Potential Role of Oral Rinses Targeting the Viral Lipid Envelope in SARS-CoV-2 Infection.

Emerging studies increasingly demonstrate the importance of the throat and salivary glands as sites of virus replication and transmission in early COVID-19 disease. SARS-CoV-2 is an enveloped virus, characterized by an outer lipid membrane derived from the host cell from which it buds. While it is highly sensitive to agents that disrupt lipid biomembranes, there has been no discussion about the potential role of oral rinsing in preventing transmission. Here, we review known mechanisms of viral lipid membrane disruption by widely available dental mouthwash components that include ethanol, chlorhexidine, cetylpyridinium chloride, hydrogen peroxide, and povidone-iodine. We also assess existing formulations for their potential ability to disrupt the SARS-CoV-2 lipid envelope, based on their concentrations of these agents, and conclude that several deserve clinical evaluation. We highlight that already published research on other enveloped viruses, including coronaviruses, directly supports the idea that oral rinsing should be considered as a potential way to reduce transmission of SARS-CoV-2. Research to test this could include evaluating existing or specifically tailored new formulations in well-designed viral inactivation assays, then in clinical trials. Population-based interventions could be undertaken with available mouthwashes, with active monitoring of outcome to determine efficacy. This is an under-researched area of major clinical need.

Identification by quantitative carrier test of surrogate spore-forming bacteria to assess sporicidal chemicals for use against Bacillus anthracis.

The spores of six strains of Bacillus anthracis (four virulent and two avirulent) were compared with those of four other types of spore-forming bacteria for their resistance to four liquid chemical sporicides (sodium hypochlorite at 5,000 ppm available chlorine, 70,000 ppm accelerated H2O2, 1,000 ppm chlorine dioxide, and 3,000 ppm peracetic acid). All test bacteria were grown in a 1:10 dilution of Columbia broth (with manganese) incubated at 37 degrees C for 72 h. The spore suspensions, heat treated at 80 degrees C for 10 min to rid them of any viable vegetative cells, contained 1 x 10(8) to 3 x 10(8) CFU/ml. The second tier of the quantitative carrier test (QCT-2), a standard of ASTM International, was used to assess for sporicidal activity, with disks (1 cm in diameter) of brushed and magnetized stainless steel as spore carriers. Each carrier, with 10 microl (> or = 10(6) CFU) of the test spore suspension in a soil load, was dried and then overlaid with 50 microl of the sporicide being evaluated. The contact time at room temperature ranged from 5 to 20 min, and the arbitrarily set criterion for acceptable sporicidal activity was a reduction of > or = 10(6) in viable spore count. Each test was repeated at least three times. In the final analysis, the spores of Bacillus licheniformis (ATCC 14580(T)) and Bacillus subtilis (ATCC 6051(T)) proved to be generally more resistant than the spores of the strains of B. anthracis tested. The use of one or both of the safe and easy-to-handle surrogates identified here should help in developing safer and more-effective sporicides and also in evaluating the field effectiveness of existing and newer formulations in the decontamination of objects and surfaces suspected of B. anthracis contamination.

A disc-based quantitative carrier test method to assess the virucidal activity of chemical germicides.

Suspension tests for virucidal activity of chemical germicides are easier to perform, but they normally do not present the test product with a strong enough challenge. In contrast, carrier tests, where the test virus is dried on an animate or inanimate surface, offer the test formulation a higher level of challenge because it first has to penetrate successfully the inoculum to gain access to and inactivate the target organism on the carrier. Since pathogens in nature are normally found adsorbed to surfaces and/or embedded in organic or cellular debris, the results of carrier tests are more relevant to predicting the activity of chemical germicides under field situations. The method described below uses discs (1 cm in diameter) of brushed stainless steel discs as carriers. Ten micro l of the test virus in a soil load is placed on each disc and the inoculum dried under ambient conditions. The dried inoculum is then exposed to 50 micro l of the test formulation or a control solution for a defined contact time at the specified temperature. EBSS (0.95 ml) is added to each carrier holder to dilute/neutralize the germicide, the inoculum eluted and the eluates titrated in cell cultures to determine the degree of loss in virus viability. At least five test and three control carriers are used in each test. Controls are also included to test for toxicity of the test formulation to the host cells and any interference sub-cytotoxic levels of the formulation may have on the ability of the virus to infect the cells. The method has been used with several types of human and animal pathogenic viruses to test the activity of all major classes of chemical germicides against them.