Quantification of Antibody-dependent Enhancement of the Zika Virus in Primary Human Cells

Summary

We describe a method to evaluate the effect of pre-existing immunity against dengue virus on the Zika virus infection by using human serum, primary human cells, and infection quantification by quantitative real-time polymerase chain reaction.

Abstract

The recent emergence of the flavivirus Zika and neurological complications, such as Guillain-Barré syndrome and microcephaly in infants, has brought serious public safety concerns. Among the risk factors, antibody-dependent enhancement (ADE) poses the most significant threat, as the recent re-emergence of the Zika virus (ZIKV) is primarily in areas where the population has been exposed and is in a state of pre-immunity to other closely related flaviviruses, especially dengue virus (DENV). Here, we describe a protocol for quantifying the effect of human serum antibodies against DENV on ZIKV infection in primary human cells or cell lines.

Introduction

Among the mosquitoes-borne viral diseases, Zika infection is one of the most clinically important¹. The infection is caused by the flavivirus ZIKV which, in most cases, uses Aedes aegypti as its primary vector^1,2. However, there are studies that have reported Aedes albopictus as a primary vector in some ZIKV outbreaks³. Although the infection is asymptomatic in many cases, the most common symptoms are fever, headache, and muscle pain². There is no cure or vaccine available for ZIKV infection and the treatment available is....

Protocol

Serum samples used in this study were obtained from human participants of a cohort from Columbia. Sample collection was approved by the internal review board (IRB) at Universidad de Pamplona (Columbia, South America) and Los Potios Hospital⁸. The samples were anonymously provided and investigators had no access to patient information. The serum samples were checked for the DENV serotype. The samples were further confirmed to neutralize DENV infection in vitro. For control, serum samples from healthy individuals (HC) from the USA were used.

NOTE: This protocol can be used to examine the ADE o....

Results

In Figure 1, there is a step-by-step diagrammatic illustration of all the steps involved to carry out the ADE protocol. It is a schematic diagram showing the whole procedure of ADE of ZIKV due to pre-existing immunity to DENV. Figure 2 shows how human serum samples were categorized into three different groups: DENV infection-confirmed samples are referred to as the DENV-infected group, DENV antibody-confirmed samples are referred.......

Discussion

Cross-reactivity of DENV antibodies leading to the ADE of other DENV serotypes has hindered the development of an effective vaccine¹¹. ZIKV belongs to the same family, Flaviviridae, and has a considerable homology with other flaviviruses, especially DENV¹². The main target of neutralizing antibodies for both ZIKV and DENV is the envelope protein, which shares a very high structural and quaternary sequence homology between the two viruses^13,

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Fetal Bovine Serum	GEMINI	100-106
iCycler	BioRad	785BR02188	Model No. CFX96 Optics Module
Microfuge 18 Centrifuge	Beckman Coulter	367160
Nanodrop-1000	Thermoscientific	1072
Quantifast SYBR-One step RT-PCR kit	Qiagen	204154	Used for 1 step RT-qPCR
RNeasy RNA Isolation Kit	Qiagen	74106	Used for RNA extraction
RPMI-medium	Gibco	11875093