Virucidal Efficacy of Olanexidine Gluconate as a Hand Antiseptic Against Human Norovirus

Genetic diversity of murine norovirus associated with ethanol sensitivity

RNA viruses have high genetic diversity, allowing rapid adaptation to environmental pressures, such as disinfection. This diversity increases the likelihood of mutations influencing the viral sensitivity to disinfectants. Ethanol is widely used to control viral transmission; however, insufficient disinfection facilitates the survival of less-sensitive viruses. Further, the underlying mechanisms of ethanol-induced changes in viral sensitivity remain unclear. Here, we assessed the genetic characteristics of ethanol-adapted murine norovirus (MNV) and associated changes in viral sensitivity. Experimental ethanol-facilitated MNV adaptation and subsequent genetic characteristic evaluation of the whole genome sequence was performed. MNV was exposed to 70% ethanol for 5 s to achieve ± 3-log10 inactivation. Twelve MNV populations were identified as "less sensitive," consisting of nine treated and three control populations. Less-sensitive MNV populations exhibited significantly higher synonymous nucleotide diversity (πS) in ORF1 (p = 0.001), which encodes the non-structural protein, than sensitive populations. Ethanol sensitivity and πS were negatively correlated in ORF1 (R = - 0.49, p = 0.003), indicating that high genetic diversity in ORF1 could be linked to reduced ethanol sensitivity. This study demonstrates an association between nucleotide diversity in specific coding regions of the MNV genome and ethanol sensitivity. These findings are vital for improving disinfection methods and anticipating emerging viruses that are more resistant to disinfectants. KEY POINTS: • Several MNV populations reduced sensitivity to ethanol. • Higher synonymous diversity in ORF1 linked to reduced ethanol sensitivity. • Synonymous mutations can influence viral adaptation to ethanol.

Sensitivity Evaluation of Enveloped and Non-enveloped Viruses to Ethanol Using Machine Learning: A Systematic Review

Viral diseases are a severe public health issue worldwide. During the coronavirus pandemic, the use of alcohol-based sanitizers was recommended by WHO. Enveloped viruses are sensitive to ethanol, whereas non-enveloped viruses are considerably less sensitive. However, no quantitative analysis has been conducted to determine virus ethanol sensitivity and the important variables influencing the inactivation of viruses to ethanol. This study aimed to determine viruses' sensitivity to ethanol and the most important variables influencing the inactivation of viruses exposed to ethanol based on machine learning. We examined 37 peer-reviewed articles through a systematic search. Quantitative analysis was employed using a decision tree and random forest algorithms. Based on the decision tree, enveloped viruses required around ≥ 35% ethanol with an average contact time of at least 1 min, which reduced the average viral load by 4 log10. In non-enveloped viruses with and without organic matter, ≥ 77.50% and ≥ 65% ethanol with an extended contact time of ≥ 2 min were required for a 4 log10 viral reduction, respectively. Important variables were assessed using a random forest based on the percentage increases in mean square error (%IncMSE) and node purity (%IncNodePurity). Ethanol concentration was a more important variable with a higher %IncMSE and %IncNodePurity than contact time for the inactivation of enveloped and non-enveloped viruses with the available organic matter. Because specific guidelines for virus inactivation by ethanol are lacking, data analysis using machine learning is essential to gain insight from certain datasets. We provide new knowledge for determining guideline values related to the selection of ethanol concentration and contact time that effectively inactivate viruses.

Disinfection efficacy and mechanism of olanexidine gluconate against norovirus

BACKGROUND

The purpose of this study was to evaluate the virucidal activity of a new olanexidine-containing formulation for hand hygiene (olanexidine gluconate hand rub; OLG-HR) against non-enveloped viruses and to understand its mechanism of action.

METHODS

The virucidal activities of OLG-HR against two strains of caliciviruses and three adenovirus serotypes were evaluated through suspension tests. Also, virus-like particles were used to predict the effect of olanexidine gluconate on virus particle structure.

RESULTS

The results of suspension tests under conditions with and without interfering substances (1.5% BSA) indicated that OLG-HR had a broad-spectrum effect against non-enveloped viruses, and the virucidal effect was unaffected by organic contaminants. Furthermore, olanexidine inhibited the binding ability of virus-like particles to the binding receptor of human norovirus and increased the aggregation of virus-like particles in a dose-dependent manner. Transmission electron microscopy showed that the morphology of the virus-like particles was affected by exposure to olanexidine, indicating that the protein-denaturing effect of olanexidine gluconate caused the loss of receptor-binding capability of the viral capsid protein.

CONCLUSIONS

This study suggests that olanexidine gluconate is a potential biological and environmental disinfectant against norovirus and adenovirus.

Antiviral Activity of Olanexidine-Containing Hand Rub against Human Noroviruses

Human norovirus (HuNoV) is the leading cause of epidemic and sporadic acute gastroenteritis worldwide. HuNoV transmission occurs predominantly by direct person-to-person contact, and its health burden is associated with poor hand hygiene and a lack of effective antiseptics and disinfectants. Specific therapies and methods to prevent and control HuNoV spread previously were difficult to evaluate because of the lack of a cell culture system to propagate infectious virus. This barrier has been overcome with the successful cultivation of HuNoV in nontransformed human intestinal enteroids (HIEs). Here, we report using the HIE cultivation system to evaluate the virucidal efficacy of an olanexidine gluconate-based hand rub (OLG-HR) and 70% ethanol (EtOH_70%) against HuNoVs. OLG-HR exhibited fast-acting virucidal activity against a spectrum of HuNoVs including GII.4 Sydney[P31], GII.4 Den Haag[P4], GII.4 New Orleans[P4], GII.3[P21], GII.17[P13], and GI.1[P1] strains. Exposure of HuNoV to OLG-HR for 30 to 60 s resulted in complete loss of the ability of virus to bind to the cells and reduced in vitro binding to glycans in porcine gastric mucin. By contrast, the virucidal efficiency of EtOH_70% on virus infectivity was strain specific. Dynamic light scattering (DLS) and electron microscopy of virus-like particles (VLPs) show that OLG-HR treatment causes partial disassembly and possibly conformational changes in VP1, interfering with histo-blood group antigen (HBGA) binding and infectivity, whereas EtOH_70% treatment causes particle disassembly and clumping of the disassembled products, leading to loss of infectivity while retaining HBGA binding. The highly effective inactivation of HuNoV infectivity by OLG-HR suggests that this compound could reduce HuNoV transmission.

Clinical application of skin antisepsis using aqueous olanexidine: a scoping review

Surgical site infections (SSIs) and catheter-related bloodstream infections (CRBSIs) caused by bacteria from surfaces poorly disinfected with chlorhexidine gluconate (CHG) and povidone-iodine (PVP-I) are increasing. Olanexidine gluconate (OLG) was developed in 2015 in Japan to prevent SSI and CRBSI caused by bacteria resistant to CHG and PVP-I. This scoping review aimed to identify the knowledge gap between what is known and what is not known about the disinfection efficacy of OLG. We searched MEDLINE through PubMed, the Cochrane Central Register of Controlled Trials, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the International Clinical Trials Registry Platform search database, ClinicalTrials.gov, and the Web-based database of Japanese medical articles for works published to July 18, 2021. Manual reference searches were also carried out. A total of 131 studies were screened. Forty-seven studies were included in this review and classified into two major categories: studies on pharmacological effects and spectrum (n = 29) and studies on clinical and adverse effects (n = 18). Olanexidine gluconate showed bactericidal activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci, in addition to common Gram-positive and Gram-negative bacteria. In clinical settings, although there is limited evidence on SSI prevention, 1.5% OLG might be more effective than 10% PVP-I and 1% CHG in preventing SSI. However, the clinical usefulness of OLG is unclear due to the limited number of clinical studies. Also, clinical research is limited to studies targeting SSI prevention, and there are no clinical studies on CRBSI. Further clinical studies are needed on SSI and CRBSI prevention.

Olanexidine gluconate formulations as environmental disinfectants for enveloped viruses infection control

This study investigated the potential of olanexidine gluconate as environmental disinfectant against enveloped viruses in the suspension test and three non-porous surface tests. In the suspension test, olanexidine gluconate showed immediate virucidal activity. In addition, non-porous surface tests demonstrated that, although the immediate effect of aqueous formulations was weak, the final virucidal efficacy outcompeted that of ethanol for disinfection. Furthermore, the effectiveness of olanexidine gluconate persisted even after drying on environmental surfaces. This study demonstrated the potential usage of olanexidine gluconate formulations as an environmental disinfectant in the infection control of enveloped viruses.

Transmission routes, preventive measures and control strategies of SARS-CoV-2 in the food factory

SARS-CoV-2 virus represents a health threat in food factories. This infectious virus is transmitted by direct contact and indirectly via airborne route, whereas contamination through inanimate objects/surfaces/equipment is uncertain. To limit the potential spread of the pathogen in the food industry, close working between individuals should be avoided and both personal and respiratory hygiene activities should be enforced. Despite the high infectivity, SARS-CoV-2, being an enveloped virus with a fragile lipid envelop, is sensitive to biocidal products and sanitizers commonly used in the food factory. In the context of the building design, interventions that promote healthy air quality should be adopted, especially in food areas with high-occupancy rates for prolonged times, to help minimize the potential exposure to airborne SARS-CoV-2. Air ventilation and filtration provided by heating, ventilation and air conditioning systems, are effective and easy-to-organize tools to reduce the risk of transmission through the air. In addition to conventional sanitation protocols, aerosolization of hydrogen peroxide, UV-C irradiation or in-situ ozone generation are complementary techniques for an effective virucidal treatment of the air.

Alcohol abrogates human norovirus infectivity in a pH-dependent manner

Alcohol-based disinfectants are widely used for the sanitization of microorganisms, especially those that cause infectious diseases, including viruses. However, since the germicidal mechanism of alcohol is lipolysis, alcohol-based disinfectants appear to have a minimal effect on non-enveloped viruses, such as noroviruses. Because there is no cultivation method for human norovirus (HuNoV) in vitro, murine norovirus and feline calicivirus have been used as surrogates for HuNoV to analyze the efficacy of disinfectant regents. Therefore, whether these disinfectants and their conditions are effective against HuNoVs remain unknown. In this study, we report that ethanol or isopropanol alone can sufficiently suppress GII.4 genotype HuNoV replication in human iPSC-derived intestinal epithelial cells. Additionally, pH adjustments and salting-out may contribute toward the virucidal effect of alcohol against other HuNoV genotypes and cancel the impediment of organic substance contamination, respectively. Therefore, similar to sodium hypochlorite, alcohol-based disinfectants containing electrolytes can be used for HuNoV inactivation.