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.

Antibodies binding diverse pertactin epitopes protect mice from Bordetella pertussis infection.

Infection by the bacterium Bordetella pertussis continues to cause considerable morbidity and mortality worldwide. Many current acellular pertussis vaccines include the antigen pertactin, which has presumptive adhesive and immunomodulatory activities, but is rapidly lost from clinical isolates after the introduction of these vaccines. To better understand the contributions of pertactin antibodies to protection and pertactin's role in pathogenesis, we isolated and characterized recombinant antibodies binding four distinct epitopes on pertactin. We demonstrate that four of these antibodies bind epitopes that are conserved across all three classical Bordetella strains, and competition assays further showed that antibodies binding these epitopes are also elicited by B. pertussis infection of baboons. Surprisingly, we found that representative antibodies binding each epitope protected mice against experimental B. pertussis infection. A cocktail of antibodies from each epitope group protected mice against a subsequent lethal dose of B. pertussis and greatly reduced lung colonization levels after sublethal challenge. Each antibody reduced B. pertussis lung colonization levels up to 100-fold when administered individually, which was significantly reduced when antibody effector functions were impaired, with no antibody mediating antibody-dependent complement-induced lysis. These data suggest that antibodies binding multiple pertactin epitopes protect primarily by the same bactericidal mechanism, which overshadows contributions from blockade of other pertactin functions. These antibodies expand the available tools to further dissect pertactin's role in infection and understand the impact of antipertactin antibodies on bacterial fitness.

Immunogenicity of a new enhanced tetanus-reduced dose diphtheria-acellular pertussis (Tdap) vaccine against Bordetella pertussis in a murine model.

BACKGROUND: The necessity of the tetanus-reduced dose diphtheria-acellular pertussis (Tdap) vaccine in adolescence and adults has been emphasized since the resurgence of small-scale pertussis in Korea and worldwide due to the waning effect of the vaccine and variant pathogenic stains in the late 1990s. GreenCross Pharma (GC Pharma), a Korean company, developed the Tdap vaccine GC3111 in 2010. Recently, they enhanced the vaccine, GC3111, produced previously in 2010 to reinforce the antibody response against filamentous hemagglutinin (FHA). In this study, immunogenicity and efficacy of the enhanced Tdap vaccine compared and evaluated with two Tdap vaccines, GC3111 vaccine produced in 2010 previously and commercially available Tdap vaccine in a murine model. METHODS: Two tests groups and positive control group of Balb/c mice were primed with two doses of the diphtheria-tetanus-acellular pertussis (DTaP) vaccine followed by a single booster Tdap vaccine at 9 week using the commercially available Tdap vaccine or 2 Tdap vaccines from GC Pharma (GC3111, enhanced GC3111). Humoral response was assessed 1 week before and 2 and 4 weeks after Tdap booster vaccination. The enhanced GC3111 generated similar humoral response compare to the commercial vaccine for filamentous hemagglutinin (FHA). The interferon gamma (IFN-γ) (Th1), interleukin 5 (IL-5) (Th2) and interleukin 17 (IL-17) (Th17) cytokines were assessed 4 weeks after booster vaccination by stimulation with three simulators: heat inactivated Bordetella pertussis (hBp), vaccine antigens, and hBp mixed with antigens (hBp + antigen). A bacterial challenge test was performed 4 weeks after booster vaccination. RESULTS: Regarding cell-mediated immunity, cytokine secretion differed among the three simulators. However, no difference was found between two test groups and positive control group. All the vaccinated groups indicated a Th1 or Th1/Th2 response. On Day 5 post-bacterial challenge, B. pertussis colonies were absent in the lungs in two test groups and positive control group. CONCLUSIONS: Our results confirmed the immunogenicity of GC Pharma's Tdap vaccine; enhanced GC3111 was equivalent to the presently used commercial vaccine in terms of humoral response as well as cell-mediated cytokine expression.

Structural basis for antibody binding to adenylate cyclase toxin reveals RTX linkers as neutralization-sensitive epitopes.

RTX leukotoxins are a diverse family of prokaryotic virulence factors that are secreted by the type 1 secretion system (T1SS) and target leukocytes to subvert host defenses. T1SS substrates all contain a C-terminal RTX domain that mediates recruitment to the T1SS and drives secretion via a Brownian ratchet mechanism. Neutralizing antibodies against the Bordetella pertussis adenylate cyclase toxin, an RTX leukotoxin essential for B. pertussis colonization, have been shown to target the RTX domain and prevent binding to the αMß2 integrin receptor. Knowledge of the mechanisms by which antibodies bind and neutralize RTX leukotoxins is required to inform structure-based design of bacterial vaccines, however, no structural data are available for antibody binding to any T1SS substrate. Here, we determine the crystal structure of an engineered RTX domain fragment containing the αMß2-binding site bound to two neutralizing antibodies. Notably, the receptor-blocking antibodies bind to the linker regions of RTX blocks I-III, suggesting they are key neutralization-sensitive sites within the RTX domain and are likely involved in binding the αMß2 receptor. As the engineered RTX fragment contained these key epitopes, we assessed its immunogenicity in mice and showed that it elicits similar neutralizing antibody titers to the full RTX domain. The results from these studies will support the development of bacterial vaccines targeting RTX leukotoxins, as well as next-generation B. pertussis vaccines.

Does Bordetella pertussis vaccine offer any cross-protection against Bordetella bronchiseptica? Implications for pet owners with cystic fibrosis.

WHAT IS KNOWN AND OBJECTIVE: The Gram-negative bacterium, Bordetella bronchiseptica, causes lower airway respiratory disease in people with cystic fibrosis (CF), as well as in companion animals, especially dogs. Presently, there are several acellular vaccines available for B. pertussis but no vaccine available for B. bronchiseptica. However given the shared protein homology between these two closely related species, we wished to explore whether pertussis vaccines may offer some cross-protection against B. bronchiseptica. COMMENT: Bordetella pertussis and B. bronchiseptica are closely related phylogenetically, as well as sharing protein homology in several pertussis vaccine components, including (i) pertussis toxin (PT), (ii) filamentous haemagglutinin (FHA), (iii) pertactin and (iv) fimbriae (types 2 and 3). Given that pertussis vaccine contains cross-reactive antigens with B. bronchiseptica, licensed pertussis vaccines may therefore offer cross-protection against B. bronchiseptica. WHAT IS NEW AND CONCLUSION: Cystic fibrosis pet owners should ensure that they have an up-to-date vaccination record relating to their pertussis vaccine. Although no monovalent human pertussis vaccines are currently available, licensed non-live booster vaccines for B. pertussis are available for individuals in the age range >10 years old. People with CF should ensure that they are adequately and currently protected against pertussis, to avoid whooping cough, which may also offer some cross-protection against B. bronchiseptica and therefore help further mitigate the risk of zoonotic infection of this organism from pets to their owners.

Tracheal colonization factor A (TcfA) is a biomarker for rapid and specific detection of Bordetella pertussis.

Pertussis is a highly contagious disease for which prompt, point-of-care diagnosis remains an unmet clinical need. Results from conventional test modalities (nucleic acid detection, serology, and culture) take hours to days. To overcome this challenge, we identified a new biomarker (tracheal colonization factor A, TcfA) for detection of Bordetella pertussis infection by lateral flow immunoassay (LFIA). We developed a library of 28 epitope-mapped monoclonal antibodies against TcfA and incorporated three antibodies into a LFIA. The LFIA did not cross-react with common bacterial or fungal organisms, but did react with nine distinct B. pertussis strains. The minimal linear epitope sequences targeted by the LFIA were conserved in 98% of 954 B. pertussis isolates collected across 12 countries from 1949-2017. The LFIA's limit of detection was 3.0 × 105 CFU/mL with B. pertussis cells in buffer, 6.2 × 105 CFU/mL with nasopharyngeal washes from a non-human primate model, and 2.3 ng/mL with recombinant TcfA. The LFIA reacted with patient nasopharyngeal swab specimens containing as few as 1.8 × 106 B. pertussis genomes/mL and showed no false-positives. Rapid (< 20 min) LFIA detection of TcfA as a biomarker for B. pertussis infection is feasible and may facilitate early detection of pertussis.

Anti-FIM and Anti-FHA Antibodies Inhibit Bordetella pertussis Growth and Reduce Epithelial Cell Inflammation Through Bacterial Aggregation.

The pertussis vaccination is highly recommended for infants, children, and pregnant women. Despite a high coverage of vaccination, pertussis continues to be of public health concern as a re-emerging infectious disease. The mechanism by which vaccine-elicited anti-pertussis antibodies mediate direct bactericidal effects is poorly understood. In this study, we showed that the interaction of B. pertussis with A549 epithelial cells induce release of biological factors which enhance bacteria growth. Complement-depleted antisera from vaccine-immunized guinea pigs or monoclonal antibodies targeting FHA and FIM mediate bacteria aggregation and elicit bactericidal effects. Our in vitro results indicated that aggregation of bacteria through anti-FIM and anti-FHA specific antibodies is one of the major biological mechanisms to clear bacterial infections and restore epithelial cell survival in vitro. Our data also indicates that the anti-pertussis antibodies reduce secretion of proinflammatory chemokines and cytokines by preventing interaction of B. pertussis with host cells. The results of this study not only demonstrate mechanism of action of anti-FIM and anti-FHA antibodies, but also opens translational applications for potential therapeutic approaches or development of analytical assays such as in vitro potency assays.

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.

Population dynamics and antigenic drift of Bordetella pertussis following whole cell vaccine replacement, Barcelona, Spain, 1986-2015.

Among the factors associated with the resurgence of whooping cough, special emphasis has been given to pathogen adaptation after the introduction of the acellular vaccine (ACV). To assess the impact of the vaccine transition strategy from whole-cell vaccine (WCV) to ACV on population dynamics of Bordetella pertussis in Barcelona (Spain), we studied 339 isolates collected from 1986 to 2015 by PFGE and multi-locus variable-number tandem repeat analysis (MLVA). Additionally, allelic variants for the pertussis toxin and its promoter, pertactin, type 3 fimbriae and fimbrial serotyping were assessed to determine its antigenic drift. A shift was observed in the B. pertussis population as well as in its antigenic profile concurrently with the introduction of ACV in Barcelona. Four out of the five most prevalent PFGE profiles were replaced by new profiles following the ACV introduction. MLVA type 27 was the dominant genotype, and its frequency increased from 25% to 79.3% after WCV replacement. Antigen typing demonstrated the emergence of prn2, ptxP3, fim3-2 and a shift from the fimbriae 3 to the fimbriae 2 serotypes after the ACV introduction. Our findings support the presence of population and antigenic dynamic changes in B. pertussis likely driven by the introduction of ACV.

Rare Detection of Bordetella pertussis Pertactin-Deficient Strains in Argentina.

Pertussis resurgence had been attributed to waning vaccine immunity and Bordetella pertussis adaptation to escape vaccine-induced immunity. Circulating bacteria differ genotypically from strains used in production of pertussis vaccine. Pertactin-deficient strains are highly prevalent in countries that use acellular vaccine (aP), suggesting strong aP-imposed selection of circulating bacteria. To corroborate this hypothesis, systematic studies on pertactin prevalence of infection in countries using whole-cell vaccine are needed. We provide pertussis epidemiologic data and molecular characterization of B. pertussis isolates from Buenos Aires, Argentina, during 2000-2017. This area used primary vaccination with whole-cell vaccine. Since 2002, pertussis case incidences increased at regular 4-year outbreaks; most cases were in infants <1 year of age. Of the B. pertussis isolates analyzed, 90.6% (317/350) contained the ptxP3-ptxA1-prn2-fim3-2 allelic profile. Immunoblotting and sequencing techniques detected only the 2 pertactin-deficient isolates. The low prevalence of pertactin-deficient strains in Argentina suggests that loss of pertactin gene expression might be driven by aP vaccine.

Superior B. pertussis Specific CD4+ T-Cell Immunity Imprinted by Natural Infection.

Pertussis remains endemic in vaccinated populations due to waning of vaccine-induced immunity and insufficient interruption of transmission. Correlates of long-term protection against whooping cough remain elusive but increasing evidence from experimental models indicates that the priming of particular lineages of B. pertussis (Bp) specific CD4+ T cells is essential to control bacterial load. Critical hallmarks of these protective CD4+ T cell lineages in animals are suggested to be their differentiation profile as Th1 and Th17 cells and their tissue residency. These features seem optimally primed by previous infection but insufficiently or only partially by current vaccines. In this review, evidence is sought indicating whether infection also drives such superior Bp specific CD4+ T cell lineages in humans. We highlight key features of effector immunity downstream of Th1 and Th17 cell cytokines that explain clearing of primary Bp infections in naïve hosts, and effective prevention of infection in convalescent hosts during secondary challenge. Outstanding questions are put forward that need answers before correlates of human Bp infection-primed CD4+ T cell immunity can be used as benchmark for the development of improved pertussis vaccines.

Vaccine acquired pertussis immunity was weakened at 4 years of age and asymptomatic pertussis infection was suspected based on serological surveillance.

Serological surveillance of pertussis antibodies was performed in 118 children aged 1-12 years. The positivity of pertussis toxin (PT) antibodies was low at 4-6 years and significantly higher at 8-9 years, compared with those at 6 years. Fimbriae 2 (Fim2) antibody showed similar response to the PT antibody. Higher antibody titers against Fim3 were observed among subjects ≥5 years and highest at 8 years. Data demonstrated that the vaccine-induced antibodies decayed by 4-5 years and subclinical pertussis infection was suspected thereafter, suggesting the need for additional dose at around 4-5 years.

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

During the 2008-2012 pertussis epidemic in Australia, pertactin (Prn)-negative Bordetella pertussis emerged. We analyzed 78 isolates from the 2013-2017 epidemic and documented continued expansion of Prn-negative ptxP3 B. pertussis strains. We also detected a filamentous hemagglutinin-negative and Prn-negative B. pertussis isolate.

Pertactin-deficient Bordetella pertussis isolates: evidence of increased circulation in Europe, 1998 to 2015.

IntroductionPertussis outbreaks have occurred in several industrialised countries using acellular pertussis vaccines (ACVs) since the 1990s. High prevalence of pertactin (PRN)-deficient Bordetella pertussis isolates has been found in these countries.AimsTo evaluate in Europe: (i) whether proportions of PRN-deficient strains increased in consecutive collections of B. pertussis clinical isolates; (ii) if the frequency of PRN-deficient strains in countries correlated with the time since ACV introduction; (iii) the presence of pertussis toxin (PT)-, filamentous haemagglutinin (FHA)- or fimbriae (Fim)-deficient isolates.MethodsB. pertussis clinical isolates were obtained from different European countries during four periods (EUpert I-IV studies): 1998 to 2001 (n = 102), 2004 to 2005 (n = 154), 2007 to 2009 (n = 140) and 2012 to 2015 (n = 265). The isolates' selection criteria remained unchanged in all periods. PRN, PT, FHA and Fim2 and Fim3 expression were assessed by ELISA.ResultsIn each period 1.0% (1/102), 1.9% (3/154), 6.4% (9/140) and 24.9% (66/265) of isolates were PRN-deficient. In EUpert IV, PRN-deficient isolates occurred in all countries sampled and in six countries their frequency was higher than in EUpert III (for Sweden and the United Kingdom, p < 0.0001 and p = 0.0155, respectively). Sweden and Italy which used ACVs since the mid 1990s had the highest frequencies (69%; 20/29 and 55%; 11/20, respectively) while Finland, where primary immunisations with ACV containing PRN dated from 2009 had the lowest (3.6%). Throughout the study, no PT- or FHA-deficient isolate and one Fim2/3-deficient was detected.ConclusionResults suggest that the longer the period since the introduction of ACVs containing PRN, the higher the frequency of circulating PRN-deficient isolates.

Boosting Teenagers With Acellular Pertussis Vaccines Containing Recombinant or Chemically Inactivated Pertussis Toxin: A Randomized Clinical Trial.

BACKGROUND: Protection induced by acellular pertussis (aP) vaccines is partial and short-lived, especially in teenagers, calling for novel immunization strategies. METHODS: We conducted an investigator-driven proof-of-concept randomized controlled trial in aP-primed adolescents in Geneva to assess the immunogenicity and reactogenicity of a novel recombinant aP (r-aP) vaccine including recombinant pertussis toxin (PT) and filamentous hemagglutinin (FHA) coadministered with tetanus-diphtheria toxoids (Td), compared to a licensed tetanus-diphtheria-aP vaccine containing chemically detoxified PT (cd/Tdap). The primary immunological endpoints were day 28/365 geometric mean concentrations (GMCs) of total and neutralizing anti-PT antibodies. Memory B cells were assessed. RESULTS: Sixty-two aP-primed adolescents were randomized and vaccinated with r-aP + Td or cd/Tdap. Reactogenicity, adverse events, and baseline GMCs were similar between the groups. Day 28 PT-neutralizing GMCs were low after cd/Tdap (73.91 [95% confidence interval {CI}, 49.88-109.52] IU/mL) and approximately 2-fold higher after r-aP + Td (127.68 [95% CI, 96.73-168.53] IU/mL; P = .0162). Anti-PT GMCs were also low after cd/Tdap (52.43 [95% CI, 36.41-75.50] IU/mL) and 2-fold higher after r-aP + Td (113.74 [95% CI, 88.31-146.50] IU/mL; P = .0006). Day 28 anti-FHA GMCs were similar in both groups. Day 365 anti-PT (but not PT-neutralizing) GMCs remained higher in r-aP + Td vaccinees. PT-specific memory B cells increased significantly after r-aP + Td but not cd/Tdap boosting. CONCLUSIONS: Boosting aP-primed adolescents with r-aP induced higher anti-PT and PT-neutralizing responses than cd/Tdap and increased PT-specific memory B cells. Despite this superior immunogenicity, r-aP may have to be given repeatedly, earlier, and/or with novel adjuvants to exert an optimal influence in aP-primed subjects. CLINICAL TRIALS REGISTRATION: NCT02946190.

Randomized Controlled Trial of the Safety and Immunogenicity of Revaccination With Tetanus-Diphtheria-Acellular Pertussis Vaccine (Tdap) in Adults 10 Years After a Previous Dose.

BACKGROUND: Reduced-antigen-content tetanus, diphtheria, and acellular pertussis (Tdap) vaccine is recommended in many countries for boosting immunity in adolescents and adults. Although immunity to these antigens wanes with time, currently available Tdap products are not labeled for repeat administration in the United States. METHODS: We performed an observer-blinded, randomized controlled trial in 1330 adults aged 18 to <65 years who received either the Tdap (n = 1002) or tetanus-diphtheria (Td) (n = 328) vaccine 8 to 12 years after a dose of Tdap vaccine administered previously. Solicited adverse events following immunization were documented for 7 days after vaccination, and serious adverse events and adverse events of medical significance were documented for 6 months after vaccination. Levels of antibodies against component vaccine antigens were measured before and 1 month after vaccination. RESULTS: A solicited adverse event was reported by 87.7% of Tdap and 88.0% of Td vaccine recipients. We found no significant differences in the rates of injection-site reactions, systemic reactions, or serious adverse events between the vaccine groups. A robust antibody response to each pertussis antigen in the Tdap-vaccinated group was found; postvaccination-to-prevaccination geometric mean antibody concentration ratios were 8:1 (pertussis toxoid), 5.9 (filamentous hemagglutinin), 6.4 (pertactin), and 5.2 (fimbriae 2 and 3). Postvaccination geometric mean concentrations of tetanus antibody (4.20 and 4.74 IU/mL, respectively) and diphtheria antibody (10.1 and 12.6 IU/mL, respectively) were similar in the Tdap and Td groups, and the rates of seroprotection against tetanus and diphtheria were >99% in both groups. CONCLUSIONS: A second dose of Tdap vaccine in adults approximately 10 years after a previous dose was well tolerated and immunogenic. These data might facilitate consideration of providing Tdap booster doses to adults.

Probiotics and the immunological response to infant vaccinations; a double-blind randomized controlled trial.

OBJECTIVES: To examine the effect of a combination of probiotics on the antibody response to pneumococcal and pertussis vaccination in healthy Danish children, aged 8-14 months, at the time of starting day care. Moreover, the cytokine response to lipopolysaccharide of whole blood was assessed. METHODS: A total of 290 children were randomly allocated to receive a combination of Bifidobacterium animalis ssp. lactis and Lactobacillus rhamnosus GG daily for a 6-month intervention period, and blood samples were drawn at the start and end of the study. Specific antibody response towards Streptococcus pneumoniae serotypes and Bordetella pertussis toxin, as well as endotoxin-induced interleukin-6 (IL-6) and interferon-γ (IFN-γ) production in blood were analysed by Luminex and ELISA. RESULTS: There was no significant difference between the average individual changes from baseline to end of study in antibody concentrations for S. pneumoniae for both the probiotics (340.4% ± 11.2%) and the placebo group (382.9% ± 10.4%) (p 0.525), nor for B. pertussis toxin in the two groups (probiotics 190.1% ± 12.6% versus placebo 238.8% ± 1.1%, p 0.340). The average individual change in IL-6 concentration was significantly lower in the probiotics versus the placebo group (2.9% ± 10.3% versus 33.7% ± 9.0%, p 0.024), whereas there was no difference in IFN-γ concentration (0.0% ± 0.2% versus -0.2% ± 0.1%, p 0.279). CONCLUSIONS: The probiotic intervention did not affect the antibody response against S. pneumoniae and B. pertussis toxin in healthy Danish children.

Development and validation of a robust multiplex serological assay to quantify antibodies specific to pertussis antigens.

Despite wide spread vaccination, the public health burden of pertussis remains substantial. Current acellular pertussis vaccines comprise upto five Bordetella pertussis (Bp) antigens. Performing an ELISA to quantify antibody for each antigen is laborious and challenging to apply to pediatric samples where serum volume may be limited. We developed a microsphere based multiplex antibody capture assay (MMACA) to quantify antibodies to five pertussis antigens; pertussis toxin, pertactin, filamentous hemagglutinin and fimbrial antigens 2/3, and adenylate cyclase toxin in a single reaction (5-plex) with a calibrated reference standard, QC reagents and SAS® based data analysis program. The goodness of fit (R2) of the standard curves for five analytes was ≥0.99, LLOQ 0.04-0.15 IU or AU/mL, accuracy 1.9%-23.8% (%E), dilutional linearity slopes 0.93-1.02 and regression coefficients r2 = 0.91-0.99. MMACA had acceptable precision within a median CV of 16.0%-22.8%. Critical reagents, antigen conjugated microsphere and reporter antibody exhibited acceptable (<12.3%) lot-lot variation. MMACA can be completed in <3 h, requires low serum volume (5µL/multiplex assay) and has fast data turnaround time (<1 min). MMACA has been successfully developed and validated as a sensitive, specific, robust and rugged method suitable for simultaneous quantification of anti-Bp antibodies in serum, plasma and DBS.

Increasing FIM2/3 antigen-content improves efficacy of Bordetella pertussis vaccines in mice in vivo without altering vaccine-induced human reactogenicity biomarkers in vitro.

Current acellular-pertussis (aP) vaccines appear inadequate for long-term pertussis control because of short-lived efficacy and the increasing prevalence of pertactin-negative isolates which may negatively impact vaccine efficacy. In this study, we added fimbriae (FIM)2 and FIM3 protein to licensed 2-, 3- or 5-component aP vaccines (Pentavac®, Boostrix®, Adacel®, respectively) to assess whether an aP vaccine with enhanced FIM content demonstrates enhanced efficacy. Vaccine-induced protection was assessed in an intranasal mouse challenge model. In addition, potential reactogenicity was measured by biomarkers in a human whole blood assay (WBA) in vitro and benchmarked the responses against licensed whole cell pertussis (wP) and aP vaccines including Easyfive®, Pentavac® and Pentacel®. The results show that commercial vaccines demonstrated reduced efficacy against pertactin-negative versus pertactin-positive strains. However, addition of higher amounts of FIM2/3 to aP vaccines reduced lung colonization and increased vaccine efficacy against a pertactin-negative strain in a dose-dependent manner. Improvements in efficacy were similar for FIM2 and FIM3-expressing strains. Increasing the amount of FIM2/3 proteins in aP formulations did not alter vaccine-induced biomarkers of potential reactogenicity including prostaglandin E2, cytokines and chemokines in human newborn cord and adult peripheral blood tested in vitro. These results suggest that increasing the quantity of FIM proteins in current pertussis vaccine formulations may further enhance vaccine efficacy against B. pertussis infection without increasing the reactogenicity of the vaccine.

Mucosal and systemic immune responses elicited by recombinant Lactococcus lactis expressing a fusion protein composed of pertussis toxin and filamentous hemagglutinin from Bordetella pertussis.

We constructed a food-grade expression system harboring a F1S1 fusion protein of Bordetella pertussis to be produced in Lactococcus lactis NZ3900 as a new oral vaccine model against whooping cough, caused by B. pertussis. F1S1 was composed of N-terminally truncated S1 subunit of pertussis toxin and type I immunodominant domain of filamentous hemagglutinin which are both known as protective immunogens against pertussis. The recombinant L. lactis was administered via oral or intranasal routes to BALB/c mice and the related specific systemic and mucosal immune responses were then evaluated. The results indicated significantly higher levels of specific IgA in the lung extracts and IgG in sera of mucosally-immunized mice, compared to their controls. It was revealed that higher levels of IgG2a, compared to IgG1, were produced in all mucosally-immunized mice. Moreover, immunized mice developed Th1 responses with high levels of IFN-γ production by the spleen cells. These findings provide evidence for L. lactis to be used as a suitable vehicle for expression and delivery of F1S1 fusion protein to mucosa and induction of appropriate systemic and mucosal immune responses against pertussis.