Use of Urea Wash ELISA to Distinguish Zika and Dengue Virus Infections

Wen-Yang Tsai; Han Ha Youn; Jasmine Tyson; Carlos Brites; Jih-Jin Tsai; Celia Pedroso; Jan Felix Drexler; Angel Balmaseda; Eva Harris; Wei-Kung Wang


Emerging Infectious Diseases. 2018;24(7):1355-1359. 

In This Article

Abstract and Introduction


Serologic testing remains crucial for Zika virus diagnosis. We found that urea wash in a Zika virus nonstructural protein 1 IgG ELISA distinguishes secondary dengue virus infection from Zika virus infection with previous dengue (sensitivity 87.5%, specificity 93.8%). This test will aid serodiagnosis, serosurveillance, and monitoring of Zika complications in dengue-endemic regions.


The rapid spread of Zika virus and its association with fetal microcephaly and other birth defects (congenital Zika syndrome) present a pressing need for sensitive and specific diagnostic tests.[1,2] Centers for Disease Control and Prevention guidelines for laboratory diagnosis of Zika virus infection include a positive reverse transcription PCR as soon as possible after symptom onset to confirm Zika virus and a negative IgM test result to exclude Zika virus.[3] Serologic testing remains a crucial component of Zika diagnosis because most Zika virus infections are asymptomatic, many persons seek Zika virus testing beyond the period during which RNA is detectable, and Zika virus can be transmitted sexually or after asymptomatic infection.[1–3]

Zika virus belongs to the family Flaviviridae, in which several arboviruses, including the 4 serotypes of dengue virus (DENV-1–4), cause substantial disease in humans. Because of cross-reactivity of antienvelope antibody to Zika virus and other flaviviruses, positive or equivocal IgM results based on envelope protein require further testing with plaque-reduction neutralization tests.[3–5] These tests can confirm acquisition of Zika virus as the first flavivirus infection (primary Zika virus [pZIKV] infection) but are more challenging to interpret for those who have experienced previous flavivirus infections.

Several studies have demonstrated that DENV–immune serum and monoclonal antibodies can enhance Zika virus replication in vitro and in vivo[6–9] and raised concerns that previous DENV infection might increase the risk for and severity of congenital Zika syndrome. A recent study reported that a nonstructural protein 1 (NS1)–based blockade of binding ELISA can distinguish Zika virus and other flavivirus infections.[10] However, it cannot distinguish pZIKV, Zika virus infection with previous dengue (DENV-ZIKV), and secondary DENV (sDENV) infections, which is critical in Zika virus– and DENV-endemic regions.