Stability of the COVID-19 At-Home Test after Exposure to Extreme Temperatures.

To ensure sufficient sensitivity and specificity of lateral flow tests for the detection of SARS-CoV-2 antigen, manufacturers recommend appropriate conditions for storage, including a temperature range. However, there is a high likelihood that kits will be exposed to temperatures outside of this range during transit to some regions. In this prospective study, we evaluated the sensitivity and specificity of the COVID-19 At-Home Test kits (manufactured by SD Biosensor/distributed by Roche) currently being delivered through a US Government program, after exposure to a range of hot and cold temperatures. COVID-19 At-Home Test kits were stored at up to 5 different temperatures: frozen (-4.0°F [-20.0°C]), refrigerated (42.8°F [6.0°C]), room temperature (68.0°F [20.0°C]), warm (98.0°F [36.7°C]), and excessive heat (118.0 to 126.0°F [47.8 to 52.2°C]) for 24 h and left at room temperature for 60, 90, or 120 min before use. Test kits were also stored for 48 h, 1 week, or 2 weeks in frozen, warm, and excessive heat conditions, and left for 60 or 120 min before use. In each scenario (storage temperature + time at room temperature), 5 positive and 5 negative control samples were applied, and line intensity was recorded using a color scale (0 to 100%). In every scenario, every positive sample resulted in strong signal intensity (≥26%), and every negative sample returned a negative result. This study suggests that exposure of up to 2 weeks to extreme temperatures, such as those that may occur in transit, does not impact the stability of the COVID-19 At-Home Test. IMPORTANCE COVID-19 At-Home Test kits may be exposed to extreme temperatures in transit, which may impact test sensitivity and specificity. We investigated assay ability to identify SARS-CoV-2 antigen after 24 h to 2 weeks in frozen, refrigerated, room temperature, warm, or excessive heat conditions. The assay correctly identified all positive and negative samples in all scenarios. This study suggests that exposure of up to 2 weeks to extreme temperatures, such as those that may occur in transit, does not impact the stability of the COVID-19 At-Home Test.

Oct4-Mediated Inhibition of Lsd1 Activity Promotes the Active and Primed State of Pluripotency Enhancers.

An aberrant increase in pluripotency gene (PpG) expression due to enhancer reactivation could induce stemness and enhance the tumorigenicity of cancer stem cells. Silencing of PpG enhancers (PpGe) during embryonic stem cell differentiation involves Lsd1-mediated H3K4me1 demethylation and DNA methylation. Here, we observed retention of H3K4me1 and DNA hypomethylation at PpGe associated with a partial repression of PpGs in F9 embryonal carcinoma cells (ECCs) post-differentiation. H3K4me1 demethylation in F9 ECCs could not be rescued by Lsd1 overexpression. Given our observation that H3K4me1 demethylation is accompanied by strong Oct4 repression in P19 ECCs, we tested if Oct4 interaction with Lsd1 affects its catalytic activity. Our data show a dose-dependent inhibition of Lsd1 activity by Oct4 and retention of H3K4me1 at PpGe in Oct4-overexpressing P19 ECCs. These data suggest that Lsd1-Oct4 interaction in cancer stem cells could establish a "primed" enhancer state that is susceptible to reactivation, leading to aberrant PpG expression.

Evaluation of Contamination Risk by the cobas e 602 Serology Module Before Viral Load Testing on the cobas 6800 System.

BACKGROUND: Diagnosis of HCV, HBV, and HIV involves antibody screening followed by confirmation and/or treatment decision using nucleic acid tests. However, minimal data exist evaluating the risk of nucleic acid cross-contamination on serology devices upstream of molecular testing despite the potential clinical and laboratory workflow advantages of single specimen vial testing for both procedures. METHODS: We conducted a checkerboard study investigating the potential risk of HCV, HBV, and HIV nucleic acid cross-contamination on 480 negative specimens by a serology screening instrument that uses disposable tips for sample transfer, rather than a fixed needle, before molecular testing. RESULTS: Nucleic acid contamination was observed in 0 of 480 negative specimens when processed with alternating high-titer HCV, HBV, or HIV specimens on the serology platform. CONCLUSIONS: This study suggests that specimens analyzed by a serology instrument using disposable tips for sample transfer may be suitable for direct primary specimen reflex testing by a sensitive nucleic acid confirmatory test.

Assay Integrity of a PCR Influenza Point-of-Care Test Remains Following Artificial System Contamination.

BACKGROUND: Healthcare providers who have access to tests at the point of care (POC) are increasingly requesting the same performance from the POC test as they expect from the laboratory. With the introduction of the cobas® Liat instrument, highly sensitive molecular diagnostic testing can be performed closer to the patient in CLIA-waived, POC settings. As more sensitive tests become available, there is concern regarding contamination of instrumentation owing to improper handling, mistakes made when processing, or environmental contamination. Recent concerns were raised when a nurse performed environmental surveillance for flu A/B by inserting a dry swab into the cobas Liat instrument and then ran it as a sample on the instrument, generating a positive result. This finding stimulated questions about the possibility of system contamination contributing to false-positive results, ultimately leading to the possibility of providing incorrect treatment to patients. METHODS: To assess the likelihood of system contamination contributing to the generation of false-positive results, in this study we contaminated a cobas Liat System with flu A/B-positive control material. The system contamination was then assessed by swabbing exposed surfaces. Following confirmed system contamination, negative control samples were processed to determine whether system contamination had an impact on the expected negative results. RESULTS: Instrument contamination was confirmed, and no detectable flu A/B signal was observed for any of the negative control tubes run immediately following confirmation of system contamination. CONCLUSION: Environmental contamination of the Liat instrument does not have an impact on the integrity of the result.