ADP-ribosyltransferase activity of pertussis toxin and immunomodulation by Bordetella pertussis.

Pertussis toxin is produced by the causative agent of whooping cough, Bordetella pertussis, and is an adenosine diphosphate (ADP)-ribosyltransferase capable of covalently modifying and thereby inactivating many eukaryotic G proteins involved in cellular metabolism. The toxin is a principal determinant of virulence in whooping cough and is a primary candidate for an acellular pertussis vaccine, yet it is unclear whether the ADP-ribosyltransferase activity is required for both pathogenic and immunoprotective activities. A B. pertussis strain that produced an assembled pertussis holotoxin with only 1 percent of the ADP-ribosyltransferase activity of the native toxin was constructed and was found to be deficient in pathogenic activities associated with B. pertussis including induction of leukocytosis, potentiation of anaphylaxis, and stimulation of histamine sensitivity. Moreover, this mutant strain failed to function as an adjuvant and was less effective in protecting mice from intracerebral challenge infection. These data suggest that the ADP-ribosyltransferase activity is necessary for both pathogenicity and optimum immunoprotection. These findings bear directly on the design of a nontoxic pertussis vaccine.

Antibodies to Bordetella pertussis in human colostrum and their protective activity against aerosol infection of mice.

Colostrum samples from Indonesian mothers were assayed for antibodies which agglutinate Bordetella pertussis and for antibodies to the filamentous hemagglutinin and the lymphocytosis-promoting factor of B. pertussis. Agglutinins were assayed by a microtiter method, and 36 of 58 samples tested (62%) had titers above 1:10 (range, less than 1:10 to 1:160). An enzyme-linked immunosorbent assay detected anti-filamentous hemagglutinin in 39 of 60 samples (65%) and anti-lymphocytosis-promoting factor in 26 of 60 samples assayed (43%). A total of 52 samples (87%) were positive for at least one of these antibodies. Pooled colostrum samples were separated by affinity chromatography into fractions enriched secretory immunoglobulin A (sIgA) or IgG and examined for their ability to passively protect suckling mice from aerosol challenge with B. pertussis. Samples (160 micrograms of protein) were given intraperitoneally 90 min before challenge. Death, rate of gain in body weight, and leukocytosis were used as indicators of illness. Colostrum containing anti-lymphocytosis-promoting factor or agglutinins was protective, whereas colostrum lacking these but containing anti-filamentous hemagglutinin gave little protection. The sIgA-enriched and IgG-enriched fractions appeared to be equal in their ability to protect against respiratory challenge with B. pertussis.