A blood transfusion can be a life-saving gift – but if that blood unwittingly contains a deadly virus, it can kill instead of cure. Medical staff therefore needs to be able to quickly and easily screen blood for viruses and a new system developed by researchers in China can do just that: it checks for three viruses – HIV, hepatitis C and hepatitis B – all at once and could even be adapted for more.

The quickest way to test a sample for viruses is by looking for their DNA or RNA –unlike antibody based tests this doesn’t need to wait for the body’s immune response to kick in before showing a result. Nongyue He’s team at Southwest University uses a process called amplification to multiply several viruses’ DNA or RNA at the same time, making enough to generate a strong signal when tested.

After amplification, the system uses nanoparticles modified with nucleic acids to match up to unique parts of each virus’ genome, like jigsaw pieces. These nanoparticles are chemoluminescent, meaning they emit light when added to certain chemicals giving a visible signal to show that a virus is present. This, unlike most systems that use fluorescence as a signal, allows detection of viruses at lower concentrations and without spectroscopic instruments. The nanoparticles are also magnetic, so they can be purified easily – in future, this could allow the system to be fully automated.

Shengxi Chen, an expert in viral detection at Arizona State University, US, says that the system has potential to ’benefit treatments in the future’. By making certain adjustments the system could test for other types of viruses in future – He says that their next step is to attempt detection of five viruses at once.