The role of Toll-like receptor-4 in pertussis vaccine-induced immunity

<p>Abstract</p> <p>Background</p> <p>The gram-negative bacterium <it>Bordetella pertussis </it>is an important causative agent of pertussis, an infectious disease of the respiratory tract. After introduction of whole-cell vaccines (wP) in the 1950's, pertussis incidence has decreased significantly. Because wP were found to be reactogenic, in most developed countries they have been replaced by acellular vaccines (aP). We have previously shown a role for Toll-like receptor 4 (Tlr4) in pertussis-infected mice and the pertussis toxin (Ptx)-IgG response in wP-vaccinated children, raising the issue of the relative importance of Tlr4 in wP vaccination of mice. Here we analyze the effects of wP and aP vaccination and <it>B. pertussis </it>challenge, in <it>Tlr4</it>-deficient C3H/HeJ and wild-type C3H/HeOuJ mice. aP consists of Ptx, filamentous hemagglutinin (FHA), and pertactin (Prn).</p> <p>Results</p> <p>We show an important role of Tlr4 in wP and (to a lesser extent) aP vaccination, induction of Th1 and Th17 cells by wP but not aP vaccination, and induction of Th17 cells by infection, confirming data by Higgins et al. (<it>J Immunol </it>2006, <b>177:</b>7980–9). Furthermore, in <it>Tlr4</it>-deficient mice, compared to wild-type controls (i) after vaccination only, Ptx-IgG (that was induced by aP but not wP vaccination), FHA-IgG, and Prn-IgG levels were similar, (ii) after infection (only), lung IL-1α and IL-1β expression were lower, (iii) after wP vaccination and challenge, Prn-IgG level and lung IL-5 expression were higher, while lung IL-1β, TNF-α, IFN-γ, IL-17, and IL-23 expression were lower, and lung pathology was absent, and (iv) after aP vaccination and challenge, Prn-IgG level and lung IL-5 expression were higher, while Ptx-IgG level was lower.</p> <p>Conclusion</p> <p>Tlr4 does not influence the humoral response to vaccination (without challenge), plays an important role in natural immunity, wP and aP efficacy, and induction of Th1 and Th17 responses, is critical for lung pathology and enhances pro-inflammatory cytokine production after wP vaccination and challenge, and diminishes Th2 responses after both wP and aP vaccination and challenge. wP vaccination does not induce Ptx-IgG. A role for LPS in the efficacy of wP underlines the usefulness of LPS analogs to improve bacterial subunit vaccines such as aP.</p

Crucial role of antibodies to pertactin in Bordetella pertussis immunity

Pertussis, a serious infectious disease of the respiratory tract caused by Bordetella pertussis, is reemerging in vaccinated populations. Efforts to curtail this disease are hampered by limited insight into the basis of protective immunity. Opsonophagocytosis was recently found to play a central role in cellular bactericidal activity against B. pertussis. In the present study, we studied the specificity of opsonic antibodies. Anti-pertactin antibodies, but not anti-pertussis toxin, anti-fimbriae, or anti-filamentous hemagglutinin antibodies, were found to be crucial for B. pertussis phagocytosis. These data are consistent with field studies showing that levels of antibodies to pertactin correlate with protection.Centro de Investigación y Desarrollo en Fermentaciones Industriale

Studies on Prn Variation in the Mouse Model and Comparison with Epidemiological Data

The virulence factor pertactin (Prn) is a component of pertussis vaccines and one of the most polymorphic Bordetella pertussis antigens. After the introduction of vaccination shifts in predominant Prn types were observed and strains with the Prn vaccine type (Prn1) were replaced by strains carrying non-vaccine types (Prn2 and Prn3), suggesting vaccine-driven selection. The aim of this study was to elucidate the shifts observed in Prn variants. We show that, although Prn2 and Prn3 circulated in similar frequencies in the 1970s and 1980s, in the 1990s Prn2 strains expanded and Prn3 strains disappeared, suggesting that in vaccinated populations Prn2 strains are fitter than Prn3 strains. We established a role for Prn in the mouse model by showing that a Prn knock-out (Prn-ko) mutation reduced colonization in trachea and lungs. Restoration of the mutation resulted in a significant increase in colonization compared to the knock-out mutant. The ability of clinical isolates with different Prn variants to colonize the mouse lung was compared. Although these isolates were also polymorphic at other loci, only variation in the promoter for pertussis toxin (ptxP) and Prn were found to contribute significantly to differences in colonization. Analysis of a subset of strains with the same ptxP allele revealed that the ability to colonize mice decreased in the order Prn1>Prn2 and Prn3. Our results are consistent with the predominance of Prn1 strains in unvaccinated populations. Our results show that ability to colonize mice is practically the same for Prn2 and Prn3. Therefore other factors may have contributed to the predominance of Prn2 in vaccinated populations. The mouse model may be useful to assess and predict changes in the B. pertussis population due to vaccination

Bordetella pertussis, the Causative Agent of Whooping Cough, Evolved from a Distinct, Human-Associated Lineage of B. bronchiseptica

Bordetella pertussis, B. bronchiseptica, B. parapertussis(hu), and B. parapertussis(ov) are closely related respiratory pathogens that infect mammalian species. B. pertussis and B. parapertussis(hu) are exclusively human pathogens and cause whooping cough, or pertussis, a disease that has resurged despite vaccination. Although it most often infects animals, infrequently B. bronchiseptica is isolated from humans, and these infections are thought to be zoonotic. B. pertussis and B. parapertussis(hu) are assumed to have evolved from a B. bronchiseptica–like ancestor independently. To determine the phylogenetic relationships among these species, housekeeping and virulence genes were sequenced, comparative genomic hybridizations were performed using DNA microarrays, and the distribution of insertion sequence elements was determined, using a collection of 132 strains. This multifaceted approach distinguished four complexes, representing B. pertussis, B. parapertussis(hu), and two distinct B. bronchiseptica subpopulations, designated complexes I and IV. Of the two B. bronchiseptica complexes, complex IV was more closely related to B. pertussis. Of interest, while only 32% of the complex I strains were isolated from humans, 80% of the complex IV strains were human isolates. Comparative genomic hybridization analysis identified the absence of the pertussis toxin locus and dermonecrotic toxin gene, as well as a polymorphic lipopolysaccharide biosynthesis locus, as associated with adaptation of complex IV strains to the human host. Lipopolysaccharide structural diversity among these strains was confirmed by gel electrophoresis. Thus, complex IV strains may comprise a human-associated lineage of B. bronchiseptica from which B. pertussis evolved. These findings will facilitate the study of pathogen host-adaptation. Our results shed light on the origins of the disease pertussis and suggest that the association of B. pertussis with humans may be more ancient than previously assumed

Bordetella pertussis Clones Identified by Multilocus Variable-Number Tandem-Repeat Analysis

Multilocus variable-number tandem-repeat analysis (MLVA) of 316 Bordetella pertussis isolates collected over 40 years from Australia and 3 other continents identified 66 MLVA types (MTs), including 6 predominant MTs. Typing of genes encoding acellular vaccine antigens showed changes that may be vaccine driven in 2 MTs prevalent in Australia

Crucial role of antibodies to pertactin in Bordetella pertussis immunity

Pertussis, a serious infectious disease of the respiratory tract caused by Bordetella pertussis, is reemerging in vaccinated populations. Efforts to curtail this disease are hampered by limited insight into the basis of protective immunity. Opsonophagocytosis was recently found to play a central role in cellular bactericidal activity against B. pertussis. In the present study, we studied the specificity of opsonic antibodies. Anti-pertactin antibodies, but not anti-pertussis toxin, anti-fimbriae, or anti-filamentous hemagglutinin antibodies, were found to be crucial for B. pertussis phagocytosis. These data are consistent with field studies showing that levels of antibodies to pertactin correlate with protection.Centro de Investigación y Desarrollo en Fermentaciones Industriale

Bordetella pertussis isolates from argentinean whooping cough patients display enhanced biofilm formation capacity compared to Tohama I reference strain

Pertussis is a highly contagious disease mainly caused by Bordetella pertussis. Despite the massive use of vaccines, since the 1950s the disease has become re-emergent in 2000 with a shift in incidence from infants to adolescents and adults. Clearly, the efficacy of current cellular or acellular vaccines, formulated from bacteria grown in stirred bioreactors is limited, presenting a challenge for future vaccine development. For gaining insights into the role of B. pertussis biofilm development for host colonization and persistence within the host, we examined the biofilm forming capacity of eight argentinean clinical isolates recovered from 2001 to 2007. All clinical isolates showed an enhanced potential for biofilm formation compared to the reference strain Tohama I. We further selected the clinical isolate B. pertussis 2723, exhibiting the highest biofilm biomass production, for quantitative proteomic profiling by means of two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) coupled with mass spectrometry, which was accompanied by targeted transcriptional analysis. Results revealed an elevated expression of several virulence factors, including adhesins involved in biofilm development. In addition, we observed a higher expression of energy metabolism enzymes in the clinical isolate compared to the Tohama I strain. Furthermore, all clinical isolates carried a polymorphism in the bvgS gene. This mutation was associated to an increased sensitivity to modulation and a faster rate of adhesion to abiotic surfaces. Thus, the phenotypic biofilm characteristics shown by the clinical isolates might represent an important, hitherto underestimated, adaptive strategy for host colonization and long time persistence within the host.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Fermentaciones Industriale

Bordetella pertussis expresses a functional type III secretion system that subverts protective innate and adaptive immune responses

Certain bacteria use a type III secretion system (TTSS) to deliver effector proteins that interfere with cell function into host cells. While transcription of genes encoding TTSS components has been demonstrated, studies to date have failed to identify TTSS effector proteins in Bordetella pertussis. Here we present the first evidence of a functionally active TTSS in B. pertussis. Three known TTSS effectors, Bsp22, BopN, and BopD, were identified as TTSS substrates in B. pertussis 12743. We found expression of Bsp22 in a significant proportion of clinical isolates but not in common laboratory-adapted strains of B. pertussis. We generated a TTSS mutant of B. pertussis 12743 and showed that it induced significantly lower respiratory tract colonization in mice than the wild-type bacteria. Respiratory infection of mice with the mutant bacteria induced significantly greater innate proinflammatory cytokine production in the lungs soon after challenge, and this correlated with significantly higher antigen-specific interleukin-17, gamma interferon, and immunoglobulin G responses later in infection. Our findings suggest that the TTSS subverts innate and adaptive immune responses during infection of the lungs and may be a functionally important virulence factor for B. pertussis infection of humans.Instituto de Biotecnologia y Biologia Molecula

Comparative genomic profiling of Dutch clinical Bordetella pertussis isolates using DNA microarrays: Identification of genes absent from epidemic strains

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