Membrane Rigidity-Tunable Fusogenic Nanosensor for High Throughput Detection of Fusion-Competent Influenza A Virus

The emergence of fatal viruses that pose continuous threats to global health has fueled the intense effort to develop direct, accurate, and high-throughput virus detection platforms. Current diagnostic methods, including qPCR and rapid antigen tests, indicate how much of the virus is present, whether small fragments or whole viruses. However, these methods do not indicate the probability of the virus to be active, capable of interacting with host cells and initiating the infection cycle. Herein, a sialic acid-presenting fusogenic liposome (sLipo-Chol) nanosensor with purposefully modulated membrane rigidity to rapidly detect the fusion-competent influenza A virus (IAV) is developed. This nanosensor possesses virus-specific features, including hemagglutinin (HA) binding and HA-mediated membrane fusion. It is explored how the fusogenic capability of sLipo-Chol with different membrane rigidities impacts their sensing performance by integrating Forster resonance energy transfer (FRET) pairs into the bilayers. The addition of an intact virus led to instant FRET signal changes, thus enabling the direct detection of diverse IAV subtypes-even in avian fecal samples-within an hour at room temperature. Therefore, the sensing approach, with an understanding of the cellular pathogenesis of influenza viruses, will aid in developing bioinspired nanomaterials for evolution into nanosystems to detect infection-competent viruses.