Pertactin-Negative and Filamentous Hemagglutinin-Negative Bordetella pertussis, Australia, 2013-2017

[Impact of vaccination on the evolution of Bordetella pertussis]

Vaccines against pertussis, or whooping cough, have been commercialized and used in most countries worldwide for decades. The history of these vaccines is distinctive, marked by the transition from whole-cell vaccines to acellular vaccines in many developed countries over the last two decades. This particular history has had a significant impact on the evolution of Bordetella pertussis, the etiological agent of whooping cough. Both genetic and phenotypic changes appeared, with the emergence of novel alleles for antigens targeted by the vaccines and changes in the expression of these antigens. The main consequence of these changes is the resurgence of whooping cough in many countries and the appearance of strains capable of evading vaccine-induced immunity. The emergence of novel strains under vaccine pressure underscores the importance of considering biological evolution in the conception of new vaccines and vaccine strategies.

Genomic characterization of Bordetella pertussis in South Africa, 2015-2019

Pertussis remains a public health concern in South Africa, with an increase in reported cases and outbreaks in recent years. Whole genome sequencing was performed on 32 Bordetella pertussis isolates sourced from three different surveillance programmes in South Africa between 2015 and 2019. Genome sequences were characterized using multilocus sequence typing, vaccine antigen genes (ptxP, ptxA, ptxB, prn and fimH) and overall genome structure. All isolates were sequence type 2 and harboured the pertussis toxin promoter allele ptxP3. The dominant genotype was ptxP3-ptxA1-ptxB2-prn2-fimH2 (31/32, 96.9 %), with no pertactin-deficient or other mutations in vaccine antigen genes identified. Amongst 21 isolates yielding closed genome assemblies, eight distinct genome structures were detected, with 61.9 % (13/21) of the isolates exhibiting three predominant structures. Increases in case numbers are probably not due to evolutionary changes in the genome but possibly due to other factors such as the cyclical nature of B. pertussis disease, waning immunity due to the use of acellular vaccines and/or population immunity gaps.

The whole-cell proteome shows the characteristics of macrolides-resistant Bordetella pertussis in China linked to the biofilm formation

The macrolides-resistant Bordetella pertussis (MR-Bp) isolates in China evolved from the ptxP1/fhaB3 allele and rapidly became predominant, suggestive of an adaptive transmission ability. This was different from the global prevalent ptxP3 strains, in which MR-Bp was rarely reported. The study aimed to determine the underlying mechanism responsible for fitness and resistance in these two strains. We identify proteomic differences between ptxP1/fhaB3 and ptxP3/fhaB1 strains using tandem mass tag (TMT)-based proteomics. We then performed in-depth bioinformatic analysis to determine differentially expressed genes (DEGs), followed by gene ontology (GO), and protein-protein interaction (PPI) network analysis. Further parallel reaction monitoring (PRM) analysis confirmed the expression of four target proteins. Finally, the crystal violet method was used to determine biofilm-forming ability. The results showed that the main significantly different proteins between the two represent isolates were related to biofilm formation. Furthermore, we have confirmed that ptxP1/fhaB3 showed hyperbiofilm formation in comparison with ptxP3/fhaB1. It is suggested that the resistance and adaptability of ptxP1/fhaB3 strains may be related to the formation of biofilm through proteomics. In a word, we determined the significantly different proteins between the ptxP1/fhaB3 and ptxP3/fhaB1 strains through whole-cell proteome, which were related to biofilm formation.

Coping Strategies for Pertussis Resurgence

Pertussis (whooping cough) is a respiratory disease caused primarily by Bordetella pertussis, a Gram-negative bacteria. Pertussis is a relatively contagious infectious disease in people of all ages, mainly affecting newborns and infants under 2 months of age. Pertussis is undergoing a resurgence despite decades of high rates of vaccination. To better cope with the challenge of pertussis resurgence, we evaluated its possible causes and potential countermeasures in the narrative review. Expanded vaccination coverage, optimized vaccination strategies, and the development of a new pertussis vaccine may contribute to the control of pertussis.

Real-Time Nanopore Q20+ Sequencing Enables Extremely Fast and Accurate Core Genome MLST Typing and Democratizes Access to High-Resolution Bacterial Pathogen Surveillance

Next-generation whole-genome sequencing is essential for high-resolution surveillance of bacterial pathogens, for example, during outbreak investigations or for source tracking and escape variant analysis. However, current global sequencing and bioinformatic bottlenecks and a long time to result with standard technologies demand new approaches. In this study, we investigated whether novel nanopore Q20+ long-read chemistry enables standardized and easily accessible high-resolution typing combined with core genome multilocus sequence typing (cgMLST). We set high requirements for discriminatory power by using the slowly evolving bacterium Bordetella pertussis as a model pathogen. Our results show that the increased raw read accuracy enables the description of epidemiological scenarios and phylogenetic linkages at the level of gold-standard short reads. The same was true for our variant analysis of vaccine antigens, resistance genes, and virulence factors, demonstrating that nanopore sequencing is a legitimate competitor in the area of next-generation sequencing (NGS)-based high-resolution bacterial typing. Furthermore, we evaluated the parameters for the fastest possible analysis of the data. By combining the optimized processing pipeline with real-time basecalling, we established a workflow that allows for highly accurate and extremely fast high-resolution typing of bacterial pathogens while sequencing is still in progress. Along with advantages such as low costs and portability, the approach suggested here might democratize modern bacterial typing, enabling more efficient infection control globally.

Emergence and spread of MT28 ptxP3 allele macrolide-resistant Bordetella pertussis from 2021 to 2022 in China

OBJECTIVES

To reveal the clinical and molecular characteristics of Bordetella pertussis (BP) prevalent in Shanghai, China.

METHODS

A total of 9430 children with suspected pertussis from 2021 to 2022 were included, and nasopharyngeal swab samples were collected for polymerase chain reaction detection, culture, antimicrobial susceptibility testing, and 23S rRNA gene A2047G detection. BP strains were typed using multilocus variable-number tandem-repeat analysis and virulence genotyping.

RESULTS

Of 9430 cases, 5.1% and 1.6% were confirmed by polymerase chain reaction and culture, respectively. Infants (aged <1 year) accounted for 24.7% and presented much more severe symptoms than noninfants. Pertussis was most frequently detected in infants aged 0-6 months (11.3∼14.0%) and children aged >6-10 years (10.8∼21.7%). Macrolide-resistant BP (MRBP) accounted for 89.3%, and all carried the A2047G mutation. There were six multilocus variable-number tandem-repeat analysis types (MTs), including MT28 (62.0%), MT195 (20%), MT27 (10.0%), MT104 (4.7%), MT55 (2.7%), and MT32 (0.7%). BP strains with pertussis toxin (ptx)P3/(pertactin) prn2/ptxC2/ptxA1/(fimbrial proteins) fim2-1/fim3-1, including MT27, MT28, and MT32, accounted for 72.7%, among which MT27 and MT32 were macrolide-sensitive BP, whereas most (94.6∼100%) of MT28 were MRBP. Strains harboring ptxP1/prn1/ptxC1/ptxA1/fim2-1/fim3-1, including MT55, MT104, and MT195, belonged to macrolide-sensitive BP.

CONCLUSION

The emergence and spread of MT28 ptxP3-MRBP was first reported in China, highlighting the importance of continuous surveillance of ptxP3-MRBP to prevent its potential circulation.

Genomic dissection of the microevolution of Australian epidemic Bordetella pertussis

Whooping cough (pertussis) is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis. Despite high vaccine coverage, pertussis has re-emerged in many countries including Australia and caused two large epidemics in Australia since 2007. Here, we undertook a genomic and phylogeographic study of 385 Australian B. pertussis isolates collected from 2008 to 2017. The Australian B. pertussis population was found to be composed of mostly ptxP3 strains carrying different fim3 alleles, with ptxP3-fim3A genotype expanding far more than ptxP3-fim3B. Within the former, there were six co-circulating epidemic lineages (EL1 to EL6). The multiple ELs emerged, expanded, and then declined at different time points over the two epidemics. In population genetics terms, both hard and soft selective sweeps through vaccine selection pressures have determined the population dynamics of Australian B. pertussis. Relative risk estimation suggests that once a new B. pertussis lineage emerged, it was more likely to spread locally within the first 1.5 years. However, after 1.5 years, any new lineage was likely to expand to a wider region. Phylogenetic analysis revealed the expansion of ptxP3 strains was also associated with replacement of the type III secretion system allele bscI1 with bscI3. bscI3 is associated with decreased T3SS secretion and may allow B. pertussis to reduce immune recognition. This study advanced our understanding of the epidemic population structure and spatial and temporal dynamics of B. pertussis in a highly immunized population.

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.

Genomic and transcriptomic variation in Bordetella spp. following induction of erythromycin resistance

Background

The emergence of macrolide resistance in Bordetella pertussis, the causative agent of pertussis, due to mutations in the 23S rRNA gene has been recently recognized. However, resistance mechanisms to macrolides in Bordetella parapertussis and Bordetella holmesii remain unknown.

Objectives

This study investigated genomic changes induced by in vitro exposure to erythromycin in these three main pathogens responsible for pertussis-like disease.

Methods

A set of 10 clinical and reference strains of B. pertussis, B. parapertussis and B. holmesii was exposed to erythromycin for 15 weeks or 30 subculture passages. Antibiotic pressure was achieved by growth on the selective media with erythromycin Etest strips or impregnated discs. Genome polymorphisms and transcriptomic profiles were examined by short- and long-read sequencing of passaged isolates.

Results

B. parapertussis and B. holmesii isolates developed significant in vitro resistance to erythromycin (MIC >256 mg/L) within 2 to 7 weeks and at 5 to 12 weeks, respectively. B. pertussis remained phenotypically susceptible to the antibiotic following 15 weeks of exposure, with the MIC between 0.032 to 0.38 mg/L. Genomic analysis revealed that B. holmesii developed resistance due to mutations in the 23S rRNA gene. The resistance mechanism in B. parapertussis was hypothesized as being due to upregulation of an efflux pump mechanism.

Conclusions

These findings indicate that both B. holmesii and B. parapertussis can be more prone to induced resistance following exposure to treatment with erythromycin than B. pertussis. The surveillance of macrolide resistance in Bordetella isolates recovered from patients with pertussis, especially persistent disease, is warranted.

Pertactin-Deficient Bordetella pertussis with Unusual Mechanism of Pertactin Disruption, Spain, 1986-2018

Bordetella pertussis not expressing pertactin has increased in countries using acellular pertussis vaccines (ACV). The deficiency is mostly caused by pertactin gene disruption by IS481. To assess the effect of the transition from whole-cell vaccine to ACV on the emergence of B. pertussis not expressing pertactin in Spain, we studied 342 isolates collected during 1986–2018. We identified 93 pertactin-deficient isolates. All were detected after introduction of ACV and represented 38% of isolates collected during the ACV period; 58.1% belonged to a genetic cluster of isolates carrying the unusual prn::del(–292, 1340) mutation. Pertactin inactivation by IS481 insertion was identified in 23.7% of pertactin-deficient isolates, arising independently multiple times and in different phylogenetic branches. Our findings support the emergence and dissemination of a cluster of B. pertussis with an infrequent mechanism of pertactin disruption in Spain, probably resulting from introduction of ACV.

Can vaccines control bacterial virulence and pathogenicity? Bordetella pertussis: the advantage of fitness over virulence

Some vaccines, such as diphtheria toxoid and acellular pertussis vaccines (aPVs), may favor the emergence of less pathogenic strains of the respective bacteria they target. This review discusses the impact of the wide use of aPV on Bordetella pertussis phenotype evolutions and their beneficial consequences in the light of the diphtheria toxoid immunization program experience and structuring evidence review in a causal analysis following Bradford Hill’s causality criteria. All aPVs contain the pertussis toxin (PT), the main virulence factor of B.pertussis, alone or with one adhesin (filamentous hemagglutinin (FHA)), two adhesins (FHA and pertactin (PRN)) or four adhesins (FHA, PRN and two fimbriae (Fim 2/3)). In countries where the coverage of aPVs containing PRN is high, PRN negative B.pertussis isolates are increasing in prevalence, but isolates nonproducing the other antigens are rarely reported. We hypothesize that the selective pressure at play with PRN should exist against all aVP antigens, although detection biases may hinder its detection for other antigens, especially PT. PT being responsible for clinically frank cases of the disease, the opportunity to collect PT negative isolates is far lower than to collect PRN negative isolates which have a limited clinical impact. The replacement of the current B.pertussis by far less pathogenic isolates no longer producing the factors contained in aPVs should be expected as a consequence of the wide aPV use.

Fha Deficient Bordetella pertussis Isolates in Iran with 50 Years Whole Cell Pertussis Vaccination

Background:

Bordetella pertussis, a highly contagious respiratory. Notably, the resurgence of pertussis has recently been associated with the lacking production of vaccine virulence factors. This study aimed to screen pertactin (Prn) and filamentous hemagglutinin (Fha) production in Iran with 50 years’ whole cell vaccine (WCV) immunization program.

Methods:

Overall, 130 B. pertussis isolates collected from Pertussis Reference Laboratory of Iran during 2005–2018. Real-time PCR was performed by targeting IS481, ptxP, IS1001 and IS1002 for species confirmation of B. pertussis. Western-blot was used to evaluate the expression of virulence factors (pertactin and filamentous hemagglutinin).

Results:

All tested B. pertussis isolates expressed Prn and all except two isolates expressed Fha. We have sequenced genomes of these strains and identified differences compared with genome reference B. pertussis Tohama I.

Conclusion:

Many countries reporting Prn and Fha-deficiency due to acellular vaccine (ACV) pressure. Our results demonstrate in a country with WCV history, Fha-deficient isolates may rise independently. However, Prn-deficient isolates are more under the ACV pressure in B. pertussis isolates. Continues surveillance will provide a better understanding of the effect of WCV on the evolution of the pathogen deficiency.

Evolution of Bordetella pertussis over a 23-year period in France, 1996 to 2018

BackgroundBordetella pertussis is the main agent of whooping cough. Vaccination with acellular pertussis vaccines has been largely implemented in high-income countries. These vaccines contain 1 to 5 antigens: pertussis toxin (PT), filamentous haemagglutinin (FHA), pertactin (PRN) and/or fimbrial proteins (FIM2 and FIM3). Monitoring the emergence of B. pertussis isolates that might partially escape vaccine-induced immunity is an essential component of public health strategies to control whooping cough.AimWe aimed to investigate temporal trends of fimbriae serotypes and vaccine antigen-expression in B. pertussis over a 23-year period in France (1996-2018).MethodsIsolates (n = 2,280) were collected through hospital surveillance, capturing one third of hospitalised paediatric pertussis cases. We assayed PT, FHA and PRN production by Western blot (n = 1,428) and fimbriae production by serotyping (n = 1,058). Molecular events underlying antigen deficiency were investigated by genomic sequencing.ResultsThe proportion of PRN-deficient B. pertussis isolates has increased steadily from 0% (0/38) in 2003 to 48.4% (31/64) in 2018 (chi-squared test for trend, p < 0.0001), whereas only 5 PT-, 5 FHA- and 9 FIM-deficient isolates were found. Impairment of PRN production was predominantly due to IS481 insertion within the prn gene or a 22 kb genomic inversion involving the prn promoter sequence, indicative of convergent evolution. FIM2-expressing isolates have emerged since 2011 at the expense of FIM3.ConclusionsB. pertussis is evolving through the rapid increase of PRN-deficient isolates and a recent shift from FIM3 to FIM2 expression. Excluding PRN, the loss of vaccine antigen expression by circulating B. pertussis isolates is epidemiologically insignificant.

Isolate-Based Surveillance of Bordetella pertussis, Austria, 2018-2020

Pertussis is a vaccine-preventable disease, and its recent resurgence might be attributable to the emergence of strains that differ genetically from the vaccine strain. We describe a novel pertussis isolate-based surveillance system and a core genome multilocus sequence typing scheme to assess Bordetella pertussis genetic variability and investigate the increased incidence of pertussis in Austria. During 2018–2020, we obtained 123 B. pertussis isolates and typed them with the new scheme (2,983 targets and preliminary cluster threshold of <6 alleles). B. pertussis isolates in Austria differed genetically from the vaccine strain, both in their core genomes and in their vaccine antigen genes; 31.7% of the isolates were pertactin-deficient. We detected 8 clusters, 1 of them with pertactin-deficient isolates and possibly part of a local outbreak. National expansion of the isolate-based surveillance system is needed to implement pertussis-control strategies.

Evolutionary genomics of recent clinical Bordetella pertussis isolates from Iran: wide circulation of multiple ptxP3 lineages and report of the first ptxP3 filamentous hemagglutinin-negative B. pertussis

Here we investigated nationwide clinical Bordetella pertussis isolated during 2005-2017 from different provinces of Iran, a country with more than 50 years whole cell vaccine immunisation history. Our results revealed the ongoing increase in the population of ptxP3/fim3-2 B. pertussis isolates in different provinces which were differentiated into nine clades. The largest clade (clade 8) which was previously found to be prevalent in Tehran was also prevalent across the country and clade 5 with ptxP3/prn9 genotype has also increased in frequency (14% of all ptxP3 isolates) in recent years. Furthermore, we detected the first ptxP3 B. pertussis isolates that does not express filamentous hemagglutinin (FhaB) as one of the major antigens of the pathogen and a key component of the acellular pertussis vaccine.

Comparative Phosphoproteomics of Classical Bordetellae Elucidates the Potential Role of Serine, Threonine and Tyrosine Phosphorylation in Bordetella Biology and Virulence

The Bordetella genus is divided into two groups: classical and non-classical. Bordetella pertussis, Bordetella bronchiseptica and Bordetella parapertussis are known as classical bordetellae, a group of important human pathogens causing whooping cough or whooping cough-like disease and hypothesized to have evolved from environmental non-classical bordetellae. Bordetella infections have increased globally driving the need to better understand these pathogens for the development of new treatments and vaccines. One unexplored component in Bordetella is the role of serine, threonine and tyrosine phosphorylation. Therefore, this study characterized the phosphoproteome of classical bordetellae and examined its potential role in Bordetella biology and virulence. Applying strict identification of localization criteria, this study identified 70 unique phosphorylated proteins in the classical bordetellae group with a high degree of conservation. Phosphorylation was a key regulator of Bordetella metabolism with proteins involved in gluconeogenesis, TCA cycle, amino acid and nucleotide synthesis significantly enriched. Three key virulence pathways were also phosphorylated including type III secretion system, alcaligin synthesis and the BvgAS master transcriptional regulatory system for virulence genes in Bordetella. Seven new phosphosites were identified in BvgA with 6 located in the DNA binding domain. Of the 7, 4 were not present in non-classical bordetellae. This suggests that serine/threonine phosphorylation may play an important role in stabilizing/destabilizing BvgA binding to DNA for fine-tuning of virulence gene expression and that BvgA phosphorylation may be an important factor separating classical from non-classical bordetellae. This study provides the first insight into the phosphoproteome of classical Bordetella species and the role that Ser/Thr/Tyr phosphorylation may play in Bordetella biology and virulence.

Live attenuated pertussis vaccine BPZE1 induces a broad antibody response in humans

BACKGROUNDThe live attenuated BPZE1 vaccine candidate induces protection against B. pertussis and prevents nasal colonization in animal models. Here we report on the responses in humans receiving a single intranasal administration of BPZE1.METHODSWe performed multiple assays to dissect the immune responses induced in humans (n = 12) receiving BPZE1, with particular emphasis on the magnitude and characteristics of the antibody responses. Such responses were benchmarked to adolescents (n = 12) receiving the complete vaccination program of the currently used acellular pertussis vaccine (aPV). Using immunoproteomics analysis, potentially novel immunogenic B. pertussis antigens were identified.RESULTSAll BPZE1 vaccinees showed robust B. pertussis-specific antibody responses with regard to significant increase in 1 or more of the following parameters: IgG, IgA, and memory B cells to B. pertussis antigens. BPZE1-specific T cells showed a Th1 phenotype, and the IgG exclusively consisted of IgG1 and IgG3. In contrast, all aPV vaccines showed a Th2-biased response. Immunoproteomics profiling revealed that BPZE1 elicited broader and different antibody specificities to B. pertussis antigens as compared with the aPV that primarily induced antibodies to the vaccine antigens. Moreover, BPZE1 was superior at inducing opsonizing antibodies that stimulated ROS production in neutrophils and enhanced bactericidal function, which was in line with the finding that antibodies against adenylate cyclase toxin were only elicited by BPZE1.CONCLUSIONThe breadth of the antibodies, the Th1-type cellular response, and killing mechanisms elicited by BPZE1 may hold prospects of improving vaccine efficacy and protection against B. pertussis transmission.TRIAL REGISTRATIONClinicalTrials.gov NCT02453048, NCT00870350.FUNDINGILiAD Biotechnologies, Swedish Research Council (Vetenskapsrådet), Swedish Heart-Lung Foundation.

Analysis of antibiotic sensitivity and resistance genes of Bordetella pertussis in Chinese children

OBJECTIVE

To understood the pathogen detection status and clinical characteristics of suspected pertussis in children and to observe the drug sensitivity and drug resistance genes of Bordetella pertussis (B. pertussis).

METHODS

Three hundred fifty-one cases were collected and their nasopharyngeal swab samples were analyzed by culture and fluorescent quantitative polymerase chain reaction. The susceptibility to erythromycin, clindamycin, ampicillin, levofloxacin, and sulfamethoxazole-trimethoprim were tested by E-test for the positive strains, and the susceptibility to erythromycin was also tested for the KB disk diffusion method. The 23S rRNA gene of the positive strains was amplified and sequenced, and statistical analysis was performed in conjunction with clinical data.

RESULTS

The positive rate of bacterial culture was 16.8% (59/351), and the positive rate of PCR was 62.4% (219/351). Two cases were positive about bacterial culture and negative for PCR. There were 221 confirmed cases of pertussis. The E-test results showed that the rate of the sensitivity of the 55 strains of pertussis to erythromycin and clindamycin was 50.9% (28/55), the minimum antibiotic concentration50 (MIC50) and MIC90 values were 0.094/>256 and 0.75/>256 mg/L, respectively, and the MIC50/MIC90 to ampicillin, levofloxacin, and sulfamethoxazole were 0.125/0.19, 0.38/0.5, and 0.125/0.25 mg/L, respectively. The KB disk diffusion method showed 27 of the 55 strains 49.1% (27/55) was resistant to erythromycin; all of the resistant strains had the 23S rRNA gene A2047G mutation, and their MIC of erythromycin was >256 mg/L.

CONCLUSION

The diagnosis of pertussis by a fluorescent quantitative polymerase chain reaction method is more sensitive than that of bacterial culture. The resistance of B. pertussis to erythromycin was prominent. All of the strains of B. pertussis resistant to erythromycin in our center had the A2047G mutation of the 23S rRNA gene.

The Role of Virulence Proteins in Protection Conferred by Bordetella pertussis Outer Membrane Vesicle Vaccines

The limited protective immunity induced by acellular pertussis vaccines demands development of novel vaccines that induce broader and longer-lived immunity. In this study, we investigated the protective capacity of outer membrane vesicle pertussis vaccines (omvPV) with different antigenic composition in mice to gain insight into which antigens contribute to protection. We showed that total depletion of virulence factors (bvg(-) mode) in omvPV led to diminished protection despite the presence of high antibody levels. Antibody profiling revealed overlap in humoral responses induced by vaccines in bvg(-) and bvg(+) mode, but the potentially protective responses in the bvg(+) vaccine were mainly directed against virulence-associated outer membrane proteins (virOMPs) such as BrkA and Vag8. However, deletion of either BrkA or Vag8 in our outer membrane vesicle vaccines did not affect the level of protection. In addition, the vaccine-induced immunity profile, which encompasses broad antibody and mixed T-helper 1, 2 and 17 responses, was not changed. We conclude that the presence of multiple virOMPs in omvPV is crucial for protection against Bordetella pertussis. This protective immunity does not depend on individual proteins, as their absence or low abundance can be compensated for by other virOMPs.

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.

Surfaceome analysis of Australian epidemic Bordetella pertussis reveals potential vaccine antigens

Since acellular vaccines (ACV) were introduced in Australia, epidemic Bordetella pertussis strains changed from single nucleotide polymorphism (SNP) cluster II to SNP cluster I. Our previous proteomic analysis identified potential proteomic adaptations in the whole cell and secretome of SNP cluster I. Additionally, current ACVs were shown to be less efficacious against cluster I in mice models and there is a pressing need to discover new antigens to improve the ACV. One important source of novel antigens is the surfaceome. Therefore, in this study we established surface shaving in B. pertussis to compare the surfaceome of SNP cluster I (L1423) and II (L1191), and identify novel surface antigens for vaccine development. Surface shaving using 1 μg of trypsin for 5 min identified 126 proteins with the most abundant being virulence-associated and known outer membrane proteins. Cell viability counts showed minimal lysis from shaving. The proportion of immunogenic proteins was higher in the surfaceome than in the whole cell and secretome. Key differences in the surfaceome were identified between SNP cluster I and II, consistent with those identified in the whole cell proteome and secretome. These differences include unique transport proteins and decreased immunogenic proteins in L1423, and provides further evidence of proteomic adaptation in SNP cluster I. Finally, a comparison of proteins in each sub-proteome identified 22 common proteins. These included 11 virulence proteins (Prn, PtxA, FhaB, CyaA, TcfA, SphB1, Vag8, BrkA, BopD, Bsp22 and BipA) and 11 housekeeping proteins (TuF, CtpA, TsF, OmpH, GltA, SucC, SucD, FusA, GroEL, BP3330 and BP3561) which were immunogenic, essential and consistently expressed thus demonstrating their potential as future targets. This study established surface shaving in B. pertussis, confirmed key expression differences and identified unknown surface proteins which may be potential vaccine antigens.