Physical Inactivation of SARS-CoV-2 and Other Coronaviruses: A Review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for the ongoing pandemic of Coronavirus Disease 2019 (COVID-19). Other members of the enveloped RNA virus family Coronaviridae have been responsible for a variety of human diseases and economically important animal diseases. Disinfection of air, environmental surfaces, and solutions is part of infection prevention and control (IPAC) for such viruses and their associated diseases. This article reviews the literature on physical inactivation (disinfection) approaches for SARS-CoV-2 and other coronaviruses. Data for thermal (heat) inactivation, gamma irradiation, and ultraviolet light in the C range (UVC) irradiation have been reviewed. As expected, the susceptibilities of different members of the Coronaviridae to these physical inactivation approaches are similar. This implies that knowledge gained for SARS-CoV-2 should be applicable also to its emerging mutational variants and to other future emerging coronaviruses. The information is applicable to a variety of disinfection applications, including IPAC, inactivation of live virus for vaccine or laboratory analytical use, and waste stream disinfection

Authenticating Hybrid Cell Lines

Hybrid (both intra-species and inter-species) cell lines arise through intentional or nonintentional fusion of somatic cells having different origins. Hybrid cell lines can pose a problem for authentication testing to confirm cell line identity, since the results obtained may not conform to the results expected for the two parental cell types. Thus, depending on the identity testing methodology, a hybrid cell may display characteristics of one of the parental cell type or of both. In some instances, the hybrid cell line may display characteristics that are different from those displayed by either parental cell type; these differences may not necessarily indicate cellular cross-contamination. Testing should be performed as soon as possible after an intended fusion has occurred, so that a baseline reference profile is available for later comparison. In this article, we describe the various approaches that have been used for identifying hybrid cell lines and the results that might be expected when using various technologies for this purpose

Combating SARS-CoV-2: Leveraging microbicidal experiences with other emerging/re-emerging viruses

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan City, China, late in December 2019 is another example of an emerging zoonotic virus that threatens public health and international travel and commerce. When such a virus emerges, there is often insufficient specific information available on mechanisms of virus dissemination from animal to human or from person to person, on the level or route of infection transmissibility or of viral release in body secretions/excretions, and on the survival of virus in aerosols or on surfaces. The effectiveness of available virucidal agents and hygiene practices as interventions for disrupting the spread of infection and the associated diseases may not be clear for the emergent virus. In the present review, we recommend approaches for infection prevention and control for SARS-CoV-2 which can be invoked based on pre-existing data on microbicidal and hygiene effectiveness for related and unrelated enveloped viruse

β-Deuteration of N-nitrosoethylmethylamine causes a shift in DNA methylation from rat liver to esophagus

While N-nitrosoethylmethylamine (NEMA) is carcinogenic primarily for the liver, its β-trideuterated derivative, N-nitroso([2-D3]ethyl)methylamine (NEMA-d3), also produces a high incidence of tumors in the esophagus. To determine whether this shift in organ specificity is associated with an altered pattern of DNA alkylation, [methyl-14C]- and [1-ethyl-14C]-labeled NEMA-d3 were administered to adult male Fischer 344 rats as a single i.p. dose (0.05 mmol/kg; 4 h survival). Levels of methylated and ethylated purines in the DNA of various organs were determined by radiochromatography on Sephasorb-HP columns. When compared to previous data using undeuterated NEMA, 7-niethylguanine levelswerefoundtobereducedby ∽30%inliverandkldney, but were 160% greater in esophagus. This resulted in a decrease in the 7-methylguanine ratio for liver/esophagus from 109 to 29. O6-Methlguanine was diminished in liver and kidney, but levels in lung and esophagus were too low for quantitative detection. Similarly, deuteration led to an 18% decrease of 7-ethylguanine In hepatic DNA. The observed increase in esophageal DNA methylation correlates with the increased carcinogenicity of NEMA-d3 relative to undeuterated NEMA in that organ. Since pharmacokinetic studies have shown that β-trideuteration of NEMA does not alter its bioavailability, the data suggest that the observed shift in target organ results from isotopically-induced changes in the balance among competing metabolic pathways in different rat tissue

Short tandem repeat profiling: part of an overall strategy for reducing the frequency of cell misidentification

The role of cell authentication in biomedical science has received considerable attention, especially within the past decade. This quality control attribute is now beginning to be given the emphasis it deserves by granting agencies and by scientific journals. Short tandem repeat (STR) profiling, one of a few DNA profiling technologies now available, is being proposed for routine identification (authentication) of human cell lines, stem cells, and tissues. The advantage of this technique over methods such as isoenzyme analysis, karyotyping, human leukocyte antigen typing, etc., is that STR profiling can establish identity to the individual level, provided that the appropriate number and types of loci are evaluated. To best employ this technology, a standardized protocol and a data-driven, quality-controlled, and publically searchable database will be necessary. This public STR database (currently under development) will enable investigators to rapidly authenticate human-based cultures to the individual from whom the cells were sourced. Use of similar approaches for non-human animal cells will require developing other suitable loci sets. While implementing STR analysis on a more routine basis should significantly reduce the frequency of cell misidentification, additional technologies may be needed as part of an overall authentication paradigm. For instance, isoenzyme analysis, PCR-based DNA amplification, and sequence-based barcoding methods enable rapid confirmation of a cell line’s species of origin while screening against cross-contaminations, especially when the cells present are not recognized by the species-specific STR method. Karyotyping may also be needed as a supporting tool during establishment of an STR database. Finally, good cell culture practices must always remain a major component of any effort to reduce the frequency of cell misidentification

Recommendation of short tandem repeat profiling for authenticating human cell lines, stem cells, and tissues

Cell misidentification and cross-contamination have plagued biomedical research for as long as cells have been employed as research tools. Examples of misidentified cell lines continue to surface to this day. Efforts to eradicate the problem by raising awareness of the issue and by asking scientists voluntarily to take appropriate actions have not been successful. Unambiguous cell authentication is an essential step in the scientific process and should be an inherent consideration during peer review of papers submitted for publication or during review of grants submitted for funding. In order to facilitate proper identity testing, accurate, reliable, inexpensive, and standardized methods for authentication of cells and cell lines must be made available. To this end, an international team of scientists is, at this time, preparing a consensus standard on the authentication of human cells using short tandem repeat (STR) profiling. This standard, which will be submitted for review and approval as an American National Standard by the American National Standards Institute, will provide investigators guidance on the use of STR profiling for authenticating human cell lines. Such guidance will include methodological detail on the preparation of the DNA sample, the appropriate numbers and types of loci to be evaluated, and the interpretation and quality control of the results. Associated with the standard itself will be the establishment and maintenance of a public STR profile database under the auspices of the National Center for Biotechnology Information. The consensus standard is anticipated to be adopted by granting agencies and scientific journals as appropriate methodology for authenticating human cell lines, stem cells, and tissues

Emerging SARS-CoV-2 Mutational Variants of Concern Should Not Vary in Susceptibility to Microbicidal Actives

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is evolving, with emergence of mutational variants due to the error-prone replication process of RNA viruses, in general. More recently, the Delta and Omicron variants (including sub-variants BA.1–5) predominate globally, and a Delta–Omicron recombinant termed Deltacron has emerged. The emergence of variants of concern (VOC) demonstrating immune evasion and potentially greater transmissibility and virulence naturally raises concern in both the infection control communities and the public at large, as to the continued suitability of interventions intended to mitigate the risk of viral dissemination and acquisition of the associated disease COVID-19. We evaluated the virucidal efficacy of targeted surface hygiene products (an ethanol/quaternary ammonium compound (QAC)-containing disinfectant spray, a QAC disinfectant wipe, a lactic acid disinfectant wipe, and a citric acid disinfectant wipe) through both theoretical arguments and empirical testing using international standard methodologies (ASTM E1053-20 hard surface test and EN14476:2013+A2:2019 suspension test) in the presence of soil loads simulating patients’ bodily secretions/excretions containing shed virus. The results demonstrate, as expected, complete infectious viral inactivation (≥3.0 to ≥4.7 log10 reduction in infectious virus titer after as little as 15 s contact time at room temperature) by these surface hygiene agents of the original SARS-CoV-2 isolate and its Beta and Delta VOC. Through appropriate practices of targeted surface hygiene, it is expected that irrespective of the SARS-CoV-2 VOC encountered as the current pandemic unfolds (and, for that matter, any emerging and/or re-emerging enveloped virus), the chain of infection from virus-contaminated fomites to the hand and mucous membranes of a susceptible person may be disrupted