Development of a high-throughput assay to measure measles neutralizing antibodies

PLoS One. 2019 Aug 15;14(8):e0220780. doi: 10.1371/journal.pone.0220780. eCollection 2019.

Abstract

Measles virus is highly infectious and remains a leading cause of vaccine preventable deaths in children. Neutralizing antibody responses elicited by measles virus infection or immunization are a serological correlate of protection. We describe a high-throughput neutralization assay to improve surveillance for measles immunity. Measles virus-antibody mixtures were incubated on Vero cell monolayers and 24 hours later cell-lysates harvested and subjected to one-step SYBR green RT-qPCR to amplify a target sequence within the measles virus nucleoprotein gene. Neutralization endpoint titers were interpolated to determine the dilution that inhibited the relative amplicon copy number by at least 90% compared to the mean signal obtained in virus control wells in the absence of serum. Anti-measles virus and anti-measles hemagglutinin antisera specifically neutralized measles virus in the microneutralization RT-qPCR assay while pre-immune sera and sera raised against other viruses did not. The microneutralization RT-qPCR assay obeyed the Percentage Law for measles virus inputs ranging from 100-5000 TCID50/well. The linear range of the assay corresponds to measles antibody concentrations of 30 to 3000 mIU/mL. Bland-Altman analysis and two-way analysis of variance demonstrated that results obtained using the microneutralization RT-qPCR assay were comparable to those obtained using a plaque reduction neutralization test and correctly identified human serum samples that were seropositive (95% and 100%, sensitivity and specificity, respectively). Furthermore, these comparisons suggest that a concentration of 300 mIU/mL may be a conservative cut-point to use to identify individuals likely to be protected against severe measles disease when the endpoint is based on 90% inhibition of virus replication. Measles virus microneutralization RT-qPCR is a rapid, sensitive, specific, and robust assay for detecting measles neutralizing antibodies that may help to improve immunization strategies nationally and achieve measles elimination globally.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Neutralizing / analysis*
  • Chlorocebus aethiops
  • Enzyme-Linked Immunosorbent Assay*
  • Humans
  • Measles / diagnosis
  • Measles / immunology
  • Measles / prevention & control*
  • Measles virus / immunology*
  • Neutralization Tests / methods
  • Population Surveillance
  • Sensitivity and Specificity
  • Vero Cells

Substances

  • Antibodies, Neutralizing

Grants and funding

This work was supported by a CRADA (#2017-0028-CRD to JB) with Johns Hopkins Bloomberg School of Public Health under a grant from Bill and Melinda Gates Foundation, Seattle, WA (grant #OPP1094816 to WJM, https://www.gatesfoundation.org/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.