Clinical laboratory assays on a USB stick could become a powerful tool in the treatment and containment of HIV-1 in low-resource regions, such as sub-Saharan Africa
Imagine a small USB device that plugs into a computer and, using a small sample of blood, is capable of detecting the presence of HIV and measuring its viral load in that individual. Such technology exists and was created by a team of scientists in the United Kingdom (UK). However, it is not yet ready for use by clinical laboratories.
Researchers at Imperial College London company, DNA Electronics, have developed a diagnostic USB stick that measures the presence of human immunodeficiency virus (HIV), as well as the viral load in a person’s blood, and in less than 30 minutes. The platform promises to be an important milestone for the medical laboratory treatment and containment of pandemic diseases that pose a serious threat to global health.
A story published on the mobile technology news blog Quartz pointed out that more than 24-million of the 37-million people worldwide infected with HIV live in sub-Saharan Africa. It is widely recognized that high cost and lack of access to medical care and clinical laboratory services remain a barrier to diagnosis, treatment, and containment of the disease. “[I]mproving diagnostics is now a key part of global strategies to combat [HIV],” wrote the study authors in a paper published in Nature Research journal Scientific Reports.
Monitoring Viral Load Crucial for Treating and Tracking Drug Resistance
Despite improvements in HIV treatment over the past two decades, routine antibodies-based diagnostic tests have shown only whether the virus is present—they have not shown viral load. “[M]onitoring viral load is crucial to the success of HIV treatment,” stated senior author Graham Cooke, MD, PhD, in a press release. Cooke is with the Department of Medicine, Imperial College London. He pointed out that regular monitoring ensures the therapy is working and that the patient is adhering to medication recommendations. This helps prevent the development of drug-resistant strains of the virus.
“At the moment, testing often requires costly and complex equipment that can take a couple of days to produce a result,” observed Cooke. “We have taken the job done by this equipment, which is the size of a large photocopier, and shrunk it down to a USB chip.”
USB Platform Combines Semiconductor and DNA Amplification Technologies
The new test combines CMOS (complementary metal-oxide-semiconductor) chip technology with a pH-LAMP (loop-mediated isothermal amplification) assay. According to their research paper, the scientists first optimized a novel low-buffer HIV-1 pH-LAMP assay, then incorporated the assay into a pH sensitive CMOS chip.
According to the press release, the test works by placing a small sample of blood onto a spot on the USB stick. Any HIV virus present in the sample triggers a change in acidity, which the chip transforms into an electrical signal. This is sent to the USB stick, which displays the result on a computer or electronic device. “The CMOS chip platform is able to detect small changes in pH generated by on-chip reactions,” the study authors noted. This is accomplished through heaters and thermal sensors embedded in the chip. The assay simultaneously amplifies and detects HIV-1 RNA.
USB Test Could Allow HIV Patients to Monitor Their Own Viral Loads
The scientists used the new USB technology to screen 991 clinical samples with 95% accuracy. The median time to detection was 20.8 minutes, the press release reported.
“[The technology] shows great potential as a route to a point of care diagnostic suitable for use in clinical settings without access to a laboratory infrastructure, as is often the case in the developing world,” the study authors wrote in Scientific Reports.
They pointed out that, currently, most novel viral load detection devices require a desktop platform and laboratory processing. This significantly limits access in poorer, remote regions. The new method has the advantage of working on a USB-compatible stick without the need for an additional power supply, refrigeration, labeling, or fluorescence detection.
“The sensitivity, specificity, and reproducibility are close to that required to produce a point-of-care device which would be of benefit in resource-poor regions, and could be performed on [a] USB stick or similar low-power device,” wrote the study authors.
According to Cooke, when further developed, the new technology could allow HIV patients to regularly monitor their own virus levels, similarly to diabetics monitoring blood sugar levels.
Researchers Working to Expand Platform’s Detection Capabilities
The Imperial College team developed the new USB test platform in conjunction with its spin out DNA Electronics (DNAe). Researchers at DNAe describe the USB platform as highly adaptable. They are now investigating whether the device can be used to test for other viruses, such as hepatitis. Additionally, they are using the same technology to develop a device for detecting bacterial and fungal sepsis, as well as antibiotic resistance, according to the press release.
As Professor Christofer Toumazou, PhD, stated in the press release, “This is a great example of how this new analysis technology has the potential to transform how patients with HIV are treated.” Toumazou is DNAe’s Founder and Executive Chairman, as well as Regius Professor at the Department of Electrical and Electronic Engineering at Imperial.
For pathology and clinical laboratory professionals, this is one more example of how remote medical pathology is evolving to bring better quality of care to patients in both developing and developed nations.
—Pamela Scherer McLeod