In recent months, highly pathogenic avian influenza (HPAI) has broken out in various parts of the world, causing concerns about human transmission. In response to this, scientists and relevant agencies have been seeking instruments capable of rapidly detecting avian influenza viruses to reduce the risk of virus transmission. Now, American scientists have developed a low-cost, highly efficient device for rapid detection of the H5N1 avian influenza virus.
When birds and other animals inhale droplets containing avian influenza viruses, they are susceptible to infection and can further spread the disease through droplets. Moreover, the virus is prone to mutations during infection and transmission, and the mutated virus can also be transmitted to humans through droplets (aerosols) or the air. Currently, humans lack immunity to avian influenza, which can lead to fatal consequences in severe cases.
Rapid direct detection of respiratory pathogen aerosols has long faced technical challenges. The current methods for detecting the H5N1 virus usually require sample preparation in a laboratory, such as tests based on polymerase chain reaction (PCR). Therefore, there is an urgent need for an instrument that can rapidly detect H5N1 virus particles without sample preparation to prevent the rapid spread of the epidemic.
Researchers from the Department of Energy, Environmental, and Chemical Engineering at Washington University in St. Louis, along with academic units such as the Department of Neurology and Hope Center for Neurological Diseases at the university, collaborated to develop a fast and sensitive H5N1 detection device. The research findings were published at the end of February in the American Chemical Society (ACS) journal.
The researchers used a modified electrochemical capacitor biosensor (ECB) to detect H5N1 viruses in the air. Previously, this device successfully detected COVID-19 (SARS-CoV-2) virus particles.
The improved ECB device used by the researchers is composed of a screen-printed carbon electrode (SPCE) with Prussian blue nanocrystals (PB) and a network of graphene oxide (GO). The sensor is equipped with sensitive probes (aptamers or antibodies) that can detect H5N1 viruses and Escherichia coli. When these pathogens are present, it triggers a capacitance response and alerts the user.
The detection method is also simple. The researchers first use a wet cyclone particle sampler to collect droplets that may contain pathogens, then place these droplets into the ECB device, yielding results within 5 minutes.
To test the device’s limit of detection (LoD) for H5N1 viruses and E. coli, the researchers conducted tests on the two pathogens. The results showed that the detection limit for H5N1 was 56 virus particles per milliliter, while for E. coli, it was 5 bacteria per milliliter.
The researchers combined the ECB detector with a customized wet cyclone bioaerosol sampler and found that the entire equipment could detect over 93 virus particles or 8 bacteria in 1 cubic meter of air. Furthermore, compared to results from traditional digital PCR methods, the overall accuracy of this device exceeded 90%.
The research team stated that this biosensor is suitable for detecting other respiratory pathogens and can serve as an important tool for real-time monitoring of airborne pathogens and risk assessment. It can help scientists and non-specialized personnel efficiently detect extremely low concentrations of viruses and bacteria. The researchers expressed to the American Chemical Society, “This device has high sensitivity and can detect H5N1 viruses below the infectious dose.”
The research team also plans to further enhance the performance of the sensor to make it more user-friendly and practical.