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

Repetitive DNA sequences are abundant in the genome of most biological species. These sequences are naturally “preamplified”, which makes them a preferential target for a variety of biological assays. Current methods to detect specific DNA sequences are based on the quantitative polymerase chain reaction (PCR), which relies on target amplification by Taq polymerase and uses a fluorescent resonance energy transfer (FRET)-based probe. Here, to rapidly detect a repetitive DNA sequence, we combine a highly sensitive magnetic modulation biosensing (MMB) system and a modified double-quenched FRET-based probe. The high numbers of copies of the female-specific XhoI sequence of the domestic chicken (Gallus gallus), combined with the low background fluorescence levels of the modified double-quenched probe and the high sensitivity of the MMB system, allow us to determine the chick sex in ovo within 13 min, with 100% sensitivity and specificity. Compared to quantitative PCR, the presented assay is 4–9 times faster. More broadly, by specifically tailoring the primers and probe, the proposed assay can detect any target DNA sequence, either repetitive or nonrepetitive.

The functions attributed to bacterial TA systems are controversial and remain largely unknown. Our study suggests new insights into the potential functions of bacterial TA systems.