Virucidal efficacy of laundry sanitizers against SARS-CoV-2 and other coronaviruses and influenza viruses.

The clothes laundering process affords numerous opportunities for dissemination of infectious virus from contaminated clothing to appliance surfaces and other household surfaces and eventually to launderer's hands. We have explored the efficacy of laundry sanitizers for inactivating coronaviruses and influenza viruses. Virucidal efficacy was tested using standardized suspension inactivation methods (EN 14476) or hard-surface inactivation methods (ASTM E1053-20) against SARS-CoV-2, human coronavirus 229E (HCoV 229E), influenza A virus (2009-H1N1 A/Mexico), or influenza B virus (B/Hong Kong). Efficacy was measured in terms of log10 reduction in infectious virus titer, after 15 min contact time (suspension studies) or 5 min contact time (hard surface studies) at 20 ± 1 °C. In liquid suspension studies, laundry sanitizers containing p-chloro-m-xylenol (PCMX) or quaternary ammonium compounds (QAC) caused complete inactivation (≥ 4 log10) of HCoV 229E and SARS-CoV-2 within 15 min contact time at 20 ± 1 °C. In hard surface studies, complete inactivation (≥ 4 log10) of each coronavirus or influenza virus, including SARS-CoV-2, was observed following a 5-min contact time at 20 ± 1 °C. Respiratory viruses may remain infectious on clothing/fabrics and environmental surfaces for hours to days. The use of a laundry sanitizer containing microbicidal actives may afford mitigation of the risk of contamination of surfaces during handling of the laundry and washing appliances (i.e., washer/dryer or basin), adjacent surfaces, the waste water stream, and the hands of individuals handling clothes contaminated with SARS-CoV-2, influenza viruses, or other emerging enveloped viruses.

Direct and quantitative capture of viable bacteriophages from experimentally contaminated indoor air: A model for the study of airborne vertebrate viruses including SARS-CoV-2.

AIM: The air indoors has profound health implications as it can expose us to pathogens, allergens and particulates either directly or via contaminated surfaces. There is, therefore, an upsurge in marketing of air decontamination technologies, but with no proper validation of their claims. We addressed the gap through the construction and use of a versatile room-sized (25 m3 ) chamber to study airborne pathogen survival and inactivation. METHODS AND RESULTS: Here, we report on the quantitative recovery and detection of an enveloped (Phi6) and a non-enveloped bacteriophage (MS2). The two phages, respectively, acted as surrogates for airborne human pathogenic enveloped (e.g., influenza, Ebola and coronavirus SARS-CoV-2) and non-enveloped (e.g., norovirus) viruses from indoor air deposited directly on the lawns of their respective host bacteria using a programmable slit-to-agar air sampler. Using this technique, two different devices based on HEPA filtration and UV light were tested for their ability to decontaminate indoor air. This safe, relatively simple and inexpensive procedure augments the use of phages as surrogates for the study of airborne human and animal pathogenic viruses. CONCLUSIONS: This simple, safe and relatively inexpensive method of direct recovery and quantitative detection of viable airborne phage particles can greatly enhance their applicattion as surrogates for the study of vertebrate virus survival in indoor air and assessment of technologies for their decontamination. SIGNIFICANCE AND IMPACT OF THE STUDY: The safe, economical and simple technique reported here can be applied widely to investigate the role of indoor air for virus survival and transmission and also to assess the potential of air decontaminating technologies.

ECC-RT-PCR: a new method to determine the viability and infectivity of Giardia cysts.

BACKGROUND: Giardia sp is a major cause of diarrheal illness worldwide, and millions of people are infected each year. Rapid methods to determine the infectivity and virulence of isolates are critical for the development of intervention strategies to control the transmission of Giardia sp cysts, which occurs through contaminated surfaces, food, and water. However, determining the viability, infectivity, and virulence of Giardia sp cysts using molecular methods is a technical challenge because of the lack of a cell culture model. METHOD: This study was designed to evaluate mRNA expression in trophozoites and to assess trophozoite attachment to cell monolayer and changes in transcellular resistance as an indicator of Giardia sp viability and infectivity. Heat shock mRNA in Giardia cysts and variant-specific protein (VSP) mRNA in trophozoites were quantified by reverse transcription polymerase chain reaction (RT-PCR). C2bb (Caco-2) cells were grown on transwell chambers to study the attachment of trophozoites, changes in transcellular resistance, and expression of VSP in trophozoites. RESULTS: The results of these molecular and cell culture studies indicate a direct linear correlation between the viability and infectivity of fresh stocks of Giardia sp cysts. The attachment of trophozoites to cell monolayer, expression of VSP, and change in the transcellular resistance was directly correlated with their infectivity in neonatal mice. PCR was successfully combined with the electrophysiological analysis of cell culture (ECC-RT-PCR) post-trophozoite attachment. CONCLUSION: This study shows that the ECC-RT-PCR, a new integrated cell culture assay, can be used as a rapid and cost-effective tool for assessing the viability and infectivity of environmental isolates of Giardia sp cysts.

Comparison of molecular markers for determining the viability and infectivity of Cryptosporidium oocysts and validation of molecular methods against animal infectivity assay.

BACKGROUND: Globally, disinfectants are widely used to intervene in the dissemination of Cryptosporidium oocysts. However, extensive investigations of oocyst inactivation by various disinfectants are not feasible due to the limitations imposed by animal infectivity methods. Molecular techniques provide an alternative strategy; however, non-metabolic genes have been used as markers for determining viability/infectivity. METHODS: In this study we used amyloglucosidase (AG) - a metabolic protein - as a marker to determine viability/infectivity of Cryptosporidium. Oocysts were exposed to 6% hydrogen peroxide for 2min. Samples were analyzed by cell culture polymerase chain reaction (CC-PCR) using PCR primers specific for heat shock protein 70 (hsp70) and AG. Both target genes were amplified with the same level of intensity. RESULTS: Based on the results it can be concluded that AG is a valid target for the study of environmental survival and for the evaluation of the efficacy of microbicides against Cryptosporidium using molecular and cellular assays. Comparison of the CC-PCR assay and mouse infectivity assay showed a fairly good correlation under these test conditions. CONCLUSION: Results indicate that the CC-PCR assay presents a valid and cost-effective alternative to the mouse infectivity assay.