Clonal Expansion of a Streptococcus pneumoniae Serotype 3 Capsule Variant Sequence Type 700 With Enhanced Vaccine Escape Potential After 13-Valent Pneumococcal Conjugate Vaccine Introduction.

BACKGROUND: Streptococcus pneumoniae serotype 3 remains a problem globally. Malawi introduced 13-valent pneumococcal conjugate vaccine (PCV13) in 2011, but there has been no direct protection against serotype 3 carriage. We explored whether vaccine escape by serotype 3 is due to clonal expansion of a lineage with a competitive advantage. METHODS: The distribution of serotype 3 Global Pneumococcal Sequence Clusters (GPSCs) and sequence types (STs) globally was assessed using sequences from the Global Pneumococcal Sequencing Project. Whole-genome sequences of 135 serotype 3 carriage isolates from Blantyre, Malawi (2015-2019) were analyzed. Comparative analysis of the capsule locus, entire genomes, antimicrobial resistance, and phylogenetic reconstructions were undertaken. Opsonophagocytosis was evaluated using serum samples from vaccinated adults and children. RESULTS: Serotype 3 GPSC10-ST700 isolates were most prominent in Malawi. Compared with the prototypical serotype 3 capsular polysaccharide locus sequence, 6 genes are absent, with retention of capsule polysaccharide biosynthesis. This lineage is characterized by increased antimicrobial resistance and lower susceptibility to opsonophagocytic killing. CONCLUSIONS: A serotype 3 variant in Malawi has genotypic and phenotypic characteristics that could enhance vaccine escape and clonal expansion after post-PCV13 introduction. Genomic surveillance among high-burden populations is essential to improve the effectiveness of next-generation pneumococcal vaccines.

Anti-Pneumococcal Capsular Polysaccharide Antibody Response and CD5 B Lymphocyte Subsets.

The role of CD19(+) CD5(+) and CD19(+) CD5(-) B cell subpopulations in the antibody response to pneumococcal capsular polysaccharides (caps-PSs) is controversial. In the present study, we evaluated the role of human CD19(+) CD5(+) and CD19(+) CD5(-) cell populations in the serotype-specific antibody response to caps-PS. After vaccination of 5 healthy human adults with Pneumovax (23-valent pneumococcal polysaccharide vaccine [PPV23]), IgG anti-caps-PS serotype 4 antibody-producing cells resided mainly in the CD19(+) CD5(-) B cell subset, as assessed by enzyme-linked immunosorbent spot (ELISpot) analysis. Moreover, in a humanized SCID mouse model, CD19(+) CD5(-) B cells were more effective than CD19(+) CD5(+) cells in producing IgG anti-cap-PS antibodies. Finally, an association was found between the level of IgG anti-caps-PS antibodies and the number of CD19(+) CD5(-) B cells in 33 humans vaccinated with PPV23. Taken together, our data suggest that CD5 defines a functionally distinct population of B cells in humans in the anti-caps-PS immune response.

Genomics Reveals the Worldwide Distribution of Multidrug-Resistant Serotype 6E Pneumococci.

The pneumococcus is a leading pathogen infecting children and adults. Safe, effective vaccines exist, and they work by inducing antibodies to the polysaccharide capsule (unique for each serotype) that surrounds the cell; however, current vaccines are limited by the fact that only a few of the nearly 100 antigenically distinct serotypes are included in the formulations. Within the serotypes, serogroup 6 pneumococci are a frequent cause of serious disease and common colonizers of the nasopharynx in children. Serotype 6E was first reported in 2004 but was thought to be rare; however, we and others have detected serotype 6E among recent pneumococcal collections. Therefore, we analyzed a diverse data set of ∼1,000 serogroup 6 genomes, assessed the prevalence and distribution of serotype 6E, analyzed the genetic diversity among serogroup 6 pneumococci, and investigated whether pneumococcal conjugate vaccine-induced serotype 6A and 6B antibodies mediate the killing of serotype 6E pneumococci. We found that 43% of all genomes were of serotype 6E, and they were recovered worldwide from healthy children and patients of all ages with pneumococcal disease. Four genetic lineages, three of which were multidrug resistant, described ∼90% of the serotype 6E pneumococci. Serological assays demonstrated that vaccine-induced serotype 6B antibodies were able to elicit killing of serotype 6E pneumococci. We also revealed three major genetic clusters of serotype 6A capsular sequences, discovered a new hybrid 6C/6E serotype, and identified 44 examples of serotype switching. Therefore, while vaccines appear to offer protection against serotype 6E, genetic variants may reduce vaccine efficacy in the longer term because of the emergence of serotypes that can evade vaccine-induced immunity.

Effect of reduced two-dose (1+1) schedule of 10 and 13-valent pneumococcal conjugate vaccines (SynflorixTM and Prevenar13TM)) on nasopharyngeal carriage and serotype-specific immune response in the first two years of life: Results from an open-labelled randomized controlled trial in Indian children.

INTRODUCTION: This study aimed to assess the effect of a reduced dose regime (1 + 1) of PCV10 and PCV13 along with 3-dose regimes on pneumococcal vaccine-type (VT) carriage and immunogenicity in the first two years of life in PCV-naïve Indian children. METHODS: A total of 805 healthy infants aged 6-8 weeks were randomised to 7 groups (n = 115). Six groups received SynflorixTM(PCV10) or Prevenar13TM(PCV13) in the following schedules: 3 + 0 (three primary at 6, 10, and 14 weeks); 2 + 1 (two primary 6 and 14 weeks with booster at 9 months; 1 + 1 (one primary at 14 weeks with booster at 9 months). The 7th group was a PCV-naïve control group. Nasopharyngeal swabs were collected at 6, 18 weeks, 9, 10, 15, and 18 months of age. Venous blood samples were collected at 18 weeks, 9, 10, and 18 months of age for assessment of sero-specific IgG antibodies. Additionally, functional activity using a serotype specific opsonophagocytic assay (OPA) was assessed at 10 and 18 months of age in a subset (20%) of participants. RESULTS: All schedules of PCV13 showed significant 13VT carriage reduction in the second year of life as compared to control. At 15 months of age, PCV13 (1 + 1) showed 45 % reduction in 13VT-carriage compared to the control [OR = 0.55 (95% CI; 0.31-0.97), p= 0.038]. None of the PCV10 schedules showed significant reduction in 10VT carriage in the second year. Although not powered for these outcomes, at 18 months of age, 1 + 1 and 2 + 1 schedules of both vaccines demonstrated higher sero-responders for all serotypes, higher geometric mean concentrations (GMC) for all serotypes except 23F [with both vaccines], higher percent OPA responders and OPA geometric mean titres (GMT) compared to the 3 + 0 schedules for all serotypes. CONCLUSION: The reduced dose schedule (1 + 1) of PCV13 results in significant VT-carriage reduction in the second year of life. Immune protection provided by 1 + 1 schedules of PCV10 and PCV13 in the second year of life is comparable to WHO-recommended 3-dose schedules.

Pneumococcal carriage following PCV13 delivered as one primary and one booster dose (1 + 1) compared to two primary doses and a booster (2 + 1) in UK infants.

In January 2020 the UK changed from a 2 + 1 schedule for 13-valent pneumococcal conjugate vaccine (PCV13) to a 1 + 1 schedule (doses at 3 and 12 months) based on a randomized immunogenicity trial comparing the two schedules. Carriage prevalence measured at the time of booster and 6 months later in 191 of the 213 study infants was 57 % (109/191) and 60 % (114/190) respectively. There were eight episodes of vaccine-type (VT) or vaccine-related 6C carriage in the 2 + 1 and six in the 1 + 1 group; ≥4-fold rises in serotype-specific IgG in 71 children with paired post-booster and follow up blood samples at 21-33 months of age were found in 20 % (7/35) of the 2 + 1 and 15 % (6/41) of the 1 + 1 group. VTs identified in carriage and inferred from serology were similar comprising 3, 19A and 19F. Dropping a priming dose from the 2 + 1 PCV 13 schedule did not increase VT carriage in the study cohort. Ongoing population level carriage studies will be important to confirm this.

Quality of antibody responses by adults and young children to 13-valent pneumococcal conjugate vaccination and Streptococcus pneumoniae colonisation.

Childhood pneumococcal conjugate vaccine (PCV) protects against invasive pneumococcal disease caused by vaccine-serotype (VT) Streptococcus pneumoniae by generating opsonophagocytic anti-capsular antibodies, but how vaccination protects against and reduces VT carriage is less well understood. Using serological samples from PCV-vaccinated Malawian individuals and a UK human challenge model, we explored whether antibody quality (IgG subclass, opsonophagocytic killing, and avidity) is associated with protection from carriage. Following experimental challenge of adults with S. pneumoniae serotype 6B, 3/21 PCV13-vaccinees were colonised with pneumococcus compared to 12/24 hepatitis A-vaccinated controls; PCV13-vaccination induced serotype-specific IgG, IgG1, and IgG2, and strong opsonophagocytic responses. However, there was no clear relationship between antibody quality and protection from carriage or carriage intensity after vaccination. Similarly, among PCV13-vaccinated Malawian infants there was no relationship between serotype-specific antibody titre or quality and carriage through exposure to circulating serotypes. Although opsonophagocytic responses were low in infants, antibody titre and avidity to circulating serotypes 19F and 6A were maintained or increased with age. These data suggest a complex relationship between antibody-mediated immunity and pneumococcal carriage, and that PCV13-driven antibody quality may mature with age and exposure.

Sequential administration of Prevnar 13™ and PNEUMOVAX™ 23 in healthy participants 50 years of age and older.

In most countries worldwide, pneumococcal conjugate vaccines have been included in the infant immunization program, resulting in a significant reduction in the burden of pneumococcal disease in children and adults. Shifting serotype distribution due to the indirect effect of infant vaccination with the 13-valent pneumococcal conjugate vaccine (PCV13) may continue to increase the gap between 23-valent pneumococcal polysaccharide vaccine (PPSV23) and PCV13 serotype coverage for older adults in the coming years. This clinical study (V110-029; NCT02225587) evaluated the safety and immunogenicity of sequential administration of PCV13 followed approximately 8 weeks later, or approximately 26 weeks later, by PPSV23 in healthy adults ≥50 years of age. Both dosing intervals were generally well tolerated as measured by the nature, frequency, and intensity of reported adverse events (AEs) in both vaccination groups. Serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) measured 30 days following receipt of PPSV23 in either group and at Week 30 were generally comparable between the 2 groups for 6 serotypes unique to PPSV23 and 12 serotypes shared between PCV13 and PPSV23, regardless of the interval between receipt of PCV13 and PPSV23. In addition, administration of PPSV23 given either 8 weeks or 26 weeks following PCV13 did not negatively impact immune responses induced by PCV13. Furthermore, administration of PPSV23 given either 8 weeks or 26 weeks after PCV13 elicited serotype-specific OPA GMTs to serotypes unique to PPSV23, which could provide earlier protection against pneumococcal disease caused by these serotypes in comparison with the current Advisory Committee on Immunization Practices recommended interval of at least 12 months.

Generation of recombinant hyperimmune globulins from diverse B-cell repertoires.

Plasma-derived polyclonal antibody therapeutics, such as intravenous immunoglobulin, have multiple drawbacks, including low potency, impurities, insufficient supply and batch-to-batch variation. Here we describe a microfluidics and molecular genomics strategy for capturing diverse mammalian antibody repertoires to create recombinant multivalent hyperimmune globulins. Our method generates of diverse mixtures of thousands of recombinant antibodies, enriched for specificity and activity against therapeutic targets. Each hyperimmune globulin product comprised thousands to tens of thousands of antibodies derived from convalescent or vaccinated human donors or from immunized mice. Using this approach, we generated hyperimmune globulins with potent neutralizing activity against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in under 3 months, Fc-engineered hyperimmune globulins specific for Zika virus that lacked antibody-dependent enhancement of disease, and hyperimmune globulins specific for lung pathogens present in patients with primary immune deficiency. To address the limitations of rabbit-derived anti-thymocyte globulin, we generated a recombinant human version and demonstrated its efficacy in mice against graft-versus-host disease.

Immunogenicity of a single-dose compared with a two-dose primary series followed by a booster dose of ten-valent or 13-valent pneumococcal conjugate vaccine in South African children: an open-label, randomised, non-inferiority trial.

BACKGROUND: Routine childhood immunisation with pneumococcal conjugate vaccine (PCV) has changed the epidemiology of pneumococcal disease across age groups, providing an opportunity to reconsider PCV dosing schedules. We aimed to evaluate the post-booster dose immunogenicity of ten-valent (PCV10) and 13-valent (PCV13) PCVs between infants randomly assigned to receive a single-dose compared with a two-dose primary series. METHODS: We did an open-label, non-inferiority, randomised study in HIV-unexposed infants at a single centre in Soweto, South Africa. Infants were randomly assigned to receive one priming dose of PCV10 or PCV13 at ages 6 weeks (6w + 1 PCV10 and 6w + 1 PCV13 groups) or 14 weeks (14w + 1 PCV10 and 14w + 1 PCV13 groups) or two priming doses of PCV10 or PCV13, one each at ages 6 weeks and 14 weeks (2 + 1 PCV10 and 2 + 1 PCV13 groups); all participants then received a booster dose of PCV10 or PCV13 at 40 weeks of age. The primary endpoint was geometric mean concentrations (GMCs) of serotype-specific IgG 1 month after the booster dose, which was assessed in all participants who received PCV10 or PCV13 as per the assigned randomisation group and for whom laboratory results were available at that timepoint. The 1 + 1 vaccine schedule was considered non-inferior to the 2 + 1 vaccine schedule if the lower bound of the 96% CI for the GMC ratio was greater than 0·5 for at least ten PCV13 serotypes and eight PCV10 serotypes. Safety was a secondary endpoint. This trial is registered with ClinicalTrials.gov (NCT02943902) and is ongoing. FINDINGS: Of 1695 children assessed, 600 were enrolled and randomly assigned to one of the six groups between Jan 9 and Sept 20, 2017; 542 were included in the final analysis of the primary endpoint (86-93 per group). For both PCV13 and PCV10, a 1+1 dosing schedule (either beginning at 6 or 14 weeks) was non-inferior to a 2 + 1 schedule. For PCV13, the lower limit of the 96% CI for the ratio of GMCs between the 1 + 1 and 2 + 1 groups was higher than 0·5 for ten serotypes in the 6w+1 group (excluding 6B, 14, and 23F) and 11 serotypes in the 14w + 1 group (excluding 6B and 23F). For PCV10, the lower limit of the 96% CI for the ratio of GMCs was higher than 0·5 for all ten serotypes in the 6w+1 and 14w + 1 groups. 84 serious adverse events were reported in 72 (12%) of 600 participants. 15 occurred within 28 days of vaccination, but none were considered to be related to PCV injection. There were no cases of culture-confirmed invasive pneumococcal disease. INTERPRETATION: The non-inferiority in post-booster immune responses following a single-dose compared with a two-dose primary series of PCV13 or PCV10 indicates the potential for reducing PCV dosing schedules from a 2 + 1 to 1 + 1 series in low-income and middle-income settings with well established PCV immunisation programmes. FUNDING: The Bill & Melinda Gates Foundation (OPP1 + 152352).

Assignment of Serotype-Specific IgG1, IgG2, and IgA Weight-Based Antibody Units to the Human Pneumococcal Standard Reference Serum, 007sp.

In 2011, the human pneumococcal standard reference serum, 007sp, was established as a replacement for the previous standard, lot 89SF, supplies of which were dwindling. The pneumococcal reference serum is used primarily in the standardized pneumococcal enzyme-linked immunosorbent assay (World Health Organization reference enzyme-linked immunosorbent assay) but has also been used in functional assays. Serotype-specific IgG values for 24 pneumococcal capsular serotypes have previously been assigned to 007sp by bridging to the original values derived for lot 89SF. In this study, by bridging to existing values in lot 89SF, we assign weight-based serotype-specific IgA, IgG1, and IgG2 to 007sp for 11 pneumococcal capsular serotypes (1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, and 23F), as well as serotype 19A-specific IgA. Concentrations for serotype-specific IgA, IgG1, and IgG2 present in 007sp were comparable to those previously assigned to lot 89SF. In addition, the concentration of serotype-specific IgG1 plus IgG2 assigned to 007sp significantly correlated to previously assigned 007sp IgG values. The accuracy of antibody assignments to 007sp from lot 89SF was assessed by comparing the concentration of serotype-specific IgA, IgG1, and IgG2 in 16 unknown samples using both 007sp and lot 89SF as the standard. Interpolated values for the unknown samples were highly correlated with average R2 values of 0.9729, 0.9951, and 0.9933 for IgA, IgG1, and IgG2, respectively, for all serotypes demonstrating the precise nature assignments to 007sp made in this study. Nonparallelism between 007sp and lot 89SF has precluded the derivation of serotype-specific IgM values.IMPORTANCE A well-characterized antibody standard is an indispensable reagent for use in assays designed to measure antibodies with precision and where assays between laboratories need to be comparable. The human pneumococcal standard reference serum, lot 89SF, greatly facilitated the standardization of enzyme-linked immunosorbent assay methodologies during a critical period when the first pneumococcal polysaccharide-conjugate vaccines were being evaluated for licensure. Due to dwindling supplies of lot 89SF, a new reference standard, 007sp, was produced in 2011. Understanding the isotype and subclass composition of either natural or vaccine induced responses to pathogens has assumed increasing importance. In this study, we have assigned IgA, IgG1, and IgG2 values to pneumococcal serotypes 1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F by bridging to existing values in lot 89SF.

Pneumococcal conjugate vaccine 13 delivered as one primary and one booster dose (1 + 1) compared with two primary doses and a booster (2 + 1) in UK infants: a multicentre, parallel group randomised controlled trial.

BACKGROUND: Infants in the UK were first offered a pneumococcal conjugate vaccine (PCV7) in 2006, given at 2 and 4 months of age and a booster dose at 13 months (2 + 1 schedule). A 13-valent vaccine (PCV13) replaced PCV7 in 2010. We aimed to compare the post-booster antibody response in UK infants given a reduced priming schedule of PCV13 (ie, a 1 + 1 schedule) versus the current 2 + 1 schedule and to assess the potential effect on population protection. METHODS: In this multicentre, parallel group, randomised controlled trial, we recuited infants due to receive their primary immunisations aged up to 13 weeks on first vaccinations by information booklets mailed out via the NHS Child Health Information Service and the UK National Health Application and Infrastructure Services. Eligible infants were randomly assigned (1:1) to receive PCV13 at 2, 4, and 12 months (2 + 1 schedule) or 3 and 12 months of age (1 + 1 schedule) delivered with other routine vaccinations. Randomisation was done by computer-generated permuted block randomisation, with a block size of six. Participants and clinical trial staff were not masked to treatment allocation. The primary endpoint was serotype-specific immunoglobulin G concentrations values (geometric mean concentrations [GMC] in µg/mL) measured in blood samples collected at 13 months of age. Analysis was by modified intention to treat with all individuals included by randomised group if they had a laboratory result. This trial is registered on the EudraCT clinical trial database, number 2015-000817-32, and ClinicalTrials.gov, number NCT02482636. FINDINGS: Between September, 2015, and June, 2016, 376 infants were assessed for eligibility. 81 infants were excluded for not meeting the inclusion criteria (n=50) or for other reasons (n=31). 213 eligible infants were enrolled and randomly allocated to group 1 (n=106; 2 + 1 schedule) or to group 2 (n=107; 1 + 1 schedule). In group 1, 91 serum samples were available for analysis 1 month after booster immunisation versus 86 in group 2. At month 13, post-booster, GMCs were equivalent between schedules for serotypes 3 (0·61 µg/mL in group 1 vs 0·62 µg/mL in group 2), 5 (1·74 µg/mL vs 2·11 µg/mL), 7F (3·98 µg/mL vs 3·36 µg/mL), 9V (2·34 µg/mL vs 2·50 µg/mL), and 19A (8·38 µg/mL vs 8·83 µg/mL). Infants given the 1 + 1 schedule had significantly greater immunogenicity post-booster than those given the 2 + 1 schedule for serotypes 1 (8·92 µg/mL vs 3·07 µg/mL), 4 (3·43 µg/mL vs 2·55 µg/mL), 14 (16·9 µg/mL vs 10·49 µg/mL), and 19F (14·76 µg/mL vs 11·12 µg/mL; adjusted p value range <0·001 to 0·047). The 2 + 1 schedule was superior for serotypes 6A, 6B, 18C and 23F (adjusted p value range <0·0001 to 0·017). In a predefined numerical subset of all of the infants recruited to the study (n=40 [20%]), functional serotype-specific antibody was similar between schedules. 26 serious adverse events were recorded in 21 (10%) infants across the study period; 18 (n=13) were in the 2 + 1 group and eight (n=8) in the 1 + 1 group. Only one serious adverse event, a high temperature and refusal to feed after the first vaccination visit in a child on the 2+1 schedule was considered related to vaccine. INTERPRETATION: Our findings show that for nine of the 13 serotypes in PCV13, post-booster responses in infants primed with a single dose are equivalent or superior to those seen following the standard UK 2 + 1 schedule. Introducing a 1 + 1 schedule in countries with a mature PCV programme and established herd immunity is likely to maintain population control of vaccine-type pneumococcal disease. FUNDING: NIHR and the Bill & Melinda Gates Foundation.

Immunogenicity and safety of a booster dose of the 13-valent pneumococcal conjugate vaccine in children primed with the 10-valent or 13-valent pneumococcal conjugate vaccine in the Czech Republic and Slovakia.

BACKGROUND: Although both the 13-valent pneumococcal conjugate vaccine (PCV13) and the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) are widely used, it is unclear how interchangeable they are in terms of immunogenicity. METHODS: Two phase 3, open-label, multicenter studies were conducted to assess the immunogenicity and safety of a booster dose of PCV13 in children primed with PHiD-CV or PCV13. In the Czech Republic, 12-15-month-old children received a PCV13 booster after 3-dose priming with either PHiD-CV or PCV13. In Slovakia, 11-12-month-old children received PCV13 following 2-dose priming with either PHiD-CV or PCV13. Serum IgG concentrations were assessed by enzyme-linked immunosorbent assay and functional antibodies were assessed by opsonophagocytic assay (OPA) before the booster and at 1 and 12months afterward. The primary objective of these studies was to assess non-inferiority of OPA titers for serotype 19A in PHiD-CV-primed subjects compared to those in PCV13-primed children 1month post-booster. RESULTS: A total of 98 subjects in the Czech Republic and 89 subjects in Slovakia were included. One month after the PCV13 booster dose, the IgG and OPA immune responses to serotype 19A in subjects primed with 2 or 3 doses of PHiD-CV were non-inferior to those in subjects primed with PCV13. Non-inferior and persistent immune responses to most other vaccine serotypes were also observed after the PCV13 booster in PHiD-CV-primed subjects. No safety issues were raised in either study. CONCLUSIONS: Overall, robust IgG and OPA immunological responses were observed after booster vaccination with PCV13 in children primed with 2 or 3 doses of PHiD-CV or PCV13, including for serotypes not included in PHiD-CV. These results suggest that these vaccines are interchangeable in terms of safety and immunogenicity and that PCV13 can be used as a booster in the context of mixed schedules. (EudraCT numbers: 2012-005366-35 and 2012-005367-27).

Rare, high-affinity anti-pathogen antibodies from human repertoires, discovered using microfluidics and molecular genomics.

Affinity-matured, functional anti-pathogen antibodies are present at low frequencies in natural human repertoires. These antibodies are often excellent candidates for therapeutic monoclonal antibodies. However, mining natural human antibody repertoires is a challenge. In this study, we demonstrate a new method that uses microfluidics, yeast display, and deep sequencing to identify 247 natively paired anti-pathogen single-chain variable fragments (scFvs), which were initially as rare as 1 in 100,000 in the human repertoires. Influenza A vaccination increased the frequency of influenza A antigen-binding scFv within the peripheral B cell repertoire from <0.1% in non-vaccinated donors to 0.3-0.4% in vaccinated donors, whereas pneumococcus vaccination did not increase the frequency of antigen-binding scFv. However, the pneumococcus scFv binders from the vaccinated library had higher heavy and light chain Replacement/Silent mutation (R/S) ratios, a measure of affinity maturation, than the pneumococcus binders from the corresponding non-vaccinated library. Thus, pneumococcus vaccination may increase the frequency of affinity-matured antibodies in human repertoires. We synthesized 10 anti-influenza A and nine anti-pneumococcus full-length antibodies that were highly abundant among antigen-binding scFv. All 10 anti-influenza A antibodies bound the appropriate antigen at KD<10 nM and neutralized virus in cellular assays. All nine anti-pneumococcus full-length antibodies bound at least one polysaccharide serotype, and 71% of the anti-pneumococcus antibodies that we tested were functional in cell killing assays. Our approach has future application in a variety of fields, including the development of therapeutic antibodies for emerging viral diseases, autoimmune disorders, and cancer.

Poor Correlation between Pneumococcal IgG and IgM Titers and Opsonophagocytic Activity in Vaccinated Patients with Multiple Myeloma and Waldenstrom's Macroglobulinemia.

Patients with multiple myeloma and other B cell disorders respond poorly to pneumococcal vaccination. Vaccine responsiveness is commonly determined by measuring pneumococcal serotype-specific antibodies by enzyme-linked immunosorbent assay (ELISA), by a functional opsonophagocytosis assay (OPA), or by both assays. We compared the two methods in vaccinated elderly patients with multiple myeloma, Waldenstrom's macroglobulinemia, and monoclonal gammopathy of undetermined significance (MGUS). Postvaccination sera from 45 patients (n= 15 from each patient group) and 15 control subjects were analyzed by multiplexed OPA for pneumococcal serotypes 4, 6B, 14, and 23F, and the results were compared to IgG and IgM antibody titers measured by ELISA. While there were significant correlations between pneumococcal OPA and IgG titers for all serotypes among the control subjects (correlation coefficients [r] between 0.51 and 0.85), no significant correlations were seen for any of the investigated serotypes in the myeloma group (r= -0.18 to 0.21) or in the group with Waldenstrom's macroglobulinemia (borderline significant correlations for 2 of 4 serotypes). The MGUS group resembled the control group by having good agreement between the two test methods for 3 of 4 serotypes (r= 0.53 to 0.80). Pneumococcal postvaccination IgM titers were very low in the myeloma patients compared to the other groups and did not correlate with the OPA results. To summarize, our data indicate that ELISA measurements may overestimate antipneumococcal immunity in elderly subjects with B cell malignancies and that a functional antibody test should be used specifically for myeloma and Waldenstrom's macroglobulinemia patients.

The Antibody Response Following a Booster With Either a 10- or 13-valent Pneumococcal Conjugate Vaccine in Toddlers Primed With a 13-valent Pneumococcal Conjugate Vaccine in Early Infancy.

BACKGROUND: Both the 13- and 10-valent pneumococcal conjugate vaccines (PCV-13; PCV-10) are immunogenic and effective against vaccine-type pneumococcal disease when given to young children. However, limited data are available regarding the interchangeability of these 2 vaccines. METHODS: UK children (n = 178) who had previously been vaccinated with PCV-13 at 2 and 4 months were randomized to receive either a PCV-13 or a PCV-10 booster at 12 months of age. PCV-13 vaccine-type antipolysaccharide serum immunoglobulin G (IgG) concentrations and opsonophagocytic assay titers were measured before and at 1 and 12 months following vaccination. The primary objective was to assess noninferiority of PCV-10 compared with PCV-13. RESULTS: For 8 of the PCV-10 serotypes at least 97% of participants in both groups had IgG concentrations ≥0.35 µg/mL at 1 month after vaccination; inferior responses were seen for serotypes 5 and 9V following the PCV-10 compared with the PCV-13 booster. Post booster geometric mean IgG concentrations and opsonophagocytic assay titers were significantly superior for most serotypes in PCV-13 compared with PCV-10 recipients, whereas similar or inferior responses were seen for serotypes 4, 18C, and 19F. Although some increase in antibody was seen in PCV-10 recipients against the serotypes 6A and 19A (serotypes that cross-react with 6B and 19F in PCV-10, respectively) at 1-month post booster, these responses were significantly lower than in the PCV-13 group. CONCLUSIONS: In PCV-13 primed infants, a PCV-10 booster is generally less immunogenic than a PCV-13 booster. For the 3 serotypes in PCV-10 with higher antigen content and/or conjugation to diphtheria or tetanus toxoid carrier proteins, higher or similar booster responses were seen in PCV-10 recipients. Although these findings suggest that responses are generally better with a PCV-13 booster among PCV-13 primed children, the clinical significance of these differences in immunogenicity is unclear.

Functional anti-polysaccharide IgG titres induced by unadjuvanted pneumococcal-conjugate vaccine when delivered by microprojection-based skin patch.

Adequate access to effective and affordable vaccines is essential for the prevention of mortality due to infectious disease. Pneumonia--a consequence of Streptococcus pneumoniae infection--is the world's leading cause of death in children aged under 5 years. The development of a needle-free, thermostable pneumococcal-conjugate vaccine (PCV) could revolutionise the field by reducing cold-chain and delivery constraints. Skin patches have been used to deliver a range of vaccines, with some inducing significantly higher vaccine-specific immunogenicity than needle-injected controls in pre-clinical models, though they have yet to be used to deliver a PCV. We dry-coated a licensed PCV onto a microprojection-based patch (the Nanopatch) and delivered it to mouse skin. We analysed resulting anti-polysaccharide IgG responses. With and without adjuvant, anti-polysaccharide IgG titres induced by Nanopatch immunisation were significantly higher than dose-matched intramuscular controls. These improved responses were primarily obtained against pneumococcal serotypes 4 and 14. Importantly, capsule-specific IgG correlated with functionality in an opsonophagocytic killing assay. We demonstrate enhanced anti-PCV immunogenicity when delivered by Nanopatch over intramuscular injection. As the first study of a PCV delivered by a skin vaccination technology, this report indicates the potential for reduced costs and greater global distribution of such a vaccine.

Serotype-specific effectiveness and correlates of protection for the 13-valent pneumococcal conjugate vaccine: a postlicensure indirect cohort study.

BACKGROUND: Efficacy of the 13-valent pneumococcal conjugate vaccine (PCV13) was inferred before licensure from an aggregate correlate of protection established for the seven-valent vaccine (PCV7). We did a postlicensure assessment of serotype-specific vaccine effectiveness and immunogenicity in England, Wales, and Northern Ireland to derive the correlates of protection for individual serotypes. METHODS: We assessed vaccine effectiveness against invasive pneumococcal disease using the indirect cohort method. We measured serotype-specific IgG concentration in infants after they were given two priming doses of PCV7 (n=126) or PCV13 (n=237) and opsonophagocytic antibody titre from a subset of these infants (n=100). We derived correlates of protection by relating percentage protection to a threshold antibody concentration achieved by an equivalent percentage of infants. We used multivariable logistic regression to estimate vaccine effectiveness and reverse cumulative distribution curves to estimate correlates of protection. FINDINGS: For the 706 cases of invasive pneumococcal disease included in the study, PCV13 vaccine effectiveness after two doses before age 12 months or one dose from 12 months was 75% (95% CI 58-84). Vaccine effectiveness was 90% (34-98) for the PCV7 serotypes and 73% (55-84) for the six additional serotypes included in PCV13. Protection was shown for four of the six additional PCV13 serotypes (vaccine effectiveness for serotype 3 was not significant and no cases of serotype 5 infection occurred during the observation period). The vaccine effectiveness for PCV13 and PCV7 was lower than predicted by the aggregate correlate of protection of 0·35 µg/mL used during licensing. Calculated serotype-specific correlates of protection were higher than 0·35 µg/mL for serotypes 1, 3, 7F, 19A, 19F, and lower than 0·35 µg/mL for serotypes 6A, 6B, 18C, and 23F. Opsonophagocytic antibody titres of 1 in 8 or higher did not predict protection. INTERPRETATION: PCV13 provides significant protection for most of the vaccine serotypes. Although use of the aggregate correlate of protection of 0·35 µg/mL has enabled the licensing of effective new PCVs, serotype-specific correlates of protection vary widely. The relation between IgG concentration after priming and long-term protection needs to be better understood. FUNDING: Public Health England and UK Department of Health Research and Development Directorate.