Multiplex opsonophagocytosis assay (MOPA): A useful tool for the monitoring of the 7-valent pneumococcal conjugate vaccine

D. Bogaert, M. Sluijter, R. De Groot, P. W M Hermans*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

17 Citations (Scopus)

Abstract

Pneumococcal conjugate vaccination is highly efficacious against invasive diseases in young children. Since host protection is mainly mediated by opsonin-dependent phagocytosis, the in vitro measurement of opsonophagocytic activity of the anti-capsular antibodies is assumed to be a reliable correlate of protection to monitor vaccine efficacy. Unfortunately, the methods used so far are all tedious to perform and material-consuming. Therefore, we modified the multi-specificity opsonophagocytosis killing assay (MSOPKA) into a high-throughput method, which simultaneously measures the opsonophagocytosis against the seven serotypes covered by the current conjugate vaccine in a single assay. In the so-called multiplex opsonophagocytosis assay (MOPA), a mixture containing equal numbers of colony forming units (CFUs) of chloramphenicol- resistant serotype 4, spectinomycin-resistant serotype 6B, streptomycin- resistant serotype 9V, erythromycin-resistant serotype 14, rifampicin-resistant serotype 18C, tetracycline-resistant serotype 19F, and trimethoprim-resistant serotype 23F pneumococci was used as a target mixture and incubated with serial dilutions of test serum. After opsonophagocytosis by differentiated HL-60 cells in the presence of complement, the samples were spotted onto different blood agar plates containing the seven selective antibiotics, respectively. Opsonophagocytosis was calculated as the highest serum dilution resulting in 90% or more reduction in CFUs. The data obtained by this assay correlated well with the data obtained by the MSOPKA. In conclusion, the MOPA simultaneously measures opsonophagocytosis capacity of serum against the capsular serotypes included in the 7-valent pneumococcal conjugate vaccine in a high-throughput fashion, requiring low volumes of patient sera.

Original languageEnglish
Pages (from-to)4014-4020
Number of pages7
JournalVaccine
Volume22
Issue number29-30
DOIs
Publication statusPublished - 28 Sept 2004

Keywords

  • Conjugate vaccine
  • Correlate of protection
  • Opsonophagocytosis
  • Streptococcus pneumoniae

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