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.

Ecological study of cave nectar bats reveals low risk of direct transmission of bat viruses to humans.

Bats are reservoirs of various viruses. The widely distributed cave nectar bat ( Eonycteris spelaea) is known to carry both filoviruses and coronaviruses. However, the potential transmission of theses bat viruses to humans is not fully understood. In this study, we tracked 16 E. spelaea bats in Mengla County, Yunnan Province, China, using miniaturized GPS devices to investigate their movements and potential contact with humans. Furthermore, to determine the prevalence of coronavirus and filovirus infections, we screened for the nucleic acids of the Menglà virus (MLAV) and two coronaviruses (GCCDC1-CoV and HKU9-CoV) in anal swab samples taken from bats and for antibodies against these viruses in human serum samples. None of the serum samples were found to contain antibodies against the bat viruses. The GPS tracking results showed that the bats did not fly during the daytime and rarely flew to residential areas. The foraging range of individual bats also varied, with a mean cumulative nightly flight distance of 25.50 km and flight speed of up to 57.4 km/h. Taken together, these results suggest that the risk of direct transmission of GCCDC1-CoV, HKU9-CoV, and MLAV from E. spelaea bats to humans is very low under natural conditions.

Identification of ZDHHC17 as a Potential Drug Target for Swine Acute Diarrhea Syndrome Coronavirus Infection.

The recent emergence and spread of zoonotic viruses highlights that animal-sourced viruses are the biggest threat to global public health. Swine acute diarrhea syndrome coronavirus (SADS-CoV) is an HKU2-related bat coronavirus that was spilled over from Rhinolophus bats to swine, causing large-scale outbreaks of severe diarrhea disease in piglets in China. Unlike other porcine coronaviruses, SADS-CoV possesses broad species tissue tropism, including primary human cells, implying a significant risk of cross-species spillover. To explore host dependency factors for SADS-CoV as therapeutic targets, we employed genome-wide CRISPR knockout library screening in HeLa cells. Consistent with two independent screens, we identified the zinc finger DHHC-type palmitoyltransferase 17 (ZDHHC17 or ZD17) as an important host factor for SADS-CoV infection. Through truncation mutagenesis, we demonstrated that the DHHC domain of ZD17 that is involved in palmitoylation is important for SADS-CoV infection. Mechanistic studies revealed that ZD17 is required for SADS-CoV genomic RNA replication. Treatment of infected cells with the palmitoylation inhibitor 2-bromopalmitate (2-BP) significantly suppressed SADS-CoV infection. Our findings provide insight on SADS-CoV-host interactions and a potential therapeutic application. IMPORTANCE The recent emergence of deadly zoonotic viral diseases, including Ebola virus and SARS-CoV-2, emphasizes the importance of pandemic preparedness for the animal-sourced viruses with potential risk of animal-to-human spillover. Over the last 2 decades, three significant coronaviruses of bat origin, SARS-CoV, MERS-CoV, and SARS-CoV-2, have caused millions of deaths with significant economy and public health impacts. Lack of effective therapeutics against these coronaviruses was one of the contributing factors to such losses. Although SADS-CoV, another coronavirus of bat origin, was only known to cause fatal diarrhea disease in piglets, the ability to infect cells derived from multiple species, including human, highlights the potential risk of animal-to-human spillover. As part of our effort in pandemic preparedness, we explore SADS-CoV host dependency factors as targets for host-directed therapeutic development and found zinc finger DHHC-type palmitoyltransferase 17 is a promising drug target against SADS-CoV replication. We also demonstrated that a palmitoylation inhibitor, 2-bromopalmitate (2-BP), can be used as an inhibitor for SADS-CoV treatment.

Clinical characteristics of COVID-19 infection in chronic obstructive pulmonary disease: a multicenter, retrospective, observational study.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has been a global pandemic disease, with more than 4 million cases and nearly 300,000 deaths. Little is known about COVID-19 in patients with chronic obstructive pulmonary disease (COPD). We aimed to evaluate the influence of preexisting COPD on the progress and outcomes of COVID-19. METHODS: This was a multicenter, retrospective, observational study. We enrolled 1,048 patients aged 40 years and above, including 50 patients with COPD and 998 patients without COPD, and with COVID-19 confirmed via high-throughput sequencing or real-time reverse transcription-polymerase chain reaction, between December 11, 2019 and February 20, 2020. We collected data of demographics, pathologic test results, radiologic imaging, and treatments. The primary outcomes were composite endpoints determined by admission to an intensive care unit, the use of mechanical ventilation, or death. RESULTS: Compared with patients who had COVID-19 but not COPD, those with COPD had higher rates of fatigue (56.0% vs. 40.2%), dyspnea (66.0% vs. 26.3%), diarrhea (16.0% vs. 3.6%), and unconsciousness (8.0% vs. 1.7%) and a significantly higher proportion of increased activated partial thromboplastin time (23.5% vs. 5.2%) and D-dimer (65.9% vs. 29.3%), as well as ground-glass opacities (77.6% vs. 60.3%), local patchy shadowing (61.2% vs. 41.4%), and interstitial abnormalities (51.0% vs. 19.8%) on chest computed tomography. Patients with COPD were more likely to develop bacterial or fungal coinfection (20.0% vs. 5.9%), acute respiratory distress syndrome (ARDS) (20.0% vs. 7.3%), septic shock (14.0% vs. 2.3%), or acute renal failure (12.0% vs. 1.3%). Patients with COPD and COVID-19 had a higher risk of reaching the composite endpoints [hazard ratio (HR): 2.17, 95% confidence interval (CI): 1.40-3.38; P=0.001] or death (HR: 2.28, 95% CI: 1.15-4.51; P=0.019), after adjustment. CONCLUSIONS: In this study, patients with COPD who developed COVID-19 showed a higher risk of admission to the intensive care unit, mechanical ventilation, or death.