Functional categories of differentially expressed genes between the <i>ptxP1</i> and <i>ptxP3</i> strains.

<p>The gene count (absolute number of genes) of differentially expressed genes per category (blue). And the gene count of differentially expressed genes relative to the total number of genes (red) present in the genomes of the analyzed strains.</p

Genes from the vir-core regulon were significantly upregulated in the <i>ptxP3</i> strains compared to the <i>ptxP1</i> strains.

<p>Genes from the vir-core regulon were significantly upregulated in the <i>ptxP3</i> strains compared to the <i>ptxP1</i> strains.</p

Relative differences in gene expression between <i>ptxP3</i> and <i>ptxP1</i> strains, as detected by microarrays and Q-PCR.

<p>Relative differences in gene expression between <i>ptxP3</i> and <i>ptxP1</i> strains, as detected by microarrays and Q-PCR.</p

Differentially expressed genes in <i>ptxP3</i> vs. <i>ptxP1 Bordetella pertussis</i> strains.

<p>Differentially expressed genes in <i>ptxP3</i> vs. <i>ptxP1 Bordetella pertussis</i> strains.</p

Role of the <i>ptxP3</i> and <i>ptxP1</i> mutations and the genetic background of <i>ptxP1</i> and <i>ptxP3</i> strains in colonizing the trachea (A) and lungs (B) in mice.

<p>Mice were intranasally infected with the wildtype <i>ptxP1</i> strain, the <i>ptxP3</i> strain, isogenic strains carrying the <i>ptxP3</i> allele in the <i>ptxP1</i> genetic background (P1 gb:<i>ptxP3</i>) or the <i>ptxP1</i> allele in the <i>ptxP3</i> genetic background (P3 gb:<i>ptxP1</i>). CFUs were determined in the trachea and lungs four days post-infection. The mean is indicated by a thin line. P-values (uncorrected for multiple tests) were shown if greater than 0.05. The experiment was performed two times representative result is shown.</p

Genome-Wide Gene Expression Analysis of <i>Bordetella pertussis</i> Isolates Associated with a Resurgence in Pertussis: Elucidation of Factors Involved in the Increased Fitness of Epidemic Strains

<div><p><i>Bordetella pertussis (B. pertussis)</i> is the causative agent of whooping cough, which is a highly contagious disease in the human respiratory tract. Despite vaccination since the 1950s, pertussis remains the most prevalent vaccine-preventable disease in developed countries. A recent resurgence pertussis is associated with the expansion of <i>B. pertussis</i> strains with a novel allele for the pertussis toxin (ptx) promoter <i>ptxP3</i> in place of resident <i>ptxP1</i> strains. The recent expansion of <i>ptxP3</i> strains suggests that these strains carry mutations that have increased their fitness. Compared to the <i>ptxP1</i> strains, <i>ptxP3</i> strains produce more Ptx, which results in increased virulence and immune suppression. In this study, we investigated the contribution of gene expression changes of various genes on the increased fitness of the <i>ptxP3</i> strains. Using genome-wide gene expression profiling, we show that several virulence genes had higher expression levels in the <i>ptxP3</i> strains compared to the <i>ptxP1</i> strains. We provide the first evidence that wildtype <i>ptxP3</i> strains are better colonizers in an intranasal mouse infection model. This study shows that the <i>ptxP3</i> mutation and the genetic background of <i>ptxP3</i> strains affect fitness by contributing to the ability to colonize in a mouse infection model. These results show that the genetic background of <i>ptxP3</i> strains with a higher expression of virulence genes contribute to increased fitness.</p></div

Comparison of gene expression measurements by microarray hybridization and quantitative real-time PCR.

<p>Log-transformed (in base 10) fold change values of the Q-PCR data (y-axis) were plotted against the log-transformed fold change values of microarray data (x-axis). The coefficient of determination (R 2) is given.</p

Characteristics of <i>ptxP1</i> and <i>ptxP3</i> strains used in this study.

<p>Characteristics of <i>ptxP1</i> and <i>ptxP3</i> strains used in this study.</p

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Introduction<p>To reduce the pertussis disease burden, nowadays several countries recommend acellular pertussis (aP) booster vaccinations for adults. We aimed to evaluate the immunogenicity of a first adult aP booster vaccination at childbearing age.</p>Methods<p>In 2014, healthy adults aged 25–29 years (n = 105), vaccinated during infancy with four doses of whole-cell pertussis (wP) vaccine, received a Tdap (tetanus, diphtheria, and aP) booster vaccination. Blood samples were collected longitudinally pre-booster, 2 and 4 weeks, and 1 year and 2 years post-booster. Tdap vaccine antigen-specific antibody levels and memory B- and T-cell responses were determined at all time points. Antibody persistence was calculated using a bi-exponential decay model.</p>Results<p>Upon booster vaccination, the IgG levels specific to all Tdap vaccine antigens were significantly increased. After an initial rapid decline in the first year, PT-IgG antibody decay was limited (15%) in the second year post-booster. The duration of a median level of PT-IgG ≥20 IU/mL was estimated to be approximately 9 years. Vaccine antigen-specific memory B- and T-cell numbers increased and remained at high levels although a significant decline was observed after 4 weeks post-booster. However, Th1, Th2, and Th17 cytokine production remained above pre-booster levels for 2 years.</p>Conclusion<p>The Tdap booster vaccination in wP-primed Dutch adults induced robust long-term humoral and cellular immune responses to pertussis antigens. Furthermore, PT-IgG levels are predicted to remain above the presumed protective cut-off for at least 9 years which might deserves further attention in evaluating the current recommendation to revaccinate women during every new pregnancy.</p