The stability of the serotypes of Bordetella pertussis with particular reference to serotype 1,2,3,4.

Strains of Bordetella pertussis in which all the organisms contain agglutinogens 1 and 3 or 1,2 and 4 are easy to identify as serotypes 1,0,3,0 and 1,2,0,4 respectively; and similarly, stable strains of serotype 1,0,3,4 are occasionally found. During repeated subcultures, passage in vivo, and lyophilization and preservation for many years, these serotypes do not change. Mixing 1,0,3,0 and 1,2,0,4 serotypes and culturing them together in vivo and in vitro produces cultures from which organisms of the same two serotypes can be isolated.

The serotypes of Bordetella pertussis isolated in Great Britain between 1941 and 1968 and a comparison with the serotypes observed in other countries over this period.

Classification, by agglutinogens, of 634 isolates of Bordetella pertussis collected from 1971 to 1968 in Great Britain demonstrated that a change from a predominantly 1,2,0,4 serotype (75% of those examined during 1941-4) to a predominantly 1,0,3,0 serotype (73% of those examined during 1966-8) occurred sometime after 1953. Furthermore, evidence from the examination of isolates collected between 1941 and 1953 suggests that the change may have been gradual. Isolates of serotype 1,2,3,4 made up 20-30% of the total of our cross-country selection for the periods 1941-4, 1946-9, 1950-3 and 1966-8, but over shorter periods in individual areas the percentage varied from negligible to as high as half of those isolated.

The importance of agglutinin production in mice in the determination of the definitive serotype of Bordetella pertussis.

A schedule for the routine serotyping of strains of Bordetella pertussis based on agglutinin production in mice to the K-antigens has been worked out. Mice have been found as satisfactory as rabbits but far more economical for the production of the very small volumes of serum which are required. Agglutinin production, used in conjunction with direct agglutination, provides definitive information about serotype.

The effects of humoral, cellular and non-specific immunity on intracerebral Bordetella pertussis infections in mice.

When mice were injected intracerebrally with doses of Bordetella pertussis vaccine greater than 5 ImD 50 and challenged intracerebrally 14 days later with virulent B. pertussis there was an immediate reduction in the numbers of organisms. An analysis of this in vivo bactericidal effect has shown that large doses of an unrelated vaccine, Salmonella typhosa, equivalent in cell mass to about 50 ImD 50 of B.