Amplification-Free Detection of SARS-CoV-2 Down to Single Virus Level by Portable Carbon Nanotube Biosensors.

The rapid and sensitive detection of trace-level viruses in a simple and reliable way is of great importance for epidemic prevention and control. Here, a multi-functionalized floating gate carbon nanotube field effect transistor (FG-CNT FET) based biosensor is reported for the single virus level detection of SARS-CoV-2 virus antigen and RNA rapidly with a portable sensing platform. The aptamers functionalized sensors can detect SARS-CoV-2 antigens from unprocessed nasopharyngeal swab samples within 1 min. Meanwhile, enhanced by a multi-probe strategy, the FG-CNT FET-based biosensor can detect the long chain RNA directly without amplification down to single virus level within 1 min. The device, constructed with packaged sensor chips and a portable sensing terminal, can distinguish 10 COVID-19 patients from 10 healthy individuals in clinical tests both by the RNAs and antigens by a combination detection strategy with an combined overall percent agreement (OPA) close to 100%. The results provide a general and simple method to enhance the sensitivity of FET-based biochemical sensors for the detection of nucleic acid molecules and demonstrate that the CNT FG FET biosensor is a versatile and reliable integrated platform for ultrasensitive multibiomarker detection without amplification and has great potential for point-of-care (POC) clinical tests.

Corrigendum to "Comprehensive Humoral and Cellular Immune Responses to SARS-CoV-2 Variants in Diverse Chinese Population".

[This corrects the article DOI: 10.34133/2022/9873831.].

Spatial-temporal Evolution and Influencing Factors of Digital Financial Inclusion: County-level Evidence from China.

The vigorous development of information and communications technology has accelerated reshaping of the financial industry. The COVID-19 pandemic has further catalyzed the demand for digital financial services. Digital financial inclusion relies on information technology to overcome spatial limitations. In this case, the research question is whether it adheres to the spatial laws governing conventional financial activities. This study uses exploratory spatial data analysis and a geographical detector to elucidate the spatiotemporal characteristics and factors influencing digital financial inclusion at the county level in China (Data don't include that of Hong Kong, Macao and Taiwan of China) from 2014 to 2020. The research findings indicate: first, China's county-level digital financial inclusion is generally increasing and exhibits significant spatial autocorrelation. Second, population density, level of traditional financial development, government regulation, and education level are key determinants of China's county-level digital financial inclusion. Third, policies should be differentiated by region to narrow the spatial gap in digital financial inclusion. The results provide a reference for other developing countries on using digital technology to develop financial inclusion.

Characteristics of COVID-19 (Delta Variant)/HIV Co-infection: A Cross-sectional Study in Henan Province, China.

Background: Since the end of July 2021, SARS-CoV-2 (Delta variant) invaded Henan Province, China, causing a rapid COVID-19 spread in the province. Among them, the clinical features of COVID-19 (Delta Variant)/HIV co-infection have attracted our attention. Methods: We included 12 COVID-19 patients living with HIV (human immunodeficiency virus) from July 30, 2021 to September 17, 2021 in Henan Province, China. Demographic, clinical, laboratory, and computed tomography (CT) imaging data were dynamically collected from first nucleic acid positive to hospital discharge. Laboratory findings included SARS-CoV-2 viral load, HIV viral load, IgM, IgG, cytokines, lymphocyte subpopulation, ferritin, etc. Statistical analyses were performed using IBM SPSS version 26·0 and GraphPad Prism version 9·0. Results: It was founded that the low Ct value persisted for about 21 days, and the viral shedding time (turn negative time) of the patients was 32·36 ± 2·643 days. Furthermore, chest CT imaging revealed that lesions were obviously and rapidly absorbed. It was surprising that IgM levels were statistically higher in patients taking azvudine or convalescent plasma than in patients not taking these drugs (P < 0·001, P = 0·0002, respectively). IgG levels were significantly higher in patients treated with the combined medication of BRII/196 and BRII/198 than in those not treated with these drugs (P = 0·0029). IgM was significantly higher in those with low HIV viral load than those with high HIV viral load (P < 0·001). In addition, as treatment progressed and patients' condition improved, IL-17a showed a decreasing trend. Conclusions: Based on this study, we found that HIV infection might not exacerbate COVID-19 severity. Supplementary Information: The online version contains supplementary material available at 10.1007/s44231-022-00018-z.

Establishment of SARS-CoV-2 Immunoglobulins (IgM, IgG) Reference Intervals for Elder Population in China based on 3,733 Samples.

BACKGROUND: Establishment of reference intervals (RIs) for different biomarkers is essential for clinical monitoring. The purpose of this study was to establish laboratory RIs of SARS-CoV-2 IgM and IgG for elder population. MATERIALS: Performance verification was conducted with reference to the Clinical and Laboratory Standards Institute (CLSI) guidelines, including linearity, imprecision, and allowable dilution ratio. Based on CLSI C28-A3 document, a total of 3,734 serum samples were collected, and 3,733 serum samples were used for the establishment of RIs for SARS-CoV-2 IgM and IgG. The subjects were grouped by gender and age. The age groups were as follows: 60 - 69 years, 70 - 79 years, 80 - 89 years, and 90 - 101 years. The RI was defined by nonparametric 95th percentile intervals. RESULTS: Percentage deviation of all the seven dilutions were all less than 12.5% during linearity evaluation. The inter-assay and intra-assay imprecision were all less than 5%. There is no significant difference between different gender and age groups for IgM (p = 0.0818, p = 0.7094), and there is significant difference between different gender and age groups for IgG (p = 0.0011, p = 0.0013). Harris-Boyd's test did not indicate partitioning for IgM and IgG. Cutoff values of RI for SARS-CoV-2 IgM and IgG were defined as 0.1523 S/CO and 0.2663 S/CO, respectively. CONCLUSIONS: RIs of SRAR-CoV-2 IgM and IgG were established for elder population, which can play an important role in the prevention and control of the epidemic.

Comprehensive Humoral and Cellular Immune Responses to SARS-CoV-2 Variants in Diverse Chinese Population.

The SARS-CoV-2 variants have been emerging and have made great challenges to current vaccine and pandemic control strategies. It is urgent to understand the current immune status of various Chinese populations given that the preexisting immunity has been established by national vaccination or exposure to past variants. Using sera from 85 individuals (including 21 convalescents of natural infection, 15 cases which suffered a breakthrough infection after being fully vaccinated, and 49 healthy vaccinees), we showed significantly enhanced neutralizing activities against SRAS-CoV-2 variants in convalescent sera, especially those who had been fully vaccinated. The neutralizing antibodies against Omicron were detectable in 75% of convalescents and 44.9% of healthy vaccinees (p = 0.006), with a GMT of 289.5, 180.9-463.3, and 42.6, 31.3-59, respectively. However, the neutralizing activities were weaker in young convalescents (aged < 18 y), with a detectable rate of 50% and a GMT of 46.4 against Omicron. We also examined and found no pan-sarbecovirus neutralizing activities in vaccinated SARS-CoV-1 survivors. A booster dose could further increase the breadth and magnitude of neutralization against WT and variants of concern (VOCs) to different degrees. In addition, we showed that COVID-19-inactivated vaccines can elicit Omicron-specific T-cell responses. The positive rates of ELISpot reactions were 26.7% (4/15) and 43.8% (7/16) in the full vaccination group and the booster vaccination group, respectively, although without statistically significant difference. The neutralizing antibody titers declined while T-cell responses remain consistent over 6 months. These findings will inform the optimization of public health vaccination and intervention strategies to protect diverse populations against SARS-CoV-2 variants. Advances. Breakthrough infection significantly boosted neutralizing activities against SARS-CoV-2 variants as compared to booster immunization with inactivated vaccine. Vaccine-induced virus-specific T-cell immunity, on the other hand, may compensate for the shortfall. Furthermore, the public health system should target the most vulnerable group due to a poorer protective serological response in both infected and vaccinated adolescents.

The efficacy of probiotics in patients with severe COVID-19.

BACKGROUND: To examine the incidence of diarrhea in severe and critical coronavirus disease 2019 (COVID-19) patients, and to observe the efficacy and prognosis of probiotic use in such patients. METHODS: A retrospective study was conducted to investigate the symptoms and incidence of diarrhea in 156 cases of COVID-19 confirmed by the First Affiliated Hospital of Zhengzhou University and the Xinyang Fifth People's Hospital, China. A total of 58 cases of severe and critical COVID-19 were identified and divided into the treatment group or the control group. The control group was given standard treatment according to the Protocols for Diagnosis and Treatment of COVID-19: Prevention, Control, Diagnosis and Management. Patients in the treatment group were administered oral probiotics as well as the standard treatment. The 2 groups were compared in terms of nutritional status (serum albumin), improvement of diarrhea symptoms, changes in inflammatory condition [procalcitonin (PCT) and C-reactive protein (CRP)], the time taken to register a negative result for respiratory tract pathogens on the nucleic acid test, and changes to white blood cell and lymphocyte cell counts. RESULTS: In this study cohort, diarrhea was detected in 15.38% (24/156) of COVID-19 patients. The incidence of diarrhea in patients with mild and moderate COVID-19 was approximately 8.16% (8/98), and the incidence of diarrhea in severe and critically ill patients was approximately 27.59% (16/58). In patients with severe and critical COVID-19, probiotic treatment obviously shortened the duration of diarrhea. Furthermore, compared with the control group, patients treated with probiotics showed a significantly reduced time to achieving a negative nucleic acid test and the inflammation indexes including PCT and CRP were significantly reduced (P<0.05). CONCLUSIONS: The incidence of diarrhea in severe and critically ill COVID-19 patients was significantly higher than that in patients with mild and moderate COVID-19. Probiotics may have a good supporting role in the treatment of patients with COVID-19 and its early application is recommended.

Dual-detection fluorescent immunochromatographic assay for quantitative detection of SARS-CoV-2 spike RBD-ACE2 blocking neutralizing antibody.

The global effort against the COVID-19 pandemic dictates that routine quantitative detection of SARS-CoV-2 neutralizing antibodies is vital for assessing immunity following periodic revaccination against new viral variants. Here, we report a dual-detection fluorescent immunochromatographic assay (DFIA), with a built-in self-calibration process, that enables rapid quantitative detection of neutralizing antibodies that block binding between the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and the angiotensin-converting enzyme 2 (ACE2). Thus, this assay is based on the inhibition of binding between ACE2 and the RBD of the SARS-CoV-2 spike protein by neutralizing antibodies, and the affinity of anti-human immunoglobulins for these neutralizing antibodies. Our self-calibrating DFIA shows improved precision and sensitivity with a wider dynamic linear range, due to the incorporation of a ratiometric algorithm of two-reverse linkage signals responding to an analyte. This was evident by the fact that no positive results (0/14) were observed in verified negative samples, while 22 positives were detected in 23 samples from verified convalescent plasma. A comparative analysis of the ability to detect neutralizing antibodies in 266 clinical serum samples including those from vaccine recipients, indicated that the overall percent agreement between DFIA and the commercial ELISA kit was 90.98%. Thus, the proposed DFIA provides a more reliable and accurate rapid test for detecting SARS-CoV-2 infections and vaccinations in the community. Therefore, the DFIA based strategy for detecting biomarkers, which uses a ratiometric algorithm based on affinity and inhibition reactions, may be applied to improve the performance of immunochromatographic assays.

Rapid and unamplified identification of COVID-19 with morpholino-modified graphene field-effect transistor nanosensor.

SARS-CoV-2 RNA is identified as a pivotal player to bolster energizing zones of COVID-19 detection. Herein, we develop a rapid and unamplified nanosensing platform for detection of SARS-CoV-2 RNA in human throat swab specimens. A gold nanoparticle (AuNP)-decorated graphene field-effect transistor (G-FET) sensor was fabricated, after which complementary phosphorodiamidate morpholino oligos (PMO) probe was immobilized on the AuNP surface. This sensor allowed for highly sensitive testing of SARS-CoV-2 RdRp as PMO does not have charges, leading to low background signal. Not only did the method present a low limit of detection in PBS (0.37 fM), throat swab (2.29 fM), and serum (3.99 fM), but also it achieved a rapid response to COVID-19 patients' samples within 2 min. The developed nanosensor was capable of analyzing RNA extracts from 30 real clinical samples. The results show that the sensor could differentiate the healthy people from infected people, which are in high agreement with RT-PCR results (Kappa index = 0.92). Furthermore, a well-defined distinction between SARS-CoV-2 RdRp and SARS-CoV RdRp was also made. Therefore, we believe that this work provides a satisfactory, attractive option for COVID-19 diagnosis.

[Effectiveness of convalescent plasma for treatment of coronavirus disease 2019 patients].

OBJECTIVE: To evaluate the effectiveness and safety of convalescent plasma therapy in patients with severe and critical coronavirus disease 2019 (COVID-19). METHODS: Plasma of 200-400 mL was collected from convalescent patients 2 weeks after being discharged from the hospital. After viral nucleic acid testing and antibody testing, the plasma was infused into 16 severe or critical COVID-19 patients. Time for viral nucleic acid amplification (NAA) test turning negative, total volume of plasma transfusion, average antibody concentration, and total antibody amount were recorded. White blood cell (WBC) counts, lymphocyte (LYM) counts, neutrophil (NEU) counts, alanine aminotransferase (ALT), aspartate aminotransferase (AST), C-reactive protein (CRP), procalcitonin (PCT), lactate dehydrogenase (LDH), creatine kinase (CK), creatine kinase isoenzyme (CK-MB), hypersensitive cardiac troponin T (hs-cTnT), and lactic acid (Lac) levels were measured and the rate of change was calculated at the baseline (d0) before plasma transfusion, and day 1 (d1), day 3 (d3) after transfusion. RESULTS: (1) Patient characteristics: among the 16 patients, 5 cases (31.25%) were severe COVID-19, and 11 cases (68.75%) were critical COVID-19; 62.50% (10/16) of the patients had primary disease; the percentage of invasive ventilation and use of extracorporeal membrane pulmonary oxygenation (ECMO) in critical patients were 90.91% (10/11) and 45.46% (5/11) respectively. (2) Antibody concentration of convalescent plasma and time for NAA test turning negative: the convalescent plasma antibody concentration in this study was ranged from 10.93 kAU/L to 114.7 kAU/L, with an average value of (56.44±39.40) kAU/L. NAA test was continuously positive before plasma transfusion in 10 patients, and the time for NAA test turning negative could be counted. Eight patients turned negative from day 2 to day 8 after transfusion. Severe patients showed a shorter time for NAA test turning negative than critical patients after transfusion [2 (2-3) vs. 5 (3-8), P = 0.036]. Two critical patients transfused plasma with lower antibody concentration remained a positive result of NAA test, and died on the 3rd and 6th day respectively. (3) Laboratory results: the change rates of WBC (0.81±0.28 vs. 1.00) and NEU (0.75±0.33 vs. 1.00) were significantly decreased at d1 after convalescent plasma treatment (both P < 0.05), and the CRP level decreased to about 63% of that before transfusion (P = 0.017). No adverse events were observed during convalescent plasma transfusion. CONCLUSIONS: Viral NAA test of most patients with COVID-19 who received convalescent plasma transfusion turned negative from day 2 to day 8 after transfusion, and the turning time of severe patients was shorter than that of critical patients. Convalescent plasma therapy can reduce the patients' CRP level, and no adverse events were found during the treatment. The antibody concentration in the convalescent plasma may be one of the factors that affect the time for the nucleic acid turning negative after transfusion. Detection and screening convalescent plasma of high-titer antibody and early application to severe and critical patients are expected to improve the efficacy of convalescent plasma.