An HIV testing USB stick has been developed that can test viral levels in the blood without the need for expensive laboratory equipment. The single use device, which is about 2cm long, measures viral load in a single drop of blood and can produce a result in under 30 minutes.
While fast testing for HIV infection is possible with certain HIV testing kits, they are not capable of assessing viral load – Only determining whether an individual has been infected with HIV.
The device was developed by a research team at Imperial College London and tech firm DNA Electronics. The device is capable of detecting and amplifying HIV-1 RNA using a low-buffer HIV-1 pH-LAMP (loop-mediated isothermal amplification) assay, which has been embedded into a metal-oxide semiconductor (CMOS) chip.
If the HIV virus is present in a blood droplet, it triggers a change in pH which is registered by the chip and converted into an electrical signal. An accompanying app on a paired computer detects the signal and confirms a positive result.
The researchers used the HIV testing USB stick to screen 991 clinical samples for the presence of HIV-1 RNA. The chip yielded a sensitivity of 95% with a median detection time of just 20.8 minutes. The sensitivity of the test is almost at the level required to produce a point-of-care device.
Many areas of the world with high numbers of HIV infections do not have access to any HIV testing facilities. Such a device would be particularly useful in areas where there are extremely limited resources for HIV testing – such as many regions of sub-Saharan Africa.
Laboratory testing can take 2-3 days to produce test results and the equipment required is expensive. According to lead researcher, Dr. Graham 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.”
Fast detection of HIV infection is important to prevent the spread of the disease; however, it is also important for individuals receiving treatment to monitor their viral loads to determine whether treatment is effective.
The HIV Testing USB stick would also allow healthcare workers to assess whether patients are taking their medication and monitor for resistance of the virus to retroviral drugs. It would also enable healthcare workers to screen far more people in areas with poor health coverage, dramatically increasing detection of the disease.
The Imperial College/DNA Electronics team has already developed a similar device that is being used to check for bacterial and fungal sepsis and work has started on developing a new form of the device that can be used to diagnose other viral diseases such as hepatitis.