Role of antibodies against Bordetella pertussis virulence factors in adherence of Bordetella pertussis and Bordetella parapertussis to human bronchial epithelial cells.
Immunization with whole-cell pertussis vaccines (WCV) containing heat-killed Bordetella pertussis cells and with acellular vaccines containing genetically or chemically detoxified pertussis toxin (PT) in combination with filamentous hemagglutinin (FHA), pertactin (Prn), or fimbriae confers protection in humans and animals against B. pertussis infection. In an earlier study we demonstrated that FHA is involved in the adherence of these bacteria to human bronchial epithelial cells. In the present study we investigated whether mouse antibodies directed against B. pertussis FHA, PTg, Prn, and fimbriae, or against two other surface molecules, lipopolysaccharide (LPS) and the 40-kDa outer membrane porin protein (OMP), that are not involved in bacterial adherence, were able to block adherence of B. pertussis and B. parapertussis to human bronchial epithelial cells. All antibodies studied inhibited the adherence of B. pertussis to these epithelial cells and were equally effective in this respect. Only antibodies against LPS and 40-kDa OMP affected the adherence of B. parapertussis to epithelial cells. We conclude that antibodies which recognize surface structures on B. pertussis or on B. parapertussis can inhibit adherence of the bacteria to bronchial epithelial cells, irrespective whether these structures play a role in adherence of the bacteria to these cells. (+info)
Role of Bordetella pertussis virulence factors in adherence to epithelial cell lines derived from the human respiratory tract.
During colonization of the respiratory tract by Bordetella pertussis, virulence factors contribute to adherence of the bacterium to the respiratory tract epithelium. In the present study, we examined the roles of the virulence factors filamentous hemagglutinin (FHA), fimbriae, pertactin (Prn), and pertussis toxin (PT) in the adherence of B. pertussis to cells of the human bronchial epithelial cell line NCI-H292 and of the laryngeal epithelial cell line HEp-2. Using B. pertussis mutant strains and purified FHA, fimbriae, Prn, and PT, we demonstrated that both fimbriae and FHA are involved in the adhesion of B. pertussis to laryngeal epithelial cells, whereas only FHA is involved in the adherence to bronchial epithelial cells. For PT and Prn, no role as adhesion factor was found. However, purified PT bound to both bronchial and laryngeal cells and as such reduced the adherence of B. pertussis to these cells. These data may imply that fimbriae play a role in infection of only the laryngeal mucosa, while FHA is the major factor in colonization of the entire respiratory tract. (+info)
Characterization of human bactericidal antibodies to Bordetella pertussis.
The Bordetella pertussis BrkA protein protects against the bactericidal activity of complement and antibody; however, some individuals mount an immune response that overcomes this bacterial defense. To further characterize this process, the bactericidal activities of sera from 13 adults with different modes of exposure to B. pertussis (infected as adults, occupational exposure, immunized with an acellular vaccine, or no identified exposure) against a wild-type strain and a BrkA complement-sensitive mutant were evaluated. All of the sera killed the BrkA mutant, suggesting past exposure to B. pertussis or cross-reactive organisms. Several samples had no or minimal activity against the wild type. All of the sera collected from the infected and occupationally exposed individuals but not all of the sera from vaccinated individuals had bactericidal activity against the wild-type strain, suggesting that some types of exposure can induce an immune response that can overcome the BrkA resistance mechanism. Adsorbing serum with the wild-type strain removed the bactericidal antibodies; however, adsorbing the serum with a lipopolysaccharide (LPS) mutant or an avirulent (bvg mutant) strain did not always result in loss of bactericidal activity, suggesting that antibodies to either LPS or bvg-regulated proteins could be bactericidal. All the samples, including those that lacked bactericidal activity, contained antibodies that recognized the LPS of B. pertussis. Bactericidal activity correlated best with the presence of the immunoglobulin G3 (IgG3) antibodies to LPS, the IgG subtype that is most effective at fixing complement. (+info)
Maternal immunization can enhance passive immunity of infants to pathogens that cause life-threatening illnesses. In most instances, immunization during pregnancy will provide important protection for the woman as well as for her offspring. The tetanus toxoid and influenza vaccines are examples of vaccines that provide a double benefit. Other vaccines under evaluation include those for respiratory syncytial virus, pneumococci, group B streptococci, and Haemophilus influenzae type b. Although most IgG antibody crosses the placenta in the third trimester, the process is time-dependent, dictating that immunization should be accomplished ideally at least 6 weeks prior to delivery. IgG1 antibodies are transferred preferentially. Maternal immunization has not interfered with active immunization of the infant. Inactivated vaccines administered in the third trimester of pregnancy pose no known risk to the woman or to her fetus. (+info)
Temporal trends in the population structure of Bordetella pertussis during 1949-1996 in a highly vaccinated population.
The population structure of Bordetella pertussis in The Netherlands in 5 successive periods, encompassing 1949-1996, was analyzed by DNA typing ("fingerprinting"). In 10 years following the introduction of wide-scale vaccination in 1953, a decrease in genotypic diversity (GD) was observed, suggesting clonal expansion of strains that were adapted to vaccine-induced immunity. In subsequent periods, GD increased to prevaccination levels, probably reflecting a gradual adaptation of the B. pertussis population involving many lineages. In the 1990s, GD decreased again. This decrease coincided with an antigenic shift in the surface protein pertactin. No evidence was found for changes in DNA types or GD in 1996, when a large pertussis epidemic occurred. Thus, gradual changes in the bacterial population previous to 1996 were probably the cause of the 1996 epidemic. The results herein suggest that vaccination has selected for strains that are adapted to a highly vaccinated population. Similar changes may have occurred in other countries, explaining the reemergence of pertussis in vaccinated populations. (+info)
Analysis with a combination of macrorestriction endonucleases reveals a high degree of polymorphism among Bordetella pertussis isolates in eastern France.
From 1990 to 1996, routine screening for whooping cough identified 399 patients with a calmodulin-dependent adenylate cyclase-positive test result and yielded 69 Bordetella pertussis isolates. None of the patients were fully vaccinated, and most were less than 6 months old. Analysis of total DNA by pulsed-field gel electrophoresis (PFGE) after XbaI, SpeI, or DraI macrorestriction yielded 19, 15, and 5 different patterns, respectively, whereas ribotyping failed to demonstrate any strain polymorphism. Discrimination among the isolates was improved by combining the PFGE profiles. Some patterns were more frequent, but the corresponding patients were not clearly epidemiologically related. The patterns for two strains obtained during a 3-month period from patients who were neighbors differed by the length of a single DNA fragment. These data strongly suggest that one type of isolate is widely spread throughout the world and is carried by individuals other than patients who develop a true illness. (+info)
Serum IgG antibody responses to pertussis toxin and filamentous hemagglutinin in nonvaccinated and vaccinated children and adults with pertussis.
Levels of IgG antibody to pertussis toxin (PT) and filamentous hemagglutinin (FHA) were measured in paired serum samples from 781 patients fulfilling at least one laboratory criterion for pertussis that was suggested by an ad hoc committee sponsored by the World Health Organization. The patients were participants or family members of participants in a double-blind efficacy trial of a monocomponent pertussis toxoid vaccine. Of 596 nonvaccinated children, 90% had significant (two-fold or more) rises in PT IgG and FHA IgG levels. Only 17 (32%) of 53 children previously vaccinated with three doses of pertussis toxoid had rises in PT IgG levels because they already had elevated PT IgG levels in their acute-phase serum samples. PT IgG and FHA IgG levels were significantly higher in acute-phase serum samples from 29 adults than in acute-phase serum samples from the nonvaccinated children. Nevertheless, significant rises in levels of PT IgG (79% of samples) and FHA IgG (90%) were demonstrated in adults. In conclusion, assay of PT IgG and FHA IgG in paired serum samples is highly sensitive for diagnosing pertussis in nonvaccinated individuals. Assay of PT IgG levels in paired sera is significantly less sensitive for diagnosis of pertussis for children vaccinated with pertussis toxoid. (+info)
The conserved lysine 860 in the additional fatty-acylation site of Bordetella pertussis adenylate cyclase is crucial for toxin function independently of its acylation status.
The Bordetella pertussis RTX (repeat in toxin family protein) adenylate cyclase toxin-hemolysin (ACT) acquires biological activity upon a single amide-linked palmitoylation of the epsilon-amino group of lysine 983 (Lys983) by the accessory fatty-acyltransferase CyaC. However, an additional conserved RTX acylation site can be identified in ACT at lysine 860 (Lys860), and this residue becomes palmitoylated when recombinant ACT (r-Ec-ACT) is produced together with CyaC in Escherichia coli K12. We have eliminated this additional acylation site by replacing Lys860 of ACT with arginine, leucine, and cysteine residues. Two-dimensional gel electrophoresis and microcapillary high performance liquid chromatography/tandem mass spectrometric analyses of mutant proteins confirmed that the two sites are acylated independently in vivo and that mutations of Lys860 did not affect the quantitative acylation of Lys983 by palmitoyl (C16:0) and palmitoleil (cis Delta9 C16:1) fatty-acyl groups. Nevertheless, even the most conservative substitution of lysine 860 by an arginine residue caused a 10-fold decrease of toxin activity. This resulted from a 5-fold reduction of cell association capacity and a further 2-fold reduction in cell penetration efficiency of the membrane-bound K860R toxin. These results suggest that lysine 860 plays by itself a crucial structural role in membrane insertion and translocation of the toxin, independently of its acylation status. (+info)