TRPV2-spike protein interaction mediates the entry of SARS-CoV-2 into macrophages in febrile conditions.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a novel strain of highly contagious coronaviruses that infects humans. Prolonged fever, particularly that above 39.5 °C, is associated with SARS-CoV-2 infection. However, little is known about the pathological effects of fever caused by SARS-CoV-2. Methods: Primary bovine alveolar macrophages (PBAMs), RAW264.7 mouse macrophages, and THP-1 human cells were transfected with plasmids carrying the genes encoding the SARS-CoV-2 spike (S) protein or receptor-binding domain (RBD). Proteins in the macrophages interacting with S-RBD at 39.5 °C or 37 °C were identified by immunoprecipitation-mass spectrometry. Glutathione S-transferase pulldown, surface plasmon resonance, and immunofluorescence were performed to evaluate the transient receptor potential vanilloid 2 (TRPV2) interaction with SARS-CoV-2-S-RBD at 39.5 °C. Using an RNA sequencing-based approach, cytokine gene expression induced by SARS-CoV-2 S transfection at 39.5 °C and 37.5 °C in primary alveolar macrophages was measured. Fluo-4 staining and enzyme-linked immunosorbent assays were used to assess the regulatory function of TRPV2 in intracellular Ca 2+ and cytokines under SARS-CoV-2-S-RBD at 39.5 °C. Additionally, cytokine release was examined after TRPV2 knockdown with shRNA oligonucleotides or inhibition using the SKF-96365 antagonist. Results: We identified an interaction between the primary alveolar macrophage receptor TRPV2 and S-RBD under febrile conditions. Febrile temperature promotes Ca2+ influx through SARS-CoV-2 infection in PBAMs, further activates the NF-κB p65 signaling pathway, and enhances the secretion of cytokines. Furthermore, knockdown or antagonist (with SKF-96365) of TRPV2 significantly decreased the release of cytokines that drive the inflammatory response. Conclusion: Collectively, our findings identified TRPV2 as a receptor of SARS-CoV-2 in conditions of febrile temperature, providing insight into critical interactions of SARS-CoV-2 with macrophages, as well as a useful resource and potential drug target for coronavirus disease 2019.

A graphene oxide coated tapered microfiber acting as a super-sensor for rapid detection of SARS-CoV-2.

COVID-19 is a new strain of highly contagious coronavirus, and at present, more than 221.4 million people have been infected with this virus, and the death toll exceeds 2793398. Early and fast detection of COVID-19 from infected individuals is critical to limit its spreading. Here, we report an innovative approach to detect the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid (N) protein by combining DNA/RNA oligomers as aptamers and a graphene oxide (GO) coated optical microfiber as a sensor system. The DNA/RNA aptamers can effectively capture the SARS-CoV-2 N protein in vitro, with the GO coated optical microfiber aptasensor for real-time monitoring of the SARS-CoV-2 N protein. Due to the extremely high surface-to-volume ratio and excellent optical and biochemical properties of the GO surface layer, the fixing effect of the microfiber surface is significantly improved and the lowest limit of detection (LOD) is 6.25 × 10-19 M. Furthermore, in order to prove the feasibility of this sensing method in clinical applications, we use this sensor to detect the N protein mixed in fetal bovine serum (FBS) samples. The experimental results show that the biosensor can quickly and effectively detect the N protein (1 × 10-9 M) in a complex sample matrix within 3 minutes. These findings suggest that this approach can be utilized for quantitative monitoring of coronavirus particles due to its high sensitivity, which can help to quickly exclude patients who do not have the infection. Collectively, the optical microfiber sensor system could be expected to become an important platform for the diagnosis of coronavirus due to its simple detection scheme and easy miniaturization.