Dimerized fusion inhibitor peptides targeting the HR1-HR2 interaction of SARS-CoV-2.

Membrane fusion is a critical and indispensable step in the replication cycles of viruses such as SARS-CoV-2 and human immunodeficiency virus type-1 (HIV-1). In this step, a trimer of the heptad repeat 1 (HR1) region interacts with the three HR2 regions and forms a 6-helix bundle (6-HB) structure to proceed with membrane fusion of the virus envelope and host cells. Recently, several researchers have developed potent peptidic SARS-CoV-2 fusion inhibitors based on the HR2 sequence and including some modifications. We have developed highly potent HIV-1 fusion inhibitors by dimerization of its HR2 peptides. Here, we report the development of dimerized HR2 peptides of SARS-CoV-2, which showed significantly higher antiviral activity than the corresponding monomers, suggesting that the dimerization strategy can facilitate the design of potent inhibitors of SARS-CoV-2.

Disinfection of otorhinolaryngological endoscopes with electrolyzed acid water: A cross-sectional and multicenter study.

Glutaraldehyde, a germicide for reprocessing endoscopes that is important for hygiene in the clinic, might be hazardous to humans. Electrolyzed acid water (EAW) has a broad anti-microbial spectrum and safety profile and might be a glutaraldehyde alternative. We sought to assess EAW disinfection of flexible endoscopes in clinical otorhinolaryngological settings and its in vitro inactivation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and bacteria commonly isolated in otorhinolaryngology. Ninety endoscopes were tested for bacterial contamination before and after endoscope disinfection with EAW. The species and strains of bacteria were studied. The in vitro inactivation of bacteria and SARS-CoV-2 by EAW was investigated to determine the efficacy of endoscope disinfection. More than 20 colony-forming units of bacteria at one or more sampling sites were detected in 75/90 microbiological cultures of samples from clinically used endoscopes (83.3%). The most common genus detected was Staphylococcus followed by Cutibacterium and Corynebacterium at all sites including the ears, noses, and throats. In the in vitro study, more than 107 CFU/mL of all bacterial species examined were reduced to below the detection limit (<10 CFU/mL) within 30 s after contact with EAW. When SARS-CoV-2 was treated with a 99-fold volume of EAW, the initial viral titer (> 105 PFU) was decreased to less than 5 PFU. Effective inactivation of SARS-CoV-2 was also observed with a 19:1 ratio of EAW to the virus. EAW effectively reprocessed flexible endoscopes contributing to infection control in medical institutions in the era of the coronavirus disease 2019 pandemic.

Three-dimensional reconstruction by electron tomography for the application to ultrastructural analysis of SARS-CoV-2 particles.

SARS-CoV-2 is the cause of COVID-19. The three-dimensional morphology of viral particles existing and multiplying in infected cells has not been established by electron tomography, which is different from cryo-electron tomography using frozen samples. In this study, we establish the morphological structure of SARS-CoV-2 particles by three-dimensional reconstruction of images obtained by electron tomography and transmission electron microscopy of biological samples embedded in epoxy resin. The characteristic roots of spike structures were found to be arranged at the surface of a virion covered with an envelope. A high-electron-density structure that appears to be a nucleocapsid was observed inside the envelope of the virion on three-dimensional images reconstructed by electron tomography. The SARS-CoV-2 particles that budded in the vacuoles in the cytoplasm were morphologically identical to those found outside the cells, suggesting that mature and infectious SARS-CoV-2 particles were already produced in the vacuoles. Here, we show the three-dimensional morphological structure of SARS-CoV-2 particles reconstructed by electron tomography. To control infection, inhibition of viral release from vacuoles would be a new target in the development of prophylactic agents against SARS-CoV-2.

Strong alkaline electrolyzed water efficiently inactivates SARS-CoV-2, other viruses, and Gram-negative bacteria.

Air spaces and material surfaces in a pathogen-contaminated environment can often be a source of infection to humans, and disinfection has become a common intervention focused on reducing the contamination levels. In this study, we examined the efficacy of SAIW, a unique electrolyzed water with chlorine-free, high pH, high concentration of dissolved hydrogen, and low oxygen reduction potential, for the inactivation of several viruses and bacteria. Infectivity assays revealed that initial viral titers of enveloped and non-enveloped viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A virus, herpes simplex virus type 1, human coronavirus, feline calicivirus, and canine parvovirus, were reduced by 2.9- to 5.5-log10 within 30 s of SAIW exposure. Similarly, the culturability of three Gram-negative bacteria (Escherichia coli, Salmonella, and Legionella) dropped down by 1.9- to 4.9-log10 within 30 s of SAIW treatment. Mechanistically, treatment with SAIW was found to significantly decrease the binding and subsequent entry efficiencies of SARS-CoV-2 on Vero cells. Finally, we showed that this chlorine-free electrolytic ion water had no acute inhalation toxicity in mice, demonstrating that SAIW holds promise for a safer antiviral and antibacterial disinfectant.

Evaluation of SARS-CoV-2 RNA quantification by RT-LAMP compared to RT-qPCR.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) is a global pandemic caused by a novel virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The viral load of SARS-CoV-2 is associated with mortality in COVID-19 patients. Measurement of viral load requires the use of reverse transcription quantitative PCR (RT-qPCR), which in turn requires advanced equipment and techniques. In this study, we aimed to evaluate the viral load measurement using reverse transcription loop-mediated isothermal amplification (RT-LAMP), which is a simpler procedure compared to RT-qPCR. MATERIALS AND METHODS: RNA was extracted by using the QIAamp Viral RNA Mini Kit. The RT-LAMP assay was performed by using the Loopamp® 2019-SARS-CoV-2 detection reagent kit and 10-fold serial dilutions of known viral load RT-LAMP were used to measure Tt, which is the time until the turbidity exceeds the threshold. Based on the relationship between viral load and Tt, the linearity and detection sensitivity of the calibration curve were evaluated. In addition, 117 clinical specimens were measured, and RT-qPCR and RT-LAMP assay results were compared. RESULTS: The dilution linearity of the calibration curve was maintained at five orders of magnitude 1.0× 106 to 1.0 × 101 copies/µL, and was confirmed to be detectable down to 1.0 × 100 copies/µL. The limit of quantification of RNA extracted from clinical specimens using RT-LAMP correlated well with that obtained using RT-qPCR (r2 = 0.930). CONCLUSION: The findings indicate that RT-LAMP is an effective method to determine the viral load of SARS-CoV-2.