Harmonization of Zika neutralization assays by using the WHO International Standard for anti-Zika virus antibody

Abstract

During outbreaks of emerging viruses, such as the Zika outbreak in 2015–2016, speed and accuracy in detection of infection are critical factors to control the spread of the disease; often serological and diagnostic methods for emerging viruses are not well developed and validated. Thus, vaccines and treatments are difficult to evaluate due to the lack of comparable methods. In this study, we show how the 1st WHO International Standard for anti-Zika antibody was able to harmonize the neutralization titres of a panel of serological Zika-positive samples from laboratories worldwide. Expression of the titres in International Unit per millilitre reduced the inter-laboratory variance, allowing for greater comparability between laboratories. We advocate the use of the International Standard for anti-Zika virus antibodies for the calibration of neutralization assays to create a common language, which will permit a clear evaluation of the results of different clinical trials and expedite the vaccine/treatment development.Zika virus: Harmonizing multisite neutralization assaysProtocols for achieving fast and effective detection of Zika virus (ZIKV) infections during outbreaks are limited by the cross-reactivity of immunoassays and the inter-laboratory variability of results, which may adversely affect response planning in the field and slow the development of new diagnostic tools and therapies. Giada Mattiuzzo and colleagues now applied the WHO International Standard for ZIKV-specific antibodies to harmonize the neutralization titres generated from a panel of serological ZIKV-positive samples analysed in multiple laboratories across the world. The use of the International Standard, which includes a standard sample (a defined pool of sera from confirmed ZIKV-positive cases) and an agreed International Unit, reduced the inter-laboratory variance in neutralization assay results performed on ZIKV of Asian lineage, and enabled a better comparison and integration of the multisite data. This work establishes the first International Standard for an Asian lineage ZIKV-specific antibody for facilitating ZIKV diagnostics, prevention and treatment.