Bordetella pertussis isolates in Finland after acellular vaccination: serotype change and biofilm formation.

OBJECTIVES: In Finland, whole cell pertussis vaccine (wP) was introduced in 1952 and was replaced by acellular pertussis vaccine (aP) without fimbrial (FIM) antigen in 2005. We aimed to analyse the changes in serotypes of circulating Bordetella pertussis before and after acellular vaccination and to explore the relationship between biofilm formation and serotype diversity after the introduction of aP vaccine. METHODS: Serotyping of 1399 B. pertussis isolates collected at the Finnish National Reference Laboratory for Pertussis and Diphtheria in Turku, Finland, from 1974 to 2023 was performed by slide agglutination or indirect ELISA. Of 278 isolates collected after 2005, 53 were selected, genotyped for fim3 and fim2 alleles, and tested for biofilm formation. The selection criteria included maintaining a relatively equal distribution of isolates per time interval, ensuring approximately a 50:50 ratio of FIM2 (N = 26) and FIM3 (N = 27) serotypes. The reference strain Tohama I was used as a control. RESULTS: During the wP era, the majority of circulating B. pertussis exhibited the FIM2 serotype. However, FIM3 strains have appeared since 1999 and become prevalent. After the implementation of aP vaccines, the distribution of serotypes has exhibited substantial variability. FIM3 isolates displayed an enhanced biofilm formation compared to FIM2 isolates (Geometric mean value (95% CI): 0.90 (0.79-1.03) vs. 0.75 (0.65-0.85); p < 0.05). Of the 27 FIM3 isolates, 8 harboured fim3-1 and 19 fim3-2 alleles. FIM3 isolates with fim3-2 allele were significantly associated with increased biofilm formation when compared to those with fim3-1 (1.07 (0.96-1.19) vs. 0.61 (0.52-0.72); p < 0.0001). CONCLUSION: Following the implementation of aP vaccines, the distribution of serotypes in Finland has exhibited substantial variability. FIM3 isolates with the fim3-2 allele displayed an enhanced biofilm formation capability compared to FIM2 isolates.

Pastern dermatitis outbreak associated with toxigenic and non-toxigenic Corynebacterium diphtheriae and non-toxigenic Corynebacterium ulcerans at a horse stable in Finland, 2021.

AIMS: Corynebacterium diphtheriae and Corynebacterium ulcerans, when producing toxin, are the cause of diphtheria, a potentially life-threatening illness in humans. Horses (Equus ferus caballus) are known to be susceptible to infection that may manifest clinically on rare occasions. In late 2021 and early 2022, specimens from five horses suffering from pastern dermatitis were cultured at the Laboratory of Clinical Microbiology at the Faculty of Veterinary Medicine, University of Helsinki, Finland. C. diphtheriae and/or C. ulcerans were recovered from all of these. This study aimed to (1) analyse the bacterial isolates and (2) describe the outbreak and identify possible sources of the infection and infection routes in the stable. METHODS AND RESULTS: Susceptibility testing, PCR for the tox gene, and Elek test for toxin production in PCR-positive isolates were performed. Whole genome sequencing was also conducted to achieve high-resolution strain typing. An epidemiological survey was done by means of a semi-structured interview of horses' caretaker, and contact tracing was done among people at the stable. Two tox gene-positive, toxin-producing C. diphtheriae belonged to sequence type (ST) 822. Other C. diphtheriae (n = 2, ST828) and C. ulcerans (n = 2, ST325 and ST838) isolates did not carry the tox gene. The epidemiological investigation explored numerous possible routes of transmission, but the definite source of infection was not identified. All established human contacts tested negative for diphtheriae. All horses recovered after antimicrobial treatment. CONCLUSIONS: Our study shows that C. diphtheriae and C. ulcerans may readily spread among horses at the same stable and complicate pastern dermatitis infections. These potentially zoonotic bacteria can cause outbreaks even in a country with a very low prevalence. Caretakers should be encouraged to wear gloves and practice good hand hygiene when treating infected skin lesions in horses.

Automated EuroFlow approach for standardized in-depth dissection of human circulating B-cells and plasma cells.

Background: Multiparameter flow cytometry (FC) immunophenotyping is a key tool for detailed identification and characterization of human blood leucocytes, including B-lymphocytes and plasma cells (PC). However, currently used conventional data analysis strategies require extensive expertise, are time consuming, and show limited reproducibility. Objective: Here, we designed, constructed and validated an automated database-guided gating and identification (AGI) approach for fast and standardized in-depth dissection of B-lymphocyte and PC populations in human blood. Methods: For this purpose, 213 FC standard (FCS) datafiles corresponding to umbilical cord and peripheral blood samples from healthy and patient volunteers, stained with the 14-color 18-antibody EuroFlow BIgH-IMM panel, were used. Results: The BIgH-IMM antibody panel allowed identification of 117 different B-lymphocyte and PC subsets. Samples from 36 healthy donors were stained and 14 of the datafiles that fulfilled strict inclusion criteria were analysed by an expert flow cytometrist to build the EuroFlow BIgH-IMM database. Data contained in the datafiles was then merged into a reference database that was uploaded in the Infinicyt software (Cytognos, Salamanca, Spain). Subsequently, we compared the results of manual gating (MG) with the performance of two classification algorithms -hierarchical algorithm vs two-step algorithm- for AGI of the cell populations present in 5 randomly selected FCS datafiles. The hierarchical AGI algorithm showed higher correlation values vs conventional MG (r2 of 0.94 vs. 0.88 for the two-step AGI algorithm) and was further validated in a set of 177 FCS datafiles against conventional expert-based MG. For virtually all identifiable cell populations a highly significant correlation was observed between the two approaches (r2>0.81 for 79% of all B-cell populations identified), with a significantly lower median time of analysis per sample (6 vs. 40 min, p=0.001) for the AGI tool vs. MG, respectively and both intra-sample (median CV of 1.7% vs. 10.4% by MG, p<0.001) and inter-expert (median CV of 3.9% vs. 17.3% by MG by 2 experts, p<0.001) variability. Conclusion: Our results show that compared to conventional FC data analysis strategies, the here proposed AGI tool is a faster, more robust, reproducible, and standardized approach for in-depth analysis of B-lymphocyte and PC subsets circulating in human blood.

Effect of immunization during pregnancy and pre-existing immunity on diphtheria-tetanus-acellular pertussis vaccine responses in infants.

Immunization during pregnancy (IP) against pertussis is recommended in many countries to protect infants. Although maternal antibodies can influence the infants' antibody responses to primary vaccinations, their effect on the development of functional antibodies and B cells remain poorly studied. We investigated the maternal immune response to IP and the effect of IP and pre-existing antibodies on infants' primary vaccine responses in an open-label, non-randomized trial. Forty-seven mothers received tetanus-diphtheria-acellular pertussis (Tdap) vaccine during pregnancy, and 22 mothers were included as controls. Sixty-nine infants received primary doses of DTaP at three and five months of age. Geometric mean concentrations of antibodies to pertussis toxin, filamentous haemagglutinin, pertactin, diphtheria, and tetanus toxins, pertussis toxin neutralizing antibodies (PTNAs), and plasma and memory B-cell frequencies were studied at delivery, and at three, five and six months. Levels of antibodies, PTNAs, and frequencies of memory B-cells were significantly increased at delivery and up to six months after in mothers with IP compared to those without IP (all p < 0.05, except for PT-specific memory B-cells). In vaccinated pregnant women, high pre-existing antibody levels were positively correlated with higher antibody responses after IP. IP blunted the infants' antibody and plasma B-cell responses to all vaccine antigens, except for tetanus toxin. This blunting effect was the strongest in infants with high concentrations of maternal antibodies. In conclusion, IP resulted in significantly higher concentrations of antibodies in infants up to three months of age (all p < 0.05); but was associated with blunting of various infants' vaccine responses.

Immunogenicity and safety of BPZE1, an intranasal live attenuated pertussis vaccine, versus tetanus-diphtheria-acellular pertussis vaccine: a randomised, double-blind, phase 2b trial.

BACKGROUND: Bordetella pertussis epidemics persist as transmission remains unabated despite high acellular pertussis vaccination rates. BPZE1, a live attenuated intranasal pertussis vaccine, was designed to prevent B pertussis infection and disease. We aimed to assess the immunogenicity and safety of BPZE1 compared with the tetanus-diphtheria-acellular pertussis vaccine (Tdap). METHODS: In this double-blind, phase 2b trial at three research centres in the USA, healthy adults aged 18-50 years were randomly assigned (2:2:1:1) via a permuted block randomisation schedule to receive BPZE1 vaccination followed by BPZE1 attenuated challenge, BPZE1 vaccination followed by placebo challenge, Tdap followed by BPZE1 attenuated challenge, or Tdap followed by placebo challenge. On day 1, lyophilised BPZE1 was reconstituted with sterile water and given intranasally (0·4 mL delivered to each nostril), whereas Tdap was given intramuscularly. To maintain masking, participants in the BPZE1 groups received an intramuscular saline injection, and those in the Tdap groups received intranasal lyophilised placebo buffer. The attenuated challenge took place on day 85. The primary immunogenicity endpoint was the proportion of participants achieving nasal secretory IgA seroconversion against at least one B pertussis antigen on day 29 or day 113. Reactogenicity was assessed up to 7 days after vaccination and challenge, and adverse events were recorded for 28 days after vaccination and challenge. Serious adverse events were monitored throughout the study. This trial is registered with ClinicalTrials.gov, NCT03942406. FINDINGS: Between June 17 and Oct 3, 2019, 458 participants were screened and 280 were randomly assigned to the main cohort: 92 to the BPZE1-BPZE1 group, 92 to the BPZE1-placebo group, 46 to the Tdap-BPZE1 group, and 50 to the Tdap-placebo group. Seroconversion of at least one B pertussis-specific nasal secretory IgA was recorded in 79 (94% [95% CI 87-98]) of 84 participants in the BPZE1-BPZE1 group, 89 (95% [88-98]) of 94 in the BPZE1-placebo group, 38 (90% [77-97]) of 42 in the Tdap-BPZE1 group, and 42 (93% [82-99]) of 45 in the Tdap-placebo group. BPZE1 induced broad and consistent B pertussis-specific mucosal secretory IgA responses, whereas Tdap did not induce consistent mucosal secretory IgA responses. Both vaccines were well tolerated, with mild reactogenicity and no serious adverse events related to study vaccination. INTERPRETATION: BPZE1 induced nasal mucosal immunity and produced functional serum responses. BPZE1 has the potential to avert B pertussis infections, which ultimately could lead to reduced transmission and diminished epidemic cycles. These results should be confirmed in large phase 3 trials. FUNDING: ILiAD Biotechnologies.

Antibody avidity to pertussis toxin after acellular pertussis vaccination and infection.

Pertussis toxin (PT) is a unique virulence factor of Bordetella pertussis, and therefore a key component of acellular pertussis vaccines. Although immunity after infection seems to persist longer than after vaccination, the exact mechanisms are not fully known. In this study the overall binding strength (avidity) of anti-PT IgG antibodies was compared after acellular booster vaccination and infection, as a parameter to evaluate long-lasting protection.Danish and Finnish serum samples from a total of 134 serologically confirmed patients and 112 children who received acellular booster vaccines were included in this study. The concentration of anti-PT IgG was first determined by ELISA, followed by two separate ELISAs to evaluate antibody avidity: either with a dilution series of urea as a bond-breaking agent of antibody and antigen binding and a constant anti-PT IgG concentration between the samples or with a constant dilution ratio of sera and detergent. In addition to urea, the use of diethylamine and ammonium thiocyanate as disruptive agents were first compared between each other.A strong Spearman correlation (R > 0.801) was noted between avidity and concentration of anti-PT IgG antibodies if a constant serum dilution method was used, and avidity was noted to be higher in patients in comparison to vaccinees in Denmark, but not in Finland. However, no correlation between antibody concentration and avidity was found if a constant anti-PT IgG concentration was used (R = -0.157). With this method, avidity after vaccination was significantly higher in comparison to that after infection in both Danish and Finnish subjects (p < 0.01). A shorter time since the latest booster vaccination was found to affect avidity positively on the next PT-antigen exposure with either vaccination or infection.

Macrolide Resistance in Bordetella pertussis: Current Situation and Future Challenges.

Pertussis is a highly contagious respiratory infection caused by Bordetella pertussis bacterium. The mainstay of treatment is macrolide antibiotics that reduce transmissibility, shorten the duration of symptoms and decrease mortality in infants. Recently, the macrolide resistance of B. pertussis has been reported globally but is especially widespread in mainland China. In this review, we aim to summarise the current understanding of the epidemiology, resistance mechanisms and clinical implications of B. pertussis macrolide resistance. Since the first appearance of macrolide-resistant B. pertussis in Arizona, USA, in 1994, only sporadic cases have been reported outside China. In certain parts of China, on the other hand, up to 70-100% of the recent clinical isolates have been found to be macrolide resistant. Reasons for macrolide resistance being centred upon China during the last decade can only be speculated on, but the dominant B. pertussis lineage is different between China and most of the high-income countries. It seems evident that efforts to increase awareness, guide molecular epidemiological surveillance and carry out systematic screening of B. pertussis positive samples for macrolide resistance should be implemented globally. In addition, practices to improve the clinical care of infants with pertussis caused by resistant strains should be studied vigorously.

Development of a standardized and validated flow cytometry approach for monitoring of innate myeloid immune cells in human blood.

Innate myeloid cell (IMC) populations form an essential part of innate immunity. Flow cytometric (FCM) monitoring of IMCs in peripheral blood (PB) has great clinical potential for disease monitoring due to their role in maintenance of tissue homeostasis and ability to sense micro-environmental changes, such as inflammatory processes and tissue damage. However, the lack of standardized and validated approaches has hampered broad clinical implementation. For accurate identification and separation of IMC populations, 62 antibodies against 44 different proteins were evaluated. In multiple rounds of EuroFlow-based design-testing-evaluation-redesign, finally 16 antibodies were selected for their non-redundancy and separation power. Accordingly, two antibody combinations were designed for fast, sensitive, and reproducible FCM monitoring of IMC populations in PB in clinical settings (11-color; 13 antibodies) and translational research (14-color; 16 antibodies). Performance of pre-analytical and analytical variables among different instruments, together with optimized post-analytical data analysis and reference values were assessed. Overall, 265 blood samples were used for design and validation of the antibody combinations and in vitro functional assays, as well as for assessing the impact of sample preparation procedures and conditions. The two (11- and 14-color) antibody combinations allowed for robust and sensitive detection of 19 and 23 IMC populations, respectively. Highly reproducible identification and enumeration of IMC populations was achieved, independently of anticoagulant, type of FCM instrument and center, particularly when database/software-guided automated (vs. manual "expert-based") gating was used. Whereas no significant changes were observed in identification of IMC populations for up to 24h delayed sample processing, a significant impact was observed in their absolute counts after >12h delay. Therefore, accurate identification and quantitation of IMC populations requires sample processing on the same day. Significantly different counts were observed in PB for multiple IMC populations according to age and sex. Consequently, PB samples from 116 healthy donors (8-69 years) were used for collecting age and sex related reference values for all IMC populations. In summary, the two antibody combinations and FCM approach allow for rapid, standardized, automated and reproducible identification of 19 and 23 IMC populations in PB, suited for monitoring of innate immune responses in clinical and translational research settings.

Whole blood based point-of-care assay for the detection of anti-pertussis toxin IgG antibodies.

Current serological diagnosis of pertussis is usually done by ELISA to determine serum specific anti-pertussis toxin (PT) IgG antibodies. However, the ELISAs are often central-laboratory based, require trained staff, and have long turnaround times. A rapid point-of-care (POC) assay for pertussis serology would aid in both diagnosis and surveillance of the disease. In this study, a quantitative lateral flow assay (LFA) with fluorescent Eu-nanoparticle reporters was used for the detection of anti-PT antibodies from whole blood. The assay was evaluated by testing overall 141 samples including 25 before and 116 one month after acellular pertussis booster vaccination. LFA results were compared to those obtained with standardized anti-PT IgG ELISAs with paired serum samples. Correlation between the assays was high (Pearson R = 0.832), and the achieved analytical sensitivity of the LFA was 29 IU/mL, which would be sufficient for clinically relevant cutoffs for determining recent infections. The paired samples, collected pre- and post-booster, demonstrated a significant increase in anti-PT IgG antibodies similar to that detected by ELISA. The developed LFA opens up several alternatives for a suitable POC test also in middle- and low-income countries.

Memory B Cell Activation Induced by Pertussis Booster Vaccination in Four Age Groups of Three Countries.

Background: Immunogenicity of acellular pertussis (aP) vaccines is conventionally assessed by measuring antibody responses but antibody concentrations wane quickly after vaccination. Memory B cells, however, are critical in sustaining long-term protection and therefore may be an important factor when assessing pertussis immunity after vaccination. Aim: We studied pertussis specific memory B cell (re)activation induced by an aP booster vaccination in four different age groups within three countries. Materials and methods: From a phase IV longitudinal interventional study, 268 participants across Finland, the Netherlands and the United Kingdom were included and received a 3-component pertussis booster vaccine: children (7-10y, n=53), adolescents (11-15y, n=66), young adults (20-34y, n=74), and older adults (60-70y, n=75). Memory B cells at baseline, day 28, and 1 year post-vaccination were measured by a pertussis toxin (Ptx), filamentous haemagglutinin (FHA), and pertactin (Prn) specific ELISpot assay. Antibody results measured previously were available for comparison. Furthermore, study participants were distributed into groups based on their baseline memory B cell frequencies, vaccine responses were monitored between these groups. Results: Geometric mean (GM) memory B cell frequencies for pertussis antigens at baseline were low. At 28 days post-vaccination, these frequencies increased within each age group and were still elevated one year post-booster compared to baseline. Highest frequencies at day 28 were found within adolescents (GM: 5, 21, and 13, for Ptx, FHA and Prn, respectively) and lowest within older adults (GM: 2, 9, and 3, respectively). Moderate to strong correlations between memory B cell frequencies at day 28 and antibody concentrations at day 28 and 1 year were observed for Prn. Memory B cell frequencies > 1 per 100,000 PBMCs at baseline were associated with significantly higher memory responses after 28 days and 1 year. Conclusions: An aP booster vaccine (re)activated memory B cells in all age groups. Still elevated memory B cell frequencies after one year indicates enhanced immunological memory. However, antigen specific memory B cell activation seems weaker in older adults, which might reflect immunosenescence. Furthermore, the presence of circulating memory B cells at baseline positively affects memory B cell responses. This study was registered at www.clinicaltrialsregister.eu: No. 2016-003678-42.

Global spatial dynamics and vaccine-induced fitness changes of Bordetella pertussis.

As with other pathogens, competitive interactions between Bordetella pertussis strains drive infection risk. Vaccines are thought to perturb strain diversity through shifts in immune pressures; however, this has rarely been measured because of inadequate data and analytical tools. We used 3344 sequences from 23 countries to show that, on average, there are 28.1 transmission chains circulating within a subnational region, with the number of chains strongly associated with host population size. It took 5 to 10 years for B. pertussis to be homogeneously distributed throughout Europe, with the same time frame required for the United States. Increased fitness of pertactin-deficient strains after implementation of acellular vaccines, but reduced fitness otherwise, can explain long-term genotype dynamics. These findings highlight the role of vaccine policy in shifting local diversity of a pathogen that is responsible for 160,000 deaths annually.

Pertussis toxin neutralizing antibody response after an acellular booster vaccination in Dutch and Finnish participants of different age groups.

ABSTRACTPertussis incidence has increased in many countries and the disease occurs among all age groups, suggesting the need for booster immunizations through life. In addition to determining the concentration of anti-pertussis toxin (PT) antibodies, the ability of PT neutralizing antibodies (PTNAs) could be used to assess vaccine responses.Altogether 258 participants [7-10-year-old (N = 73), 11-15-year-old (N = 85), 20-35-year-old (N = 50) and 60-70-year-old (N = 50)] were included. Sera were collected before, one month, and one year after a single dose of a three pertussis component containing acellular pertussis vaccine. The adolescents were primed in childhood either by acellular or whole-cell vaccination. PTNA titres were determined by a Chinese hamster ovary cell assay and anti-PT IgG/IgA antibody concentrations by multiplex immunoassay.In all age groups, a significant increase in levels of PTNAs and anti-PT IgG was observed one month after vaccination and remained at least two-fold higher one year post-booster, in comparison to pre-booster. Young adults had the lowest response. The strongest increase in PTNAs was observed in participants who had ≥10 IU/mL concentration of anti-PT IgG antibodies pre-booster. At pre-booster, whole-cell-primed adolescents had higher PTNAs than acellular-primed peers (p = 0.047). One year post-booster, the Finnish whole-cell-primed adolescents had a higher level of PTNAs than acellular-primed adolescents (p = 0.049), however, this was not observed in Dutch adolescents. In conclusion, PTNAs increased after vaccination in all age groups, and the strongest increase was related to the presence of high pre-booster antibodies.

Evaluation of Anti-PT Antibody Response after Pertussis Vaccination and Infection: The Importance of Both Quantity and Quality.

Pertussis toxin (PT) is considered the main virulence factor causing whooping cough or pertussis. The protein is widely studied and its composition was revealed and sequenced already during the 1980s. The human immune system creates a good response against PT when measured in quantity. However, the serum anti-PT antibodies wane rapidly, and only a small amount of these antibodies are found a few years after vaccination/infection. Therefore, multiple approaches to study the functionality (quality) of these antibodies, e.g., avidity, neutralizing capacity, and epitope specificity, have been investigated. In addition, the long-term B cell memory (Bmem) to PT is crucial for good protection throughout life. In this review, we summarize the findings from functional PT antibody and Bmem studies. These results are discussed in line with the quantity of serum anti-PT antibodies. PT neutralizing antibodies and anti-PT antibodies with proper avidity are crucial for good protection against the disease, and certain epitopes have been identified to have multiple functions in the protection. Although PT-specific Bmem responses are detectable at least five years after vaccination, long-term surveillance is lacking. Variation of the natural boosting of circulating Bordetella pertussis in communities is an important confounding factor in these memory studies.

Pertussis seroprevalence among adults of reproductive age (20-39 years) in fourteen European countries.

The reported incidence of pertussis in European countries varies considerably. We aimed to study specific Bordetella pertussis seroprevalence in Europe by measuring serum IgG antibody levels to pertussis toxin (anti-PT IgG). Fourteen national laboratories participated in this study including Belgium, Denmark, Finland, Greece, Hungary, Italy, Lithuania, Malta, Norway, Poland, Portugal, Romania, Spain, and Sweden. Each country collected approximately 250 samples (N = 7903) from the age groups 20-29 years (N = 3976) and 30-39 years (N = 3927) during 2010-2013. Samples were anonymous residual sera from diagnostic laboratories and were analyzed at the national laboratories by a Swedish reference method, a commercial ELISA kit, or were sent to Sweden for analysis. The median anti-PT IgG concentrations ranged from 4 to 13.6 IU/mL. The proportion of samples with anti-PT IgG ≥100 IU/mL, indicating a recent infection ranged from 0.2% (Hungary) to 5.7% (Portugal). The highest proportion of sera with anti-PT IgG levels between 50 and <100 IU/mL, indicating an infection within the last few years, was found in Portugal (12.3%) and Italy (13.9%). This study shows that the circulation of B. pertussis is quite extensive in adults, aged 20-39 years, despite well-established vaccination programs in Europe.

Circulation of pertussis and poor protection against diphtheria among middle-aged adults in 18 European countries.

Reported incidence of pertussis in the European Union (EU) and the European Economic Area (EEA) varies and may not reflect the real situation, while vaccine-induced protection against diphtheria and tetanus seems sufficient. We aimed to determine the seroprevalence of DTP antibodies in EU/EEA countries within the age groups of 40-49 and 50-59 years. Eighteen countries collected around 500 samples between 2015 and 2018 (N = 10,302) which were analysed for IgG-DTP specific antibodies. The proportion of sera with pertussis toxin antibody levels ≥100 IU/mL, indicative of recent exposure to pertussis was comparable for 13/18 countries, ranging between 2.7-5.8%. For diphtheria the proportion of sera lacking the protective level (<0.1 IU/mL) varied between 22.8-82.0%. For tetanus the protection was sufficient. Here, we report that the seroprevalence of pertussis in these age groups indicates circulation of B. pertussis across EU/EEA while the lack of vaccine-induced seroprotection against diphtheria is of concern and deserves further attention.

Simultaneous Determination of Antibodies to Pertussis Toxin and Adenylate Cyclase Toxin Improves Serological Diagnosis of Pertussis.

Serological diagnosis of pertussis is mainly based on anti-pertussis toxin (PT) IgG antibodies. Since PT is included in all acellular vaccines (ACV), serological assays do not differentiate antibodies induced by ACVs and infection. Adenylate cyclase toxin (ACT) is not included in the ACVs, which makes it a promising candidate for pertussis serology with the specific aim of separating infection- and ACV-induced antibodies. A multiplex lateral flow test with PT and ACT antigens was developed to measure serum antibodies from pertussis-seropositive patients (n = 46), healthy controls (n = 102), and subjects who received a booster dose of ACV containing PT, filamentous hemagglutinin, and pertactin (n = 67) with paired sera collected before and one month after the vaccination. If the diagnosis was solely based on anti-PT antibodies, 98.5-44.8% specificity (before and after vaccination, respectively) and 78.2% sensitivity were achieved, whereas if ACT was used in combination with PT, the sensitivity of the assay increased to 91.3% without compromising specificity. No increase in the level of anti-ACT antibodies was found after vaccination. This exploratory study indicates that the use of ACT for serology would be beneficial in combination with a lower quantitative cutoff for anti-PT antibodies, and particularly in children and adolescents who frequently receive booster vaccinations.

IL17F rs763780 single nucleotide polymorphism is associated with asthma after bronchiolitis in infancy.

AIM: Interleukin-17F (IL-17F) is involved with asthma. The aim of this study was to evaluate the association of IL17F polymorphisms with childhood asthma after bronchiolitis in infancy. METHODS: We invited 166 children who were hospitalised for bronchiolitis at younger than 6 months of age to follow-up visits at 5-7 years and 11-13 years of ages. Asthma and allergy diagnoses, asthma-presumptive symptoms and use of inhaled corticosteroids (ICSs) were registered. Blood samples were available for IL17F rs763780 (T/C), rs11465553 (C/T) and rs7741835 (C/T) determinations in 165 cases. RESULTS: The presence of IL17F rs11465553 and rs7741835 variations showed no significant associations with any asthma or allergy outcome at either 5-7 years or 11-13 years of ages. Instead, children with the variant IL17F rs763780 genotype had used more often ICSs between the follow-up visits from 5-7 to 11-13 years (adjusted OR 3.58) than those with the wild genotype. Children with the variant IL17F rs763780 genotype reported more often doctor-diagnosed atopic dermatitis (adjusted OR 2.71) at 11-13 years of age than those with the wild genotype. CONCLUSION: This prospective long-term follow-up study provided preliminary evidence on the association of the IL17F rs763780 polymorphism with asthma at school age after bronchiolitis in infancy.

Interleukin 17F gene variations showed no association with BCG osteitis risk after newborn vaccination.

AIM: Interleukin-17 (IL-17) family cytokines promote the host defence against mycobacterial infections. We have previously shown an association between IL17A variations and Bacillus Calmette-Guérin (BCG) osteitis. This paper evaluates the association of three IL17F polymorphisms with BCG osteitis after newborn vaccination. METHODS: IL17F rs763780, rs11465553 and rs7741835 single nucleotide polymorphisms (SNPs) were studied in 132 adults, who presented with BCG osteitis in infancy. The genotypes and minor allele frequencies (MAFs) were compared between cases and Finnish population-based controls (N = 99) from the 1000 Genomes Project, and MAFs were compared between cases and allele data of Finnish subjects from the large Genome Aggregation Database. RESULTS: There were no significant differences between former BCG osteitis patients and population-based controls in the IL17F rs763780 (wild 84.4% vs 84.8%), rs11465553 (86.4% vs 91.9%) or rs7741835 (65.7% vs 67.7%) genotypes. Homozygous variant genotypes were only present in 1.5%, 0.8% and 3.8% of cases, respectively. Likewise, MAFs of the three IL17F SNPs did not substantially differ from those of 11 252, 11 939 and 1371 Finnish subjects, respectively, from the available Genome Aggregation Database. CONCLUSION: IL17F rs763780, rs11465553 and rs7741835 variations showed no association with the risk of BCG osteitis after newborn vaccination.