Objective The events of the last year have highlighted the complexity of implementing molecular diagnostic testing for infectious diseases at a large scale. The purpose of this study was to...

The events of the last year have highlighted the complexity of implementing large-scale molecular diagnostic testing for novel pathogens. The purpose of this study was to determine the chemical influences of sample collection media and storage on the stability and detection of viral nucleic acids by qRT-PCR. We studied the mechanism(s) through which viral transport media (VTM) and number of freeze-thaw cycles influenced the analytical sensitivity of qRT-PCR detection of SARS-CoV-2. Our goal is to reinforce testing capabilities and identify weaknesses that could arise in resource-limited environments that do not have well-controlled cold chains. The sensitivity of qRT-PCR analysis was studied in four VTM for synthetic single-stranded RNA (ssRNA) and double-stranded DNA (dsDNA) simulants of the SARS-CoV-2 genome. The sensitivity and reproducibility of qRT-PCR for the synthetic ssRNA and dsDNA were found to be highly sensitive to VTM with the best results observed for ssRNA in HBSS and PBS-G. Surprisingly, the presence of epithelial cellular material with the ssRNA increased the sensitivity of the qRT-PCR assay. Repeated freeze-thaw cycling decreased the sensitivity of the qRT-PCR with two noted exceptions. The choice of VTM is critically important to defining the sensitivity of COVID-19 molecular diagnostics assays and this study suggests they can impact upon the stability of the SARS-CoV-2 viral genome. This becomes increasingly important if the virus structure is destabilised before analysis, which can occur due to poor storage conditions. This study suggests that COVID-19 testing performed with glycerol-containing PBS will produce a high level of stability and sensitivity. These results are in agreement with clinical studies reported for patient-derived samples.

The potential for liquid biopsy samples to be used in place of more invasive tissue biopsy for the monitoring of patient tumours has become more prevalent in recent years. To...

No genome sequence of a species from Barnettozyma, a yeast genus in the family Phaffomycetaceae, is currently available. We isolated two B. californica strains from soils in Ireland and generated draft sequences of their 11.7-Mb genomes. Single nucleotide polymorphism (SNP) analysis showed 20,490 differences between the strains and suggests that B. californica is haploid.