Abstract
Despite widened access to HIV testing, around half of those infected worldwide are unaware of their HIV-positive status and linkage to care remains a major challenge. Current rapid HIV tests are typically analogue risking incorrect interpretation, no facile electronic data capture, poor linkage to care and data loss for public health. Smartphone-connected diagnostic devices have potential to dramatically improve access to testing and patient retention with electronic data capture and wireless connectivity. We report a pilot clinical study of surface acoustic wave biosensors based on low-cost components found in smartphones to diagnose HIV in 133 patient samples. We engineered a small, portable, laboratory prototype and dual-channel biochips, with in-situ reference control coating and miniaturised configuration, requiring only 6 µL plasma. The dual-channel biochips were functionalized by ink-jet printing with capture coatings to detect either anti-p24 or anti-gp41 antibodies, and a reference control. Biochips were tested with 31 plasma samples from patients with HIV, and 102 healthy volunteers. SH-SAW biosensors showed excellent sensitivity, specificity, low sample volumes and rapid time to result, and were benchmarked to commercial rapid HIV tests. Testing for individual biomarkers found sensitivities of 100% (anti-gp41) and 64.5% (anti-p24) (combined sensitivity of 100%) and 100% specificity, within 5 min. All positive results were recorded within 60 s of sample addition with an electronic readout. Next steps will focus on a smartphone-connected device prototype and user-friendly app interface for larger scale evaluation and field studies, towards our ultimate goal of a new generation of affordable, connected point-of-care HIV tests.
Highlights
The United Nations Sustainable Development Goals herald a major commitment by the world to halt the spread of HIV/AIDS by 2030.1 Yet despite huge advances in testing and antiretroviral therapy, around half of the estimated 37 million people living with HIV in the world do not know their HIV-positive status,[2,3] leading to late presentation complicated by significant immunosuppression, opportunistic infections and related mortality,[4] and contributing to the spread of HIV in the community.[5,6]
Our findings highlight the potential of shear horizontal surface acoustic wave (SH-SAW) biosensors with dual-channel biochips to detect the presence of anti-HIV antibodies at clinically-relevant levels, with 100% sensitivity and 100% specificity, within very short (60 s) timescales at low (6 μl) sample volumes
With further development into a fully userfriendly, sample-preparation free smartphone-connected format, SH-SAW biosensors have potential as a foundation for the generation of low cost, rapid, POC screening tests
Summary
The United Nations Sustainable Development Goals herald a major commitment by the world to halt the spread of HIV/AIDS by 2030.1 Yet despite huge advances in testing and antiretroviral therapy, around half of the estimated 37 million people living with HIV in the world do not know their HIV-positive status,[2,3] leading to late presentation complicated by significant immunosuppression, opportunistic infections and related mortality,[4] and contributing to the spread of HIV in the community.[5,6] Pilot studies have shown that widening access to testing, through placing testing sites in locations such as community centres and money transfer shops, is key to reaching sections of the population who would not normally encounter HIV testing through traditional services.[7] self-testing is acceptable, feasible, and has been made legal in some countries with internet and smartphone-based apps under development to facilitate testing and linkage to care.[8,9] Patients can only engage with care if they are aware of their HIV status. Diagnosis early in infection carries significant benefits of increased life-expectancy by 10 years and facilitates access to treatment, for example, reducing the risk of mother to child transmission to under 1% whereas late diagnosis carries an increased risk of onwards transmission and death.
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