-primate animal model that consistently mimics human pertussis for the majority of key infection characteristics is lacking.

• There remains ample opportunity for an improved non-primate animal model of pertussis with the use of current molecular biology tools and with further exploration of species not previously considered.

Graphical abstract

Histamine-sensitizing factor, mouse-protective antigens, and other antigens of some members of the genus Bordetella

The three species of the genus Bordetella-B. pertussis, B. parapertussis, and B. bronchiseptica-have many antigens in common. Studies on representative strains of these species have shown that there are only a few specific antigens in each species. Whole-cell vaccines and extracts from B. pertussis contained specific mouse-protective antigen and a histamine-sensitizing factor. In addition, whole-cell vaccines and some saline extracts protected mice against intracranial challenge with B. bronchiseptica. Cells and a saline extract of B. parapertussis also protected against B. bronchiseptica but not against B. pertussis. Whole cells of B. bronchiseptica protected against B. bronchiseptica, but only one of three saline extracts protected against this challenge. Neither whole cells nor saline extracts from B. bronchiseptica protected against B. pertussis. The antigen in B. pertussis responsible for cross-protection against B. bronchiseptica was less resistant to heat than the protective antigen in B. bronchiseptica. Since histamine-sensitizing factor was not detected in B. bronchiseptica or B. parapertussis cells or extracts, this factor is not required to protect mice against B. bronchiseptica challenge. Whether B. pertussis vaccines protected against B. bronchiseptica by a nonspecific mechanism was not established, but it is clear that the specific antigen responsible for protection against B. pertussis was found only in B. pertussis and not in B. bronchiseptica or B. parapertussis.

Histamine-sensitizing factors from microbial agents, with special reference to Bordetella pertussis

Images

Endotoxin-induced hypersensitivity to histamine in mice. I. Contrasting effects of bacterial lipopolysaccharides and the classical histamine-sensitizing factor of Bordetella pertussis

Pieroni, Robert E. (Massachusetts Department of Public Health, Boston), Edward J. Broderick, and Leo Levine. Endotoxin-induced hypersensitivity to histamine in mice. I. Contrasting effects of bacterial lipopolysaccharides and the classical histamine-sensitizing factor of Bordetella pertussis. J. Bacteriol. 91:2169-2174. 1966.-The capacity of typhoid and possibly of pertussis endotoxins to induce histamine-shock susceptibility in some of the mice that survive graded doses of these endotoxins was confirmed. It was demonstrated, however, that pertussis endotoxin cannot be the main source of the typical histamine sensitization of pertussis vaccine. The following points are made. (i) With typhoid and pertussis endotoxins as inducers of histamine shock, no systematic relation between deaths and induction dose could be found, and 100% mortality could not be achieved. In contrast, with pertussis protective fraction as inducer, there was clear dose-response regression, with 100% mortality possible. (ii) The major part of the histamine-sensitizing activity of pertussis vaccine or its extracts was destroyed by trypsinization or by heating for 30 min at 100 C. These processes do not affect the histamine-sensitizing activity of the endotoxins. The implication for purified pertussis vaccine with high histamine-sensitization capacity is that endotoxin need not necessarily be present. The significance and possible mechanisms of action of endotoxin-induced histamine sensitivity are briefly discussed.