High purity and recovery of native filamentous hemagglutinin (FHA) from Bordetella pertussis using affinity chromatography

Filamentous hemagglutinin (FHA) is a critical adhesion molecule produced by Bordetella pertussis (BP), the causative agent of highly contagious respiratory infection known as whooping cough. FHA plays a pivotal role in the pathogenesis of whooping cough and is a key component of acellular pertussis vaccines (aPV). However, conventional purification methods for FHA often involve labor-intensive processes and result in low purity and recovery rates. Therefore, this study explores the use of monoclonal and polyclonal antibodies as specific tools to achieve highly pure and efficient FHA purification. To generate FHA-specific antibodies, polyclonal antibodies were produced by immunizing sheep and monoclonal antibodies (MAbs) were generated by immunizing mice with recombinant and native FHA. The MAbs were selected based on affinity, isotypes, and specificity, which were assessed through ELISA and Western blot assays. Two immunoaffinity columns, one monoclonal and one polyclonal, were prepared for FHA antigen purification. The purity and recovery rates of these purifications were determined using ELISA, SDS-PAGE, and immunoblotting. Furthermore, the MAbs were employed to develop an ELISA assay for FHA antigen concentration determination. The study's findings revealed that immunoaffinity column-based purification of FHA resulted in a highly pure antigen with recovery rates of approximately 57% ± 6.5% and 59% ± 7.9% for monoclonal and polyclonal columns, respectively. Additionally, the developed ELISA exhibited appropriate reactivity for determining FHA antigen concentration. This research demonstrates that affinity chromatography is a viable and advantageous method for purifying FHA, offering superior purity and recovery rates compared to traditional techniques. This approach provides a practical alternative for FHA purification in the context of aPV development.

Pertussis Vaccines Scarcely Provide Protection against Bordetella parapertussis Infection in Children-A Systematic Review and Meta-Analysis

BACKGROUND

Pertussis, or whooping cough, is a global public health concern. Pertussis vaccines have demonstrated good protection against Bordetella pertussis infections, but their effectiveness against Bordetella parapertussis remains debated due to conflicting study outcomes.

METHODS

A systematic review and meta-analysis were conducted to assess the effectiveness of pertussis vaccines in protecting children against B. parapertussis infection. A comprehensive search of PubMed, Web of Science, and Scopus databases was conducted, and randomized controlled trials (RCTs) and observational studies that met inclusion criteria were included in the analysis.

RESULTS

The meta-analysis, involving 46,533 participants, revealed no significant protective effect of pertussis vaccination against B. parapertussis infection (risk ratio: 1.10, 95% confidence interval: 0.83 to 1.44). Subgroup analyses by vaccine type and study design revealed no significant protection. The dearth of recent data and a limited pool of eligible studies, particularly RCTs, underscore a critical gap that warrants future research in the domain.

CONCLUSIONS

These findings offer crucial insights into the lack of effectiveness of pertussis vaccines against B. parapertussis. Given the rising incidence of cases and outbreaks, coupled with the lack of cross-protection by the existing vaccines, there is an urgent need to develop vaccines that include specific antigens to protect against B. parapertussis.

Genome Characteristic of Bordetella parapertussis Isolated from Iran

Pertussis also known as whooping cough is a respiratory infection in humans particularly with severe symptoms in infants and usually caused by Bordetella pertussis. However, Bordetella parapertussis can also cause a similar clinical syndrome. During 2012 to 2015, from nasal swabs sent from different provinces to the pertussis reference laboratory of Pasture Institute of Iran for pertussis confirmation, seven B. parapertussis isolates were identified by bacterial culture, biochemical tests, and the presence of IS1001 insertion in the genome. The expression of pertactin (Prn) as one the major virulence factor for bacterial adhesion was investigated using western blot. Moreover, the genomic characteristic of one recently collected isolate, IRBP134, from a seven-month infant was investigated using Illumina NextSeq sequencing protocol. The results revealed the genome with G+C content 65% and genome size 4.7 Mbp. A total of 81 single nucleotide polymorphisms and 13 short insertions and deletions were found in the genome compared to the B. parapertussis 12822 as a reference genome showing ongoing evolutionary changes. A phylogeny relationship of IRBP134 was also investigated using global B. parapertussis available genomes.

Role of Extracellular Trap Release During Bacterial and Viral Infection

Neutrophils are innate immune cells that play an essential role during the clearance of pathogens that can release chromatin structures coated by several cytoplasmatic and granular antibacterial proteins, called neutrophil extracellular traps (NETs). These supra-molecular structures are produced to kill or immobilize several types of microorganisms, including bacteria and viruses. The contribution of the NET release process (or NETosis) to acute inflammation or the prevention of pathogen spreading depends on the specific microorganism involved in triggering this response. Furthermore, studies highlight the role of innate cells different from neutrophils in triggering the release of extracellular traps during bacterial infection. This review summarizes the contribution of NETs during bacterial and viral infections, explaining the molecular mechanisms involved in their formation and the relationship with different components of such pathogens.

Effect of change in vaccine schedule on pertussis epidemiology in France: a modelling and serological study

BACKGROUND

In April-May, 2013, France modified its pertussis vaccination schedule, which uses the acellular pertussis vaccine, from three primary doses at 2, 3, and 4 months of age and a first booster at 16-18 months of age (former schedule) to two primary doses at 2 and 4 months of age and a first booster at 11 months of age (new schedule). We aimed to assess the subsequent effect of the vaccine schedule change on pertussis epidemiology in France.

METHODS

In this modelling study, using data collected between Jan 1, 2012, and Dec 31, 2019, from French national surveillance sources, we analysed the PCR test results of nasopharyngeal swabs collected from symptomatic outpatients aged 2-20 years with suspected pertussis. We developed a negative binomial regression model for the number of confirmed pertussis cases by year and age to assess the relative risks of pertussis depending on vaccine schedule. The linear predictor included the year, the age group, the population size, and a proxy of waning immunity. We tested different models in which waning immunity could vary with vaccine schedule and type of primary vaccine. The models were fitted to the 2012-18 data via Bayesian Markov chain Monte Carlo sampling, and the 2019 data were left out for external model validation. We also compared the anti-pertussis toxin (PT) antibody concentrations in leftover sera from children not tested for pertussis or recent respiratory tract infection aged 2-5 years born before and after the vaccine schedule change.

FINDINGS

We collected data on 7493 confirmed cases of pertussis. The model that best fitted the 2012-18 epidemiological data supported a faster waning of immunity following vaccination with the new vaccine schedule. 3 years after vaccination, the risk of developing pertussis was 1·7 (95% CI 1·4-2·0) times higher for children vaccinated according to the new schedule than those vaccinated according to the former schedule. The model correctly predicted the age distribution of cases in 2019. Geometric mean concentrations (GMC) of anti-PT IgG were 50% lower in children aged 2 years vaccinated with the new schedule (GMC=5·85 IU/mL [95% CI 4·08-8·39]) than in children of the same age vaccinated with the former schedule (GMC=11·62 IU/mL [95% CI 9·05-14·92]; p=0·0016), and 43% lower in children aged 3 years vaccinated with the new schedule (GMC=3·88 IU/mL [95% CI 2·82-5·34]) than those with the former schedule (GMC=6·80 IU/mL [95% CI 4·77-9·70]; p=0·026).

INTERPRETATION

A shorter-lived protection induced by the new vaccine schedule recommended in France since 2013 is associated with an increase of pertussis cases in children aged 2-5 years. If similar findings are observed in other countries and clinical trials, these findings should be considered in future pertussis vaccination policies.

FUNDING

INCEPTION, Labex-IBEID, Institut Pasteur, and Santé Publique France.

Geographic disparities and socio-demographic predictors of pertussis risk in Florida

BACKGROUND

Pertussis is a toxin-mediated respiratory illness caused by Bordetella pertussis that can result in severe complications and death, particularly in infants. Between 2008 and 2011, children less than 3 months old accounted for 83% of the pertussis deaths in the United States. Understanding the geographic disparities in the distribution of pertussis risk and identifying high risk geographic areas is necessary for guiding resource allocation and public health control strategies. Therefore, this study investigated geographic disparities and temporal changes in pertussis risk in Florida from 2010 to 2018. It also investigated socioeconomic and demographic predictors of the identified disparities.

METHODS

Pertussis data covering the time period 2010-2018 were obtained from Florida HealthCHARTS web interface. Spatial patterns and temporal changes in geographic distribution of pertussis risk were assessed using county-level choropleth maps for the time periods 2010-2012, 2013-2015, 2016-2018 and 2010-2018. Tango's flexible spatial scan statistics were used to identify high-risk spatial clusters which were displayed in maps. Ordinary least squares (OLS) regression was used to identify significant predictors of county-level risk. Residuals of the OLS model were assessed for model assumptions including spatial autocorrelation.

RESULTS

County-level pertussis risk varied from 0 to 116.31 cases per 100,000 people during the study period. A total of 11 significant (p < 0.05) spatial clusters were identified with risk ratios ranging from 1.5 to 5.8. Geographic distribution remained relatively consistent over time with areas of high risk persisting in the western panhandle, northeastern coast, and along the western coast. Although county level pertussis risks generally increased from 2010-2012 to 2013-2015, risk tended to be lower during the 2016-2018 time period. Significant predictors of county-level pertussis risk were rurality, percentage of females, and median income. Counties with high pertussis risk tended to be rural (p = 0.021), those with high median incomes (p = 0.039), and those with high percentages of females (p < 0.001).

CONCLUSION

There is evidence that geographic disparities exist and have persisted over time in Florida. This study highlights the application and importance of Geographic Information Systems (GIS) technology and spatial statistical/epidemiological tools in identifying areas of highest disease risk so as to guide resource allocation to reduce health disparities and improve health for all.

Recent increase in pertussis incidence in South Korea: An age-period-cohort analysis

OBJECTIVES

Pertussis or whooping cough—one of the most contagious diseases—is caused by the Gram-negative bacterium Bordetella pertussis. Despite a high vaccination rate, Korea recently experienced a resurgence of pertussis. This study explores patterns and possible explanations for this resurgence through an age-period-cohort analysis.

METHODS

Using secondary data from the infectious disease portal of the Korea Disease Control and Prevention Agency and the Korea Statistical Information Service of Statistics Korea, this study analyzed the incidence of pertussis in Korea to determine which factors contributed to the recent increase using an age-period-cohort model.

RESULTS

Analysis of the age effect indicated that the age group most vulnerable to pertussis was 0-year to 2-year-olds. Analysis of the period effect showed a sharp increase in the incidence rate after 2016. Analysis of the cohort effect showed a significant decrease in incidence beginning with the 1955 birth cohort, with the risk increasing again with the 2000s birth cohort.

CONCLUSIONS

Previous studies have suggested 3 main possible explanations for our results. First, the increased incidence rate can be attributed to contact rates. Second, the rate of immunity through natural exposure has decreased due to the low number of circulating pathogens, in turn affecting the trend of infection. Lastly, variations in pathogens may have also contributed to the increase in incidence. Given that the most significant increase in incidence was observed among infants younger than 1 year old, sufficient maternal immunity must be prioritized to provide passive immunity to newborns via the placenta.

Bioengineering of Bordetella pertussis Adenylate Cyclase Toxin for Vaccine Development and Other Biotechnological Purposes

The adenylate cyclase toxin, CyaA, is one of the key virulent factors produced by Bordetella pertussis, the causative agent of whooping cough. This toxin primarily targets innate immunity to facilitate bacterial colonization of the respiratory tract. CyaA exhibits several remarkable characteristics that have been exploited for various applications in vaccinology and other biotechnological purposes. CyaA has been engineered as a potent vaccine vehicle to deliver antigens into antigen-presenting cells, while the adenylate cyclase catalytic domain has been used to design a robust genetic assay for monitoring protein-protein interactions in bacteria. These two biotechnological applications are briefly summarized in this chapter.

Bordetella pertussis, a reemerging pathogen in pediatric respiratory infections. A study in Quito, Ecuador

Bordetella pertussis is the causative agent of pertussis, which mainly affects unvaccinated children, while Bordetella parapertussis causes a disease presenting clinical characteristics that are indistinguishable from whooping cough. Despite high vaccination coverage, pertussis remains a public health concern worldwide, with approximately 140000 cases reported annually. Here we determined the prevalence of B. pertussis and B. parapertussis infection among infants under one year of age by polymerase chain reaction (PCR); our aim being to identify whether the data obtained relates to the relevant sociodemographic and clinical data. The study included 86 samples of nasopharyngeal swabs from infants aged between 0-12 months, who were reported as probable cases of whooping cough by the health centers around the Ecuadorian highlands, from August 2016 to July 2017. The nasopharyngeal swabs were cultured and microbiological and molecular analyses were performed. B. pertussis was identified by PCR in 41% of the samples (30/86), more than half of which corresponded to infants aged between 0-3 months. Moreover, a statistically significant correlation (p<0.05) between the identification of bacteria in culture and the catarrhal stage of the disease was observed. The results obtained from the study highlighted the need for an active national surveillance of pertussis, in particular for laboratory testing, to provide a highly sensitive and more specific diagnosis of Bordetella infection.

Genomic epidemiology of Iranian Bordetella pertussis: 50 years after the implementation of whole cell vaccine

Pertussis caused by Bordetella pertussis, remains a public health problem worldwide, despite high vaccine coverage in infants and children in many countries. Iran has been using whole cell vaccine for the last 50 years with more than 95% vaccination rate since 1988 and has experienced pertussis resurgence in recent years. Here, we sequenced 55 B. pertussis isolates mostly collected from three provinces with the highest number of pertussis cases in Iran, including Tehran, Mazandaran, and Eastern-Azarbayjan from the period of 2008-2016. Most isolates carried ptxP3/prn2 alleles (42/55, 76%), the same genotype as isolates circulating in acellular vaccine-administrating countries. The second most frequent genotype was ptxP3/prn9 (8/55, 14%). Only three isolates (5%) were ptxP1. Phylogenetic analysis showed that Iranian ptxP3 isolates can be divided into eight clades (Clades 1-8) with no temporal association. Most of the isolates from Tehran grouped together as one distinctive clade (Clade 8) with six unique single nucleotide polymorphisms (SNPs). In addition, the prn9 isolates were grouped together as Clade 5 with 12 clade-supporting SNPs. No pertactin deficient isolates were found among the 55 Iranian isolates. Our findings suggest that there is an ongoing adaptation and evolution of B. pertussis regardless of the types of vaccine used.

Conserved Patterns of Symmetric Inversion in the Genome Evolution of Bordetella Respiratory Pathogens

Whooping cough (pertussis), primarily caused by Bordetella pertussis, has resurged in the United States, and circulating strains exhibit considerable chromosome structural fluidity in the form of rearrangement and deletion. The genus Bordetella includes additional pathogenic species infecting various animals, some even causing pertussis-like respiratory disease in humans; however, investigation of their genome evolution has been limited. We studied chromosome structure in complete genome sequences from 167 Bordetella species isolates, as well as 469 B. pertussis isolates, to gain a generalized understanding of rearrangement patterns among these related pathogens. Observed changes in gene order primarily resulted from large inversions and were only detected in species with genomes harboring multicopy insertion sequence (IS) elements, most notably B. holmesii and B. parapertussis While genomes of B. pertussis contain >240 copies of IS481, IS elements appear less numerous in other species and yield less chromosome structural diversity through rearrangement. These data were further used to predict all possible rearrangements between IS element copies present in Bordetella genomes, revealing that only a subset is observed among circulating strains. Therefore, while it appears that rearrangement occurs less frequently in other species than in B. pertussis, these clinically relevant respiratory pathogens likely experience similar mutation of gene order. The resulting chromosome structural fluidity presents both challenges and opportunity for the study of Bordetella respiratory pathogens.IMPORTANCE Bordetella pertussis is the primary agent of whooping cough (pertussis). The Bordetella genus includes additional pathogens of animals and humans, including some that cause pertussis-like respiratory illness. The chromosome of B. pertussis has previously been shown to exhibit considerable structural rearrangement, but insufficient data have prevented comparable investigation in related species. In this study, we analyze chromosome structure variation in several Bordetella species to gain a generalized understanding of rearrangement patterns in this genus. Just as in B. pertussis, we observed inversions in other species that likely result from common mutational processes. We used these data to further predict additional, unobserved inversions, suggesting that specific genome structures may be preferred in each species.

Pertussis seronegativity in pregnant women in the city of Al Ain, United Arab Emirates

OBJECTIVE

As the current recommendation of administering Tdap (tetanus-diphtheria-acellular pertussis) to all pregnant women has not been widely implemented in the United Arab Emirates (UAE), we aimed to ascertain the prevalence of pertussis seronegativity during pregnancy.

METHODS

IgG antibodies against Bordetella pertussis toxin (PT) were measured in 213 women attending the antenatal clinic at Oasis hospital, Al Ain, UAE. Results were compared by maternal age, nationality and gestational age with the Kruskal-Wallis test for IgG-PT levels and the Chi-squared test for serology status.

RESULTS

The mean age±SD of the participants was 30.4±5.6 years, mean gestational age±SD of 25.5±3.3 weeks. Serum concentration of IgG-PT <10IU/ml were found in 160 out of 213 women (75%; 95% confidence interval 69%, 81%). There was no significant difference in the geometric mean of serum IgG-PT concentration across maternal age (P=0.80) or nationality (P=0.90). There were no differences in the prevalence of seronegativity with maternal age (P=0.65) or nationality (P=0.90).

CONCLUSION

With a high prevalence of pertussis seronegativity in pregnant women, there is a potential benefit of introducing pertussis vaccination during pregnancy into our national immunization program.

Shotgun proteomic analysis of Bordetella parapertussis provides insights into the physiological response to iron starvation and potential new virulence determinants absent in Bordetella pertussis

Bordetella parapertussis is one of the pathogens that cause whooping cough. Even though its incidence has been rising in the last decades, this species remained poorly investigated. This study reports the first extensive proteome analysis of this bacterium. In an attempt to gain some insight into the infective phenotype, we evaluated the response of B. parapertussis to iron starvation, a critical stress the bacteria face during infection. Among other relevant findings, we observed that the adaptation to this condition involves significant changes in the abundance of two important virulence factors of this pathogen, namely, adenylate cyclase and the O-antigen. We further used the proteomic data to search for B. parapertussis proteins that are absent or classified as pseudogenes in the genome of Bordetella pertussis to unravel differences between both whooping cough causative agents. Among them, we identified proteins involved in stress resistance and virulence determinants that might help to explain the differences in the pathogenesis of these species and the lack of cross-protection of current acellular vaccines. Altogether, these results contribute to a better understanding of B. parapertussis biology and pathogenesis. SIGNIFICANCE: Whooping cough is a reemerging disease caused by both Bordetella pertussis and Bordetella parapertussis. Current vaccines fail to induce protection against B parapertussis and the incidence of this species has been rising over the years. The proteomic analysis of this study provided relevant insights into potential virulence determinants of this poorly-studied pathogen. It further identified proteins produced by B. parapertussis not present in B. pertussis, which might help to explain both the differences on their respective infectious process and the current vaccine failure. Altogether, the results of this study contribute to the better understanding of B. parapertussis pathogenesis and the eventual design of improved preventive strategies against whooping cough.

BspR/BtrA, an Anti-σ Factor, Regulates the Ability of Bordetella bronchiseptica To Cause Cough in Rats

Whooping cough is a contagious respiratory disease caused by Bordetella pertussis. This disease is characterized by severe paroxysmal coughing, which becomes a heavy burden for patients and occasionally results in death; however, its pathogenesis remains largely unknown. The major obstacle to analyzing Bordetella-induced coughing is the lack of conventional animal models that replicate coughing. As Bordetella pertussis is highly adapted to humans, infection models in experimental animals are not considered to be well established. In the present study, we examined coughing in rats infected with B. bronchiseptica, which shares many virulence factors with B. pertussis. Using this rat model, we demonstrated that some of the major virulence factors of Bordetella are not involved in cough production, but an anti-σ factor, BspR/BtrA, of B. bronchiseptica regulates the production of unknown cough-causing bacterial factor(s). Our results provide important clues to understand the mechanism by which Bordetella induces cough.

Bordetella pertussis, B. parapertussis, and B. bronchiseptica cause respiratory infections, many of which are characterized by coughing of the infected hosts. The pathogenesis of the coughing remains to be analyzed, mainly because there were no convenient infection models of small animals that replicate coughing after Bordetella infection. Here, we present a coughing model of rats infected with B. bronchiseptica. Rats, which are one of natural hosts of B. bronchiseptica, were readily infected with the organisms and showed frequent coughing. B. pertussis also caused coughing in rats, which is consistent with previous reports, but the cough response was less apparent than the B. bronchiseptica-induced cough. By using the rat model, we demonstrated that adenylate cyclase toxin, dermonecrotic toxin, and the type III secretion system are not involved in cough production, but BspR/BtrA (different names for the same protein), an anti-σ factor, regulates the production of unknown factor(s) to cause coughing. Rat coughing was observed by inoculation of not only the living bacteria but also the bacterial lysates. Infection with bspR (btrA)-deficient strains caused significantly less frequent coughing than the wild type; however, intranasal inoculation of the lysates from a bspR (btrA)-deficient strain caused coughing similarly to the wild type, suggesting that BspR/BtrA regulates the production of the cough factor(s) only when the bacteria colonize host bodies. Moreover, the cough factor(s) was found to be heat labile and produced by B. bronchiseptica in the Bvg⁺ phase. We consider that our rat model provides insight into the pathogenesis of cough induced by the Bordetella infection.

IMPORTANCE Whooping cough is a contagious respiratory disease caused by Bordetella pertussis. This disease is characterized by severe paroxysmal coughing, which becomes a heavy burden for patients and occasionally results in death; however, its pathogenesis remains largely unknown. The major obstacle to analyzing Bordetella-induced coughing is the lack of conventional animal models that replicate coughing. As Bordetella pertussis is highly adapted to humans, infection models in experimental animals are not considered to be well established. In the present study, we examined coughing in rats infected with B. bronchiseptica, which shares many virulence factors with B. pertussis. Using this rat model, we demonstrated that some of the major virulence factors of Bordetella are not involved in cough production, but an anti-σ factor, BspR/BtrA, of B. bronchiseptica regulates the production of unknown cough-causing bacterial factor(s). Our results provide important clues to understand the mechanism by which Bordetella induces cough.

Bordetella parapertussis Bacteremia: Clinical Expression and Bacterial Genomics

Whooping cough's primary etiological agent is Bordetella pertussis. The closely related Bordetella parapertussis rarely causes severe disease. Here we report an unusual case of bacteremia caused by B. parapertussis, review the literature, and characterize the genomic sequence of the bacterial isolate in comparison with B. parapertussis isolates from respiratory infections.

Pertussis disease and transmission and host responses: insights from the baboon model of pertussis

Whooping cough is a highly contagious, acute respiratory disease, caused by the Gram-negative bacterium Bordetella pertussis (Bp). Despite the introduction and widespread use of vaccines starting in the 1950s pertussis cases continue to be reported, with a significant global impact. The role of specific virulence factors in disease and the immune mechanisms associated with protection following natural infection or vaccination are still not completely understood. The recently-developed baboon model of clinical pertussis provides a valuable tool for the study of pertussis. Baboons infected with B. pertussis exhibit all of the manifestations of human pertussis including paroxysmal coughing, mucus production, leukocytosis and transmission. The establishment of this model provides the opportunity to address unanswered questions about the natural progression of this disease and host responses to infection and vaccination in a very relevant model. In this review, we present an overview of our knowledge of pertussis along with recent advances resulting from use of the baboon model. Remaining questions and future research directions are discussed. We hope that the knowledge gained through use of the baboon model of pertussis and clinical studies will allow the development of more efficacious vaccines, conferring long lasting protection against disease and transmission.

Contact tracing with a real-time location system: A case study of increasing relative effectiveness in an emergency department

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Contact tracing is an essential step in infectious disease control and prevention.

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Using Electronic medical record (EMR) is challenging and misses a number of potential exposures.

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Real time location system (RTLS) doubled the potential exposures list for pertussis disease beyond the conventional method of EMR-based contact identification

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RTLS is more efficient and timely in the process of contact tracing.

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Further studies with larger sample size are needed to confirm the findings.

Background

Contact tracing is the systematic method of identifying individuals potentially exposed to infectious diseases. Electronic medical record (EMR) use for contact tracing is time-consuming and may miss exposed individuals. Real-time location systems (RTLSs) may improve contact identification. Therefore, the relative effectiveness of these 2 contact tracing methodologies were evaluated.

Methods

During a pertussis outbreak in the United States, a retrospective case study was conducted between June 14 and August 31, 2016, to identify the contacts of confirmed pertussis cases, using EMR and RTLS data in the emergency department of a tertiary care medical center. Descriptive statistics and a paired t test (α = 0.05) were performed to compare contacts identified by EMR versus RTLS, as was correlation between pertussis patient length of stay and the number of potential contacts.

Results

Nine cases of pertussis presented to the emergency department during the identified time period. RTLS doubled the potential exposure list (P < .01). Length of stay had significant positive correlation with contacts identified by RTLS (ρ = 0.79; P = .01) but not with EMR (ρ = 0.43; P = .25).

Conclusions

RTLS doubled the potential pertussis exposures beyond EMR-based contact identification. Thus, RTLS may be a valuable addition to the practice of contact tracing and infectious disease monitoring.

Bordetella Pertussis virulence factors in the continuing evolution of whooping cough vaccines for improved performance

Despite high vaccine coverage, whooping cough caused by Bordetella pertussis remains one of the most common vaccine-preventable diseases worldwide. Introduction of whole-cell pertussis (wP) vaccines in the 1940s and acellular pertussis (aP) vaccines in 1990s reduced the mortality due to pertussis. Despite induction of both antibody and cell-mediated immune (CMI) responses by aP and wP vaccines, there has been resurgence of pertussis in many countries in recent years. Possible reasons hypothesised for resurgence have ranged from incompliance with the recommended vaccination programmes with the currently used aP vaccine to infection with a resurged clinical isolates characterised by mutations in the virulence factors, resulting in antigenic divergence with vaccine strain, and increased production of pertussis toxin, resulting in dampening of immune responses. While use of these vaccines provide varying degrees of protection against whooping cough, protection against infection and transmission appears to be less effective, warranting continuation of efforts in the development of an improved pertussis vaccine formulations capable of achieving this objective. Major approaches currently under evaluation for the development of an improved pertussis vaccine include identification of novel biofilm-associated antigens for incorporation in current aP vaccine formulations, development of live attenuated vaccines and discovery of novel non-toxic adjuvants capable of inducing both antibody and CMI. In this review, the potential roles of different accredited virulence factors, including novel biofilm-associated antigens, of B. pertussis in the evolution, formulation and delivery of improved pertussis vaccines, with potential to block the transmission of whooping cough in the community, are discussed.

Membrane-Active Properties of an Amphitropic Peptide from the CyaA Toxin Translocation Region

The adenylate cyclase toxin CyaA is involved in the early stages of infection by Bordetella pertussis, the causative agent of whooping cough. CyaA intoxicates target cells by a direct translocation of its catalytic domain (AC) across the plasma membrane and produces supraphysiological levels of cAMP, leading to cell death. The molecular process of AC translocation remains largely unknown, however. We have previously shown that deletion of residues 375–485 of CyaA selectively abrogates AC translocation into eukaryotic cells. We further identified within this “translocation region” (TR), P454 (residues 454–484), a peptide that exhibits membrane-active properties, i.e., is able to bind and permeabilize lipid vesicles. Here, we analyze various sequences from CyaA predicted to be amphipatic and show that although several of these peptides can bind membranes and adopt a helical conformation, only the P454 peptide is able to permeabilize membranes. We further characterize the contributions of the two arginine residues of P454 to membrane partitioning and permeabilization by analyzing the peptide variants in which these residues are substituted by different amino acids (e.g., A, K, Q, and E). Our data shows that both arginine residues significantly contribute, although diversely, to the membrane-active properties of P454, i.e., interactions with both neutral and anionic lipids, helix formation in membranes, and disruption of lipid bilayer integrity. These results are discussed in the context of the translocation process of the full-length CyaA toxin.

Characterization of Post-Translational Modifications and Cytotoxic Properties of the Adenylate-Cyclase Hemolysin Produced by Various Bordetella pertussis and Bordetella parapertussis Isolates

Bordetella pertussis and Bordetella parapertussis are the causal agents of whooping cough in humans. They produce diverse virulence factors, including adenylate cyclase-hemolysin (AC-Hly), a secreted toxin of the repeat in toxins (RTX) family with cyclase, pore-forming, and hemolytic activities. Post-translational modifications (PTMs) are essential for the biological activities of the toxin produced by B. pertussis. In this study, we compared AC-Hly toxins from various clinical isolates of B. pertussis and B. parapertussis, focusing on (i) the genomic sequences of cyaA genes, (ii) the PTMs of partially purified AC-Hly, and (iii) the cytotoxic activity of the various AC-Hly toxins. The genes encoding the AC-Hly toxins of B. pertussis and B. parapertussis displayed very limited polymorphism in each species. Most of the sequence differences between the two species were found in the C-terminal part of the protein. Both toxins harbored PTMs, mostly corresponding to palmitoylations of the lysine 860 residue and palmoylations and myristoylations of lysine 983 for B. pertussis and AC-Hly and palmitoylations of lysine 894 and myristoylations of lysine 1017 for B. parapertussis AC-Hly. Purified AC-Hly from B. pertussis was cytotoxic to macrophages, whereas that from B. parapertussis was not.

Characterization of Post-Translational Modifications and Cytotoxic Properties of the Adenylate-Cyclase Hemolysin Produced by Various Bordetella pertussis and Bordetella parapertussis Isolates

Bordetella pertussis and Bordetella parapertussis are the causal agents of whooping cough in humans. They produce diverse virulence factors, including adenylate cyclase-hemolysin (AC-Hly), a secreted toxin of the repeat in toxins (RTX) family with cyclase, pore-forming, and hemolytic activities. Post-translational modifications (PTMs) are essential for the biological activities of the toxin produced by B. pertussis. In this study, we compared AC-Hly toxins from various clinical isolates of B. pertussis and B. parapertussis, focusing on (i) the genomic sequences of cyaA genes, (ii) the PTMs of partially purified AC-Hly, and (iii) the cytotoxic activity of the various AC-Hly toxins. The genes encoding the AC-Hly toxins of B. pertussis and B. parapertussis displayed very limited polymorphism in each species. Most of the sequence differences between the two species were found in the C-terminal part of the protein. Both toxins harbored PTMs, mostly corresponding to palmitoylations of the lysine 860 residue and palmoylations and myristoylations of lysine 983 for B. pertussis and AC-Hly and palmitoylations of lysine 894 and myristoylations of lysine 1017 for B. parapertussis AC-Hly. Purified AC-Hly from B. pertussis was cytotoxic to macrophages, whereas that from B. parapertussis was not.

The characterization of Bordetella pertussis strains isolated in the Central-Western region of Brazil suggests the selection of a specific genetic profile during 2012-2014 outbreaks

Pertussis is a worldwide acute respiratory disease caused by the bacterium Bordetella pertussis. Despite high vaccine coverage, the bacterium continues to circulate in populations and is still one of the most common vaccine-preventable diseases. In Brazil, pertussis incidence has presented a significant decrease since 1990 but since 2011 a sudden increase in incidence has been observed. Thus, the aim of this study was to perform a molecular epidemiological characterization of B. pertussis strains isolated in the Central-Western region (specifically in Distrito Federal) of Brazil from August 2012 to August 2014. During this period, 92 B. pertussis strains were isolated from the outbreaks. All strains were characterized by serotyping and XbaI pulsed-field gel electrophoresis profiles. From August to December 2012, the most prevalent serotype observed was 1,3 (13/17). During 2013 the prevalence of serotype 1,3 decreased (13/30) and from January 2014 to August 2014 the most prevalent serotype was 1,2 (33/45). Fourteen PFGE profiles were identified. Of these, BP-XbaI0039 prevalence increased from 3/17 in 2012 to 10/30 in 2013, and 35/45 in 2014. These results evidence the selection of a specific genetic profile during this period, suggesting the occurrence of a bacterial genomic profile with high circulation potential.

Pertussis: Microbiology, Disease, Treatment, and Prevention

Pertussis is a severe respiratory infection caused by Bordetella pertussis, and in 2008, pertussis was associated with an estimated 16 million cases and 195,000 deaths globally. Sizeable outbreaks of pertussis have been reported over the past 5 years, and disease reemergence has been the focus of international attention to develop a deeper understanding of pathogen virulence and genetic evolution of B. pertussis strains. During the past 20 years, the scientific community has recognized pertussis among adults as well as infants and children. Increased recognition that older children and adolescents are at risk for disease and may transmit B. pertussis to younger siblings has underscored the need to better understand the role of innate, humoral, and cell-mediated immunity, including the role of waning immunity. Although recognition of adult pertussis has increased in tandem with a better understanding of B. pertussis pathogenesis, pertussis in neonates and adults can manifest with atypical clinical presentations. Such disease patterns make pertussis recognition difficult and lead to delays in treatment. Ongoing research using newer tools for molecular analysis holds promise for improved understanding of pertussis epidemiology, bacterial pathogenesis, bioinformatics, and immunology. Together, these advances provide a foundation for the development of new-generation diagnostics, therapeutics, and vaccines.

Old Disease and New Challenges: Major Obstacles of Current Strategies in the Prevention of Pertussis

Context

Universal immunization against Bordetella pertussis has partially controlled the burden of the disease and its transmission. However, according to recent data, the epidemiology of this vaccine-preventable disease has changed. Now, younger infants, adolescents, and adults are at greater risk of infection. This article has studied the interaction between the various factors involved in the changing epidemiology of pertussis and the major obstacles faced by the current strategies in its prevention.

Evidence Acquisition

In this narrative review, the most recently published sources of information on pertussis control measures, consisting of textbooks and articles, have been reviewed. We focused on the more recent data about the changing epidemiology or pertussis in Scopus through the use of the MeSH-term words [pertussis] or [whooping cough] and [epidemiology] or [outbreak] or [resurgence], but our search was not restricted to this particular strategy; we also tried to find all of the most recent available data in the general field through other means.

Results

Primary and booster doses of the pertussis vaccine seem to partially control transmission of the disease, but despite the different preventive strategies available, pertussis continues to cause mortality and morbidity among high-risk groups.

Conclusions

Adding booster doses of acellular pertussis vaccine to the current national immunization practices with whole-cell vaccines for young adults and pregnant women seems to be a good option for controlling mortality and morbidity among high-risk groups such as very young infants.