Highly sensitive and specific Zika virus serological assays using a magnetic modulation biosensing system.

Background: Zika virus has created global alarm as it has been associated with catastrophic fetal abnormalities, including microcephaly, spontaneous abortion, and intrauterine growth restriction. Current serological assays that detect antiviral antibodies suffer from low sensitivity and high cross-reactivity among different flaviviruses.

Methods: Here, utilizing a novel Magnetic Modulation Biosensing (MMB) system and the Zika non-structural 1 (NS1) protein, we show highly sensitive and specific Zika serological assays. We blindly tested 60 reverse transcription-PCR Zika-positive samples and healthy patients' serum samples, as well as 44 serum samples from ELISA West Nile- and dengue-positive patients. The Zika-positive samples were collected from Israeli travelers returning from Zika endemic areas.

Results: The MMB Zika assays have 88-97% sensitivity, much higher than the current state-of-the-art Euroimmun ELISA assays (38-74%). Additionally, the specificity is 100%, and the cross reactivity with West Nile and dengue viruses is minimal (0-4%). Furthermore, the MMB assays detected Zika IgM antibodies as early as 5 days and as late as 180 days post symptoms onset, significantly extending the number of days that the antibodies are detectable.

Conclusions: The sensitivity, specificity, and simplicity of the MMB assays may significantly improve Zika diagnosis and provide accurate results for public health agencies.