An investigation into the cause of the 1983 whooping cough epidemic in the Netherlands

The association of public health interventions regarding both infant sleep position and pertussis immunization with sudden infant death syndrome rates: an ecological study

BACKGROUND

Infections may play a role in the etiology of sudden infant death syndrome (SIDS), with Bordetella pertussis being a potential agent. The objective was to analyze the association of SIDS and infant pertussis hospitalization rates over time, comparing a previously unvaccinated population (West Germany) versus a predominantly vaccinated population (East Germany).

METHODS

We calculated SIDS rates per 1000 live births per state. Live births and SIDS were available from 1980 onwards for the West German states and from 1991 onwards for the East German states. We applied interrupted time series (ITS) analyses to investigate the role of two public health interventions in 1991 (West Germany) and in 2000 (West and East Germany), respectively. Infant pertussis hospitalizations were available for five West German and three East German states between 1994 and 2019. We used multilayer and multivariate correlation analyses to determine the correlation between SIDS and pertussis hospitalization rates, including Pearson correlation test and vector autoregressive (VAR) analysis.

RESULTS

In West Germany, the average annual SIDS rate (per 1000 live births) increased from 1.08 in 1980 to 1.68 in 1991, before declining to 1.18 in 1992 and subsequently to 0.10 in 2020. In East Germany, the average annual SIDS rate (per 1000 live births) decreased from 0.79 in 1991 to 0.12 in 2020. The results of the ITS model indicated a significant change in both level and slope at the 1991 interventions (West Germany) and in slope at the 2000 interventions (West and East Germany). The correlation coefficients between SIDS and infant pertussis hospitalization rates were 0.69 (95% CI [confidence interval] 0.41, 0.85; p < 0.001) in West Germany, and 0.41 (95% CI 0.03, 0.69; p = 0.037) in East Germany. The correlation decreased during later periods (2000-2019, 2010-2019), particularly in East Germany. The results of the VAR analysis corroborated the findings of the main analyses.

CONCLUSIONS

SIDS and infant pertussis hospitalization rates were correlated in both West and East Germany. Further studies - including improved diagnostic assessment of pertussis - seem warranted.

CLINICAL TRIAL NUMBER

Not applicable.

Strain variation and antigenic divergence among Bordetella pertussis circulating strains isolated from patients in Iran

Despite global efforts and widespread vaccination to control whooping cough (pertussis) caused by B. pertussis, the re-emergence of pertussis still is being reported all over the world. Antigenic divergence in B. pertussis virulence factors is one of the reasons of pertussis resurgence, resulting in dissimilarity of local and vaccine strains. In this study, clonal spread and variation of B. pertussis virulence factor in isolated strains from Iranian patients have been analyzed. A total of 100 B. pertussis isolates were obtained from Pertussis Reference Laboratory of Pasteur Institute of Iran. Real-time PCR were performed to confirm the B. pertussis strains. The genomic patterns of B. pertussis strains were analyzed by pulsed-field gel electrophoresis (PFGE). Predominant alleles of local strains were ptxP3, ptxA1, prn2, fim 2-1, fim3-2, and cya2. PFGE results showed 25 patterns clustered into 18 PFGE groups. A few similarities between the circulating isolates, vaccine, and standard strains were obtained. Significantly, 48% of the isolates showed dominant pattern with different allelic profiles from vaccine strains. According to the genomic profiles, the clonal spread was observed among the circulating strains. Predominant virulence factor profile was also comparable with other countries. It may be suggested that strain variation between vaccine and local strains may have an effect on pertussis resurgence in Iran like other parts of the world.

Multi-locus variable-number tandem repeat analysis of Bordetella pertussis isolates circulating in Poland in the period 1959-2013

PURPOSE

Despite the long history of pertussis vaccination and high vaccination coverage in Poland and many other developed countries, pertussis incidence rates have increased substantially, making whooping cough one of the most prevalent vaccine-preventable diseases. Among the factors potentially involved in pertussis resurgence, the adaptation of the Bordetella pertussis population to country-specific vaccine-induced immunity through selection of non-vaccine-type strains still needs detailed studies.

METHODOLOGY

Multi-locus variable-number tandem repeat analysis (MLVA), also linked to MLST and PFGE profiling, was applied to trace the genetic changes in the B. pertussis population circulating in Poland in the period 1959-2013 versus country-specific vaccine strains.

RESULTS

Generally, among 174 B. pertussis isolates, 31 MLVA types were detected, of which 11 were not described previously. The predominant MLVA types of recent isolates in Poland were different from those of the typical isolates circulating in other European countries. The MT27 type, currently predominant in Europe, was rarely seen and detected in only five isolates among all studied. The features of the vaccine strains used for production of the pertussis component of a national whole-cell diphtheria-tetanus-pertussis (DTP) vaccine, as studied by MLVA and MLST tools, were found to not match those observed in the currently circulating B. pertussis isolates in Poland.

CONCLUSIONS

Differences traced by MLVA in relation to the MLST and PFGE profiling confirmed that the B. pertussis strain types currently observed elsewhere in Europe, even if appearing in Poland, were not able to successfully disseminate within a human population in Poland that has been vaccinated with a whole-cell pertussis vaccine not used in other countries.

Serum reactome induced by Bordetella pertussis infection and Pertussis vaccines: qualitative differences in serum antibody recognition patterns revealed by peptide microarray analysis

Background

Pertussis (whooping cough) remains a public health problem despite extensive vaccination strategies. Better understanding of the host-pathogen interaction and the detailed B. pertussis (Bp) target recognition pattern will help in guided vaccine design. We characterized the specific epitope antigen recognition profiles of serum antibodies (‘the reactome’) induced by whooping cough and B. pertussis (Bp) vaccines from a case–control study conducted in 1996 in infants enrolled in a Bp vaccine trial in Sweden (Gustafsson, NEJM, 1996, 334, 349–355).

Methods

Sera from children with whooping cough, vaccinated with Diphtheria Tetanus Pertussis (DTP) whole-cell (wc), acellular 5 (DPTa5), or with the 2 component (a2) vaccines and from infants receiving only DT (n = 10 for each group) were tested with high-content peptide microarrays containing 17 Bp proteins displayed as linear (n = 3175) peptide stretches. Slides were incubated with serum and peptide-IgG complexes detected with Cy5-labeled goat anti-human IgG and analyzed using a GenePix 4000B microarray scanner, followed by statistical analysis, using PAM (Prediction Analysis for Microarrays) and the identification of uniquely recognized peptide epitopes.

Results

367/3,085 (11.9%) peptides were recognized in 10/10 sera from children with whooping cough, 239 (7.7%) in DTPwc, 259 (8.4%) in DTPa5, 105 (3.4%) DTPa2, 179 (5.8%) in the DT groups. Recognition of strongly recognized peptides was similar between whooping cough and DPTwc, but statistically different between whooping cough vs. DTPa5 (p < 0.05), DTPa2 and DT (p < 0.001 vs. both) vaccines. 6/3,085 and 2/3,085 peptides were exclusively recognized in (10/10) sera from children with whooping cough and DTPa2 vaccination, respectively. DTPwc resembles more closely the whooping cough reactome as compared to acellular vaccines.

Conclusion

We could identify a unique recognition signature common for each vaccination group (10/10 children). Peptide microarray technology allows detection of subtle differences in epitope signature responses and may help to guide rational vaccine development by the objective description of a clinically relevant immune response that confers protection against infectious pathogens.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-015-0090-3) contains supplementary material, which is available to authorized users.

Whole-Genome Sequence of a Bordetella pertussis Brazilian Vaccine Strain

Despite the reduction in incidence after vaccination, pertussis disease is still considered a public health problem worldwide, mainly due to recent and potential new outbreaks. We report here the complete genome of the Bordetella pertussis Butantan strain used in the Brazilian National Immunization Program as a whole-cell pertussis antigen to compose vaccines such as DTwP (diphtheria, tetanus, and whole-cell pertussis).

Genetic analysis of Bordetella pertussis isolates from the 2008-2010 pertussis epidemic in Japan

A large pertussis epidemic occurred between 2008 and 2010 in Japan. To investigate epidemic strains, we analyzed 33 Bordetella pertussis isolates from the epidemic period by sequencing virulence-associated genes (fim3, ptxP, ptxA, and prn) and performing multilocus variable-number tandem repeat analysis (MLVA), and compared these results with those of 101 isolates from non-epidemic, earlier and later time periods. DNA sequencing of the fim3 allele revealed that the frequency of fim3B was 4.3%, 12.8%, 30.3%, and 5.1% within isolates in 2002–2004, 2005–2007, 2008–2010, and 2011–2012, respectively. The isolation rate of the fim3B strain therefore temporarily increased during the epidemic period 2008–2010. In contrast, the frequencies of the virulence-associated allelic variants, ptxP3, ptxA1, and prn2, increased with time during overall study period, indicating that these variants were not directly involved in the occurrence of the 2008–2010 epidemic. MLVA genotyping in combination with analysis of allele types showed that the prevalence of an MT27d strain temporarily increased in the epidemic period, and that this strain carried virulence-associated allelic variants (fim3B, ptxP3, ptxA1, and prn2) also identified in recent epidemic strains of Australia, Europe, and the US. Phenotypic analyses revealed that the serotype Fim3 strain was predominant (≥87%) during all the periods studied, and that the frequency of adhesion pertactin (Prn) non-expressing B. pertussis decreased by half in the epidemic period. All MT27d strains expressed Prn and Fim3 proteins, suggesting that B. pertussis MT27d strains expressing Prn and Fim3B have the potential to cause large epidemics worldwide.

Genotypic and phenotypic characterization of Bordetella pertussis strains used in different vaccine formulations in Latin America

AIM

To characterize Bordetella pertussis vaccine strains in comparison with current circulating bacteria.

METHODS AND RESULTS

Genomic and proteomic analyses of Bp137 were performed in comparison with other vaccine strains used in Latin America (Bp509 and Bp10536) and with the clinical Argentinean isolate Bp106. Tohama I strain was used as reference strain. Pulse-field gel electrophoresis (PFGE) and pertussis toxin promoter (ptxP) sequence analysis revealed that Bp137 groups with Bp509 in PFGE group III and contains ptxP2 sequence. Tohama I (group II) and Bp10536 (group I) contain ptxP1 sequence, while Bp106 belongs to a different PFGE cluster and contains ptxP3. Surface protein profiles diverged in at least 24 peptide subunits among the studied strains. From these 24 differential proteins, Bp10536 shared the expression of ten proteins with Tohama I and Bp509, but only three with Bp137. In contrast, seven proteins were detected exclusively in Bp137 and Bp106.

CONCLUSIONS

Bp137 showed more features in common with the clinical isolate Bp106 than the other vaccine strains here included.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results presented show that the old strains included in vaccines are not all equal among them. These findings together with the data of circulating bacteria should be taken into account to select the best vaccine to be included in a national immunization programme.

SNP-based typing: a useful tool to study Bordetella pertussis populations

To monitor changes in Bordetella pertussis populations, mainly two typing methods are used; Pulsed-Field Gel Electrophoresis (PFGE) and Multiple-Locus Variable-Number Tandem Repeat Analysis (MLVA). In this study, a single nucleotide polymorphism (SNP) typing method, based on 87 SNPs, was developed and compared with PFGE and MLVA. The discriminatory indices of SNP typing, PFGE and MLVA were found to be 0.85, 0.95 and 0.83, respectively. Phylogenetic analysis, using SNP typing as Gold Standard, revealed false homoplasies in the PFGE and MLVA trees. Further, in contrast to the SNP-based tree, the PFGE- and MLVA-based trees did not reveal a positive correlation between root-to-tip distance and the isolation year of strains. Thus PFGE and MLVA do not allow an estimation of the relative age of the selected strains. In conclusion, SNP typing was found to be phylogenetically more informative than PFGE and more discriminative than MLVA. Further, in contrast to PFGE, it is readily standardized allowing interlaboratory comparisons. We applied SNP typing to study strains with a novel allele for the pertussis toxin promoter, ptxP3, which have a worldwide distribution and which have replaced the resident ptxP1 strains in the last 20 years. Previously, we showed that ptxP3 strains showed increased pertussis toxin expression and that their emergence was associated with increased notification in the Netherlands. SNP typing showed that the ptxP3 strains isolated in the Americas, Asia, Australia and Europe formed a monophyletic branch which recently diverged from ptxP1 strains. Two predominant ptxP3 SNP types were identified which spread worldwide. The widespread use of SNP typing will enhance our understanding of the evolution and global epidemiology of B. pertussis.

Appearance of Fim3 and ptxP3-Bordetella pertussis strains, in two regions of Sweden with different vaccination programs

After introduction of a mono-component vaccine, containing only pertussis toxoid (PT), the incidence of pertussis was significantly higher in the Gothenburg area among children during the period October 1, 1997 until end of 2006 compared to the Rest of Sweden where a vaccine containing PT and two other pertussis antigens was used. To investigate a possible cause of this difference, the Bordetella pertussis populations in both regions were compared by determining the fimbrial serotype (Fim), the PFGE-type and the pertussis toxin promoter allele type (ptxP). Strains with the ptxP1 allele were successively replaced by ptxP3 strains producing more pertussis toxin. In Gothenburg compared to the Rest of Sweden, Fim3 and ptxP3 strains were observed earlier and reached higher frequencies in the studied period. Since ptxP3 strains have been shown to be more virulent, their higher prevalence may have contributed to the higher incidence of pertussis in the Gothenburg area. In addition we found a high degree of linkage between PFGE-profile and ptxP3. Our results highlight the importance of strain typing to gain insight into the mechanisms of immunity-associated selection of microbial subtypes and the causes of changes in incidences of infectious diseases.

Effect of vaccination on Bordetella pertussis strains, China

Strains in China may differ from those in countries that have long histories of high vaccination coverage.

Whole-cell pertussis vaccine was introduced in China in the early 1960s. We used standard typing methods to compare 96 Bordetella pertussis isolates collected before and after introduction of vaccination, during 1953–2005. The following vaccine-type alleles of the pertussis toxin (ptx) gene were characteristic for all prevaccination strains: ptxA2, ptxA3, and ptxA4. The shift to ptxA1 occurred since 1963. All isolates collected since 1983 contained ptxA1. Pertactin (prn) allele 1, prn1, was predominant, although prn2 and prn3 have been detected since 2000. Serotypes fimbriae (Fim) 2 and Fim2,3 were found in all isolates collected before 1986. During 1997–2005, Fim3 became prevalent. Although changes in electrophoresis profiles over time were observed, the predominant profiles during 1997–2005 resembled those during the prevaccine era and those found in Europe before the 1990s. B. pertussis strains in China may differ from those in countries that have a long history of high vaccine coverage.

Comparative genomics of prevaccination and modern Bordetella pertussis strains

Background

Despite vaccination since the 1950s, pertussis has persisted and resurged. It remains a major cause of infant death worldwide and is the most prevalent vaccine-preventable disease in developed countries. The resurgence of pertussis has been associated with the expansion of Bordetella pertussis strains with a novel allele for the pertussis toxin (Ptx) promoter, ptxP3, which have replaced resident ptxP1 strains. Compared to ptxP1 strains, ptxP3 produce more Ptx resulting in increased virulence and immune suppression. To elucidate how B. pertussis has adapted to vaccination, we compared genome sequences of two ptxP3 strains with four strains isolated before and after the introduction vaccination.

Results

The distribution of SNPs in regions involved in transcription and translation suggested that changes in gene regulation play an important role in adaptation. No evidence was found for acquisition of novel genes. Modern strains differed significantly from prevaccination strains, both phylogenetically and with respect to particular alleles. The ptxP3 strains were found to have diverged recently from modern ptxP1 strains. Differences between ptxP3 and modern ptxP1 strains included SNPs in a number of pathogenicity-associated genes. Further, both gene inactivation and reactivation was observed in ptxP3 strains relative to modern ptxP1 strains.

Conclusions

Our work suggests that B. pertussis adapted by successive accumulation of SNPs and by gene (in)activation. In particular changes in gene regulation may have played a role in adaptation.

Acellular pertussis vaccination facilitates Bordetella parapertussis infection in a rodent model of bordetellosis

Despite over 50 years of population-wide vaccination, whooping cough incidence is on the rise. Although Bordetella pertussis is considered the main causative agent of whooping cough in humans, Bordetella parapertussis infections are not uncommon. The widely used acellular whooping cough vaccines (aP) are comprised solely of B. pertussis antigens that hold little or no efficacy against B. parapertussis. Here, we ask how aP vaccination affects competitive interactions between Bordetella species within co-infected rodent hosts and thus the aP-driven strength and direction of in-host selection. We show that aP vaccination helped clear B. pertussis but resulted in an approximately 40-fold increase in B. parapertussis lung colony-forming units (CFUs). Such vaccine-mediated facilitation of B. parapertussis did not arise as a result of competitive release; B. parapertussis CFUs were higher in aP-relative to sham-vaccinated hosts regardless of whether infections were single or mixed. Further, we show that aP vaccination impedes host immunity against B. parapertussis-measured as reduced lung inflammatory and neutrophil responses. Thus, we conclude that aP vaccination interferes with the optimal clearance of B. parapertussis and enhances the performance of this pathogen. Our data raise the possibility that widespread aP vaccination can create hosts more susceptible to B. parapertussis infection.

Synergic effect of genotype changes in pertussis toxin and pertactin on adaptation to an acellular pertussis vaccine in the murine intranasal challenge model

The Bordetella pertussis pertussis toxin and pertactin (Prn) are protective antigens and are contained in acellular pertussis vaccines. Polymorphisms in the A subunit of pertussis toxin (PtxA) and pertactin have been proposed to mediate vaccine resistance and contribute to pertussis reemergence. To test this hypothesis, previous studies compared clinical isolates expressing different alleles for the proteins. However, other virulence factors or virulence factor expression levels also may vary, confounding the analysis. To overcome these limitations, we constructed isogenic mutants of B. pertussis Tohama expressing the alleles ptxA1 or ptxA2 and prn1 or prn2 and compared the efficacies of an acellular pertussis vaccine against the mutants in a mouse model. While the vaccine was effective against all of the B. pertussis strains regardless of the allele expression pattern, the strain expressing ptxA1 and prn2 displayed a survival advantage over the other strains. These results suggest that an allele shift to the ptxA1 prn2 genotype may play a role in the emergence of pertussis in vaccinated populations.

Changes in the genomic content of circulating Bordetella pertussis strains isolated from the Netherlands, Sweden, Japan and Australia: adaptive evolution or drift?

Background

Bordetella pertussis is the causative agent of human whooping cough (pertussis) and is particularly severe in infants. Despite worldwide vaccinations, whooping cough remains a public health problem. A significant increase in the incidence of whooping cough has been observed in many countries since the 1990s. Several reasons for the re-emergence of this highly contagious disease have been suggested. A particularly intriguing possibility is based on evidence indicating that pathogen adaptation may play a role in this process. In an attempt to gain insight into the genomic make-up of B. pertussis over the last 60 years, we used an oligonucleotide DNA microarray to compare the genomic contents of a collection of 171 strains of B. pertussis isolates from different countries.

Results

The CGH microarray analysis estimated the core genome of B. pertussis, to consist of 3,281 CDSs that are conserved among all B. pertussis strains, and represent 84.8% of all CDSs found in the 171 B. pertussis strains. A total of 64 regions of difference consisting of one or more contiguous CDSs were identified among the variable genes. CGH data also revealed that the genome size of B. pertussis strains is decreasing progressively over the past 60 years. Phylogenetic analysis of microarray data generated a minimum spanning tree that depicted the phylogenetic structure of the strains. B. pertussis strains with the same gene content were found in several different countries. However, geographic specificity of the B. pertussis strains was not observed. The gene content was determined to highly correlate with the ptxP-type of the strains.

Conclusions

An overview of genomic contents of a large collection of isolates from different countries allowed us to derive a core genome and a phylogenetic structure of B. pertussis. Our results show that B. pertussis is a dynamic organism that continues to evolve.

Bordetella pertussis and vaccination: the persistence of a genetically monomorphic pathogen

Before childhood vaccination was introduced in the 1950s, pertussis or whooping cough was a major cause of infant death worldwide. Widespread vaccination of children was successful in significantly reducing morbidity and mortality. However, despite vaccination, pertussis has persisted and, in the 1990s, resurged in a number of countries with highly vaccinated populations. Indeed, pertussis has become the most prevalent vaccine-preventable disease in developed countries with estimated infection frequencies of 1-6%. Recently vaccinated children are well protected against pertussis disease and its increase is mainly seen in adolescents and adults in which disease symptoms are often mild. The etiologic agent of pertussis, Bordetella pertussis, is extremely monomorphic and its ability to persist in the face of intensive vaccination is intriguing. Numerous studies have shown that B. pertussis populations changed after the introduction of vaccination suggesting adaptation. These adaptations did not involve the acquisition of novel genes but small genetic changes, mainly SNPs, and occurred in successive steps in a period of 40 years. The earliest adaptations resulted in antigenic divergence with vaccine strains. More recently, strains emerged with increased pertussis toxin (Ptx) production. Here I argue that the resurgence of pertussis is the compound effect of pathogen adaptation and waning immunity. I propose that the removal by vaccination of naïve infants as the major source for transmission was the crucial event which has driven the changes in B. pertussis populations. This has selected for strains which are more efficiently transmitted by primed hosts in which immunity has waned. The adaptation of B. pertussis to primed hosts involved delaying an effective immune response by antigenic divergence with vaccine strains and by increasing immune suppression through higher levels of Ptx production. Higher levels of Ptx may also benefit transmission by enhancing clinical symptoms. The study of B. pertussis populations has not only increased our understanding of pathogen evolution, but also suggests way to improve pertussis vaccines, underlining the public health significance of population-based studies of pathogens.