Serotype-specific IgG Antibody Research Articles

Long-term antibody trajectories after PPSV23 in elderly: Results from a 4-year follow-up study.

The 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended for standalone or sequential use in the elderly in many countries to prevent pneumococcal disease, making it crucial to assess vaccine response and long-term persistence. We aimed to describe the trajectories of circulating antibody levels to the PPSV23 in the elderly following immunization. Eligible individuals aged 65 to 70years were enrolled and vaccinated with one dose of PPSV23. Blood samples were collected at baseline (day 0), 4-6weeks, one year, two years, three years, and four years after vaccination from November 2019 to December 2023. Serotype-specific IgG antibodies were measured for 7(4,6B,9V,14,18C,19F and 23F) out of the 23 vaccine serotypes. Group-based trajectory modeling (GBTM) was applied to identify distinct trajectories of IgG concentration at each visit after immunization. A total of 237 participants completed all six visits over the four-year follow-up period, and the geometric mean concentrations (GMC) of antibodies against the seven serotypes remained elevated above the baseline levels by the fourth year. Females and those with a body mass index (BMI) over 25 have generally higher antibody levels pre- and post-immunization across the seven serotypes, with serotypes 6B, 18C show significant difference in higher BMI individuals, and serotype 9V show significant difference in females after immunization. Based on GBTM, we identified two or three distinct trajectory types of IgG concentration changes across serotypes, with the exception of serotype 4, and we found that participants who showed a more rapid decline in antibody levels two years after vaccination had significantly higher baseline antibody levels. Pneumococcal IgG antibody levels persist for a minimum of four years post-vaccination; Our findings indicate that BMI, gender, and pre-vaccination antibody concentrations should be considered when developing vaccination and revaccination strategies in the elderly.

Safety and Immunogenicity of a 4-Component Generalized Modules for Membrane Antigens Shigella Vaccine in Healthy European Adults: Randomized, Phase 1/2 Study.

We report data from stage 1 of an ongoing 2-staged, phase 1/2 randomized clinical trial with a 4-component generalized modules for membrane antigens-based vaccine against Shigella sonnei and Shigella flexneri 1b, 2a, and 3a (altSonflex1-2-3; GSK). Europeans aged 18-50 years (N = 102) were randomized (2:1) to receive 2 injections of altSonflex1-2-3 or placebo at 3- or 6-month interval. Safety and immunogenicity were assessed at prespecified time points. The most common solicited administration-site event (until 7 days after each injection) and unsolicited adverse event (until 28 days after each injection) were pain (altSonflex1-2-3, 97.1%; placebo, 58.8%) and headache (32.4%; 23.5%), respectively. All serotype-specific functional IgG antibodies peaked 14-28 days after injection 1 and remained substantially higher than prevaccination at 3 or 6 months postvaccination; the second injection did not boost but restored the initial immune response. The highest seroresponse rates (≥4-fold increase in titers over baseline) were obtained against S. flexneri 2a (enzyme-linked immunosorbent assay [ELISA] after injection 1, 91.0%; after injection 2 [day 113; day 197], 100%; 97.0% and serum bactericidal activity [SBA] after injection 1, 94.4%; after injection 2, 85.7%; 88.9%) followed by S. sonnei (ELISA after injection 1, 77.6%; after injection 2, 84.6%; 78.8% and SBA after injection 1, 83.3%; after injection 2, 71.4%; 88.9%). Immune responses against S. flexneri 1b and S. flexneri 3a, as measured by both ELISA and SBA, were numerically lower compared to those against S. sonnei and S. flexneri 2a. No safety signals or concerns were identified. altSonflex1-2-3 induced functional serotype-specific immune responses, allowing further clinical development in the target population. Clinical Trials Registration . NCT05073003.

Baseline Pneumococcal IgG Levels and Response to 23-Valent Pneumococcal Polysaccharide Vaccine among Adults from Beijing, China.

To investigate the baseline levels of serotype-specific IgG antibodies to Streptococcus pneumoniae (S. pneumoniae) and assess their impact on the assessment of vaccine immunogenicity. We used a subset of serum samples from a randomized controlled trial. The blood of 584 healthy participants was collected on day 0 before and day 28 after the 23-valent pneumococcal polysaccharide vaccine (PPSV23) vaccination. Serotype-specific IgG against PPSV23-covered serotypes were measured by the World Health Organization (WHO) reference enzyme-linked immunosorbent assay (ELISA). Vaccine immunogenicity was compared using conversion rates (proportion of participants with IgG levels following immunization that are 2-fold greater than the baseline) and geometric mean fold rises (GMFRs) between the two groups, which were grouped according to pre-vaccination (baseline) IgG antibody levels. Our data showed that over half of individuals have baseline IgG levels for 15 out of 23 serotypes above 1.3 µg/mL, and geometric mean concentrations (GMCs) were generally higher in the elderly group and the female group; significant differences were found in 15 serotypes for vaccine immunogenicity based on the seroconversion rate or GMFRs between individuals with baseline IgG ≥ 1.3 µg/mL and individuals with baseline IgG < 1.3 µg/mL. The seroconversion rate decreased with the increase of baseline IgG levels according to a linear regression model. The assessment of vaccine immunogenicity could be impacted by the fact that many adults had high baseline antibody levels. This study is registered in the Chinese Clinical Trial Registry, number NCT05298800.

Waning of antibody levels induced by a 13-valent pneumococcal conjugate vaccine, using a 3 + 0 schedule, within the first year of life among children younger than 5 years in Blantyre, Malawi: an observational, population-level, serosurveillance study

Pneumococcal conjugate vaccines (PCVs) induce serotype-specific IgG antibodies, effectively reducing vaccine-serotype carriage and invasive pneumococcal disease (IPD). IgG production wanes approximately 1 month after vaccination in absence of serotype-specific exposure. With uncertainty surrrounding correlate of protection (CoP) estimates and with persistent vaccine-serotype carriage and vaccine-serotype IPD after PCV13 introduction, we aimed to profile population-level immunogenicity among children younger than 5 years in Blantyre, Malawi. For this serosurveillance study, we used a random subset of samples from a prospective population-based serosurvey in Blantyre, Malawi, done between Dec 16, 2016, and June 27, 2018. Sample selection was based on age category optimisation among children younger than 5 years, adequate sample volume, and available budget. We measured serotype-specific IgGs against the 13 vaccine serotypes (1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F) and two non-vaccine serotypes (12F and 33F), as well as IgGs against three pneumococcal proteins (PsaA, NanA, and Ply), using ELISA and a direct-binding electrochemiluminescence-based multiplex assay. We estimated population-level, serotype-specific immunogenicity profiles using a linear spline regression model. Analyses included samples stratified to 20 3-month age strata (eg, age <3 months to 57-59 months). We evaluated 638 plasma samples: 556 primary samples and 82 unique secondary samples (each linked to one primary sample). Immunogenicity profiles revealed a consistent pattern among vaccine serotypes except serotype 3: a vaccine-induced IgG peak followed by waning to a nadir and subsequent increase in titre. For serotype 3, we observed no apparent vaccine-induced increase. Heterogeneity in parameters included age range at post-vaccination nadir (from 11·2 months [19A] to 27·3 months [7F]). The age at peak IgG titre ranged from 2·69 months (5) to 6·64 months (14). Titres dropped below CoPs against IPD among nine vaccine serotypes (1, 3, 4, 5, 6B, 7F, 9V, 18C, and 23F) and below CoPs against carriage for ten vaccine serotypes (1, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, and 23F). Increasing antibody concentrations among older children and seroincident events were consistent with ongoing vaccine-serotype exposure. A 3 + 0 PCV13 schedule with high uptake has not led to sustained population-level antibody immunity beyond the first year of life. Indeed, post-vaccine antibody concentrations dropped below putative CoPs for several vaccine serotypes, potentially contributing to persistent vaccine-serotype carriage and residual vaccine-serotype IPD in Malawi and other similar settings. Policy decisions should consider alternative vaccine strategies, including a booster dose, to achieve sustained vaccine-induced antibody titres, and thus control. Bill & Melinda Gates Foundation, Wellcome UK, and National Institute for Health and Care Research.

Immunogenicity and safety of double dosage of pneumococcal vaccines in adult kidney transplant recipients and waiting list patients: A non-blinded, randomized clinical trial

BackgroundPneumococcal prime-boost vaccination is recommended for solid organ transplant recipients, but is not thoroughly tested in this population. Furthermore, a pneumococcal vaccine dose effect has never been investigated, though observed in healthy adults. To assess whether a double dose of 13-valent pneumococcal conjugate vaccine (PCV13) and of 23-valent pneumococcal polysaccharide vaccine (PPV23) increases the immunogenicity of prime-boost vaccination in kidney transplant recipients (KTRs) and patients on the kidney transplant waiting list (WLPs), a phase 3, randomized, non-blinded trial was conducted. MethodsKTRs and WLPs were in parallel groups assigned either normal or double dosage of both vaccines 12 weeks apart. A ′protective response′ was an average geometric mean concentration ≥ 1 mg/L based on 12 vaccine shared serotype-specific IgG antibodies. Furthermore, number of antibodies with ≥ 2-fold rises and individual serotype-specific antibody concentrations were evaluated. Follow-up was 48 weeks. ResultsSeventy-four KTRs and 65 WLPs were enrolled. In WLPs, double dosage resulted in a significantly higher proportion of participants with a ′protective response′ (66.7%), 5 weeks after PPV23, compared to normal dosage (35.5%), p = 0.015. KTRs exhibited no dose effect. After PPV23, all four groups had increased their number of serotypes with ≥ 2-fold rises (p ≤ 0.05 for both WLPs groups; p ≤ 0.01 for both KTRs groups). Vaccines were safe, well tolerated and still immunogenic at week 48. ConclusionsData suggests that double dosage of pneumococcal vaccines used according to the prime-boost strategy might be recommendable for WLPs. Furthermore, our data supports PPV23́s additive effect to PCV13 in KTRs and WLPs. (EudraCT: 2016–004123-23)

Persistence of Immunity Following 2-Dose Priming with a 10-Valent Pneumococcal Conjugate Vaccine at 6 and 10 Weeks or 6 and 14 Weeks of Age in Nepalese Toddlers.

The pneumococcal conjugate vaccine has had a substantial impact on invasive pneumococcal disease. Previously, we compared immunity following vaccination with the 10-valent pneumococcal conjugate vaccine (PCV10) administered at 2 slightly different schedules: at 6 and 10 weeks of age, and at 6 and 14 weeks of age, both followed by a 9-month booster. In this study, we followed up those participants to evaluate the medium-term persistence of serotype-specific pneumococcal immunity at 2-3 years of age. Children from the previous studies were contacted and after taking informed consent from their parents, blood samples and nasopharyngeal swabs were collected. Serotype-specific IgG antibody concentrations were determined by enzyme-linked immunosorbent assay, for the 10 vaccine serotypes, at a WHO pneumococcal serology reference laboratory. Two hundred twenty of the 287 children who completed the primary study returned at 2-3 years of age to provide a blood sample and nasopharyngeal swab. The nasopharyngeal carriage rate of PCV10 serotypes in the 6 + 14 group was higher than the 6 + 10 group (13.4% vs. 1.9%). Nevertheless, the proportion of toddlers with serum pneumococcal serotype-specific IgG greater than or equal to 0.35 µg/mL was comparable for all PCV10 serotypes between the 6 + 10 week and 6 + 14 week groups. Similarly, the geometric mean concentrations of serum pneumococcal serotype-specific IgG levels were similar in the 2 groups for all serotypes, except for serotype 19F which was 32% lower in the 6 + 10 group than the 6 + 14 group. Immunization with PCV10 at 6 + 10 weeks or 6 + 14 weeks, with a booster at 9 months in each case, results in similar persistence of serotype-specific antibody at 2-3 years of age. Thus, protection from pneumococcal disease is expected to be similar when either schedule is used.

An observational study of the reactogenicity and immunogenicity of 13-valent pneumococcal conjugate vaccine in women of childbearing age in Papua New Guinea

BackgroundMaternal immunization with pneumococcal conjugate vaccine (PCV) may protect young infants in high-risk settings against the high risk of pneumococcal infections in early life. The aim of this study was to determine the safety and immunogenicity of 13-valent PCV (PCV13) in healthy women of childbearing age in PNG.MethodsAs part of this observational study, 50 non-pregnant women of childbearing age (18-45 yrs. old) living in the highlands of PNG were vaccinated with a single dose of PCV13. Local and systemic reactogenicity were assessed 24–48 h after vaccination. Venous blood samples were collected before and 1 month after vaccination to measure PCV13 serotype-specific IgG antibody concentrations.ResultsNo severe adverse effects were reported during the 1-month follow-up period. IgG antibody concentrations significantly increased after vaccination for all PCV13 serotypes. One month after vaccination IgG antibody levels ≥2.5 μg/mL were reached in at least 75% of women for all PCV13 serotypes, except serotype 3, and ≥ 5 μg/mL in at least 75% of women for 7 serotypes (serotypes 6B, 9 V, 14, 18C, 19A, 19F and 23F).ConclusionPCV13 is safe and immunogenic in women of childbearing age living in a high-risk setting in PNG. This supports the implementation of studies to investigate the safety and immunogenicity of maternal PCV vaccination in high-risk settings as a strategy to protect infants in these settings against the high risk of pneumococcal infections in early life.Trial registrationNCT04183322. Registered 3 December 2019 - Retrospectively registered

Pneumococcal 13-valent polysaccharide vaccination (PCV13) response in patients with pulmonary aspergillosis

Background Response to pneumococcal 23-valent polysaccharide vaccine (PPV23) is poor in patients with pulmonary aspergillosis, pneumococcal 13-valent polysaccharide vaccine (PCV13) is believed to be more antigenic. Thus practice at the national aspergillosis centre (NAC), Manchester University NHS foundation trust (MFT) is to give PCV13. However, response to PCV13 has not been studied. Methods We conducted a retrospective, observational study of patients with pulmonary aspergillosis at the NAC, MFT. Patients who had non-protective pre-vaccine levels, and received PCV13 between January-2015 and July-2019 with serology available within 3 months after vaccination were included. Serotype-specific pneumococcal IgG antibodies were quantified for 12 pneumococcal serotypes. Non-protective immunity was defined as pre-vaccine level &lt;0.35μg/mL to &gt; 6 out of 12 serotypes. Protective response was defined as level &gt;1.3μg/mL, or an increase in concentration ≥4-fold for at least 9 of 12 serotypes within 3 months. Results 47 of 144 patients receiving PCV13 had non-protective pre-vaccination levels and repeat serology within 3 months post-vaccination. 52% and 20%, of patients who received 2 and 1 doses (respectively) developed protective immunity; χ2(1)=2.987,p= 0.084. 42.86%, 69.23%, 42.86%, 50%, and 0% of patients with chronic pulmonary aspergillosis (CPA), allergic bronchopulmonary aspergillosis (ABPA), severe asthma with fungal sensitisation, aspergillus bronchitis, and mixed ABPA and CPA developed protective immunity; χ2(4)=6.329,p=0.176. Conclusion Patients with CPA respond poorly to PCV13 compared to ABPA. Response to two doses of PCV13 is comparable to one dose of PPV-231. Patients with pulmonary aspergillosis should receive two doses of PCV13 rather than one dose.

Immunogenicity Comparison of a Next Generation Pneumococcal Conjugate Vaccine in Animal Models and Human Infants.

Evaluation of a pneumococcal conjugate vaccine (PCV) in an animal model provides an initial assessment of the performance of the vaccine prior to evaluation in humans. Cost, availability, study duration, cross-reactivity and applicability to humans are several factors which contribute to animal model selection. PCV15 is an investigational 15-valent PCV which includes capsular polysaccharides from pneumococcal serotypes (ST) 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F and 33F all individually conjugated to cross-reactive material 197 (CRM197). Immunogenicity of PCV15 was evaluated in infant rhesus macaques (IRM), adult New Zealand white rabbits (NZWR) and CD1 mice using multiplexed pneumococcal electrochemiluminescent (Pn ECL) assay to measure serotype-specific IgG antibodies, multiplexed opsonophagocytosis assay (MOPA) to measure serotype-specific functional antibody responses and bacterial challenge in mice to evaluate protection against a lethal dose of S. pneumoniae. PCV15 was immunogenic and induced both IgG and functional antibodies to all 15 vaccine serotypes in all animal species evaluated. PCV15 also protected mice from S. pneumoniae serotype 14 intraperitoneal challenge. Opsonophagocytosis assay (OPA) titers measured from sera of human infants vaccinated with PCV15 in a Phase 2 clinical trial showed a good correlation with that observed in IRM (rs=0.69, P=0.006), a medium correlation with that of rabbits (rs=0.49, P=0.06), and no correlation with that of mice (rs=0.04, P=0.89). In contrast, there was no correlation in serum IgG levels between human infants and animal models. These results demonstrate that PCV15 is immunogenic across multiple animal species, with IRM and human infants showing the best correlation for OPA responses.

Safety and immunogenicity of a vaccine for extra-intestinal pathogenic Escherichia coli (ESTELLA): a phase 2 randomised controlled trial

ExPEC4V (JNJ-63871860) is a bioconjugate vaccine, containing O-antigens from Escherichia coli serotypes O1A, O2, O6A, and O25B, developed for the prevention of invasive extra-intestinal pathogenic E coli (ExPEC) disease. We aimed to assess safety, reactogenicity, and immunogenicity of ExPEC4V in healthy adults. In this phase 2 randomised, double-blind placebo-controlled study, we recruited healthy adults (≥18 years with a body-mass index of 35 kg/m2 or less) between Nov 16, 2015, and Aug 8, 2017, and randomly assigned them to receive a single dose of ExPEC4V (antigen O1A:O2:O6A:O25B content 4:4:4:4 μg [group 1]; 4:4:4:8 μg [group 2], 8:8:8:8 μg [group 3], 8:8:8:16 μg [group 4], or 16:16:16:16 μg [group 5]) or placebo. The primary objectives were evaluation of the safety, tolerability, and immunogenicity of ExPEC4V and determination of its dose-dependent immunogenicity 15 days after vaccination by ELISA in individuals who had received at least one vaccination dose. Antibody titres and safety evaluation were used to select two ExPEC4V doses for assessment up to day 360. This trial is registered at ClinicalTrials.gov, number NCT02546960. Of 848 enrolled participants, 843 (99%) received the ExPEC4V vaccine (757) or placebo (86) and were included in the safety analysis. Of 757 participants vaccinated with ExPEC4V, 222 (29%) had a solicited local adverse event and 325 (43%) had any solicited systemic adverse event, compared with 11 (13%) and 30 (35%) of 86 participants in the control group. Symptoms were mild-to-moderate. The most frequently reported solicited local adverse event was pain or tenderness (205 [27·1%] of 757 in combined ExPEC4V groups) and the most frequently reported solicited systemic adverse event was fatigue (208 [27·6%] of 757). Only 13 (2%) of 843 had a grade 3 event. At day 15, 80% or more of all participants achieved a two times or greater increase in serotype-specific IgG antibodies (except O25B at the lowest dose, 103 [72%] of 144). At day 360, 66% (95% CI 56·47-74·33) of participants in group 2 and 71% (62·13-78·95) of participants in group 4 selected for long-term follow-up maintained a two times or greater increase in serotype-specific antibody compared with baseline. EXPEC4V seemed well tolerated and elicited robust and functional antibody responses across all serotypes, doses, and age groups. For the two dosages evaluated (4:4:4:8 μg and 8:8:8:16 μg), the immune response persisted for 1 year. Janssen Pharmaceuticals.

Serotype-Specific IgG Antibody Waning after Pneumococcal Conjugate Primary Series Vaccinations with either the 10-Valent or the 13-Valent Vaccine.

The two currently available ten- and thirteen-valent pneumococcal conjugate vaccines (PCV10 and PCV13) both induce serotype-specific IgG anti-polysaccharide antibodies and are effective in preventing vaccine serotype induced invasive pneumococcal disease (IPD) as well as in reducing overall vaccine-serotype carriage and transmission and thereby inducing herd protection in the whole population. IgG levels decline after vaccination and could become too low to prevent carriage acquisition and/or pneumococcal disease. We compared the levels of 10-valent (PCV10) and 13-valent (PCV13) pneumococcal vaccine induced serum IgG antibodies at multiple time points after primary vaccinations. Data from two separate studies both performed in the Netherlands in infants vaccinated at 2, 3, and 4 months of age with either PCV10 or PCV13 were compared. Antibody levels were measured at 5, 8, and 11 months of age, during the interval between the primary immunization series and the 11-months booster dose. Serotype-specific IgG levels were determined by multiplex immunoassay. Although antibody kinetics showed significant variation between serotypes and between vaccines for the majority of the 10 shared serotypes, i.e., 1, 5, 7F, 9V, 14, 18C, and 23F, antibody concentrations were sufficiently high for both vaccines, immediately after the primary series and throughout the whole period until the booster dose. In contrast, for serotypes 4 and 19F in the PCV10 group and for serotypes 4 and 6B in the PCV13 group, IgG antibody concentrations already come within reach of the frequently used seroprotection level of 0.35 μg/mL immediately after the primary series at the five month time point and/or at eight months. This paper addresses the importance of revealing differences in serotype-specific and pneumococcal vaccine-dependent IgG antibody patterns during the interval between the primary series and the booster dose, an age period with a high IPD incidence. Trial registration: www.trialregister.nl NTR3069 and NTR2316.

Pneumococcal conjugate vaccine triggers a better immune response than pneumococcal polysaccharide vaccine in patients with chronic lymphocytic leukemia A randomized study by the Swedish CLL group

AimTo determine if patients with untreated chronic lymphocytic leukemia (CLL) benefit from vaccination with a 13-valent pneumococcal conjugated vaccine (PCV13), Prevenar13®, compared to a 23-valent pneumococcal polysaccharide vaccine (PPSV23), Pneumovax®, in terms of immune response. BackgroundStreptococcus pneumoniae causes substantial morbidity in patients with CLL, a group known to respond poorly to polysaccharide vaccines. Comparative studies with conjugated vaccines are lacking. Methods128 treatment naïve CLL patients from eight hematology clinics in Sweden were randomized to vaccination with PCV13 (n = 63) or PPSV23 (n = 65) after stratification by IgG level and CLL clinical stage (Rai). Blood samples for evaluation of immune response were obtained at baseline, and at one and six months after vaccination. Analyses for each of the 12 pneumococcal serotypes common for PCV13 and PPSV23 were performed by opsonophagocytic assay (OPA) and enzyme-linked immunosorbent assay (ELISA). ResultsPCV13 elicited a superior immune response than PPSV23 in 10/12 serotypes one month after vaccination and in 5/12 serotypes six months after vaccination, measured as OPA geometric mean titers (GMTs). Geometric mean concentrations of serotype-specific IgG antibodies elicited by PCV13 as measured by ELISA, were higher than those elicited by PPSV23 in half of the common serotypes, both after one and six months. PPSV23 did not trigger a better immune response than PCV13 for any of the serotypes, regardless of analysis method or time point of analysis. Negative predictive factors for vaccination response were hypogammaglobulinemia and long disease duration. Both vaccines were well tolerated. ConclusionsIn patients with previously untreated CLL, the efficacy of PCV13 in terms of immune response is superior to PPSV23 for most serotypes common for the two vaccines. We therefore propose that PCV13 should be included in vaccination programs against Streptococcus pneumoniae for CLL patients and administered as early as possible during the course of the disease.

T cells control the generation of nanomolar-affinity anti-glycan antibodies.

Vaccines targeting glycan structures at the surface of pathogenic microbes must overcome the inherent T cell-independent nature of immune responses against glycans. Carbohydrate conjugate vaccines achieve this by coupling bacterial polysaccharides to a carrier protein that recruits heterologous CD4 T cells to help B cell maturation. Yet they most often produce low- to medium-affinity immune responses of limited duration in immunologically fit individuals and disappointing results in the elderly and immunocompromised patients. Here, we hypothesized that these limitations result from suboptimal T cell help. To produce the next generation of more efficacious conjugate vaccines, we have explored a synthetic design aimed at focusing both B cell and T cell recognition to a single short glycan displayed at the surface of a virus-like particle. We tested and established the proof of concept of this approach for 2 serotypes of Streptococcus pneumoniae. In both cases, these vaccines elicited serotype-specific, protective, and long-lasting IgG antibodies of nanomolar affinity against the target glycans in mice. We further identified a requirement for CD4 T cells in the anti-glycan antibody response. Our findings establish the design principles for improved glycan conjugate vaccines. We surmise that the same approach can be used for any microbial glycan of interest.

Evaluation of a 15-valent Pneumococcal Conjugate Vaccine in an Adult Rhesus Macaque Immunogenicity Model

Background Streptococcus pneumoniae (pneumococcus) is a leading cause of a variety of diseases, including bacteremia, meningitis, and pneumonia, among older adults in the United States. Immunization with pneumococcal vaccines is an effective way to prevent these diseases. In this study, we evaluated the immunogenicity of 15-valent pneumococcal conjugate vaccine (PCV15) in adult rhesus macaques.MethodsAnimals were intramuscularly immunized with PNEUMOVAX® 23 and PCV15 vaccine (5 animals/group) and sera were collected before immunization and 30, 60, and 90 days after the immunization. Sera were assayed using multiplexed electrochemiluminescent (ECL) assays to measure serotype-specific IgG antibodies to all vaccine serotypes and multiplexed opsonophagocytic killing assays (MOPA) to measure functional antibody responses to 15 vaccine serotypes.ResultsAt day 30 post immunization, 16 out of the 23 serotypes in PNEUMOVAX 23 groups induced statistically significant higher ECL titers compared with pre bleed, ranging from 1.6-fold (19A) to 28.3-fold (15B). Compared with PNEUMOVAX 23, PCV15 induced much higher ECL titers. Thirteen out of the 15 serotypes in PCV15 groups induced statistically significant higher ECL titers compared with pre bleed, ranging from 7.4-fold (14) to 47.3-fold (4). The ECL antibody titers gradually decreased from day 30 to day 90 for both groups. We also compared the functional MOPA titers of the day 30 sera compared with pre bleed for 15 vaccine serotypes. Out of the 14 common vaccine serotypes, 7 serotypes in the PNEUMOVAX 23 immunized macaques had a >4 fold increase in MOPA titer, ranging from 4-fold (22F) to 3902-fold (33F) and 11 serotypes in the PCV15 immunized macaques had a >4-fold increase in MOPA titer, ranging from 6.3-fold (23F) to 4445-fold (7F). Twelve out of the 14 common serotypes in PCV15 group had higher MOPA titers compared with the PNEUMOVAX 23 group, although they didn’t reach statistical significance due to high variability.ConclusionThese data demonstrate that a single dose of PCV15 is highly immunogenic in adult rhesus macaques and has better immunogenicity for most common serotypes compared with PNEUMOVAX 23. However, PNEUMOVAX 23 offers broader serotype coverage with 9 additional serotypes contained in the vaccine.Disclosures J. Xie, Merck & Co. Inc: Employee, Salary; R. Kaufhold, Merck & Co. Inc: Employee, Salary; D. Mcguinness, Merck & Co. Inc: Employee, Salary; Y. Zhang, Merck & Co. Inc.: Employee, Salary; W. Smith, Merck & Co. Inc.: Employee, Salary; C. Giovarelli, Merck & Co. Inc.: Employee, Salary; M. Winters, Merck & Co. Inc: Employee, Salary; L. Musey, Merck & Co. Inc: Employee, Salary; M. Kosinski, Merck & Co. Inc: Employee, Salary; J. Skinner, Merck & Co. Inc: Employee, Salary

Response to pneumococcal polysaccharide vaccination in patients with chronic and allergic aspergillosis

IntroductionPneumococcal infection causes significant morbidity in patients with underlying lung disease, and vaccination has been associated with reduced disease rates. Response to vaccination has not been studied in chronic lung conditions characterised by ongoing infection or inflammation like chronic pulmonary aspergillosis (CPA). MethodsIn a prospective observational study, consecutive patients with CPA, allergic aspergillosis and bronchiectasis attending a national referral centre received pneumococcal 23-valent polysaccharide vaccine (PPV-23) and had pre- and post-vaccination antibody concentrations quantified as part of routine clinical care. Serotype-specific pneumococcal IgG antibodies were quantified for 12 serotypes using a multiplex microsphere assay. A protective response was defined as a level of >1.3μg/mL or a ≥ fourfold rise in concentration for ≥70% of serotypes, pre to post-vaccination. C-reactive protein, Immunoglobulins and mannose binding lectin (MBL) levels were measured and correlated to vaccine response. ResultsA total of 318 patients were enrolled. In vaccine-naïve patients (n=127), the lowest pre-vaccination levels were seen with serotypes 1 and 4 and the highest with serotype 19A. A protective response post-vaccination was seen in 50% of patients. The poorest responses were observed with serotypes 1, 3 and 4. Levels of C-reactive protein did not affect efficacy. Profound MBL deficiency was found in 28.8%; there were no significant differences in response to vaccination in patients with or without MBL deficiency. Post-vaccination serotype-specific concentrations waned gradually, however they were still elevated compared to pre-vaccination after 2–5 years. ConclusionsPatients with chronic and allergic aspergillosis exhibited a poor response to PPV-23 vaccination compared to healthy adults. An alternative vaccination strategy or delay of vaccination until their underlying condition is better controlled, e.g. after treatment with antifungals may result in better response.

Reduced IL-17A Secretion Is Associated with High Levels of Pneumococcal Nasopharyngeal Carriage in Fijian Children.

Streptococcus pneumonia (the pneumococcus) is the leading vaccine preventable cause of serious infections in infants under 5 years of age. The major correlate of protection for pneumococcal infections is serotype-specific IgG antibody. More recently, antibody-independent mechanisms of protection have also been identified. Preclinical studies have found that IL-17 secreting CD4+ Th17 cells in reducing pneumococcal colonisation. This study assessed IL-17A levels in children from Fiji with high and low pneumococcal carriage density, as measured by quantitative real-time PCR (qPCR). We studied Th17 responses in 54 children who were designated as high density carriers (N=27, >8.21x105 CFU/ml) or low density carriers (N=27, <1.67x105 CFU/ml). Blood samples were collected, and isolated peripheral blood mononuclear cells (PBMCs) were stimulated for 6 days. Supernatants were harvested for cytokine analysis by multiplex bead array and/or ELISA. Th17 cytokines assayed included IL-17A, IL-21, IL-22 as well as TNF-α, IL-10, TGF-β, IL-6, IL-23 and IFNγ. Cytokine levels were significantly lower in children with high density pneumococcal carriage compared with children with low density carriage for IL-17A (p=0.002) and IL-23 (p=0.04). There was a trend towards significance for IL-22 (p=0.057) while no difference was observed for the other cytokines. These data provide further support for the role of Th17-mediated protection in humans and suggest that these cytokines may be important in the defence against pneumococcal carriage.

Natural acquired humoral immunity against serotype-specific group B Streptococcus rectovaginal colonization acquisition in pregnant women

Group B Streptococcus (GBS) rectovaginal colonization in pregnant women is associated with invasive GBS disease in newborns, preterm delivery and stillbirths. We studied the association of GBS serotype-specific capsular polysaccharide (CPS) antibody on new acquisition and clearance of rectovaginal GBS colonization in pregnant women from 20 weeks until 37 to 40 weeks' gestation. Serum serotype-specific CPS IgG antibody concentration was measured by multiplex enzyme-linked immunosorbent assay and opsonophagocytic activity (OPA) titres. Rectovaginal swabs were evaluated for GBS colonization, using standard culture methods and serotyping by latex agglutination, at five to six weekly intervals. Higher serotype III CPS antibody concentration was associated with lower risk of rectovaginal acquisition of serotype III during pregnancy (p 0.009). Furthermore, serotype-specific OPA titres to Ia and III were higher in women who remained free of GBS colonization throughout the study compared to those who acquired the homotypic serotype (p <0.001 for both serotypes). Serum CPS IgG values of ≥1μg/mL for serotype V and ≥3μg/mL for serotypes Ia and III were significantly associated with protection against rectovaginal acquisition of the homotypic serotype. A GBS vaccine that induces sufficient capsular antibody in pregnant women, including high OPA titres, could protect against rectovaginal colonization during the latter half of pregnancy.

Pneumococcal vaccine responses in elderly patients with multiple myeloma, Waldenstrom’s macroglobulinemia, and monoclonal gammopathy of undetermined significance

BackgroundVaccination with the 23-valent pneumococcal polysaccharide vaccine (PPV) has been recommended for elderly patients with B cell malignancies and dysfunctions because of their enhanced susceptibility to pneumococcal infections. More recent recommendations advocate the use of conjugate pneumococcal vaccines. MethodsWe compared responses to single dose vaccination with either PPV or the 7-valent pneumococcal conjugate vaccine (PCV7) in fifty-six patients ⩾60 years with a diagnosis of multiple myeloma (n = 24), Waldenstrom’s macroglobulinemia (n = 15) and the non-malignant B cell disorder monoclonal gammopathy of undetermined significance (MGUS) (n = 17), and 20 age-matched controls. Serum was collected prior to vaccination and 4–8 weeks later, and analyzed for IgG antibody levels to pneumococcal serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F by ELISA. Functional antibody activity towards pneumococcal serotypes 4 and 14 was measured using an opsonophagocytic killing assay (OPA). ResultsAll patient groups had lower pre-vaccination IgG antibody and OPA titers to the investigated serotypes compared to the healthy controls. Following vaccination, myeloma patients responded with significant IgG titer increases to 1/7 serotypes and OPA titer increases to 1/2 serotypes. Corresponding IgG and OPA vaccine responses were 3/7 and 0/2 for Waldenstrom patients, 4/7 and 1/2 for MGUS patients, and 4/7 and 2/2 for the healthy controls, respectively. Notably high antibody levels without corresponding OPA titers were seen among a few myeloma patients indicating the presence of non-functional antibodies. Neither of the two vaccines elicited significantly higher serotype-specific IgG concentrations, OPA titers or antibody fold increases in any of the study groups. Hypogammaglobulinemia and ongoing chemotherapy were associated with poor vaccine responses in a multivariate analysis. ConclusionOur findings confirm that B cell malignancies and disorders among elderly patients are associated with suboptimal responses to pneumococcal vaccination. Single-dose PCV7 was not shown to be superior to PPV.

L-Ficolin and Capsular Polysaccharide-Specific IgG in Cord Serum Contribute Synergistically to Opsonophagocytic Killing of Serotype III and V Group B Streptococci

Group B streptococci (GBS; Streptococcus agalactiae) are the most common cause of neonatal sepsis and meningitis. Serotype-specific IgG antibody is known to protect neonates against GBS infections by promoting opsonophagocytosis. The L-ficolin-mediated lectin pathway of the complement is also a potential mechanism for opsonization of GBS, because L-ficolin activates the complement after binding to serotype Ib, III, V, VI, and VIII GBS. In the present study, we investigated how L-ficolin and serotype-specific IgG in cord sera contribute to opsonophagocytic killing of GBS. Neither L-ficolin nor serotype-specific IgG concentrations correlated with C3b deposition on serotype Ib and VI GBS, suggesting L-ficolin- and serotype-specific IgG-independent mechanisms of complement activation. The percentage of serotype VIII GBS killed was high regardless of the concentration of L-ficolin and IgG. In contrast, L-ficolin and serotype-specific IgG can each initiate C3b deposition on serotype III and V GBS and promote phagocytosis by polymorphonuclear leukocytes, but L-ficolin and serotype-specific IgG together promote opsonophagocytic killing to a greater extent than does either alone in vitro. This synergy was observed when serotype III-specific IgG concentrations were between 1 and 6 μg/ml and when serotype V-specific IgG concentrations were between 2 and 5 μg/ml. Concentrations of serotype III-specific IgG in cord blood above 7 μg/ml are considered protective for neonates colonized with GBS, but most neonates with IgG levels of less than 7 μg/ml do not develop GBS infections. The data presented here suggest that L-ficolin enhances opsonophagocytosis of serotype III and V GBS when serotype-specific IgG alone is suboptimal for protection.

Pneumococcal polysaccharide vaccine at 12 months of age produces functional immune responses

Infections with Streptococcus pneumoniae (pneumococcus) are a cause of significant child mortality. Pneumococcal glycoconjugate vaccines are expensive and provide limited serotype coverage. The 23-valent pneumococcal polysaccharide vaccine (Pneumovax) might provide wider serotype coverage but is reported to be weakly immunogenic in children less than 2 years of age. We have previously reported that Pneumovax administered to healthy 12-month-old Fijian infants elicits significant serotype-specific IgG responses. However, the functional capacity of these responses in 12-month-old infants is not known. We sought to assess the functional, serotype-specific immune response of 12-month-old infants after immunization with Pneumovax. Functional responses of 12-month-old infants were assessed by using the opsonophagocytic and antibody avidity assay against 8 serotypes and 23 serotypes, respectively. Seventy-one percent of infants produced strong opsonophagocytic activity against 4 of 8 serotypes, and 30% produced high-avidity serotype-specific IgG antibodies to 10 of 23 serotypes at 2 weeks after Pneumovax. Responses were protective for most serotypes that cause disease in Western countries, whereas responses to most of the epidemiologically relevant serotypes for developing countries were low. This is the first comprehensive study evaluating the functional antibody response to Pneumovax in 12-month-old infants. Pneumovax induced functional antibody responses to several serotypes causing disease in Western countries but induced poorer responses to serotypes that are responsible for the majority of disease in developing countries. Pneumovax might be of benefit in some populations, but further studies are required before this can be recommended in developing countries.