Cas12a-assisted RTF-EXPAR for accurate, rapid and simple detection of SARS-CoV-2 RNA.

Developing highly accurate and simple approaches to rapidly identify and isolate SARS-CoV-2 infected patients is important for the control of the COVID-19 pandemic. We, herein, reported the performance of a Cas12a-assisted RTF-EXPAR strategy for the identification of SARS-CoV-2 RNA. This assay combined the advantages of RTF-EXPAR with CRISPR-Cas12a can detect SARS-CoV-2 within 40 min, requiring only isothermal control. Particularly, the simultaneous use of EXPAR amplification and CRISPR improved the detection sensitivity, thereby realizing ultrasensitive SARS-CoV-2 RNA detection with a detection limit of 3.77 aM (∼2 copies/µL) in an end-point fluorescence read-out fashion, and at 4.81 aM (∼3 copies/µL) level via a smartphone-assisted analysis system (RGB analysis). Moreover, Cas12a increases the specificity by intrinsic sequence-specific template recognition. Overall, this method is fast, sensitive, and accurate, needing minimal equipment, which holds great promise to meet the requirements of point-of-care molecular detection of SARS-CoV-2.

Prevalence of acute liver injury and hypertransaminemia in patients with COVID-19: a protocol for a systematic review.

INTRODUCTION: COVID-19 has spread rapidly in China and around the world. Published studies have revealed that some patients with COVID-19 had abnormal liver function in laboratory tests. However, the results were inconsistent and the analysis of epidemiological data stratified by the severity of COVID-19 was not available in previous meta-analyses. Furthermore, these meta-analyses were suspected of overestimating the incidence of liver injury in patients with COVID-19 because some studies considered transaminase elevation as liver injury, which might partially result from cardiac and muscle injury. This systematic review aims to enrol published literatures related to COVID-19 without language restriction, analyse the data based on the severity of the COVID-19 and explore the impact of varied definitions of liver injury on the incidence of liver injury. METHODS AND ANALYSIS: We have conducted a preliminary search on PubMed and Excerpta Medica Database on 13 April 2020, for the studies published after December 2019 on the prevalence of acute liver injury and hypertransaminemia in patients with COVID-19. Two reviewers will independently screen studies, extract data and assess the risk of bias. We will estimate the pooled incidence of hypertransaminemia and acute liver injury in patients with COVID-19 by using the random-effects model. The I² test will be used to identify the extent of heterogeneity. Publication bias will be assessed by funnel plot and performing the Begg's and Egger's test if adequate studies are available. We will perform a risk of bias assessment using the Joanna Briggs Institute's critical appraisal checklist. ETHICS AND DISSEMINATION: Since this study will be based on the published data, it does not require ethical approval. The final results of this study will be published in a peer-reviewed journal. PROSPERO REGISTRATION NUMBER: CRD42020179462.