The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally. Although measures to control SARS-CoV-2, namely, vaccination, medication, and chemical disinfectants are being investigated, there is an increase in the demand for auxiliary antiviral approaches using natural compounds. Here we have focused on hydroxytyrosol (HT)-rich aqueous olive pulp extract (HIDROX®) and evaluated its SARS-CoV-2-inactivating activity in vitro. We showed that the HIDROX solution exhibits time- and concentration-dependent SARS-CoV-2-inactivating activities, and that HIDROX has more potent virucidal activity than pure HT. The evaluation of the mechanism of action suggested that both HIDROX and HT induced structural changes in SARS-CoV-2, which changed the molecular weight of the spike proteins. Even though the spike protein is highly glycosylated, this change was induced regardless of the glycosylation status. In addition, HIDROX or HT treatment disrupted the viral genome. Moreover, the HIDROX-containing cream applied on film showed time- and concentration-dependent SARS-CoV-2-inactivating activities. Thus, the HIDROX-containing cream can be applied topically as an antiviral hand cream. Our findings suggest that HIDROX contributes to improving SARS-CoV-2 control measures.

Novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A virus (IAV), and norovirus (NV) are highly contagious pathogens that threaten human health. Here we focused on the antiviral potential of the medicinal herb, Saxifraga spinulosa (SS). Water-soluble extracts of SS were prepared, and their virus-inactivating activity was evaluated against the human virus pathogens SARS-CoV-2 and IAV; we also examined virucidal activity against feline calicivirus and murine norovirus, which are surrogates for human NV. Among our findings, we found that SS-derived gallocatechin gallate compounds were capable of inactivating all viruses tested. Interestingly, a pyrogallol-enriched fraction (Fr 1C) inactivated all viruses more rapidly and effectively than did any of the component compounds used alone. We found that 25 µg/mL of Fr 1C inactivated >99.6% of SARS-CoV-2 within 10 s (reduction of ≥2.33 log10 TCID50/mL). Fr 1C resulted in the disruption of viral genomes and proteins as determined by gel electrophoresis, electron microscopy, and reverse transcription–PCR. Taken together, our results reveal the potential of Fr 1C for development as a novel antiviral disinfectant.

As a result of the novel coronavirus disease 2019 pandemic, strengthening control measures against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become an urgent global issue. In addition to antiviral therapy and vaccination strategies, applying available virucidal substances for SARS-CoV-2 inactivation is also a target of research to prevent the spread of infection. Here, we evaluated the SARS-CoV-2 inactivation activity of a copper iodide (CuI) nanoparticle dispersion, which provides Cu + ions having high virucidal activity, and its mode of actions. In addition, the utility of CuI-doped film and fabric for SARS-CoV-2 inactivation was evaluated. The CuI dispersion exhibited time-dependent rapid virucidal activity. Analyses of the modes of action of CuI performed by western blotting and real-time reverse transcription polymerase chain reaction targeting viral proteins and the genome revealed that CuI treatment induced the destruction of these viral components. In this setting, the indirect action of CuI-derived reactive oxygen species contributed to the destruction of viral protein. Moreover, the CuI-doped film and fabric demonstrated rapid inactivation of the SARS-CoV-2 solution in which the viral titer was high. These findings indicated the utility of the CuI-doped film and fabric as anti-SARS-CoV-2 materials for the protection of high-touch environmental surfaces and surgical masks/protective clothes. Throughout this study, we demonstrated the effectiveness of CuI nanoparticles for inactivating SARS-CoV-2 and revealed a part of its virucidal mechanism of action. IMPORTANCE The COVID-19 pandemic has caused an unprecedented number of infections and deaths. As the spread of the disease is rapid and the risk of infection severe, hand and environmental hygiene may contribute to suppressing contact transmission of SARS-CoV-2. Here, we evaluated the SARS-CoV-2-inactivation activity of CuI nanoparticles, which provide the Cu + ion, as an antiviral agent, and provided advanced findings of the virucidal mechanisms of action of Cu + . Our results showed that the CuI dispersion as well as CuI-doped film and fabric rapidly inactivated SARS-CoV-2 with a high viral titer. We also demonstrated the CuI’s virucidal mechanisms of action, specifically, the destruction of viral proteins and the genome by CuI treatment. Protein destruction largely depended on CuI-derived reactive oxygen species. This study provides novel information about the utility and mechanisms of action of promising virucidal material against SARS-CoV-2.

During 2013–2014, we collected 1,926 serum samples from humans and 4,583 ticks (Hyalomma asiaticum or Dermacentor nuttalli) in select regions of Mongolia to determine the risk for Crimean-Congo hemorrhagic fever virus (CCHFV) infection among humans in this country. Testing of human serum samples by ELISA demonstrated an overall CCHFV antibody prevalence of 1.4%; Bayankhongor Province had the highest prevalence, 2.63%. We pooled and analyzed tick specimens by real-time reverse transcription PCR; 1 CCHFV-positive H. asiaticum tick pool from Ömnögovi was identified. In phylogenetic analyses, the virus’s partial small segment clustered with CCHFV isolates from Central Asia, and the complete medium segment grouped with CCHFV isolates from Africa, Asia, and the Middle East. This study confirms CCHFV endemicity in Mongolia and provides information on risk for CCHFV infection. Further research is needed to better define the risk for CCHFV disease to improve risk mitigation, diagnostics, and surveillance.

The use of effective disinfectants is a key method of controlling the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Hypochlorous acid water (HAW) has a broad spectrum of virucidal activities. We previously reported that acidic electrolyzed water, one of the HAW products, had potent SARS-CoV-2-inactivating activity and showed promise as a disinfectant. However, different manufacturing methods have produced several HAW products with various pH values. Here, we compared the SARS-CoV-2-inactivating activities of various HAW products. At sufficiently high volume and residual chlorine concentration (RCC), the HAW products inactivated SARS-CoV-2 efficiently regardless of pH or manufacturing method. However, although HAW products at pH 5.0–6.4 maintained high RCC and sustained virucidal activity for 21 days, the RCC rapidly decreased in HAW products at pH ≤ 3.0. Our results may guide in choosing appropriate HAW products for different usage situations.