Scientists develop dried whole blood test to detect Zika and hepatitis C without lab purification
A US-based team has developed a method for detecting Zika virus and hepatitis C virus (HCV) RNA directly from dried whole blood, bypassing the extraction and purification steps that have long constrained point-of-care molecular diagnostics. The work, published in Science Advances on 4 September 2026, reports sensitivities comparable to centralised PCR-based testing using only a simple heater and a low-cost portable fluorescence reader.
Conventional workflows for detecting RNA viruses in blood rely on centrifugation to isolate plasma or serum, followed by extraction and purification to remove proteins, RNases and other inhibitory components before amplification can proceed reliably. According to the researchers, led by Jongwon Lim and Rashid Bashir at the University of Illinois Urbana-Champaign, this sample preparation stage can account for up to 90 per cent of the total hands-on time in a diagnostic workflow, and remains dependent on centrifuges, extraction kits and trained personnel that are frequently unavailable in low-resource settings.
Point-of-care platforms developed to date have generally attempted to miniaturise this purification-centric approach rather than dispense with it, the authors note, which has limited most such systems to the “near point-of-care” category rather
than genuine field deployability.
A biphasic dried blood platform
The new protocol works by drying whole blood into a nanoporous solid matrix that passively immobilises RNA while separating it from inhibitory blood components such as RNases and proteins. Because RNA is considerably less chemically stable than DNA, owing to a 2′-hydroxyl group that renders it susceptible to hydrolysis, the researchers found that RNase inhibition alone was insufficient; drying, thermal lysis, and a primer-limited reverse transcription step all needed to be carried out as discrete, sequential stages to achieve reliable amplification. Omitting the dedicated reverse transcription step, for instance, limited detection to 10³ copies per microlitre, whereas the full five-step protocol achieved consistent detection down to 10 copies per microlitre for Zika virus.
Using this “true point-of-care” approach, described in the paper as a departure from the purification-centric paradigm, the team achieved a detection sensitivity of 10 copies per microlitre for Zika virus and 1 international unit per microlitre for HCV directly from 4 microlitres of whole blood, without any nucleic acid purification. Scaling the assay to 100 microlitres of blood, split across 25 parallel 4-microlitre reactions, achieved 10 IU sensitivity for HCV, a marked improvement on in-house extraction-based RT-PCR, which detected HCV in only one of three replicates at 500 IU input, corresponding to a recovery efficiency of around 0.06 per cent.
Multiplexing and field deployment
The platform also supports simultaneous detection of both viruses using dual-colour DARQ probes, with limits of detection of 10 copies per microlitre for Zika and 1 IU per microlitre for HCV in duplex format. The authors additionally validated a fully lyophilised version of the assay using dried, room-temperature-stable primers and reagents, paired with a palm-sized fluorometer named VPodDuo (measuring 6.3 by 2.8 by 4.7 centimetres and weighing approximately 75 grams) that communicates results to a smartphone via Bluetooth. The entire workflow, from sample preparation to readout, can reportedly be completed within two hours without cold-chain logistics.
The authors estimate the cost per reaction at approximately $3.59, with the portable fluorometer priced at $60, figures they suggest fall within target product profiles previously proposed for near-patient HCV viraemia testing.
Clinical relevance
The sensitivities achieved sit within clinically actionable ranges: the paper notes that most HCV-positive patients worldwide present with viral loads exceeding 1,318 IU/ml, and symptomatic Zika infections typically exceed 9.9 × 10⁴ copies/ml, well above the assay’s detection floor. The authors propose that the underlying “dried blood tissue engineering” concept could extend to other RNA targets, including microRNA and mRNA-based cancer diagnostics, though this remains an area for future investigation.
Reference:
Lim, J., Lee, H., Wester, M., et al. (2026). Amplification of RNA for identification of Zika and HCV in whole blood. Science Advances, 12, eaeb6129. https://doi.org/10.1126/sciadv.aeb6129
