Antibody-based assay discriminates Zika virus infection from other flaviviruses

Abstract

Zika virus (ZIKV) is a mosquito-borne flavivirus that emerged recently as a global health threat, causing a pandemic in the Americas. ZIKV infection mostly causes mild disease, but is linked to devastating congenital birth defects and Guillain-Barré syndrome in adults. The high level of cross-reactivity among flaviviruses and their cocirculation has complicated serological approaches to differentially detect ZIKV and dengue virus (DENV) infections, accentuating the urgent need for a specific and sensitive serological test. We previously generated a ZIKV nonstructural protein 1 (NS1)-specific human monoclonal antibody, which we used to develop an NS1-based competition ELISA. Well-characterized samples from RT-PCR-confirmed patients with Zika and individuals exposed to other flavivirus infections or vaccination were used in a comprehensive analysis to determine the sensitivity and specificity of the NS1 blockade-of-binding (BOB) assay, which was established in laboratories in five countries (Nicaragua, Brazil, Italy, United Kingdom, and Switzerland). Of 158 sera/ plasma from RT-PCR-confirmed ZIKV infections, 145 (91.8%) yielded greater than 50% inhibition. Of 171 patients with primary or secondary DENV infections, 152 (88.9%) scored negative. When the control group was extended to patients infected by other flaviviruses, other viruses, or healthy donors (n = 540), the specificity was 95.9%. We also analyzed longitudinal samples from DENV-immune and DENVnaive ZIKV infections and found inhibition was achieved within 10 d postonset of illness and maintained over time. Thus, the Zika NS1 BOB assay is sensitive, specific, robust, simple, low-cost, and accessible, and can detect recent and past ZIKV infections for surveillance, seroprevalence studies, and intervention trials.is a mosquito-borne flavivirus that is spread via the bite of infected Aedes mosquitoes or by sexual transmission and is responsible for the explosive 2015-2017 epidemic in the Americas. ZIKV infection during pregnancy is linked to devastating birth defects and associated anomalies, designated congenital Zika syndrome (1, 2), whereas in adults, ZIKV infection has been associated with Guillain Barré syndrome (3). Flaviviruses are enveloped RNA viruses containing an ∼11-kb positive-stranded RNA genome that encodes three structural and seven nonstructural proteins. Cells infected by flaviviruses secrete nonstructural protein 1 (NS1), which has multiple roles in immune evasion and pathogenesis (4, 5).Antibody responses generated in response to flavivirus infections are notoriously cross-reactive, representing a significant obstacle for the specific diagnosis of infection using serological assays. Multiple RT-PCR-based assays for the detection of ZIKV RNA are available, but their use is limited to the narrow window when viral RNA is detectable in body fluids. This is highly variable among patients and subject to reporting error, as symptoms are mild, and thus patients may take less notice of the day of onset, but in most cases, it is up to 7 d in serum, ...

Novel differential linear B‐cell epitopes to identify Zika and dengue virus infections in patients

“…34 Nonetheless, it is imperative to consider the possible implications of virusinfection enhancement. 31,39,40 While various reports have shown the specificity of the NS1 antigen to differentiate between ZIKV and DENV, 11,20,21,41,42 the majority of the common flavivirus peptides identified in this study are on the NS1 protein, possibly because of the conserved regions of NS1 among the flaviviruses. 35,36 Peptides identified from B-cell epitope mapping have been reported on flavivirus E, prM, NS1 and NS3 antigens from antibodies of patients and animal models.…”

“…31,37,38 Identification of antigenic epitopes and characterisation of cross-reactive epitopes are crucial in vaccine and immunodiagnostic developments. 31,39,40 While various reports have shown the specificity of the NS1 antigen to differentiate between ZIKV and DENV, 11,20,21,41,42 the majority of the common flavivirus peptides identified in this study are on the NS1 protein, possibly because of the conserved regions of NS1 among the flaviviruses. 8,43 For example, common flavivirus peptides 36 (amino acid residues 70-85), 38 (amino acid residues 119-136) and 49 (amino acid residues 315-326) were identified as ZIKV-specific in other patient cohorts from South America.…”

“…11,[20][21][22] Although computational studies have predicted multiple differential epitopes, validation on patient samples, however, remains a challenge. 11,[20][21][22] Although computational studies have predicted multiple differential epitopes, validation on patient samples, however, remains a challenge.…”

“…Previous studies have shown the possibility of using ZIKV antigens to distinguish ZIKV infections from other flavivirus infections. 11,[20][21][22] Although computational studies have predicted multiple differential epitopes, validation on patient samples, however, remains a challenge. 23 In this report, antibody and neutralising responses by ZIKV patients from Singapore were characterised longitudinally.…”

Zika virus infection of first-trimester human placentas: utility of an explant model of replication to evaluate correlates of immune protection ex vivo

“…Of particular interest is the question of whether the timing of prior exposure to dengue virus could contribute to regional differences in the frequency of microcephaly associated with ZIKV infection [51,52]. Improved serological methods should help uncover these relationships: non-cross-reactive ZIKV NS1-specific monoclonal antibodies have recently been identified in a screen of human memory B cells and have been used to develop new ZIKV-specific serologic diagnostic tests [41**,53**]. …”