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Colorimetric biosensors are simple but effective tools that are gaining popularity due to their ability to provide low-cost, rapid, and accurate detection for viruses like the Novel coronavirus, Influenza A, and Dengue virus, especially in point-of-care testing (POCT) and visual detection. In this study, a smartphone-assisted nucleic acid POCT was built using hybridization chain reaction (HCR), magnetic beads (MBs), and oxidized 3,3′,5,5′-tetramethylbenzidine (TMB2+)-mediated etching of gold nanorods (GNRs). The application of HCR without enzyme isothermal characteristics and MBs with easy separation, can quickly amplify nucleic acid signal and remove other reaction components. The blue shift of longitudinal localized surface plasmon resonance (LSPR) based on GNRs showed significant differences in etching color for different concentrations of target nucleic acid, which convert the signal into a visually semi-quantitative colorimetric result, achieving quantitative analysis with the color recognition software built into smartphones. This strategy, which only takes 40 min to detect and is two-thirds less time than the PCR, was successfully applied for the detection of the Dengue target sequence with a detection limit of 1.25 nM and exhibited excellent specificity for distinguishing single-base mutations, indicating broad application prospects in clinical laboratory diagnosis and enriching the research of nucleic acid POCT.
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Owing to the global spread of the coronavirus disease 2019 (COVID-19), education has shifted to distance online learning, whereas some face-to-face courses have been resumed with the improvement of the outbreak prevention and management situation, including a laboratory course for senior undergraduate students in chemical biology. Here, we present an innovative chemical biology experiment covering COVID-19 topics, which was created for third-year undergraduates. The basic principles of two nucleic-acid- and antigen-based diagnostic techniques for SARS-CoV-2 are demonstrated in detail. These experiments are designed to provide students with comprehensive knowledge of COVID-19 and related diagnoses in daily life. Crucially, the biosafety of this experimental manipulation was ensured by using artificial nucleic acids and recombinant protein. Furthermore, an interactive hybrid online-facing teaching model was designed to cover the key mechanism regarding PCR and serological tests of COVID-19. Finally, a satisfactory evaluation was obtained through a questionnaire, and simultaneously, reasonable improvements to the course design were suggested. The proposed curriculum provides all the necessary information for other instructors to create new courses supported by research. © 2023 American Chemical Society and Division of Chemical Education, Inc.
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Wastewater surveillance has been widely used to track the prevalence of SARS-CoV-2 in communities. Although some studies have investigated the decay of SARS-CoV-2 RNA in wastewater, understanding about its fate during wastewater transport in real sewers is still limited. This study aims to assess the impact of sewer biofilms on the dynamics of SARS-CoV-2 RNA concentration in naturally contaminated real wastewater (raw influent wastewater without extra SARS-CoV-2 virus/gene seeding) using a simulated laboratory-scale sewer system. The results indicated that, with the sewer biofilms, a 90% concentration reduction of the SARS-CoV-2 RNA was observed within 2 h both in wastewater of gravity (GS, gravity-driven sewers) and rising main (RM, pressurized sewers) sewer reactors. In contrast, the 90% reduction time was 8–26 h in control reactors without biofilms. The concentration reduction of SARS-CoV-2 RNA in wastewater was significantly more in the presence of sewer biofilms. In addition, an accumulation of c.a. 260 and 110 genome copies/cm2 of the SARS-CoV-2 E gene was observed in the sewer biofilm samples from RM and GS reactors within 12 h, respectively. These results confirmed that the in-sewer concentration reduction of SARS-CoV-2 RNA in wastewater was likely caused by the partition to sewer biofilms. The need to investigate the in-sewer dynamic of SARS-CoV-2 RNA, such as the variation of RNA concentration in influent wastewater caused by biofilm attachment and detachment, was highlighted by the significantly enhanced reduction rate of SARS-CoV-2 RNA in wastewater of sewer biofilm reactors and the accumulation of SARS-CoV-2 RNA in sewer biofilms. Further research should be conducted to investigate the in-sewer transportation of SARS-CoV-2 and their RNA and evaluate the role of sewer biofilms in leading to underestimates of COVID-19 prevalence in communities.
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Objective: To analyze and compare the effects of different clinical characteristics on the negative conversion time of nucleic acid detection after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant infection, and to provide a scientific basis for the isolation and treatment of coronavirus disease 2019 (COVID-19). Methods: The epidemiological and clinical data of 228 mild SARS-CoV-2 Omicron variant infected patients diagnosed in Shanghai were retrospectively collected from April 27, 2022 to June 8, 2022 in Wujiaochang designated Hospital, Yangpu District, Shanghai. The negative conversion time of nucleic acid detection was used as the outcome variable, and the patients were divided into A (18 days) and B (>18 days). Univariate and multivariate logistic regression analysis were used to analyze the influencing factors of the negative conversion time of nucleic acid detection. Results: The mean nucleic acid conversion time of 228 patients was (18.7+or-12.1) d, with the median time of 18 (2-46) d. Among them, 120 patients in group A had an average nucleic acid conversion time of (13.2+or-2.0) d, and 108 cases in group B had an average nucleic acid conversion time of (20.8+or-1.3) d. Univariate analysis showed that there were no statistically significant differences in the effects of hypertension, coronary heart disease, diabetes, hypokalemia, malignant tumors, neuropsychiatric diseases, chronic digestive diseases on the negative nucleic acid conversion time (P > 0.05);however, there were significant differences in the effects of combined cerebrovascular disease, leukopenia, chronic respiratory system diseases and vaccination on the negative nucleic acid conversion time (P < 0.05). Further multivariate logistic regression analysis revealed that the combination of chronic respiratory diseases and non-vaccination were significant risk factors for prolongation of negative nucleic acid conversion time (P < 0.05). Conclusions: The results of this study show that gender, age and whether hypertension, coronary heart disease, diabetes mellitus, hypokalemia, malignant tumor, neuropsychiatric disease and chronic digestive disease have no significant effect on the nucleic acid conversion time, whereas chronic respiratory disease and no vaccination are significantly correlated with the prolongation of nucleic acid conversion time in SARS-CoV-2 Omicron-infected patients.
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Objective: To explore the clinical characteristics of nucleic acid negative newborns delivered by pregnant women infected with SARS-CoV-2 (Omicron variant BA. 5.1.3) in Sanya area, and to provide evidence for understanding its clinical characteristics. Methods: A retrospective analysis was performed on 14 neonates with negative nucleic acid delivered by pregnant women who tested positive for SARS-CoV-2 (Omicron variant BA.5.1.3) in Sanya Central Hospital (the Third People's Hospital of Hainan Province) from June 2022 to September 2022 (observation group, n=14). The corresponding nucleic acid-negative newborns delivered by pregnant women detected negative with SARS-CoV-2 (Omicronon variant strain BA.5.1.3) were set as the control group (n=56), and the general data and clinical characteristics of neonates in the two groups were compared. Results: There was no significant difference between the observation group and the control group in pregnancy diabetes, pregnancy induced hypertension, gestational pre-eclampsia, fetal intrauterine distress, premature rupture of membranes (P > 0.05);there was no significant difference between the observation group and the control group in terms of sex, gestational age, birth weight, age, mode of delivery, birth Apgar score, heart screening, pulmonary disease, glucose 6-phosphate dehydrogenase (G6PD) deficiency, thalassemia, breast milk jaundice, hemolytic jaundice (P > 0.05). The bilirubin level, blue light irradiation cases and the duration of blue light irradiation of the newborns in the observation group at 7 days after birth were higher than those in the control group (P < 0.05);the ratio of blood oxygen saturation 90% in the observation group was lower than that in the control group (21.43% vs 89.29%, P < 0.05), and the ratio of blood oxygen saturation occasionally<90% was higher than that in the control group (57.14% vs 10.71%, P < 0.05). The ratio of blood oxygen saturation<90% had no significant difference compared with that in the control group (7.14% vs 0, P > 0.05), and the ratio of blood oxygen saturation reduced to the required oxygen uptake was higher than that in the control group (14.29% vs 0, P < 0.05). Conclusions: The jaundice manifestation of the nucleic acid-negative newborns delivered by pregnant women infected with SARS-CoV-2 (Omicronon variant strain BA.5.1.3) in Sanya area is relatively obvious, with blood oxygen saturation easily lower than 90% and even requiring oxygen inhalation in severe cases.
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A portable, inexpensive, and easy-to-manufacture microfluidic device is developed for the detection of SARS-CoV-2 dsDNA fragments. In this device, four reaction chambers separated by carbon fiber rods are pre-loaded with isothermal amplification and CRISPR-Cas12a reagents. The reaction is carried out by simply pulling the rods, without the need for manual pipetting. To facilitate power-free pathogen detection, the entire detection is designed to be heated with a disposable hand warmer. After the CRISPR reaction, the fluorescence signal generated by positive samples is identified by naked eye, using an inexpensive flashlight. This simple and sensitive device will serve as a new model for the next-generation viral diagnostics in either hospital or resource-limited settings. © 2023 SPIE.
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Nucleic acid (NA) therapy has gained importance over the past decade due to its high degree of selectivity and minimal toxic effects over conventional drugs. Currently, intravenous (IV) or intramuscular (IM) formulations constitute majority of the marketed formulations containing nucleic acids. However, oral administration is traditionally preferred due to ease of administration as well as higher patient compliance. To leverage the benefits of oral delivery for NA therapy, the NA of interest must be delivered to the target site avoiding all degrading and inhibiting factors during its transition through the gastrointestinal tract. The oral route presents myriad of challenges to NA delivery, making formulation development challenging. Researchers in the last few decades have formulated various delivery systems to overcome such challenges and several reviews summarize and discuss these strategies in detail. However, there is a need to differentiate between the approaches based on target so that in future, delivery strategies can be developed according to the goal of the study and for efficient delivery to the desired site. The goal of this review is to summarize the mechanisms for target specific delivery, list and discuss the formulation strategies used for oral delivery of NA therapies and delineate the similarities and differences between local and systemic targeting oral delivery systems and current challenges.
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Objective: To investigate the chest computed tomography (CT) manifestations and dynamic changes of coronavirus disease 2019 (COVID-19) in the patients younger than 18 years old infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant, and to provide a basis for determining the chest CT changes and efficacy of COVID-19 caused by Omicron virus variant in patients younger than 18 years old. Methods The clinical and imaging data of 30 cases of patients younger than 18 years old infected with COVID-19 Omicron variant, who admitted to the Third People's Hospital of Shenzhen from February 11 to March 26, 2022 were collected and retrospectively analyzed. The clinical manifestations, imaging features and dynamic changes of lesions were summarized. Results A total of 41 intrapulmonary lesions in 30 patients with COVID-19 caused by SARS-CoV-2 Omicron variant. The main manifestations were patchy or nodular ground-glass opacities and/or consolidation, with focal subpleural distribution, lesions mainly occur in the right lung (70.73%, 29/41). There were 42 lesion morphologies, with 22 (52.38%) striped shadows and 16 (38.10%) nodular shadows, with small lamellar and patchy shadows predominating. There were 36 lesion density variations, with ground glass shadows being the most common, with a total of 24 ground glass shadows (66.66%) in each lobe of the lung, and also 6 consolidation lesions (16.67%) and 6 mixed ground glass opacity and consolidation lesions (16.67%). With the progression of the disease, lesions gradually enlarged, appeared on the 2nd day (312.93 mm3), peaked on the 9th day (1 837.18 mm3). The average absorption time of the lesions was (16+or-3) days, and there was no significant difference between the absorption time of patchy and nodular lesions (ground glass and/or consolidation) (t=0.853, P > 0.05). The lesions showed focal ground-glass opacity in the early stage, 77.78% lesions were absorbed after treatment in the late stage. Inflammatory nodules were absorbed slowly (9-19 days), without residual fibrotic changes. Conclusions The imaging manifestations of COVID-19 in patients younger than 18 years old infected with SARS-CoV-2 Omicron variant have certain characteristics, showed patchy or nodular ground glass opacities and/or consolidation, mainly distributed in the subpleural area, with small and few lesions and slow change, didn't remain fibrosis. Being familiar with its clinical and imaging manifestations can assist in early diagnosis, but confirming the diagnosis requires a combination of epidemiological history, clinical symptoms, SARS-CoV-2 nucleic acid and radiological manifestations.
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COVID-19 is diagnosed by nucleic acid testing, aided by Computed Tomography. In order to rapidly screen CT images of COVID-19, Squeeze-And-Excitation Network based network model combined with Deep Learning is proposed, which can adapt to learn important parts of the feature channel. Firstly, the feature Squeeze is carried out along the space dimension, and the output dimension matches the number of input feature channels. Secondly, the feature channel learns the feature channel characteristics by capturing the channel dependencies in the previous step. Finally, the weight is updated to model the correlation of feature channels. The Precision, Recall and Specificity were selected to be 92.8%, 92.8% and 93.7%, the Accuracy of the model was 93.24% for the whole sample specificity. Compared with the mainstream model, the experimental results of this model are improved greatly. © 2022 ACM.
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COVID-19 is a novel coronavirus first emerging in Wuhan, China in December 2019 and has since spread rapidly across the globe escalating into a worldwide pandemic causing millions of fatalities. Emergency response to the pandemic included social distancing and isolation measures as well as the escalation of vaccination programmes. The most popular COVID-19 vaccines are nucleic acid-based. The vast spread and struggles in containment of the virus has allowed a gap in the market to emerge for counterfeit vaccines. This study investigates the use of handheld Raman spectroscopy as a method for nucleic acid-based vaccine authentication and utilises machine learning analytics to assess the efficacy of the method. Conventional Raman spectroscopy requires a large workspace, is cumbersome and energy consuming, and handheld Raman systems show limitations with regards to sensitivity and sample detection. Surface Enhanced Raman spectroscopy (SERS) however, shows potential as an authentication technique for vaccines, allowing identification of characteristic nucleic acid bands in spectra. SERS showed strong identification potential through Correlation in Wavelength Space (CWS) with all vaccine samples obtaining an r value of approximately 1 when plotted against themselves. Variance was observed between some excipients and a selected number of DNA-based vaccines, possibly attributed to the stability of the SERS colloid where the colloid-vaccine complex had been measured over different time intervals. Further development of the technique would include optimisation of the SERS method, stability studies and more comprehensive analysis and interpretation of a greater sample size. © 2023 IEEE.
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Peptide vaccines have advantages in easy fabrication and high safety, but their effectiveness is hampered by the poor immunogenicity of the epitopes themselves. Herein, we constructed a series of framework nucleic acids (FNAs) with regulated rigidity and size to precisely organize epitopes in order to reveal the influence of epitope spacing and carrier rigidity on the efficiency of peptide vaccines. We found that assembling epitopes on rigid tetrahedral FNAs (tFNAs) with the appropriate size could efficiently enhance their immunogenicity. Further, by integrating epitopes from SARS‐CoV‐2 on preferred tFNAs, we constructed a COVID‐19 peptide vaccine which could induce high titers of IgG against the receptor binding domain (RBD) of SARS‐CoV‐2 spike protein and increase the ratio of memory B and T cells in mice. Considering the good biocompatibility of tFNAs, our research provides a new idea for developing efficient peptide vaccines against viruses and possibly other diseases.
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The efficacious delivery of therapeutic nucleic acids to cancer still remains an open issue. Through the years, several strategies are developed for the encapsulation of genetic molecules exploiting different materials, such as viral vectors, lipid nanoparticles (LNPs), and polymeric nanoparticles (NPs). Indeed, the rapid approval by regulatory authorities and the wide use of LNPs complexing the mRNA coding for the spark protein for COVID-19 vaccination paved the way for the initiation of several clinical trials exploiting lipid nanoparticles for cancer therapy. Nevertheless, polymers still represent a valuable alternative to lipid-based formulations, due to the low cost and the chemical flexibility that allows for the conjugation of targeting ligands. This review will analyze the status of the ongoing clinical trials for cancer therapy, including vaccination and immunotherapy approaches, exploiting polymeric materials. Among those nanosized carriers, sugar-based backbones are an interesting category. A cyclodextrin-based carrier (CALAA-01) is the first polymeric material to enter a clinical trial complexed with siRNA for cancer therapy, and chitosan is one of the most characterized non-viral vectors able to complex genetic material. Finally, the recent advances in the use of sugar-based polymers (oligo- and polysaccharides) for the complexation of nucleic acids in advanced preclinical stage will be discussed.
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Molecular detection of SARS-CoV-2 in gargle and saliva complements the standard analysis of nasopharyngeal swabs (NPS) specimens. Although gargle and saliva specimens can be readily obtained non-invasively, appropriate collection and processing of gargle and saliva specimens are critical to the accuracy and sensitivity of the overall analytical method. This review highlights challenges and recent advances in the treatment of gargle and saliva samples for subsequent analysis using reverse transcription polymerase chain reaction (RT-PCR) and isothermal amplification techniques. Important considerations include appropriate collection of gargle and saliva samples, on-site inactivation of viruses in the sample, preservation of viral RNA, extraction and concentration of viral RNA, removal of substances that inhibit nucleic acid amplification reactions, and the compatibility of sample treatment protocols with the subsequent nucleic acid amplification and detection techniques. The principles and approaches discussed in this review are applicable to molecular detection of other microbial pathogens.
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Vaccines are one of the most effective means of preventing viral infections. Since Edward Jenner invented the world's first vaccine in 1796, against smallpox, various types of vaccine have been developed, including inactivated vaccines, attenuated live vaccines, recombinant protein vaccines, viral vector vaccines and nucleic acid vaccines. Viral vector vaccines and nucleic acid vaccines （mRNA vaccines and DNA vaccines） have been developed most recently. In these vaccines, genes encoding viral proteins that serve as antigens are introduced into the body. The viral vector is an excellent vaccine delivery system that efficiently delivers antigen genes to target cells, and has been utilized for vaccine development against a variety of emerging infectious diseases, including AIDS, malaria, Ebola hemorrhagic fever, dengue fever, and most recently COVID-19. Here, we provide an overview of viral vector vaccines and discuss recent efforts to develop vaccines against emerging infectious diseases.Alternate :抄録ウイルス性感染症を予防するうえで、ワクチンは最も有効な手段の一つである。1976年、エドワード・ジェンナーが世界初のワクチンである種痘を発明して以来、さまざまなウイルス性感染症に対して、不活化ワクチン、弱毒生ワクチン、組換えタンパクワクチン、ウイルスベクターワクチン、核酸ワクチンなど、多様なプラットフォームに基づくワクチン開発が進められてきた。本稿では、数あるワクチンプラットフォームの中から、ウイルスベクターワクチンに着目して、いくつかの例をあげて概説するとともに、近年、国際的な問題となっている新興感染症に対するワクチン開発などの取り組みについても述べる。
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Objective To compare the performance of two qPCR instruments in detecting SARS-CoV-2 virus in the nasopharyngeal swab samples of suspected COVID-19 isolated individuals in Jinghu district Wuhu city.Methods A total of 151 nasopharyngeal swab samples were collected from individuals with suspected COVID-19isolated during January 2021 and July 2022 at a quarantine site in the Jinghu district. Nucleic acid of SARS-CoV-2virus was quantified parallelly using ABIQ5 real-time fluorescence quantitative analyzer（Q5 analyzer） and Bole CFX96 fluorescence quantitative PCR analyzer（Bole analyzer） in the laboratory. Q5 analyzer was used as the reference instrument, while Bole analyzer was used as an experimental instrument. The detection results of N gene, ORF1ab fragment and CT value of the two RT-PCR machines were analyzed and compared using paired four grid test, Spearman test and paired sample t-test in SPSS 22 statistical software. Results The results of 151samples for different target genes tested by two instruments were in good agreement（N gene: Kappa=1, P＜0. 05;ORF1ab fragment: Kappa=0. 972, P＜0. 05）. The inter-batch repeatability rates were 4. 01% and 3. 04%for N gene and ORF fragment of the same batch positive quality controls by Q5 analyzer, and were 4. 90% and 3. 57% by Bole analyzer. The intra batch repeatability rates of the two instruments at different hole locations were similar, and CV values were less than 3%. The results of 23 positive samples showed that the differences in CT values of N gene（29. 38±7. 22） and ORF1ab（30. 83±6. 27） detected by Q5 analyzer were statistically significant（t=2. 765, P＜0. 05）, while the differences in CT values of N gene（29. 58±7. 27） and ORF1ab（30. 77±8. 02） detected by Bole analyzer were not statistically significant（t=1. 753, P＞0. 05）. The correlation coefficients of CT values of different target genes detected by the two instruments were rN=0. 960 and rORF=0. 865, showing correlated CT values（P＜0. 05）. Conclusion The CT values of N gene and ORF1ab fragment of SARS-CoV-2 virus detected by the two instruments have strong correlation and agreement, indicating that either of the instrument can be used for laboratory sample detection and analysis. The repeatability of Q5 analyzer is better than that of Bole analyzer. The detection stability of ORF fragments of both instruments is better than that of N gene, and the detection sensitivity of Q5 analyzer for N gene is higher than that for ORF fragment. The sample tubes should be placed in the middle of the PCR machine in order to reduce the system error.
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The lives and health of individuals are significantly threatened by the extremely infectious and dangerous Corona Virus Disease 2019 (COVID-19). For the containment of the epidemic, quick and precise COVID-19 detection and diagnosis are essential. Currently, artificial diagnosis based on medical imaging and nucleic acid detection are the major approaches used for COVID-19 detection and diagnosis. However, nucleic acid detection takes a long time and requires a dedicated test box, while manual diagnosis based on medical images relies too much on professional knowledge, and analysis takes a long time, and it is difficult to find hidden lesions. Thanks to the rapid development of pattern recognition algorithms, building a COVID-19 diagnostic model based on machine learning and clinical symptoms has become a feasible rapid detection solution. In this paper, support vector machines and random forest algorithms are used to build a COVID-19 diagnostic model, respectively. Based on the quantitative comparison of the performance of the two methods, the future development trends in this field are discussed. © 2023 IEEE.
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Since 2019, SARS-CoV-2 has caused a large number of infections and deaths worldwide. Vaccines and drugs treating SARS-CoV-2 have played an important role in pandemic control. After the infection peak, the society has returned to its normal status recently. However, with variants of the virus still being prevalent both in China and abroad, the research on vaccines and anti-SARS-CoV-2 drugs are still indispensable. This article summarized the characteristics and clinical trial results of inactivated vaccine, live attenuated vaccine, recombinant protein vaccine, viral vector vaccine, nucleic acid vaccine, virus-like particle vaccine, and reviewed the progress in research on anti-SARS-CoV-2 drugs both at home and abroad.
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Objective: To analyze the viral shedding time and its influencing factors in different site samples of patients infected with severe acute respiratory syndrome coronavirus 2 (SARA-CoV-2) omicron BA.2 variant. Methods: Real-time fluorescence polymerase chain reaction was used to detect SARS-CoV-2 nucleic acid in nasopharyngeal swab, sputum and anal swab from 217 patients with coronavirus disease 2019 (COVID-19) who were infected with severe acute respiratory syndrome coronavirus 2 omicron BA.2 variant confirmed by gene sequencing in The First Affiliated Hospital of Naval Medical University (Second Military Medical University). The differences of viral shedding time of different site samples were compared. Stratified analysis and multiple linear regression analysis were used to explore the influencing factors of viral shedding time in different site samples. Results: The age of the 217 COVID-19 patients was 32.0 (24.0, 50.5) years old, 59.0% of them were males (n=128), and 41.0% were females (n=89). Eight (3.7%) cases were diagnosed with asymptomatic infection, 184 (84.8%) cases were mild type, 21 (9.7%) cases were moderate type, 3 (1.4%) cases were severe type, and 1 (0.5%) case was critical type. A total of 70 (32.3%) patients were treated with molnupiravir. The viral shedding time of SARS-CoV-2 nucleic acid in nasopharyngeal swab, sputum and anal swab was 13.0 (11.0, 17.0) d, 16.5 (13.0, 21.0) d and 10.0 (5.3, 11.0) d, respectively, with the differences being significant between them (all P<0.001). Age 60 years old, underlying diseases (especially hypertension, coronary artery diseases, or neurological diseases), and clinical classification of moderate type were risk factors for prolonged viral shedding time in nasopharyngeal swab;male sex and underlying diseases were risk factors for prolonged viral shedding time in sputum;and male sex was a risk factor for prolonged viral shedding time in anal swab. Multiple linear regression analysis showed that critical type was an independent risk factor for prolonged viral shedding time in nasopharyngeal swab (P<0.05), and male sex and underlying diseases were independent risk factors for prolonged viral shedding time in sputum (both P<0.05). Conclusion: Among patients infected with omicron BA.2 variant, the viral shedding time in sputum is the longest and that in anal swab is the shortest. Male patients and/or patients with underlying diseases have longer viral shedding time in sputum.
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Objective To identify the pathogen and track the genetic source of a cluster of cases with fever in a kindergarten in Fengtai district during the normalization of COVID-19 prevention and control in Beijing.Methods A descriptive analysis method was used to investigate this cluster of cases with fever in April 2021.Pharyngeal swabs were collected and viral nucleic acid was extracted, real-time PCR was performed to identify SARS-CoV-2 and other common respiratory virus. G gene of human metapneumovirus（hMPV） was amplified by RT-PCR and was then sequenced. BioEdit was used for G gene sequence analysis and the Neighbor-Joining model in MEGA 5. 0 software was used to construct the phylogenic tree of G gene. Results A total of 16 cases were reported in one class with the incidence of 53. 3%（16/30） during 8 days of a cluster outbreak. All pharyngeal swabs collected from 12 cases were tested SARS-CoV-2 negative, six were found to be hMPV positive by multiplex-PCR, and one was positive for both human adenovirus and hMPV. Full-length sequences of G genes were obtained from 2 strains of hMPV. Sequence analysis showed that both strains were hMPV B2 and the nucleic acid homology of G gene was 96. 73%-98. 01% with strains from Japan（LC337940, LC337935, LC1922349） in 2016 and over 98. 40%with strains from Shandong（OL625642, OL625644） in 2019, Henan MN944096 in 2019.Compared with the amino acid sequence of hMPV-B2 reference strain（AY297748）, six amino acid insertions containing EKEKEK were identified between 161-166 amino acid location and N-glycosylation of G protein analysis showed that the two strains had four N-glycosylation sites. Conclusions The leading pathogen for this cluster outbreak is found to be hMPV-B2, which are highly homologous with strains from Japan, Shandong and Henan. Therefore, a non-stop surveillance of hMPV is necessary during the normalization control and prevention period for COVID-19.
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DNA has been actively utilized as bricks to construct exquisite nanostructures due to their unparalleled programmability. Particularly, nanostructures based on framework DNA (F-DNA) with controllable size, tailorable functionality, and precise addressability hold excellent promise for molecular biology studies and versatile tools for biosensor applications. In this review, we provide an overview of the current development of F-DNA-enabled biosensors. Firstly, we summarize the design and working principle of F-DNA-based nanodevices. Then, recent advances in their use in different kinds of target sensing with effectiveness have been exhibited. Finally, we envision potential perspectives on the future opportunities and challenges of biosensing platforms.