Dataset Information

Assignment of Opsonic Values to Pneumococcal Reference Serum 007sp for Use in Opsonophagocytic Assays for 13 Serotypes.

ABSTRACT: Opsonophagocytic assays (OPAs) are routinely used for assessing the immunogenicity of pneumococcal vaccines, with OPA data often being utilized for licensure of new vaccine formulations. However, no reference serum for pneumococcal OPAs is available, making evaluation of data among different laboratories difficult. This international collaboration was initiated to (i) assign consensus opsonic indexes (OIs) to FDA pneumococcal reference serum lot 007sp (here referred to as 007sp) and a panel of serum samples used for calibration of the OPA and (ii) determine if the normalization of the OPA results obtained with test samples to those obtained with 007sp decreases the variability in OPA results among laboratories. To meet these goals, six participating laboratories tested a panel of serum samples in five runs for 13 serotypes. For each serum sample, consensus OIs were obtained using a mixed-effects analysis of variance model. For the calibration serum samples, normalized consensus values were also determined on the basis of the results obtained with 007sp. For each serotype, the overall reduction in interlaboratory variability was calculated by comparing the coefficients of variation of the unadjusted and the normalized values. Normalization of the results substantially reduced the interlaboratory variability, ranging from a 15% reduction in variability for serotype 9V to a 64% reduction for serotype 7F. Normalization also increased the proportion of data within 2-fold of the consensus value from approximately 70% (average for all serotypes) to >90%. On the basis of the data obtained in this study, pneumococcal reference standard lot 007sp will likely be a useful reagent for the normalization of pneumococcal OPA results from different laboratories. The data also support the use of the 16 FDA serum samples used for calibration of the OPA as part of the initial evaluation of new assays or periodic assessment of established assays.

SUBMITTER: Burton RL

PROVIDER: S-EPMC5299120 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Assignment of Opsonic Values to Pneumococcal Reference Serum 007sp for Use in Opsonophagocytic Assays for 13 Serotypes.

Burton R L RL Antonello J J Cooper D D Goldblatt D D Kim K H KH Plikaytis B D BD Roalfe L L Wauters D D Williams F F Xie G L GL Nahm M H MH Akkoyunlu M M

Clinical and vaccine immunology : CVI 20170206 2

Opsonophagocytic assays (OPAs) are routinely used for assessing the immunogenicity of pneumococcal vaccines, with OPA data often being utilized for licensure of new vaccine formulations. However, no reference serum for pneumococcal OPAs is available, making evaluation of data among different laboratories difficult. This international collaboration was initiated to (i) assign consensus opsonic indexes (OIs) to FDA pneumococcal reference serum lot 007sp (here referred to as 007sp) and a panel of s ...[more]

PMID: 27974397

Similar Datasets

Project description:Pneumococcal conjugate vaccines (PCVs) have been effective in reducing the disease burden caused by Streptococcus pneumoniae. The first licensed PCV (PCV7) was composed of capsular polysaccharides from seven serotypes. This was followed by PCV10, then PCV13, and currently there are a number of higher valency vaccines in development. As part of licensure, new vaccine iterations require assessment of immunogenicity. Since some antibodies can be non-functional, measuring functional antibodies is desirable. To meet this need, opsonophagocytic assays (OPAs) have been developed. Previous studies have shown there can be significant variations in OPA results from different laboratories. We have previously shown that standardizing OPA data using reference serum 007sp can decrease this variation. To extend this approach to additional serotypes, a panel of sera was tested by five laboratories using a multiplexed OPA for serotypes 2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20B, 22F, and 33F. Each sample was tested in five runs with 007sp tested three times in each run. Results were analyzed using a mixed effects ANOVA model. Standardization of the results significantly decreased the inter-laboratory variation for some serotypes. For serotypes 2, 8, and 11A, the variability was reduced by 40%, 45%, and 40%, respectively. For serotypes 12F, 17F, and 20B, the reductions were more modest (14%, 19%, and 24%, respectively). Standardization had little effect for the remaining serotypes. In many cases, the impact of normalization was blunted by the results from five sera that were collected after an extended post-vaccination interval. We have previously reported consensus values for 007sp for 13 serotypes, as well as the creation of a calibration serum panel ("Ewha Panel A"). Here, we report consensus values for 11 additional serotypes for 007sp and the creation of a second serum panel ("Ewha Panel B"). These consensus values will facilitate the development of next-generation PCVs.

Project description:Pneumococcal conjugate vaccines (PCVs) have been very effective in reducing the disease burden caused by Streptococcus pneumoniae serotypes covered by the current vaccine formulations. However, the incidence of disease caused by serotypes not covered by the vaccine is increasing. Consequently, there are active efforts to develop new PCVs with additional serotypes in order to provide protection against the emergent serotypes. Due to costs and ethical issues associated with performing true vaccine efficacy studies, new PCVs are being licensed based on their immunogenicity, which may be assessed with 2 in vitro assays: enzyme-linked immunosorbent assay (ELISA) for quantitating antibody level and opsonophagocytic assay (OPA) for assessing protective function. While a standardized ELISA has been developed, OPA results from different laboratories can be quite disparate, even among laboratories utilizing the same platform. In order to harmonize OPA data, a recent international collaboration assigned opsonic indices to the US Food and Drug Administration (US FDA) reference serum, 007sp, as well as a panel of US FDA calibration sera. However, due to a low number of aliquots, the availability of these calibration sera is extremely limited. Because calibration sera are critical to establish the performance characteristics of an OPA, a second calibration serum panel was created, comprised of 20 sera collected from adults immunized with the 23-valent polysaccharide vaccine, with 150 to 500 aliquots prepared for each serum. In order to establish consensus OPA values of the 20 sera for the 13 serotypes in 13-valent PCV, the sera were tested by 4 laboratories in an international collaborative OPA study. The 007sp results of 1 laboratory deviated significantly from those obtained by the other laboratories, as well as from previously assigned values. Due to these discrepancies, the consensus values for the calibration sera were determined based on the data from the remaining laboratories. Thus, we were able to create a panel of sera with consensus opsonic values that could be used by outside laboratories to calibrate pneumococcal OPAs. Our results also confirmed findings of a previous study that normalization of OPA results significantly reduces interlaboratory variation, with normalization based on 007sp reducing variation by 43% to 74%, depending on serotype.

Project description:The polysaccharide capsule is a key virulence factor of Streptococcus pneumoniae There are numerous epidemiologically important pneumococcal capsular serotypes, and recent findings have demonstrated that several of them are commonly found among nonpathogenic commensal species. Here, we describe 9 nonpneumococcal strains carrying close homologs of pneumococcal capsular biosynthetic (cps) loci that were discovered during recent pneumococcal carriage studies of adults in the United States and Kenya. Two distinct Streptococcus infantis strains cross-reactive with pneumococcal serotype 4 and carrying cps4-like capsular biosynthetic (cps) loci were recovered. Opsonophagocytic killing assays employing rabbit antisera raised against S. infantis US67cps4 revealed serotype 4-specific killing of both pneumococcal and nonpneumococcal strains. An S. infantis strain and two Streptococcus oralis strains, all carrying cps9A-like loci, were cross-reactive with pneumococcal serogroup 9 strains in immunodiffusion assays. Antiserum raised against S. infantis US64cps9A specifically promoted killing of serotype 9A and 9V pneumococcal strains as well as S. oralis serotype 9A strains. Serotype-specific PCR of oropharyngeal specimens from a recent adult carriage study in the United States indicated that such nonpneumococcal strains were much more common in this population than serotype 4 and serogroup 9 pneumococci. We also describe S. oralis and S. infantis strains expressing serotypes identical or highly related to serotypes 2, 13, and 23A. This study has expanded the known overlap of pneumococcal capsular serotypes with related commensal species. The frequent occurrence of nonpneumococcal strains in the upper respiratory tract that share vaccine and nonvaccine capsular serotypes with pneumococci could affect population immunity to circulating pneumococcal strains.IMPORTANCE The distributions and frequencies of individual pneumococcal capsular serotypes among nonpneumococcal strains in the upper respiratory tract are unknown and potentially affect pneumococcal serotype distributions among the population and immunity to circulating pneumococcal strains. Repeated demonstration that these nonpneumococcal strains expressing so-called pneumococcal serotypes are readily recovered from current carriage specimens is likely to be relevant to pneumococcal epidemiology, niche biology, and even to potential strategies of employing commensal live vaccines. Here, we describe multiple distinct nonpneumococcal counterparts for each of the pneumococcal conjugate vaccine (PCV) serotypes 4 and 9V. Additional data from contemporary commensal isolates expressing serotypes 2, 13, and 23A further demonstrate the ubiquity of such strains. Increased focus upon this serological overlap between S. pneumoniae and its close relatives may eventually prove that most, or possibly all, pneumococcal serotypes have counterparts expressed by the common upper respiratory tract commensal species Streptococcus mitis, Streptococcus oralis, and Streptococcus infantis.

Dataset Information

Assignment of Opsonic Values to Pneumococcal Reference Serum 007sp for Use in Opsonophagocytic Assays for 13 Serotypes.

Publications

Assignment of Opsonic Values to Pneumococcal Reference Serum 007sp for Use in Opsonophagocytic Assays for 13 Serotypes.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets