Universal two-dimensional labelled probe-mediated melting curve analysis based on multiplex PCR for rapid typing of Plasmodium in a single closed tube.

Currently, malaria is still one of the major public health problems commonly caused by the four Plasmodium species. The similar symptoms of malaria and the COVID-19 epidemic of fever or fatigue lead to frequent misdiagnosis. The disadvantages of existing detection methods, such as time-consuming, costly, complicated operation, need for experienced technicians, and indistinguishable typing, lead to difficulties in meeting the clinical requirements of rapid, easy, and accurate typing of common Plasmodium species. In this study, we developed and optimized a universal two-dimensional labelled probe-mediated melting curve analysis (UP-MCA) assay based on multiplex and asymmetric PCR for rapid and accurate typing of five Plasmodium species, including novel human Plasmodium, Plasmodium knowlesi (Pk), in a single closed tube following genome extraction. The assay showed a limit of detection (LOD) of 10 copies per reaction and could accurately distinguish Plasmodium species from intra-plasmodium and other pathogens. Additionally, we proposed and validated different methods of fluorescence quenching and tag design for probes that are suitable for UP-MCA assays. Moreover, the clinical performance of the Plasmodium UP-MCA assay using a base-quenched universal probe was evaluated using 226 samples and showed a sensitivity of 100% (164/164) and specificity of 100% (62/62) at a 99% confidence interval, with the microscopy method as the gold standard. In summary, the UP-MCA assay showed excellent sensitivity, specificity, and accuracy for genotyping Plasmodium species spp. Additionally, it facilitates convenient and rapid Plasmodium detection in routine clinical practice and has great potential for clinical translation.

'Dynamic zero-COVID' policy and viral clearance during an omicron wave in Tianjin, China: a city-wide retrospective observational study.

OBJECTIVE: To report how the Chinese mainland battled its first omicron wave, which happened in Tianjin, a metropolis with 14 million residents. We also sought to better understand how clinical features affected the timing of viral clearance. DESIGN: A retrospective study of the omicron wave in Tianjin between 8 January 2022 and 3 March 2022. SETTING: Except for the first cases on 8 January, all the omicron cases were identified through PCR mass testing in the residential communities. Residential quarantine and serial PCR mass testing were dynamically adjusted according to the trends of new cases. PARTICIPANTS: All the 417 consecutive PCR-positive cases identified through mass screening of the entire city's 14 million residents. 45.3% of the cases were male, and the median age was 37 (range 0.3-90). 389 (93%) cases had complete data for analysing the correlation between clinical features and the timing of viral clearance. MAIN OUTCOME AND MEASURE: Time to viral clearance. RESULTS: Tianjin initiated the 'dynamic zero-COVID' policy very early, that is, when daily new case number was ≈0.4 cases per 1 000 000 residents. Daily new cases dropped to <5 after 3 February, and the number of affected residential subdivisions dropped to ≤2 after 13 February. 64% (267/417) of the cases had no or mild symptoms. The median interval from hospital admission to viral clearance was 10 days (range 3-28). An exploratory analysis identified a feature cluster associated with earlier viral clearance, with HRs of 3.56 (95% CI 1.66 to 7.63) and 3.15 (95% CI 1.68 to 5.91) in the training and validation sets, respectively. CONCLUSIONS: The 'dynamic zero-COVID' policy can suppress an omicron wave within a month. It might be possible to predict in advance which cases will require shorter periods of isolation based on their clinical features.

Smartphone-Based Electrochemical Immunoassay for Point-of-Care Detection of SARS-CoV-2 Nucleocapsid Protein.

Large-scale, rapid, and inexpensive serological diagnoses of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) are of great interest in reducing virus transmission at the population level; however, their development is greatly plagued by the lack of available point-of-care methods, leading to low detection efficiency. Herein, an ultrasensitive smartphone-based electrochemical immunoassay is reported for rapid (less than 5 min), low-cost, easy-to-implement detection of the SARS-CoV-2 nucleocapsid protein (SARS-CoV-2 N protein). Specifically, the electrochemical immunoassay was fabricated on a screen-printed carbon electrode coated with electrodeposited gold nanoparticles, followed by incubation of anti-N antibody (Ab) and bovine serum albumin as the working electrode. Accompanied by the antigen-antibody reaction between the SARS-CoV-2 N protein and the Ab, the electron transfer between the electroactive species [Fe(CN)6]3-/4- and the electrode surface is disturbed, resulting in reduced square-wave voltammetry currents at 0.075 V versus the Ag/AgCl reference electrode. The proposed immunoassay provided a good linear range with SARS-CoV-2 N protein concentrations within the scope of 0.01-1000 ng/mL (R2 = 0.9992) and the limit of detection down to 2.6 pg/mL. Moreover, the detection data are wirelessly transmitted to the interface of the smartphone, and the corresponding SARS-CoV-2 N protein concentration value is calculated and displayed. Therefore, the proposed portable detection mode offers great potential for self-differential diagnosis of residents, which will greatly facilitate the effective control and large-scale screening of virus transmission in resource-limited areas.

The KIR2DL2/HLA-C1C1 Gene Pairing Is Associated With an Increased Risk of SARS-CoV-2 Infection.

SARS-CoV-2 is the causative agent for the global COVID-19 pandemic; however, the interaction between virus and host is not well characterized. Natural killer cells play a key role in the early phase of the antiviral response, and their primary functions are dependent on signaling through the killer cell immunoglobulin-like receptor (KIR). This study measured the association between KIR/HLA class I ligand pairings and the occurrence and development of COVID-19. DNA of blood samples from 257 COVID-19 patients were extracted and used to detect KIR and HLA-C gene frequencies using single strain sequence-specific primer (SSP) PCR. The frequency of these genes was compared among 158 individuals with mild COVID-19, 99 with severe disease, and 98 healthy controls. The frequencies of KIR2DL2 (P=0.04, OR=1.707), KIR2DS3 (P=0.047, OR=1.679), HLA-C1C1 (P<0.001, OR=3.074) and the KIR2DL2/HLA-C1C1 pairing (P=0.038, OR=2.126) were significantly higher in the COVID-19 patients than the healthy controls. At the same time, the frequency of KIR2DL3+KIR2DL2-/HLA-C1+Others+ was lower in COVID-19 patients than in healthy individuals (P=0.004, OR=0.477). These results suggest that the protective effect of KIR2DL3 against SARS-CoV-2 infection is related to the absence of the KIR2DL2 gene. This study found no correlation between the frequencies of these genes and COVID-19 pathogenesis. Global statistical analysis revealed that the incidence of COVID-19 infection was higher in geographic regions with a high frequency of KIR2DL2. Together these results suggest that the KIR2DL2/HLA-C1C1 gene pairing may be a risk factor for SARS-CoV-2 infection.

Retrospectively analysis the Guangdong's experience on how to transport potential infected passengers by chartered aircraft during outbreaks of COVID- 19

Objective To summarize the experience of five hospitals in Guangdong Province 0n successfully transporting retained passengers by chartered flights during the outbreak of the COVID-19. Methods We retrospectively evaluated the operation and management, cabin arrangement, isolation requirements, and personnel protection in the aspect of epidemic prevention and control. Results In 11 charter missions, over one thousand "healthy" passengers with potential risk of infections were transported back to China. The medical delivery team and flight crew were kept free of infection, passengers maintained zero cluster infections and no unexpected adverse events during the air transport. Conclusions Our results indicate how to carry passengers in a scientific and orderly way is crucial for avoiding the transmission risks of the epidemic of COVID-19 among working staffers and passengers.

SARS-CoV-2 Mpro inhibitors with antiviral activity in a transgenic mouse model.

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continually poses serious threats to global public health. The main protease (Mpro) of SARS-CoV-2 plays a central role in viral replication. We designed and synthesized 32 new bicycloproline-containing Mpro inhibitors derived from either boceprevir or telaprevir, both of which are approved antivirals. All compounds inhibited SARS-CoV-2 Mpro activity in vitro, with 50% inhibitory concentration values ranging from 7.6 to 748.5 nM. The cocrystal structure of Mpro in complex with MI-23, one of the most potent compounds, revealed its interaction mode. Two compounds (MI-09 and MI-30) showed excellent antiviral activity in cell-based assays. In a transgenic mouse model of SARS-CoV-2 infection, oral or intraperitoneal treatment with MI-09 or MI-30 significantly reduced lung viral loads and lung lesions. Both also displayed good pharmacokinetic properties and safety in rats.

Meta-analysis of transcriptome datasets: An alternative method to study IL-6 regulation in coronavirus disease 2019.

In coronavirus disease 2019 (COVID-19) patients, interleukin (IL)-6 is one of the leading factors causing death through cytokine release syndrome. Hence, identification of IL-6 downstream from clinical patients' transcriptome is very valid for analyses of its mechanism. However, clinical study is conditional and time consuming to collect optional size of samples, as patients have the clinical heterogeneity. A possible solution is to deeply mine the relative existing data. Several transcriptome-based studies on other diseases or treatments have revealed different genes to be regulated by IL-6. Through our meta-analysis of these transcriptome datasets, 352 genes were suggested to be regulated by IL-6 in different biological conditions, some of which were related to virus infection and cardiovascular disease. Among them, 232 genes were not identified by current transcriptome studies from clinical research. ICAM1 and PFKFB3 were the most significantly upregulated genes in our meta-analysis and could be employed as biomarkers in patients with severe COVID-19. In general, a meta-analysis of transcriptome datasets could be an alternative way to analyze the immune response and complications of patients suffering from severe COVID-19 and other emergency diseases.

Computed Tomography Evaluation of Airway Changes in Adult Patients with COVID-19 Pneumonia.

OBJECTIVE: To investigate airway abnormalities on chest CT in adult patients with COVID-19 pneumonia. STUDY DESIGN: Observational study. PLACE AND DURATION OF STUDY: Department of Radiology, Affiliated Hospital of Jining Medical University, Jining, Shandong, China, from January to April, 2020. METHODOLOGY: CT scan images were analysed retrospectively. The main CT findings, including pulmonary opacities, airway wall visibility, wall thickening, luminal changes, and the formation of mucus plugs were evaluated. Airway segments were classified into three types based on the spatial relationship between conducting airways and pulmonary opacities. RESULTS: A total of 275 lesions were detected in 52 patients. Of these, 170 (61.82%) lesions were associated with 243 airway segments, including segments enclosed within lesions (type I, 152, 62.55%), crossing the lesions (type II, 51, 20.99%), and abutting the lesions (type III, 40, 16.46%). The bronchial walls of 154 (63.37%) segments were ill-defined; whereas, the walls of 89 (36.63%) segments were well-defined; in the latter group, 62 (69.66%) showed mild thickening. The bronchial lumen of 183 (75.31%) segments presented mild bronchiectasis and 60 (24.69%) segments appeared normal. Mucus plug was detected in one segment (0.41%). There were no cases of bronchial stenosis, and all bronchial segments located in normal lung regions appeared normal. The appearance of 196 (80.66%) affected bronchi was completely restored before hospital discharge. CONCLUSION: Typical airway changes in adult COVID-19 pneumonia include bronchial wall thickening without significant stenosis of the airway lumen and the absence of bronchial mucus plugs. Moreover, bronchi located in unaffected lung regions have a normal appearance. These characteristics have potential value in differential diagnosis. Key Words: Coronavirus disease, Airway, Computed tomography, Chest.

A typical computed tomography presentations of coronavirus disease 2019.

OBJECTIVE: This study aimed to investigate the atypical computed tomography (CT) presentations of coronavirus disease 2019 (COVID-19) patients to comprehensively understand this highly infectious disease. METHODS: The clinical and chest CT imaging data of 16 patients diagnosed with COVID-19 were retrospectively analyzed, and patients with atypical CT presentations were selected for analysis and review. RESULTS: Of the 16 patients, 6 had atypical CT presentations, including 2 with faint ground glass opacities, 2 with single nodule, 1 with predominantly linear opacities, and 1 with predominantly reticular opacities. The dynamic changes of CT showed the faint ground glass opacities gradually became weak (2 cases). The scope of the single nodule was enlarged, and it developed into consolidation and residual fibrosis (2 cases). There was no obvious change of linear opacity (1 case). The reticular opacities were enlarged, then partially absorbed and new developed ground-glass opacities were found. Finally, the lesions were absorbed with residual fibrosis (1 case). CONCLUSION: Atypical CT presentations of COVID-19 can be classified as faint ground glass opacities, single nodule, linear opacities, and reticular opacities. Understanding the atypical presentation of COVID-19 is beneficial in the assessment and epidemic prevention and control of this disease.