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Six serotypes (Ia, Ib, II, III, IV, and V) cause nearly all group B streptococcal (GBS) disease globally. Capsular polysaccharide (CPS) conjugate vaccines aim to prevent GBS disease, however, licensure of a vaccine would depend on a standardized serological assay for measuring anti-CPS IgG responses. A multiplex direct Luminex-based immunoassay (dLIA) has been developed to simultaneously measure the concentration of serum IgG specific for the six prevalent GBS CPS serotypes. Assay validation was performed using serum samples obtained from human subjects vaccinated with an investigational 6-valent GBS CPS conjugate vaccine. Results for the assay are expressed as IgG concentrations (µg/mL) using a human serum reference standard composed of pooled sera from vaccinated subjects. The lower limits of quantitation (LLOQ) for all serotypes covered in the 6-plex GBS IgG dLIA fell within the range of 0.002-0.022 µg/mL IgG. Taken together, the 6-plex GBS IgG dLIA platform is specific for the six GBS serotypes included in Pfizer's investigational vaccine, has a wide dilution adjusted assay range, and is precise (<18.5% relative standard deviation) for all serotypes, and, therefore, is suitable for quantitatively measuring vaccine-induced or naturally acquired serotype-specific anti-CPS IgG responses against GBS.

Measurement of IgG antibodies against group B streptococcus (GBS) capsular polysaccharide (CPS) by use of a standardized and internationally accepted multiplex immunoassay is important for the evaluation of candidate maternal GBS vaccines in order to compare results across studies. A standardized assay is also required if serocorrelates of protection against invasive GBS disease are to be established in infant sera for the six predominant GBS serotypes since it would permit the comparison of results across the six serotypes. We undertook an interlaboratory study across five laboratories that used standardized assay reagents and protocols with a panel of 44 human sera to measure IgG antibodies against GBS CPS serotypes Ia, Ib, II, III, IV, and V. The within-laboratory intermediate precision, which included factors like the lot of coated beads, laboratory analyst, and day, was generally below 20% relative standard deviation (RSD) for all six serotypes, across all five laboratories. The cross-laboratory reproducibility was < 25% RSD for all six serotypes, which demonstrated the consistency of results across the different laboratories. Additionally, anti-CPS IgG concentrations for the 44-member human serum panel were established. The results of this study showed assay robustness and that the resultant anti-CPS IgG concentrations were reproducible across laboratories for the six GBS CPS serotypes when the standardized assay was used.

Background: Global pediatric immunization programs with pneumococcal conjugate vaccines (PCVs) have reduced vaccine-type pneumococcal disease, but a substantial disease burden of non-PCV serotypes remains., Methods: This phase 3, randomized (1:1), double-blind study evaluated safety and immunogenicity of 20-valent PCV (PCV20) relative to 13-valent PCV (PCV13) in healthy infants. Participants received 2 infant doses and a toddler dose of PCV20 or PCV13, with diphtheria-tetanus-acellular pertussis combination vaccine at all doses and measles, mumps, rubella and varicella vaccines at the toddler dose. Primary pneumococcal immunogenicity objectives were to demonstrate noninferiority (NI) of PCV20 to PCV13 for immunoglobulin G geometric mean concentrations after infant and toddler doses and percentages of participants with predefined serotype-specific immunoglobulin G concentrations after infant doses. Safety endpoints included local reactions, systemic events and adverse events., Results: Overall, 1204 participants were vaccinated (PCV20, n = 601; PCV13, n = 603). One month after the toddler dose, 19/20 serotypes met NI for immunoglobulin G geometric mean concentrations; serotype 6B narrowly missed NI [PCV20/PCV13 geometric mean ratio: 0.57 (2-sided 95% confidence interval: 0.48-0.67); NI criterion: lower 2-sided 95% confidence interval >0.5]. Sixteen/twenty serotypes met NI for ≥1 primary objective after 2 infant doses. PCV20 induced robust opsonophagocytic activity, and boosting responses were observed for all vaccine serotypes, including those missing statistical NI. The safety/tolerability profile of PCV20 was like that of PCV13., Conclusions: PCV20 3-dose series in infants was safe and elicited robust immune responses. Based on these results and PCV13 experience, PCV20 3-dose series is expected to be protective for all 20 vaccine serotypes. NCT04546425., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Objectives: Safety and immunogenicity evaluation of a 4-dose series with 20-valent pneumococcal conjugate vaccine (PCV20)., Methods: This phase 3, double-blind study randomized healthy Japanese infants to receive 4 doses (3 infant doses, 1 toddler dose) of PCV20 by subcutaneous (SC) or intramuscular (IM) injection or 13-valent PCV (PCV13) SC. A primary immunogenicity objective was to demonstrate noninferiority of PCV20 SC to PCV13 SC for percentages of participants meeting predefined serotype-specific immunoglobulin G concentrations 1 month after Dose 3. The 7 additional PCV20 serotypes were compared with the lowest vaccine serotype result in the PCV13 group. Safety and tolerability were assessed as the primary safety objective., Results: Overall, 668 participants were randomized (PCV20 SC, n = 226; PCV13 SC, n = 224; PCV20 IM, n = 218). The primary noninferiority objective for PCV20 SC to PCV13 SC was met for 11/13 matched and 5/7 additional serotypes. Additional data showed PCV20 SC and IM elicited robust functional opsonophagocytic activity and boosting responses to all 20 vaccine serotypes. PCV20 had a similar safety/tolerability profile to PCV13, although local reactions were less frequent with PCV20 IM., Conclusions: A 4-dose series of PCV20 SC or IM elicited immune responses expected to be protective against all 20 serotypes in Japanese infants. NCT04530838., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Yasunori Ishihara, Mitsuru Fukazawa, and Shinya Enomoto are study investigators for Pfizer and have no other conflicts to declare. All other authors are current employees of Pfizer or were employees at the time of the study and may hold stock or stock options., (Copyright © 2024. Published by Elsevier Ltd.)

Streptococcus pneumoniae causes a considerable disease burden among children in China. Many isolates exhibit antimicrobial resistance but are often serotypes covered by the 13-valent pneumococcal conjugate vaccine (PCV13). Because the approved infant immunization schedule in China allows PCV13 vaccination only for those 6 weeks to 15 months of age, this phase 3 study was conducted to evaluate PCV13 immunogenicity and safety in unvaccinated older infants and children. Eligible participants were stratified by age into four cohorts: Cohort 1 ( n  = 125), 6 weeks-2 months; Cohort 2 ( n  = 354), 7-<12 months; Cohort 3 ( n  = 250), 1 -<2 years; Cohort 4 ( n  = 207), 2-<6 years. Cohort 1 received PCV13 at ages 2, 4, and 6 months; older cohorts were randomized 2:1 to PCV13 or Haemophilus influenzae type b (Hib) vaccine using age-appropriate schedules. Within-group immune responses were assessed by immunoglobulin G (IgG) concentrations and opsonophagocytic activity (OPA) titers. Safety evaluations included solicited reactogenicity events and adverse events (AEs). IgG geometric mean concentrations and OPA geometric mean titers for all 13 PCV13 serotypes increased for all participants vaccinated with PCV13, but not those vaccinated with Hib. Immune responses in Cohorts 2-4 were generally comparable with those in Cohort 1 (the infant series) for most serotypes. PCV13 was well tolerated across cohorts, with reported AEs consistent with expectations in these age groups; no new safety signals were identified. These results suggest that PCV13 administered as a catch-up regimen to infants and children 7 months-<6 years of age in China will effectively reduce vaccine-type pneumococcal disease in this population. NCT03574389.

Use of pneumococcal conjugate vaccines (PCVs) has led to substantial reductions in the global burden of pediatric pneumococcal disease. Expansion of serotype coverage has been achieved by increasing PCV valency, but this may carry the potential risk of antibody interference. A complementary 7-valent PCV (cPCV7) including polysaccharide conjugates from 7 non-13-valent (PCV13) serotypes was developed to potentially complement PCV13-mediated protection and expand serotype coverage. This study evaluated cPCV7 and PCV13 coadministered in separate limbs or separated in time in infants. This phase 2, multicenter, open-label study included 512 infants randomized 1:1:1 to receive cPCV7 coadministered with PCV13 at ages 2, 4, 6, and 12 months (cPCV7 Coadministered); cPCV7 given at ages 3, 5, 7, and 13 months, 3‒5 weeks after PCV13 (cPCV7 Separated); or PCV13 at ages 2, 4, 6, and 12 months followed by a single supplemental dose of cPCV7 at 13 months (PCV13 Control). Safety evaluations included local reactions, systemic events, and adverse events. Serotype-specific immunoglobulin G concentrations and opsonophagocytic activity titers were assessed. The safety profile of cPCV7 was similar to that of PCV13. cPCV7 was well-tolerated in infants when coadministered with or given separately from PCV13. Robust and functional immune responses for all cPCV7 serotypes were observed in both cPCV7 groups. No immunologic interference was observed for either the cPCV7 or PCV13 serotypes with coadministration. A single cPCV7 dose induced immune responses in toddlers. These findings support potential coadministration of a complementary PCV to supplement protection provided by existing PCVs. Trial registration : ClinicalTrials.gov, NCT03550313.

Group B streptococcus ( Streptococcus agalactiae , GBS) is an important cause of life-threatening disease in newborns. Pregnant women colonized with GBS can transmit the bacteria to the developing fetus, as well as to their neonates during or after delivery where infection can lead to sepsis, meningitis, pneumonia, or/and death. While intrapartum antibiotic prophylaxis (IAP) is the standard of care for prevention of invasive GBS disease in some countries, even in such settings a substantial residual burden of disease remains. A GBS vaccine administered during pregnancy could potentially address this important unmet medical need and provide an adjunct or alternative to IAP for the prevention of invasive GBS disease in neonates. A hurdle for vaccine development has been relatively low disease rates making efficacy studies difficult. Given the well-accepted inverse relationship between anti-GBS capsular polysaccharide antibody titers at birth and risk of disease, licensure using serological criteria as a surrogate biomarker represents a promising approach to accelerate the availability of a GBS vaccine.

Background: This open-label, single-arm, phase 3 study evaluated safety and immunogenicity of the 13-valent pneumococcal conjugate vaccine (PCV13) in pneumococcal vaccine-naive Japanese individuals aged 6-64 years at increased risk of pneumococcal disease (PD)., Methods: Participants received 1 PCV13 dose. Reactogenicity events were recorded for 7 days (individuals aged 6- to 17-year-old) or 14 days (individuals aged 18 to 64 years old) postvaccination. Adverse events (AEs) were collected for 1 month postvaccination. Opsonophagocytic activity (OPA) and anticapsular immunoglobulin G (IgG) geometric mean concentrations (GMCs) were measured for vaccine serotypes before and 1 month postvaccination. Post hoc analyses compared immunogenicity in participants categorized as at-risk (immunocompetent but having chronic medical conditions associated with increased PD risk) or high-risk (immunocompromised due to diseases/conditions and/or medications)., Results: 206 participants aged 6- to 17-year-old (n = 53) and 18 to 64 years old (n = 153) completed the study. Reactogenicity events were generally mild to moderate in severity. AEs were reported in 16% (33/206) of participants; 1.0% (2/206) were severe. Six AEs were vaccine-related; most were associated with local reactions. No serious AEs occurred. Circulating antibody levels for all 13 serotypes increased postvaccination. OPA geometric mean fold rises (GMFRs) from prevaccination to 1 month postvaccination were 5.5-61.7; lower limits of the 2-sided, 95% CI were > 1 for all serotypes. IgG GMFRs were consistent with OPA analyses. In post hoc analyses, 55.8% (115/206) and 44.2% (91/206) of participants were categorized as at risk and at high risk of PD, respectively; OPA GMFRs from prevaccination to 1 month postvaccination were 3.9-635.1, with lower limits of the 2-sided 95% CIs > 1 for all 13 serotypes across these risk groups; IgG GMFRs were consistent with OPA analyses., Conclusions: PCV13 was well tolerated and immunogenic in Japanese individuals aged 6-64 years considered at increased risk of PD. Results were broadly comparable with past PCV13 studies in other Japanese and non-Japanese populations. Registration number: NCT03571607; JapicCTI-184024., Competing Interests: Declaration of Competing Interest R de Solom, Y Shoji, M Oe, M Aizawa, P Giardina, B Schmoele-Thoma, and D Scott are employees of Pfizer Inc and may hold stock or stock options. All other authors have no conflicts to declare., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: The development and widespread use of pneumococcal conjugate vaccines (PCVs) substantially reduced the global burden of pneumococcal disease. Expanding the serotypes covered by PCVs may further reduce disease burden. A 20-valent PCV (PCV20) has been developed to add coverage for 7 additional serotypes (8, 10A, 11A, 12F, 15B, 22F and 33F) to those in the existing 13-valent PCV (PCV13). This phase 2 study evaluated the safety, tolerability and immunogenicity of PCV20 in healthy US infants., Methods: In this randomized, active-controlled, double-blind study, 460 infants were randomized 1:1 to receive a 4-dose series of either PCV20 or PCV13 at 2, 4, 6 and 12 months of age. Solicited local reactions and systemic events, adverse events (AEs) and serious AEs were recorded. Immunogenicity was assessed by measuring serotype-specific IgG concentrations and opsonophagocytic activity titers at 1 month after Dose 3, before Dose 4 and 1 month after Dose 4., Results: Of 460 infants, 82.8% completed the 1-month visit after Dose 4. Local reactions and systemic events were mostly mild to moderate in severity and similar between the PCV20 and PCV13 groups. Treatment-related AEs were uncommon, with no related serious AEs or deaths reported. IgG and opsonophagocytic activity responses elicited by PCV20 were robust and demonstrated a booster response after Dose 4., Conclusions: Administration of PCV20 in US infants was well tolerated, with a safety profile similar to PCV13, and induced robust serotype-specific immune responses. These findings support continued development of PCV20 in the pediatric population., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background: Group B streptococcus (GBS) is a major cause of invasive disease in young infants. Infants born to women with sufficient pre-existing anti-GBS capsular IgG antibodies are at reduced risk of GBS disease, making maternal immunisation a potential strategy for prevention. We aimed to assess the safety and immunogenicity of a novel hexavalent (serotypes Ia, Ib, II, III, IV, and V) GBS conjugate vaccine (GBS6)., Methods: This phase 1/2, placebo-controlled, observer-blinded, dose-escalation trial, was done at four clinical research centres in the USA (Kentucky, Georgia, and two sites in Utah). Healthy, non-pregnant adults aged 18-49 years were randomly assigned using an interactive, web-based response technology system. Within each dose group (low, medium, or high), participants in sentinel cohorts were randomly assigned 2:2:1 and expanded cohort participants were randomly assigned 4:4:1 to receive GBS6 with aluminium phosphate (AlPO 4 ), GBS6 without AlPO 4 , or placebo (saline control). One 0·5 mL dose of either saline placebo or 5 μg capsular polysaccharide per serotype in the low-dose group, 10 μg capsular polysaccharide per serotype in the medium-dose group, or 20 μg capsular polysaccharide per serotype in the high-dose group was administered by intramuscular injection into the deltoid muscle on day 1. The primary outcome was safety up to 6 months after vaccination, including the proportion of sentinel cohort participants with clinical laboratory abnormalities at 1 week, the proportion of all participants reporting solicited local reactions, systemic events, or use of antipyretic or pain medication within 14 days, adverse events up to 1 month, and medically attended or serious adverse events up to 6 months. The secondary outcome was GBS immunogenicity (serotype-specific IgG geometric mean concentrations at 1 month). This study is registered with ClinicalTrials.gov, NCT03170609., Findings: Between June 5, 2017, and June 25, 2018, 365 participants were randomly assigned and 364 (52 in each dose group) were vaccinated and included in the safety analysis. Unsolicited adverse events were reported by 15 (29%) participants in the 5 μg with AlPO 4 group, 13 (25%) in the 5 μg without AlPO 4 group, 22 (42%) in the 10 μg with AlPO 4 group, 12 (23%) in the 10 μg without AlPO 4 group, 25 (48%) in the 20 μg with AlPO 4 group, 21 (40%) in the 20 μg without AlPO 4 group, and 20 (38%) in the placebo group. The most common unsolicited adverse events were in the system organ class of infections and infestations in any dose or formulation of GBS6 (ranging from six [12%] in the 10 μg without AlPO 4 group to 15 [29%] in the 20 μg with AlPO 4 group and placebo group). Three participants reported at least one serious adverse event during the study, one each in the 5 μg GBS6 with AlPO 4 group (diabetic ketoacidosis, two events; resolved), 10 μg GBS6 with AlPO 4 group (died by suicide), and 20 μg GBS6 with AlPO 4 group (metrorrhagia; resolved). None of these serious adverse events were considered related to the vaccine. 11 of the 365 participants were excluded from the evaluable immunogenicity population, including one participant who did not receive the vaccine, and ten who at 1 month after vaccination were withdrawn for various reasons. GBS serotype-specific IgG geometric mean concentrations increased by 1 week after vaccination for all GBS6 groups, peaked at 2 weeks, stabilised by 1 month, and declined gradually but remained higher than placebo at 6 months., Interpretation: GBS6 was well tolerated in healthy adults and elicited robust immune responses for all dose levels and formulations that persisted 6 months after vaccination. This study supports further evaluation of GBS6 in pregnant women., Funding: Pfizer., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: 13-valent pneumococcal conjugate vaccine (PCV13) was licensed in China based on immunologic noninferiority to 7-valent PCV (PCV7). As part of the noninferiority study, immunogenicity and safety of PCV13 administered as a 3- or 2-dose infant series followed by a toddler dose were examined in healthy Chinese infants., Methods: Infants (42- to 77-days-old) were randomized to a 3-dose PCV13 or PCV7 infant series administered double-blind at 3, 4 and 5 months or PCV13 administered open-label at 2, 4 and 6 months and a 2-dose open-label series at 3 and 5 months; all subjects received a toddler dose (12 months). Serotype-specific immunoglobulin G (IgG) concentrations were measured 1 month after the infant series and before and after the toddler dose. Opsonophagocytic activity (OPA) was measured in a subset of subjects at each time point. Safety was evaluated., Results: One month after the infant series, serotype-specific immune responses (IgG ≥ 0.35 µg/mL) were similar for the 2- versus 3-dose schedules, except for serotype 6B, which was significantly lower in the 2-dose group [70.1% in the PCV13 (3, 5 + 12 mo) group vs. 93.2% in the PCV13 (3, 4, 5 + 12 mo) group and 94.7% in the PCV13 (2, 4, 6 + 12 mo) group]. IgG geometric mean concentrations and OPA geometric mean titers trended numerically higher with 3- versus 2-dose schedules. No significant differences in immunogenicity were observed between the 3- versus 2-dose schedules after the toddler dose. PCV13 was well-tolerated across all schedules., Conclusions: PCV13 administered as a 3- or 2-dose infant series followed by a toddler dose was immunogenic and well tolerated in healthy Chinese infants and likely protective against PCV13 serotypes; immune responses with a 2-dose schedule were lower for some serotypes.

A Luminex-based direct immunoassay (dLIA) platform has been developed to replace the standardized pneumococcal enzyme-linked immunosorbent assay platform. The multiplex dLIA simultaneously measures the concentration of serum immunoglobulin G (IgG) antibodies specific for pneumococcal capsular polysaccharide (PnPS) serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F. The assay uses poly-l-lysine (PLL)-conjugated PnPS, chemically coupled to spectrally distinct Luminex microspheres. Assay validation experiments were performed using residual human serum samples obtained from 13-valent pneumococcal conjugate vaccine (13vPnC) clinical studies. Assay results are expressed as IgG antibody concentrations in micrograms per milliliter using the international reference serum, 007sp. The lower limit of quantitation (LLOQ) for all serotypes covered in the 13-plex dLIA fell within the range of 0.002 to 0.038 µg/ml serum IgG. The difference between the lower limit and upper limit of the assay range was >500-fold for all serotypes, and assay variability was <20% relative standard deviation (RSD) for all serotypes. IgG antibody measurements were shown to be serotype-specific (some cross-reactivity was observed only between the structurally related serotypes 6A and 6B as well as 19A and 19F), and no interference was observed between the serotypes when the assay was performed in the 13-plex format compared to the singleplex assays. The 13-plex dLIA platform developed by Pfizer Inc. generates up to 143 test results in a single 96-well plate and is a suitable replacement of the enzyme-linked immunosorbent assay (ELISA) platform for evaluating vaccine clinical trials. IMPORTANCE The pneumococcal enzyme-linked immunosorbent assay (ELISA) measures IgG antibodies in human serum, and it is an important assay that supports licensure of pneumococcal vaccines. The immune correlate of protection, 0.35 µg/ml of IgG antibodies, was determined by the ELISA method. Pfizer has developed a new Luminex-based assay platform to replace the ELISA. These papers describe the important work of (i) validating the Luminex-based assay and (ii) bridging the immune correlate of protection (0.35 µg/ml IgG) to equivalent values reported by the Luminex platform., (Copyright © 2018 Pavliakova et al.)

This article describes the results of a study designed to bridge the World Health Organization (WHO) pneumococcal enzyme-linked immunosorbent assay (ELISA) platform to the validated Luminex-based 13-plex direct immunoassay (dLIA) platform developed by Pfizer, Inc. Both assay platforms quantify serotype-specific serum IgG antibodies (in micrograms per milliliter) against an international reference standard serum. The primary goal of this study was to determine if the dLIA is a suitable replacement for the ELISA to support clinical vaccine studies that include the evaluation of immune responses to serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F. Serum samples were selected from four pivotal 13-valent pneumococcal conjugate vaccine (13vPnC; Prevnar 13) clinical trials on the basis of their serotype-specific IgG concentrations by ELISA. In these studies, subjects were immunized either with 13vPnC or with 7-valent pneumococcal conjugate vaccine (7vPnC; Prevnar). There were 1,528 of 1,574 selected samples with sufficient remaining volume for reanalysis in the dLIA. A comparison of assay results from the dLIA and ELISA platforms showed clear and robust linear quantitative relationships across all 13 serotypes. In addition, lower IgG antibody concentrations in preimmunization samples were measured in the dLIA, thus allowing better differentiation between preimmunization and low-titer postimmunization samples. Overall, the results showed that the established population-level protective threshold IgG concentration, 0.35 µg/ml of serotype-specific serum IgG antibodies, is appropriate for use for data generated using the dLIA platform developed by Pfizer, Inc., for 10 serotypes: serotypes 1, 3, 4, 6A, 7F, 9V, 14, 18C, 19F, and 23F. On the basis of the extensive bridging analyses, however, the use of dLIA cutoff values of 0.23, 0.10, and 0.12 µg/ml is recommended for serotypes 5, 6B, and 19A, respectively. This adjustment will ensure that the consistency of the established population-level protective threshold IgG concentration is maintained when switching from the ELISA to the dLIA platform. The results of this bridging study demonstrate that the 13-plex dLIA platform is a suitable replacement for the WHO reference ELISA platform. IMPORTANCE The pneumococcal enzyme-linked immunosorbent assay (ELISA) measures IgG antibodies in human serum, and it is an important assay that supports licensure of pneumococcal vaccines. The immune correlate of protection, 0.35 µg/ml of IgG antibodies, was determined by the ELISA method. Pfizer has developed a new Luminex-based assay platform to replace the ELISA. These papers describe the important work of (i) validating the Luminex-based assay and (ii) bridging the immune correlate of protection (0.35 µg/ml IgG) to equivalent values reported by the Luminex platform., (Copyright © 2018 Tan et al.)

The pneumococcal enzyme-linked immunosorbent assay (ELISA) reference standard serum, lot 89SF, had been in use since 1990 and was replaced with a new reference standard serum, 007sp, in 2013. This serum was generated under an FDA-approved clinical protocol where 278 adult volunteers were immunized with the 23-valent unconjugated polysaccharide vaccine Pneumovax II and a unit of blood was obtained twice within 120 days following immunization. Pooled serum was prepared from the plasma, filled at 6 ml per vial, and lyophilized. Five independent laboratories participated in bridging the serotype-specific IgG assignments of 89SF to 007sp to establish equivalent reference values for 13 pneumococcal capsular serotypes (1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 23F) using the WHO reference ELISA. A subsequent follow-up study established equivalent reference values for an additional seven serotypes (8, 10A, 11A, 12F, 15B, 22F, 33F). In this study, three laboratories assigned weight-based IgG concentrations in micrograms per milliliter of serum to 007sp for four additional serotypes: 2, 9N, 17F, and 20A. This study completes the assignment of serotypes for 89SF to 007sp. In addition, the IgG antibody assignments for a 12-member WHO quality control (QC) serum panel were extended to cover the four additional serotypes. Agreement was excellent, with a concordance correlation coefficient ( r c ) of >0.996 when values from each laboratory were compared to the assigned values for the 12 WHO QC sera. The 007sp preparation has replaced 89SF as the pneumococcal reference standard. Sufficient quantities of 007sp are projected to be available for the next 25 years., (Copyright © 2017 American Society for Microbiology.)

Objective: Prophylactic antipyretic use during pediatric vaccination is common. This study assessed whether paracetamol or ibuprofen prophylaxis interfere with immune responses to the 13-valent pneumococcal conjugate vaccine (PCV13) given concomitantly with the combined DTaP/HBV/IPV/Hib vaccine., Methods: Subjects received prophylactic paracetamol or ibuprofen at 0, 6-8, and 12-16 h after vaccination, or 6-8 and 12-16 h after vaccination at 2, 3, 4, and 12months of age. At 5 and 13months, immune responses were evaluated versus responses in controls who received no prophylaxis., Results: After the infant series, paracetamol recipients had lower levels of circulating serotype-specific pneumococcal anticapsular immunoglobulin G than controls, reaching significance (P<0.0125) for 5 serotypes (serotypes 3, 4, 5, 6B, and 23F) when paracetamol was started at vaccination. Opsonophagocytic activity assay (OPA) results were similar between groups. Ibuprofen did not affect pneumococcal responses, but significantly (P<0.0125) reduced antibody responses to pertussis filamentous hemagglutinin and tetanus antigens after the infant series when started at vaccination. No differences were observed for any group after the toddler dose., Conclusions: Prophylactic antipyretics affect immune responses to vaccines; these effects vary depending on the vaccine, antipyretic agent, and time of administration. In infants, paracetamol may interfere with immune responses to pneumococcal antigens, and ibuprofen may reduce responses to pertussis and tetanus antigens. The use of antipyretics for fever prophylaxis during infant vaccination merits careful consideration. ClinicalTrials.gov identifier: NCT01392378https://clinicaltrials.gov/ct2/show/NCT01392378?term=NCT01392378&rank=1., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Premature infants have lower short-term immune responses to vaccination than term infants, but patterns of antibody persistence in preterm infants over longer periods are not well established. This study assessed the persistence of antibody response to the 13-valent pneumococcal conjugate vaccine (PCV13) in formerly preterm versus term infants., Methods: In total, 100 preterm and 100 term infants received PCV13 with routine vaccines at ages 2, 3, 4 and 12 months. Serotype-specific anticapsular immunoglobulin G (IgG)-binding antibodies and opsonophagocytic activity were determined 1 and 2 years after the last PCV13 dose., Results: At 1 and 2 years after the last vaccination (toddler dose), IgG geometric mean concentrations (GMCs) for all serotypes had declined from levels measured 1 month after the toddler dose but remained above pretoddler dose levels. IgG GMCs were significantly lower in preterm than term subjects for a majority of serotypes at both follow-up time points. IgG GMCs increased in both groups for some serotypes from the 1-year to 2-year follow-up, whereas others declined. Opsonophagocytic activity results supported the IgG results., Conclusions: The routine (3 + 1) vaccination schedule is likely to offer long-term protection against invasive pneumococcal disease in preterm infants and should be initiated regardless of gestational age or weight at birth, without delay of the toddler dose.

Background: In a previous study, Chinese infants were vaccinated with 7-valent pneumococcal conjugate vaccine (PCV7) ⩾7days before routine diphtheria, tetanus, and acellular pertussis vaccine (DTaP); PCV7 administered concomitantly with DTaP (PCV7+DTaP); or DTaP alone. This study examined antibody persistence at a single time point 3years after the last vaccination., Methods: Children who participated in the prior PCV7 study were eligible to participate. A single blood sample was drawn at enrollment. Immunoglobulin G (IgG) geometric mean concentrations (GMCs) specific to the PCV7 serotypes and percentages of subjects with IgG ⩾0.35μg/mL were compared for subjects receiving PCV7 versus PCV7+DTaP (concomitant) and for PCV7 or PCV7+DTaP (concomitant) versus DTaP alone. IgG concentrations at 3years after the last vaccination were also compared with those after the infant series and toddler dose., Results: Three years after the last vaccination with PCV7 or PCV7+DTaP (concomitant), IgG GMCs for most PCV7 serotypes were lower than after the infant series or toddler dose but remained above prevaccination concentrations. IgG GMC were similar between the PCV7 and PCV7+DTaP (concomitant) groups for 5 out of 7 serotypes but serotypes 4 and 19F were significantly lower in the PCV7+DTaP (concomitant) recipients. Three years after the last vaccination, IgG GMCs were significantly higher for 6 of 7 PCV7 serotypes among those receiving PCV7 or PCV7+DTaP (concomitant) compared with recipients of DTaP alone. Among subjects receiving DTaP alone, serotype-specific antibody concentrations were significantly higher for all serotypes 3years after the last vaccination compared with after the infant series., Conclusion: Three years after PCV7 vaccination, serotype-specific antibodies were lower than after the primary infant series but higher than prevaccination levels and higher among subjects who received PCV7 compared with those who did not. The immune response was comparable in children who received PCV7 with and without concomitant DTaP., Clinical Trial Registration: NCT01298544., (Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Immunogenicity and safety of 13-valent pneumococcal conjugate vaccine (PCV13) were compared with 7-valent pneumococcal conjugate vaccine (PCV7) in Chinese infants., Methods: Healthy infants aged 2 months were randomized to a double-blind 3-dose infant series plus 1 toddler dose of PCV7 or PCV13 at 3, 4, 5 and 12 months or open-label PCV13 at 2, 4, 6 and 12 months. Serotype-specific immunoglobulin G (IgG) binding and functionality were measured 1 month after the infant series and after the toddler dose. Local reactions, systemic events and adverse events were assessed postvaccination., Results: For the 7 common serotypes, serotype-specific binding IgGs elicited by PCV13 were noninferior to PCV7 after the 3-dose infant series; functional antibodies were comparable. For the 6 additional serotypes, PCV13 recipients had significantly higher serotype-specific IgGs and functional antibodies than PCV7 recipients after the infant series. The toddler dose boosted the immune response. Local reactions and systemic events were mild in severity and similar across groups. No new safety signals were identified., Conclusions: For the 7 common serotypes, serotype-specific binding IgG after 2 different 3-dose regimens of PCV13 were noninferior to PCV7 responses. PCV13 recipients had significantly higher immune responses to the 6 additional serotypes. PCV13 is expected to provide pneumococcal disease protection comparable to PCV7 for the common serotypes and further protection against disease caused by the 6 additional serotypes. Safety of PCV7 and PCV13 was comparable.

The pneumococcal enzyme-linked immunosorbent assay (ELISA) reference standard serum, lot 89SF, has been in use since 1990 and was replaced in 2013 with a new reference standard, 007sp, that is projected to be available for the next 25 years. 007sp was generated under an FDA-approved clinical protocol; 278 adult volunteers were immunized with the 23-valent unconjugated polysaccharide vaccine Pneumovax II, and a unit of blood was obtained twice from each immunized subject within 120 days following immunization. Pooled serum was prepared from the plasma of 262 subjects, filled at 6 ml per vial, and lyophilized. Five independent laboratories participated in bridging the serotype-specific IgG assignments for 89SF to the new reference standard, 007sp, to establish equivalent reference values for 13 pneumococcal capsular serotypes (1,3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F) by using the WHO reference ELISA. In a second study involving three laboratories, a similar protocol was used to assign weight-based IgG concentrations in micrograms per ml to 007sp of seven serotypes (8, 10A, 11A, 12F, 15B, 22F, and 33F) also present in the 23-valent pneumococcal unconjugated polysaccharide vaccine. In addition, the IgG assignments for a 12-member WHO quality control (QC) serum panel were also extended to cover these seven serotypes. Agreement was excellent, with a concordance correlation coefficient (r(c)) of >0.996 when each laboratory was compared to the assigned values for the 12 WHO QC serum samples. There are four remaining pneumococcal serotypes (2, 9N, 17F, and 20) found in Pneumovax II for which IgG assignments exist for 89SF and remain to be bridged., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Background: Life-threatening Streptococcus pneumoniae infections often occur after hematopoietic stem cell transplant (HSCT); vaccination is important for prevention., Methods: In an open-label study, patients (n = 251) 3-6 months after allogeneic HSCT received 3 doses of 13-valent pneumococcal conjugate vaccine (PCV13) at 1-month intervals, a fourth dose 6 months later, and 1 dose of 23-valent pneumococcal polysaccharide vaccine (PPSV23) 1 month later. Immunogenicity at prespecified time points and vaccine safety were assessed., Results: In the evaluable immunogenicity population (N = 216; mean age, 37.8 years), geometric mean fold rises (GMFRs) of immunoglobulin G geometric mean concentrations from baseline to postdose 3 showed significant increases in antibody levels across all PCV13 serotypes (GMFR range, 2.99-23.85; 95% confidence interval lower limit, >1); there were significant declines over the next 6 months, significant increases from predose 4 to postdose 4 (GMFR range, 3.00-6.97), and little change after PPSV23 (GMFR range, 0.86-1.12). Local and systemic reactions were more frequent after dose 4. Six patients experienced serious adverse events possibly related to PCV13 (facial diplegia, injection-site erythema and pyrexia, autoimmune hemolytic anemia, and suspected lack of vaccine efficacy after dose 3 leading to pneumococcal infection), PCV13 and PPSV23 (Guillain-Barré syndrome), or PPSV23 (cellulitis). There were 14 deaths, none related to study vaccines., Conclusions: A 3-dose PCV13 regimen followed by a booster dose may be required to protect against pneumococcal disease in HSCT recipients. Dose 4 was associated with increased local and systemic reactions, but the overall safety profile of a 4-dose regimen was considered acceptable., Clinical Trials Registration: NCT00980655., (© The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America.)

Background: This postlicensure study was conducted to assess immunogenicity and safety of PCV7 catch-up regimens in previously unvaccinated older infants and young children in China., Methods: Healthy children 121 days to <72 months were grouped by age and immunized with 1 of 4 PCV7 dosing regimens. Serotype-specific IgG geometric mean concentrations (GMCs) and percentage of subjects with IgG≥0.35μg/mL were assessed before vaccination and 1 and 12 months postvaccination. The incidence of clinically important adverse events (AEs) and serious AEs (SAEs), AEs leading to study withdrawal, and protocol-related AEs were assessed throughout the study., Results: Prevaccination serotype-specific GMCs were generally low in subjects <24 months; the majority of children 24 to <72 months had IgG concentrations ≥0.35 μg/mL. One month postvaccination, GMCs were similar across groups for the 7 PCV serotypes, ranging from 3.95 to 13.02 μg/mL; the highest antibody levels were observed for serotype 14. Regardless of dosing regimen, >90% of subjects had IgG≥0.35 μg/mL for each PCV serotype. At 12-month follow-up, IgG GMCs ranged from 0.65 to 5.19, and all remained above prevaccination IgG GMC; >70% of subjects had IgG≥0.35 μg/mL. Older children generally had the most robust immune response both at 1 month postvaccination and during 12-month follow-up. PCV7 was well tolerated. Pyrexia, which was mild to moderate in severity, was the most common AE. Two subjects reported SAEs (n=4), and there was 1 study withdrawal; none of these were considered treatment related., Conclusion: In China, PCV7 catch-up vaccinations given to older infants and young children naive to pneumococcal vaccines resulted in a robust immune response to all serotypes; this response persisted after 1 year. PCV7 was well tolerated in Chinese infants and children., (Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objectives: This study evaluated the immune response and safety profile of 13-valent pneumococcal conjugate vaccine (PCV13) in preterm infants compared with term infants., Methods: This Phase IV, open-label, 2-arm, multicenter, parallel-group study enrolled 200 healthy infants (preterm, n = 100; term, n = 100) aged 42 to 98 days. All subjects received PCV13 at ages 2, 3, 4 (infant series), and 12 (toddler dose [TD]) months, together with routine vaccines (diphtheria-tetanus-acellular pertussis, hepatitis B, inactivated poliovirus, and Haemophilus influenzae type b vaccine and meningococcal group C conjugate vaccine)., Results: Most subjects achieved an anticapsular immunoglobulin G (IgG) antibody concentration ≥ 0.35 μg/mL for all serotypes: >85% after the infant series (except preterm infants for serotypes 5, 6A, and 6B) and >97% after TD (except for serotype 3). Preterm infants had overall lower IgG geometric mean concentrations compared with term infants; however, geometric mean fold increases after TD were similar for all serotypes. Opsonophagocytic activity results were consistent with IgG results and titers increased after TD in both groups for all serotypes, including serotype 3. PCV13 was generally well tolerated, with similar safety profiles in all preterm subgroups., Conclusions: Immune responses were lower in preterm infants than in term infants. However, the majority of subjects in both groups achieved both pneumococcal serotype-specific IgG antibody levels after the infant series that exceeded the World Health Organization-established threshold of protection and functional antibody responses. Responses were uniformly higher after TD, reinforcing the importance of a timely booster dose. PCV13 was well tolerated regardless of gestational age., (Copyright © 2015 by the American Academy of Pediatrics.)

Background: Streptococcus pneumoniae infections are a major cause of morbidity and mortality in children <5 years old worldwide. To increase serotype coverage globally, a 13-valent pneumococcal conjugate vaccine (PCV13) has been developed and approved in many countries worldwide., Objective: Assess the safety and immunogenicity of PCV13 in healthy older infants and children naïve to previous pneumococcal vaccination., Methods: This was a phase 3, open-label, multicenter study conducted in Polish children (N=354) who were vaccinated according to 3 age-appropriate catch-up schedules: Group 1 (aged 7 to <12 months) received two PCV13 doses with a booster at 12-16 months of age; Group 2 (aged 12 to <24 months) received two vaccine doses only; and Group 3 (aged 24 to <72 months) received a single dose of PCV13. Statistical analyses were descriptive. The proportion of immunological "responders" achieving serotype-specific antipneumococcal polysaccharide concentrations ≥0.35μg/mL, 1-month after the last dose of vaccine, was determined for each vaccine serotype. In addition, antipolysaccharide immunoglobulin (Ig) G geometric mean concentrations (GMCs) were calculated. Safety assessments included systemic and local reactions, and adverse events., Results: The proportion of immunological responders was ≥88% across groups for all serotypes. Antipolysaccharide IgG GMCs were generally similar across groups. Each schedule elicited immune response levels against all 13 serotypes comparable to or greater than levels previously reported in infants after a 3-dose series. The 3 catch-up schedules had similar tolerability and safety profiles; a trend was present towards greater local tenderness with increasing age and subsequent dose administration., Conclusions: Immunological responses and safety results support the use of PCV13 for catch-up schedules in older infants and children naïve to pneumococcal vaccination., (Copyright © 2015. Published by Elsevier Ltd.)

Background: Polysorbate 80 (P80), a nonionic detergent used to solubilize proteins, is used in both oral and injectable medications including vaccines. Development studies with 13-valent pneumococcal conjugate vaccine (PCV13) showed that adding P80 resulted in a more robust manufacturing process. Before adding P80 to the formulation of PCV13, we investigated the immunogenicity and safety of PCV13 with and without P80., Methods: Phase 3, parallel-group, randomized, active-controlled, double-blind multicenter trial was conducted at 15 sites in Poland. Healthy infants were randomized (1:1) to receive PCV13+P80 or PCV13 without P80 given at ages 2, 3, 4 and 12 months concomitantly with DTaP-IPV-Hib at 2, 3 and 4 months; hepatitis B at 2 months and measles, mumps, and rubella at 12 months. Serotype-specific antipneumococcal immune responses were evaluated using antipolysaccharide capsular immunoglobulin (Ig)G responses and opsonophagocytic activity (OPA) assay. Safety data were also collected., Results: The 2 treatment groups were demographically similar. Following the infant immunization series, anticapsular IgG antibody geometric mean concentrations and OPA geometric mean titers for each serotype were within 2-fold between the 2 groups. Formal noninferiority criteria for comparison of proportion of responders (subjects with IgG titers ≥0.35 μg/mL) were met for 11 of the 13 serotypes. Overall population responses were highly similar. Anticapsular IgG responses were also within 2-fold following the toddler dose. Safety profiles were similar between the 2 groups., Conclusions: Addition of P80 to PCV13 did not adversely affect PCV13 immunogenicity or safety when compared with vaccine formulated without P80.

Background: Given the concurrent administration of multiple vaccines during routine pediatric immunizations, efforts to elucidate the potential interference of any vaccine on the immune response to the concomitantly administered antigens are fundamental to prelicensure clinical research., Methods: This phase 3 randomized controlled trial of 13-valent pneumococcal conjugate vaccine (PCV13) versus 7-valent PCV (PCV7) assessed immune responses of concomitantly administered meningococcal group C conjugated to diphtheria toxin cross-reactive material 197 (MnCCV-CRM197) in a 2-dose infant series and 15-month toddler dose., Results: 619 subjects were randomized, 315 to PCV13 and 304 to PCV7. MnCCV-CRM197-induced immune responses were similar between the PCV13 and PCV7 groups, with >97% of the subjects achieving a ≥1:8 meningococcal serum bactericidal assay (SBA) titer after both dose 2 and the toddler dose. Geometric mean titers were lower in the PCV13 group 191.22 (167.72, 218.02) versus 266.19 (234.86, 301.71) following dose 2 and 432.28 (361.22, 517.31) versus 730.84 (642.05, 831.91) following the toddler dose. The geometric mean (GM) meningococcal SBA titer ratios (PCV13/PCV7) were 0.72 after dose 2 and 0.59 after the toddler dose. The criteria for MnCCV-CRM197 non-inferiority for GM titers were satisfied after dose 2. Percent responders was similar up to titers of 1:128. PCV13 elicited substantial antipneumococcal responses against all 13 serotypes, with ≥90% of the subjects achieving an antibody concentration ≥0.35μg/mL after dose 3 in the infant series. Safety and tolerability were similar between the vaccine groups., Conclusions: Immunogenicity results of MnCCV-CRM197 for PCV13 compared with PCV7 included lower GMTs, but the clinical significance of this is unknown as the proportion of infants achieving protective MenC antibody titers was comparable in the two groups. Percent responders were similar up to titers of 1:128. PCV13 has an acceptable safety profile in infants and toddlers, while providing expanded coverage against pneumococcal disease., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Background: A 13-valent pneumococcal conjugate vaccine (PCV13) containing 6 additional serotypes not included in the 7-valent PCV has been developed to broaden protection against Streptococcus pneumoniae, which is responsible for over 500,000 deaths annually worldwide in children <5 years of age. This study in Japanese infants evaluated the immunogenicity and safety of PCV13 given subcutaneously, the standard route for infant vaccination in Japan., Methods: This phase 3, single-arm, open-label study was conducted at 25 sites. Subjects received PCV13 as a 3-dose infant series and a toddler dose. Parents/legal guardians recorded local reactions and systemic events after each vaccination. The proportion of subjects with serotype-specific antipneumococcal polysaccharide immunoglobulin (Ig)G antibody concentrations ≥0.35 µg/mL was calculated before and 1 month after the infant series and toddler dose., Results: A total of 193 subjects enrolled. The proportion of subjects achieving pneumococcal IgG antibody concentrations ≥0.35 µg/mL was ≥97.2% for all 13 pneumococcal serotypes 1 month after the infant series and 98.9-100% after the toddler dose. IgG geometric mean concentrations were 2.57-14.69 µg/mL after the infant series and 2.06-16.33 µg/mL after the toddler dose. IgG geometric mean concentrations increased from pre- to posttoddler dose by ≥2.8-fold, demonstrating a booster effect. Local reactions and fever were generally mild or moderate in severity., Conclusions: PCV13 was immunogenic for all serotypes and had a favorable safety profile when administered subcutaneously to Japanese infants. PCV13 should offer broader serotype protection than 7-valent PCV in preventing pneumococcal disease in Japanese children.

Objective: To assess the safety and immune responses induced by a 13-valent pneumococcal conjugate vaccine (PCV13) after immunization of infants in Mexico., Methods: PCV13 was given with other routine childhood vaccinations to 225 infants in Mexico at ages 2, 4, 6, and 12 months., Results: The proportions of subjects achieving immunoglobulin G (IgG) concentrations ≥0.35 µg/mL after the infant series and toddler dose were ≥93.1% and ≥96.7%, respectively, for all 13 serotypes. The serotype-specific pneumococcal IgG geometric mean concentrations after the infant series and toddler dose ranged from 1.18 to 9.13 µg/mL and from 1.62 to 15.41 µg/mL, respectively. The most common local reaction and systemic event after each dose were tenderness and irritability, respectively. Most fever was mild; no fever >40.0°C (i.e., severe) was reported. One subject withdrew because of Kawasaki disease 5 days after the first dose of vaccines, but this condition was not considered related to PCV13., Conclusions: Overall, PCV13 administered with routine pediatric vaccines was immunogenic and safe in healthy infants in Mexico.

Background: The immunogenicity and safety of 13-valent and 7-valent pneumococcal conjugate vaccines (PCV13 and PCV7) were compared when administered with routine vaccines in Korea., Methods: Healthy infants (n = 180) were randomly assigned (1:1) to receive PCV13 or PCV7 at 2, 4, 6 (infant series) and 12 months (toddler dose). Immune responses 1 month after the infant series and toddler dose were measured by enzyme-linked immunosorbent assay and opsonophagocytic activity (OPA) assay. IgG antibody geometric mean concentrations and OPA functional antibody geometric mean titers were calculated. Safety was assessed., Results: After the infant series, for the 7 common serotypes, proportions of responders with IgG concentrations ≥0.35 µg/mL were comparable (≥97.6%) between groups; IgG geometric mean concentrations and OPA geometric mean titers were generally similar, but tended to be lower in the PCV13 group for some serotypes. For the 6 serotypes unique to PCV13, IgG geometric mean concentrations and OPA geometric mean titers were notably higher in the PCV13 group. Importantly, although PCV7 elicited IgG antibodies to PCV13 serotypes 5 and 19A, OPA responses were minimal, whereas serotype 6A elicited both IgG and OPA responses. These observations are consistent with at least some protection by PCV7 against 6A-mediated invasive pneumococcal disease, but no cross-protection for serotypes 5 and 19A. The toddler dose elicited higher IgG and OPA responses than postinfant series responses for most serotypes; however, for serotypes 3 and 14 only OPA responses were increased posttoddler dose. Vaccine safety profiles were similar., Conclusions: PCV13 is safe and immunogenic in Korean children. PCV13 should provide broader protection than PCV7.

A randomized, double-blind, phase 3 trial evaluated the immunogenicity, safety, and tolerability of a 13-valent pneumococcal conjugate vaccine (PCV13) coadministered with trivalent inactivated influenza vaccine (TIV) in pneumococcal vaccine-naive adults. Participants ages 50 to 59 years (n = 1,116) received TIV with PCV13 (group 1) or placebo (group 2) (1:1 randomization); 1 month later, group 1 received placebo and group 2 received PCV13. A hemagglutination inhibition (HAI) assay for TIV and a standardized enzyme-linked immunosorbent assay for pneumococcal serotype-specific immunoglobulin G (IgG) were performed and opsonophagocytic activity (OPA) titers (assessed post hoc) were measured at baseline and 1 and 2 months postvaccination. The rises in HAI assay geometric mean titer (GMT) and percentage of participants in groups 1 and 2 with ≥ 4-fold increases in HAI responses (A/H1N1, 84.0% and 81.2%, respectively; A/H3N2, 71.1% and 69.5%, respectively; and B, 60.6% and 60.3%, respectively) were similar. In group 1, all serotypes met the predefined IgG geometric mean concentration (GMC) ratio noninferiority criterion relative to group 2, but GMCs were lower in group 1 than group 2. When comparing group 1 with group 2, 5 serotypes did not meet the OPA GMT ratio noninferiority criterion, and OPA GMTs were significantly lower for 10 serotypes. PCV13 injection site reactions were similar and mostly mild in both groups. Systemic events were more frequent in group 1 (86.2%) than group 2 (76.7%; P < 0.001); no vaccine-related serious adverse events occurred. Coadministration of PCV13 and TIV was well tolerated but associated with lower PCV13 antibody responses and is of unknown clinical significance. Given the positive immunologic attributes of PCV13, concomitant administration with TIV should be dictated by clinical circumstances.

Neisseria meningitidis serogroup B (MnB) is a significant cause of invasive meningococcal disease, but no broadly protective vaccine is yet approved. We assessed the safety and immunogenicity of a bivalent MnB vaccine composed of lipidated subfamily A and B variants of recombinant LP2086 (rLP2086, also known as factor H binding protein, fHBP). Forty-eight adults, ages 18-40 y, were randomized to receive 60, 120 or 200 μg of the bivalent rLP2086 vaccine or control at 0, 2 and 6 mo. Immunogenicity was assessed by rLP2086-specific immunoglobulin G (IgG) geometric mean titers for subfamily A and B proteins. Safety was determined by laboratory assessments of blood and urine and by reporting of solicited and unsolicited adverse events (AEs). The bivalent rLP2086 vaccine elicited high IgG titers following the second and third vaccination at all dose levels. In each of the four study arms, 11 of the 12 participating subjects reported ≥ 1 AE, and no serious AEs were reported. Local and systemic reactions were mainly mild to moderate. Laboratory abnormalities (including increased sodium, decreased neutrophils, and proteinuria) were not associated with clinical events and were not considered to be related to the study vaccine. Vaccinations were generally well-tolerated. Strong IgG antibody responses and the absence of clinically significant laboratory abnormalities support further development of the bivalent rLP2086 vaccine (www.clinicaltrials.gov; identifier: NCT00879814).

Recombinant forms of Neisseria meningitidis factor H binding protein (fHBP) are undergoing clinical trials in candidate vaccines against serogroup B meningococcal disease. Little is known, however, about the host response to fHBP during natural carriage and disease. Here we report a longitudinal study of the antibody response to fHBP in healthy meningococcal carriers and non-carriers, and in patients with invasive meningococcal disease. Using a highly sensitive quantitative immunoassay, anti-fHBP antibodies were detected in sera from all healthy carriers and non-carriers. Carriers had significantly higher anti-fHBP antibody concentrations than non-carriers. Antibody responses similar to those seen in non-carrier subjects were detected in the sera of patients with invasive disease upon their admission to the hospital. The serum anti-fHBP antibody concentrations in these patients generally rose to reach levels similar to those seen in carriers. No correlation between levels of surface fHBP expressed in vitro by the infecting N. meningitidis strain and the magnitude of antibody responses was observed. These data suggest that fHBP is expressed in vivo during both carriage and invasive disease at levels high enough to elicit a robust antibody response., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The capsular polysaccharide of Neisseria meningitidis serogroup W135 is expressed in both O-acetyl-positive (OA+) and O-acetyl-negative (OA-) forms. This study investigates the impact of OA status (OA+ versus OA-) on serological measurements of anti-W135 immunoglobulin G (IgG) antibodies in immunized adults. W135-specific serum antibody assignments were made for 28 postimmunization sera from adults by enzyme-linked immunosorbent assay using the meningococcal standard reference serum CDC1992. The established IgG concentration in micrograms per milliliter ([IgG]microg/ml) for CDC1992 against OA+ antigen (16.2 microg/ml) was used as a reference to assign a concentration of 10.13 microg/ml IgG against OA- antigen by cross-standardization. Overall, the IgG assignments for these sera were higher against OA+ antigen (geometric mean concentration [GMC] = 7.16 microg/ml) than against OA- antigen (GMC = 2.84 microg/ml). However, seven sera showed higher specific [IgG]microg/ml values against the OA+ antigen than against the OA- antigen. These sera were also distinguished by the inability of fluid-phase OA- antigen to compete for antibody binding to OA+ solid-phase antigen. Although there was no overall difference in functional activity measured by complement-mediated serum bactericidal assay (SBA) against OA+ and OA- target bacteria (geometric mean titers of 9,642 and 9,045, respectively), three serum specimens showed a large difference in SBA antibody titers against OA+ versus OA- W135 target bacteria, which may reflect different epitope specificities for these sera. Our data indicate that, for some sera, the agreement in anti-OA+ versus anti-OA- W135 IgG assignments is serum specific and does not reflect the functional (killing) activity in vitro.

Human sera collected from 28 consenting adult volunteers were used to define assay conditions for meningococcal vaccine clinical trial serology. Immunoassay parameters were optimized with these test sera and the standard reference serum, CDC1992. Coating conditions for serogroup Y and W135 polysaccharide antigens were found to influence the predicted serum immunoglobulin G (IgG) antibody concentrations. Sera that displayed IgG antibody binding profiles most unlike that of CDC1992 were influenced the most by coating conditions. Our results suggest that presentation of specific epitopes is influenced by antigen-coating concentrations for serogroup Y and W135 polysaccharides.

To facilitate studies of the molecular determinants of host-meningococcal lipooligosaccharide (endotoxin) interactions at patho-physiologically relevant endotoxin concentrations (i.e. < or =10 ng/ml), we have generated acetate auxotrophs NMBACE1 from encapsulated Neisseria meningitidis (serogroup B, strain NMB) and NMBACE2 from an isogenic bacterial mutant lacking the polysialic acid capsule. Growth of the auxotrophs in medium containing [(14)C]acetate yielded (14)C-lipooligosaccharides containing approximately 600 cpm/ng. Gel sieving resolved 14C-lipooligosaccharide-containing aggregates with an estimated molecular mass of > or =20 x 10(6) Da (peak A) and approximately 1 x 10(6) Da (peak B) from both strains. Lipooligosaccharides in peaks A and B had the same fatty acid composition and SDS-polyacrylamide gel electrophoresis profile. 14C-Labeled capsule copurified with (14)C-lipooligosaccharides in peak B from NMBACE1, whereas the other aggregates contained only 14C-lipooligosaccharide. For all aggregates, lipopolysaccharide-binding protein and soluble CD14-induced delivery of lipooligosaccharides to endothelial cells and cell activation correlated with disaggregation of lipooligosaccharides. These processes were inhibited by the presence of capsule but unaffected by the size of the aggregates. In contrast, endotoxin activation of cells containing membrane CD14 was unaffected by capsule but diminished when endotoxin was presented in larger aggregates. These findings demonstrate that the physical presentation of lipooligosaccharide, including possible interactions with capsule, affect the ability of meningococcal endotoxin to interact with and activate specific host targets.

The Gram-negative pathogen Neisseria meningitidis, is one of the leading causes of bacterial meningitis worldwide (1). The host range for this organism is restricted to humans, where it colonizes the mucosal epithelium of the upper airway. It occasionally disseminates causing invasive disease (sepsis, disseminated intravascular coagulation [DIC], meningitis). Epidemic meningococcal meningitis is a major health problem, most notably in sub-Saharan Africa. In 1999, an outbreak of meningococcal disease spread across Guinea-Bissau, a region that is part of what is commonly called the African meningitis belt (2). There were 2,169 reported cases and 404 deaths resulting from meningococcal disease in this outbreak from Jan. 1 to April 5, 1999. Also in 1999, there were reported outbreaks in Sudan (22,000 cases and 1,600 deaths) Rwanda (29 cases and 11 deaths), Angola (253 cases and 147 deaths), Ethiopia (126 cases and 4 deaths) and Senegal (2,709 cases and 372 deaths) (2). According to the World Health Organization (WHO), each year approx 500,000 cases of meningitis and 50,000 deaths are attributable to N. meningitidis worldwide. In the United States, meningococcal disease is less common, although small outbreaks are reported each year (3).

The invasion of epithelial cells by N. gonorrheae is accompanied by formation of a halo of actin filaments around the enveloped bacterium. The transfer of the bacterial major outer membrane protein, porin, to the host cell membrane during invasion makes it a candidate for a facilitator for the formation of this halo. Western analysis shows here that gonococcal porin P.IB associates with the actin cytoskeleton in infected cells. Using the pyrene-labeled Mg forms of yeast and muscle actins, we demonstrate that under low ionic strength conditions, P.IB causes formation of filamentous actin assemblies, although they, unlike F-actin, cannot be internally cross-linked with N,N'-4-phenylenedimaleimide (PDM). In F-buffer, low porin concentrations appear to accelerate actin polymerization. Higher P.IB concentrations lead to the formation of highly decorated fragmented F-actin-like filaments in which the actin can be cross-linked by PDM. Co-assembly of P.IB with a pyrene-labeled mutant actin, S(265)C, prevents formation of a pyrene excimer present with labeled S(265)C F-actin alone. Addition of low concentrations of porin to preformed F-actin results in sparsely decorated F-actin. Higher P.IB concentrations extensively decorate the filaments, thereby altering their morphology to a state like that observed when the components are copolymerized. With preformed labeled S(265)C F-actin, P.IB quenches the pyrene excimer. This decrease is prevented by the F-actin stabilizers phalloidin and to a lesser extent beryllium fluoride. P.IB's association with the actin cytoskeleton and its ability to interact with and remodel actin filaments support a direct role for porin in altering the host cell cytoskeleton during invasion.

Gonococcal entry into primary human urethral epithelial cells (HUEC) can occur by macropinocytosis. Scanning and transmission electron microscopy revealed lamellipodia surrounding gonococci, and confocal laser scanning microscopy analysis showed organisms colocalized with M(r) 70,000 fluorescein isothiocyanate-labeled dextran within the cells. Phosphoinositide 3-kinase inhibitors and an actin polymerization inhibitor prevented macropinocytic entry of gonococci into HUEC.

The pathogenic Neisseria species induce cytoskeletal reorganization in immortalized cell lines. In Chang conjunctival epithelium and T84 intestinal epithelium, focal cytoskeletal rearrangements in which bacteria contacted the epithelial surface were observed. We show that actin footprints are induced in gonococcus-challenged primary urethral epithelium. Moreover, the microbes induced microvillus extension from the epithelial cell surface. Our results indicate that formation of actin footprints is not an artifact of commonly used immortalized cell lines.

We previously cloned a B. bronchiseptica (Bb) genomic DNA fragment that complements a Bb alcaligin biosynthesis mutant, and reported the identification of a gene, alcA, with predicted protein sequence similarity to siderophore biosynthesis enzymes from other organisms. In the present study we show that further nt sequencing of this region revealed two open reading frames (ORFs) 3' to alcA that encode putative proteins AlcB and AlcC, with significant sequence similarity to the aerobactin biosynthesis enzymes IucB and IucC, respectively. RT-PCR analysis indicated that the three ORFs are encoded on a single transcript, and that this operon is repressed at the transcriptional level by Fe. Primer extension analysis placed the transcriptional start point (tsp) 35 nt from the 5' end of the Fur consensus sequence and 188 nt from the putative start of translation of AlcA.

The alcA gene, essential for the production of the dihydroxamate siderophore, alcaligin, by Bordetella bronchiseptica, was cloned and sequenced. The alcA gene was identified on a 4.7-kb EcoRI genomic fragment adjacent to a Tn5lac transposon insertion that inactivated alcaligin production in strain MBORD846. Analysis of the alcA nucleotide sequence revealed a putative Fur-binding site, suggesting that expression of this gene is repressed by iron. The deduced amino-acid sequence of this open reading frame had significant homology with the Escherichia coli iucD gene product, an enzyme required for biosynthesis of the dihydroxamate siderophore aerobactin.

Recent studies have shown that Bordetella bronchiseptica utilizes a siderophore-mediated transport system for acquisition of iron from the host iron-binding proteins lactoferrin and transferrin. We recently identified the B. bronchiseptica siderophore as alcaligin, which is also produced by B. pertussis. Alcaligin production by B. bronchiseptica is repressed by exogenous iron, a phenotype of other microbes that produce siderophores. In this study, we report that alcaligin production by B. bronchiseptica RB50 and GP1SN was repressed by the Bordetella global virulence regulator, bvg, in addition to being Fe repressed. Modulation of bvg locus expression with 50 mM MgSO4 or inactivation of bvg by deletion allowed strain RB50 to produce alcaligin. In modulated organisms, siderophore production remained Fe repressed. These observations contrasted with our previous data indicating that alcaligin production by B. bronchiseptica MBORD846 and B. pertussis was repressed by Fe but bvg independent. Despite bvg repression of alcaligin production, strain RB50 was still able to acquire Fe from purified alcaligin, suggesting that expression of the bacterial alcaligin receptor was not repressed by bvg. We tested 114 B. bronchiseptica strains and found that bvg repression of alcaligin production was strongly associated with Bordetella phylogenetic lineage and with host species from which the organisms were isolated.

Sequence analysis of the variable regions of the heavy and light chains of the anti-idiotypic antibody 6F9, which mimics the meningococcal group C capsular polysaccharide (MCP), was performed. The immunogenic site on 6F9 responsible for inducing an anti-MCP antibody response was determined by means of sequence and computer model analysis of these data. Complementarity-determining region 3 (CDR3) was found to be unique in that the sequence tract YRY was exposed on the surface. A synthetic peptide spanning the CDR3 domain was synthesized and complexed to proteosomes (meningococcal group B outer membrane protein). Immunizations of BALB/c mice with the peptide-proteosome complex resulted in a significant anti-MCP antibody response. Immunized mice were protected against infection with a lethal dose of Neisseria meningitidis serogroup C.

We have developed a monoclonal anti-idiotypic antibody, designated 6F9, which acts as the surrogate image of the meningococcal group C capsular polysaccharide (MCP). Murine immunization with 6F9 results in a T-dependent anti-MCP antibody response. To examine the protective nature of the antibody response elicited by 6F9 we performed a series of live challenge studies using a murine model for meningococcal infection in which mice were iron dextran treated and challenged with 10 x LD50 of meningococcal group C strain 35E. Adult BALB/c mice immunized with 6F9 had a 100% survival and a significantly reduced level of bacteremia at 24 h. Mice immunized with MCP had an 80% survival rate, all survivors were bacteremic at 24 h. Neonatal mice primed within 24 h of birth and immunized at 4 weeks of age with 6F9 had a 100% survival and cleared their bacteremia by 8 h, which was significantly faster than the MCP primed and immunized mice. Neonatal mice primed with 6F9 and challenged at 5 weeks of age had a survival rate of 90% which was significantly higher than mice primed with MCP and the control group (60% and 50% survival, respectively). Mice primed at birth and immunized at 8 days had a 100% survival and 90% of these mice had sterile blood cultures by 8 h. Mice primed and immunized with MCP all remained bacteremic at 24 h. These data indicate that the anti-Id 6F9 which mimics the capsular polysaccharide of group C meningococci is capable of inducing protective immunity in immunologically mature as well as immature animals.

Idiotype vaccines are proteins which may offer an alternative strategy for the conversion of a thymus-independent antigen into a thymus-dependent immunogen. To examine this question, we have studied the nature of the immune response to a monoclonal anti-idiotypic antibody, designated 6F9, which acts as a surrogate of Neisseria meningitidis serogroup C capsular polysaccharide, and compared this response to the nominal antigen, the meningococcal C-polysaccharide (MCP). BALB/c mice immunized with an optimal dose (100 micrograms) of 6F9 generate a specific anti-MCP IgG response which is maximal after 4 weeks. Secondary immunization with 6F9 results in a three- to five-fold increase in the specific IgG response. Mice given an optimal immunizing dose of MCP (5 micrograms) failed to generate an anti-MCP IgG response. No secondary response is detectable in mice immunized with MCP. Animals immunized with 6F9 and subsequently challenged with live meningococci group C show a significant anti-MCP IgG response. BALB/c nu/nu mice fail to generate an anti-MCP IgG antibody response to 6F9, while the nu/+ controls generate an anti-MCP IgG antibody titer 100 times that of the MCP-immunized mice. Neonatal mice that failed to respond to MCP developed early IgM and a subsequent IgG anti-MCP response after immunization with 6F9. These data demonstrate that the anti-idiotype 6F9, the combining site of which contains a surrogate image of the meningococcal group C capsular polysaccharide, evokes the responses expected of a T-dependent antigen.