CRISPR-Cas13a-powered electrochemical biosensor for the detection of the L452R mutation in clinical samples of SARS-CoV-2 variants.

Since the end of 2019, a highly contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has deprived numerous lives worldwide, called COVID-19. Up to date, omicron is the latest variant of concern, and BA.5 is replacing the BA.2 variant to become the main subtype rampaging worldwide. These subtypes harbor an L452R mutation, which increases their transmissibility among vaccinated people. Current methods for identifying SARS-CoV-2 variants are mainly based on polymerase chain reaction (PCR) followed by gene sequencing, making time-consuming processes and expensive instrumentation indispensable. In this study, we developed a rapid and ultrasensitive electrochemical biosensor to achieve the goals of high sensitivity, the ability of distinguishing the variants, and the direct detection of RNAs from viruses simultaneously. We used electrodes made of MXene-AuNP (gold nanoparticle) composites for improved sensitivity and the CRISPR/Cas13a system for high specificity in detecting the single-base L452R mutation in RNAs and clinical samples. Our biosensor will be an excellent supplement to the RT-qPCR method enabling the early diagnosis and quick distinguishment of SARS-CoV-2 Omicron BA.5 and BA.2 variants and more potential variants that might arise in the future.

The relationship between schizotypal personality features and mind wandering among college students during COVID-19 pandemic: A moderator of depression.

Introduction: Although the impact of the COVID-19 pandemic on people's mental health has been well documented in many studies, the schizotypal personality features in the general population have not received sufficient attention. Methods: Study 1 is a longitudinal study tracking changes in schizotypal personality features among college students during the COVID-19 pandemic. A total of 153 Chinese college students were assessed using the Schizotypal Personality Questionnaire. Study 2 explored the relationship between schizotypal personality features, mind wandering, and depression. A total of 557 college students completed the Schizotypal Personality Questionnaire, the Beck Depression Inventory, and the Mind-Wandering Questionnaire during the COVID-19 pandemic. Results: Study 1 results showed that the scores from later stages in the pandemic were significantly higher than those from the initial stages on each dimension of schizotypal personality, which means that the schizotypal personality features became more obvious during the COVID-19 pandemic. Study 2 results showed that there was a positive correlation between schizotypal personality features, depression, and mind wandering. Discussion: Depression played a moderating role in the relationship between schizotypal personality features and mind wandering. The schizotypal personality features of college students increase during COVID-19; it has a positive relationship with mind wandering; depression moderates the relationship. We discussed these findings and provided some suggestions about future research.

The relationship between perceived social support with anxiety, depression, and insomnia among Chinese college students during the COVID-19 pandemic: The mediating role of self-control.

Object: We aimed to investigate the associations between perceived social support and anxiety, depression, and sleep disturbance via self-control among Chinese college students during the COVID-19 pandemic. Materials and methods: The Perceived Social Support Scale, Self-control Scale, Self-rating Anxiety Scale, Self-rating Depression Scale, and Insomnia Severity Index Scale were used to survey 1,997 college students during the COVID-19 pandemic, who submitted valid questionnaires (M age = 19.93, SD age = 1.47, Range = 18-24 years, 62% female). Results: The perceived social support and self-control were significantly positively correlated, and they were significantly and negatively associated with anxiety, depression, and insomnia. Further analysis found that self-control partially mediated the relationships between perceived social support with anxiety, depression, and insomnia. Conclusion: During the COVID-19 pandemic, Chinese college students' self-control played a partial mediating effect in the relationships between perceived social support and anxiety, depression, and insomnia. This study provides new insights and inspiration for improving college students' mental health in the context of the pandemic.

Development of humanized ACE2 mouse and rat models for COVID‐19 research

To date (17 November 2021), there has been more than 254 million confirmed cases of COVID‐19, and more than 5 million death globally (World Health Organization. https://covid19.who.int/). The virus causing COVID‐19 is called Severe Acute Respiratory Syndrome Coronavirus 2 (SARS‐CoV‐2). SARS‐CoV‐2 infects host cells by the binding of its spike protein to the cellular surface protein angiotensin‐converting enzyme 2 (ACE2). The predicted 29 amino acid residues of ACE2 that interact with SARS‐CoV‐2 spike protein receptor binding domain (RBD) vary between human ACE2 and mouse or rat ACE2. Therefore, wildtype mice and rats show lower SARS‐CoV‐2 infection rate and mild symptoms compared to what is seen in humans. Small animal models that recapitulate human COVID‐19 disease are urgently needed for better understanding the transmission and therapeutic measurement. Currently, scientists use either mouse‐adapted SAS‐CoV‐2 (SAS‐CoV‐2 MA) models or random transgenic mouse models that artificially express human ACE2 under the control of cytokeratin 18 promoter or a constitutive promoter. SAS‐CoV‐2 MA may not completely reflect all aspects of the original human‐tropic SAS‐CoV‐2 and the current transgenic human ACE2 mouse models typically have high mortality rate caused by neuroinvasion and encephalitis due to very high human ACE2 expression. To overcome these limitations, we have developed humanized ACE2 mouse and rat models using CRISPR‐Cas9. Specifically, we inserted a ~3kb human ACE2 cDNA cassette into the mouse and rat Ace2 gene loci to ensure that human ACE2 expression is under the control of rodent Ace2 promoter and regulatory elements, while simultaneously disabling the rodent Ace2 gene. To accomplish this, CRISPR gRNAs targeting close to the translation initiation site of Ace2 were screened in cultured mouse and rat cells. Then CRISPR/Cas9 complex and donor DNA were subsequently microinjected into one‐cell stage embryos which were subsequently implanted into pseudo pregnant females. Resulting pups were screened for correct knockin by junction PCR and insert PCR, and the PCR products were Sanger sequenced. Targeted Locus Amplification (TLA) further confirmed the integration sites and transgene sequence. RT‐qPCR and Western blot analysis data showed that, in our models, human ACE2 is expressed in tissues expressing endogenous Ace2 (such as lung, kidney, and GI tract), while rodent endogenous Ace2 is absent from these tissues. Further breeding data indicated that both hemizygous and homozygous humanized ACE2 animals appear to be normal and fertile. Most importantly, animals displayed symptoms after infection with SARS‐CoV‐2. In summary, these data suggest that our humanized ACE2 models can be valuable for COVID‐19 research.