Identification of an immunodominant neutralizing epitope of porcine Deltacoronavirus spike protein.

Porcine deltacoronavirus (PDCoV) is a novel swine enteropathogenic coronavirus that, because of its broad host range, poses a potential threat to public health. Here, to identify the neutralizing B-cell epitopes within the S1-CTD protein, we generated three anti-PDCoV monoclonal antibodies (mAbs). Of these, the antibody designated 4E-3 effectively neutralized PDCoV with an IC50 of 3.155 µg/mL. mAb 4E-3 and one other, mAb 2A-12, recognized different linear B-cell epitopes. The minimal fragment recognized by mAb 4E-3 was mapped to 280FYSDPKSAV288 and designated S280-288, the minimal fragment recognized by mAb 2A-12 was mapped to 506TENNRFTT513, and designated S506-513. Subsequently, alanine (A)-scanning mutagenesis indicated that Asp283, Lys285, and Val288 were the critical residues recognized by mAb 4E-3. The S280-288 epitope induces PDCoV specific neutralizing antibodies in mice, demonstrating that it is a neutralizing epitope. Of note, the S280-288 coupled to Keyhole Limpet Hemocyanin (KLH) produces PDCoV neutralizing antibodies in vitro and in vivo, in challenged piglets it potentiates interferon-γ responses and provides partial protection against disease. This is the first report about the PDCoV S protein neutralizing epitope, which will contribute to research of PDCoV-related pathogenic mechanism, vaccine design and antiviral drug development.

Characterizing spatiotemporal patterns of elevated PM2.5 exposures in a megacity of China using combined mobile and stationary measurements

Exposure to PM2.5 (particles with an aerodynamic diameter equal to or less than 2.5 μm) is associated with a variety of negative health outcomes. Measurements from sparsely situated air quality monitoring stations (AQMSs) may be inappropriate to represent real PM2.5 exposures, particularly in traffic-related environments. In this study, efforts were made to characterize spatiotemporal variation of PM2.5 pollutions over Shenzhen, China from July 2019 to June 2020 using combined mobile (on-road PM2.5) and stationary (AQMS PM2.5) measurements. Monthly-average concentrations of on-road PM2.5 ranged from 10.4 ± 6.1 to 47.3 ± 23.9 μg/m3, and showed consistent trend with AQMS PM2.5 concentrations which ranged from 8.3 ± 3.1 to 37.2 ± 12.9 μg/m3. On-road PM2.5 and AQMS PM2.5 concentrations dropped by 54.6% and 30.2% in February 2020, probably due to the low anthropogenic emissions during the period of Spring Festival and COVID-19 lockdown. Weekend effect on both on-road and AQMS PM2.5 concentrations was not noticeable. Relative high on-road PM2.5 concentrations were observed during morning and evening rush hours. An "elevated concentration” concept was applied to estimate the influence of emissions on PM2.5 exposures. Elevated concentrations showed strong diurnal and spatial variation, and was about 5.0 μg/m3 on-average. Mappings of on-road PM2.5 and elevated concentrations confirmed the heterogeneity of spatial distribution of PM2.5 exposures in Shenzhen where PM2.5 pollutions were more severe in western and northern areas. Our results highlight the elevated PM2.5 exposures in traffic-related environments, and the inequity in urban exposure levels and health.

A comprehensive assessment of four whole blood stabilizers for flow-cytometric analysis of leukocyte populations.

Though cryopreservation of cell fractions is widely used in flow cytometry studies, whole blood cryopreservation is more challenging due to the presence of erythrocytes and effects of fixatives commonly used for preservation. Here, we evaluated and compared head-to-head the performance of four commercial whole blood cryopreservation kits; (1) Cytodelics, (2) Stable-Lyse V2 and Stable-Store V2 (SLSS-V2), (3) Proteomic stabilizer (PROT-1), and (4) Transfix. We found that PROT-1, Transfix, and Cytodelics maintained the distribution of major leukocyte subsets-granulocytes, T cells, natural killer cells, and B cells, on a comparable level to unpreserved samples, despite the attenuation of fluorescence intensities in flow cytometric assays. Moreover, these three stabilizers also maintained the activated phenotypes of neutrophils upon stimulation with N-formylmethionyl-leucyl-phenylalanine and lipopolysaccharides. The upregulation of adhesion molecules (CD11b), Fc receptors (CD16), and granule proteins (CD66b), as well as the shedding of surface L-selectin (CD62L), was conserved most efficiently in PROT-1 and Cytodelics when compared to samples only treated with erythrocyte lysing. However, none of the stabilizers provided a reliable detection of CCR7 for accurate quantification of T cell maturation stages. We also evaluated the performance of Cytodelics in longitudinal clinical samples obtained from acute COVID-19 patients, where it allowed reliable detection of lymphopenia and granulocyte expansion. These results support the feasibility of whole blood cryopreservation for immunophenotyping by flow cytometry, particularly in longitudinal studies. In conclusion, the performance of different stabilizers is variable and therefore the choice of stabilizers should depend on cell type of interest, as well as antibody clones and experimental design of each study.

Effect of human aminopeptidase N (hAPN) on porcine deltacoronavirus infecting HEK293 cells

HEK293 cells were used as the cell model to investigate the role of human aminopeptidase N (hAPN) in the invasion of porcine deltacoronavirus (PDCoV) into human cells. The proliferation of PDCoV on HEK293 cells was firstly identified by RT-qPCR/RT-PCR. And then, hAPN knockout cell line was constructed by CRISPR/Cas9 technology and cell viability of HEK293 hAPN knockout and wild-type cells was verified by CCK-8 assay. Effect of hAPN knockout and overexpression on PDCoV replication was detected by RT-qPCR and Western blot. Meanwhile, interaction of PDCoV S protein and hAPN protein was analyzed by homology modeling and molecular docking. Results showed that PDCoV virus copies rapidly increased at 12-36 h and reached peak level at 36 h, it could propagate at least for passage 2 on HEK293 cells. There was no significant difference in cell viability between hAPN knockout cells and wild-type cells. Knockout of hAPN inhibit PDCoV replication and overexpression of hAPN enhance PDCoV replication. Homology modeling and molecular docking analysis showed S1 protein could bind hAPN domain II. Residues TYR92, THR51, THR48, PHE16 and MET14of S1 protein receptor binding motif 1 (RBM1) can form hydrogen bonds with residues PHE490, GLN531, ARG528 and SER529 of hAPN. This study indicates that hAPN plays a critical role in HEK293 cells during PDCoV infection, which provides new theoretical evidence for further studies on the mechanism of PDCoV entry into host cells and cross-species transmission.

Comparison of COVID-19 Induced Respiratory Failure and Typical ARDS: Similarities and Differences.

Coronavirus disease 2019 (COVID-19) is a predominantly respiratory infectious disease caused by novel coronavirus infection (SARS-CoV-2), respiratory failure is the main clinical manifestation and the leading cause of death. Even though it can meet the acute respiratory distress syndrome (ARDS) Berlin definition, only some clinical features of COVID-19 are consistent with typical ARDS, and which has its own peculiar phenotypes. When compared with typical ARDS, in addition to the typical diffuse alveolar injury, COVID-19 has unique pathological and pathophysiological features, such as endothelial injury, extensive microthrombus, and pulmonary capillary hyperplasia. The clinical features of patients with respiratory failure caused by COVID-19 are heterogeneous and can be generally divided into two phenotypes: progressive respiratory distress and unique "silent hypoxemia". The "H-type" characteristics of reduced lung volume, decreased lung compliance, and unmatched ventilator-perfusion ratio. While some patients may have close to normal lung compliance, that is "L-type". Identifying the exact phenotype in whom are suffered with COVID-19 is crucial to guide clinicians to adopt appropriate treatment strategies. This review discussed the similarities and differences in the pathogenesis, pathophysiology, clinical features and treatment strategies of COVID-19 induced acute respiratory failure and typical ARDS.

Susceptibility of cell lines from different animal species to Porcine Deltacoronavirus

[Objective] To explore whether porcine deltacoronavirus (PDCoV) can infect and proliferate in different animal species-derived cell lines. [Methods] The Sichuan isolate CHN-SC2015of PDCoV was inoculated in twelve cell lines derived from hamster,poultry,monkey, human and swine. After at least five blindly passages in each cell line, the virus was identified by RT-PCR,RT-q PCR, indirect immunofluorescence assay (IFA), and sequencing. [Results] PDCoV caused distinct cytopathic effect (CPE) in Vero,PAM,PK15,ST, and LLC-PK1 cells at the 1st passage (P1) and proliferated to various degrees in PAM,PK15,ST, and LLC-PK1 cells, while the CPE gradually disappeared during subsequent passages in Vero and PAM cells. Except that in the three susceptible cell lines (PK15,LLC-PK1, and ST), the viral copies of the infected cell lines gradually decreased with the increase in passages, and PDCoV could not be detected at P4 or P5 of DEF,Marc-145,HEK-293,ZYM-SIEC02, and PAM cells. PCR results showed that PDCoV could be detected only in CEF and Vero cells at P5. The IFA results showed that PDCoV could infect other cell lines except BHK-21 and ZYM-SIEC02, and specific immunofluorescence was observed in PK15,LLC-PK1, and ST cells at P1,P3, and P9. Therefore, only three cell lines (PK15,LLC-PK1, and ST) were suitable for serial passage, with the virus titers up to 107.11,107.00, and 107.37 TCID50/mL at P9,respectively. After passage in different cell lines,CHN-SC2015 accumulated 14 nucleotide mutations corresponding to 12 amino acid mutations. [Conclusion] This study indicates that PDCoV can infect a variety of cells in vitro, suggesting that it may have the potential of cross-species transmission.

Phylogeny, Evolution, and Transmission Dynamics of Canine and Feline Coronaviruses: A Retro-Prospective Study

Canine coronavirus (CCoV) and feline coronavirus (FCoV) are endemic in companion animals. Due to their high mutation rates and tendencies of genome recombination, they pose potential threats to public health. The molecular characteristics and genetic variation of both CCoV and FCoV have been thoroughly studied, but their origin and evolutionary dynamics still require further assessment. In the present study, we applied a comprehensive approach and analyzed the S, M, and N genes of different CCoV/FCoV isolates. Discriminant analysis of principal components (DAPC) and phylogenetic analysis showed that the FCoV sequences from Chinese isolates were closely related to the FCoV clusters in Netherlands, while recombination analysis indicated that of S N-terminal domain (NTD) was the most susceptible region of mutation, and recombination of this region is an important cause of the emergence of new lineages. Natural selection showed that CCoV and FCoV subgenotypes were in selection constraints, and CCoV-IIb was in strong positive selection. Phylodynamics showed that the mean evolution rate of S1 genes of CCoV and FCoV was 1.281 × 10–3 and 1.244 × 10–3 subs/site/year, respectively, and the tMRCA of CCoV and FCoV was about 1901 and 1822, respectively. Taken together, our study centered on tracing the origin of CCoV/FCoV and provided ample insights into the phylogeny and evolution of canine and feline coronaviruses.

A Comparative Transcriptomic Analysis Reveals That HSP90AB1 Is Involved in the Immune and Inflammatory Responses to Porcine Deltacoronavirus Infection.

PDCoV is an emerging enteropathogenic coronavirus that mainly causes acute diarrhea in piglets, seriously affecting pig breeding industries worldwide. To date, the molecular mechanisms of PDCoV-induced immune and inflammatory responses or host responses in LLC-PK cells in vitro are not well understood. HSP90 plays important roles in various viral infections. In this study, HSP90AB1 knockout cells (HSP90AB1KO) were constructed and a comparative transcriptomic analysis between PDCoV-infected HSP90AB1WT and HSP90AB1KO cells was conducted using RNA sequencing to explore the effect of HSP90AB1 on PDCoV infection. A total of 1295 and 3746 differentially expressed genes (DEGs) were identified in PDCoV-infected HSP90AB1WT and HSP90AB1KO cells, respectively. Moreover, most of the significantly enriched pathways were related to immune and inflammatory response-associated pathways upon PDCoV infection. The DEGs enriched in NF-κB pathways were specifically detected in HSP90AB1WT cells, and NF-κB inhibitors JSH-23, SC75741 and QNZ treatment reduced PDCoV infection. Further research revealed most cytokines associated with immune and inflammatory responses were upregulated during PDCoV infection. Knockout of HSP90AB1 altered the upregulated levels of some cytokines. Taken together, our findings provide new insights into the host response to PDCoV infection from the transcriptome perspective, which will contribute to illustrating the molecular basis of the interaction between PDCoV and HSP90AB1.

Quantitative CT imaging features for COVID-19 evaluation: The ability to differentiate COVID-19 from non- COVID-19 (highly suspected) pneumonia patients during the epidemic period.

OBJECTIVES: COVID-19 and Non-Covid-19 (NC) Pneumonia encountered high CT imaging overlaps during pandemic. The study aims to evaluate the effectiveness of image-based quantitative CT features in discriminating COVID-19 from NC Pneumonia. MATERIALS AND METHODS: 145 patients with highly suspected COVID-19 were retrospectively enrolled from four centers in Sichuan Province during January 23 to March 23, 2020. 88 cases were confirmed as COVID-19, and 57 patients were NC. The dataset was randomly divided by 3:2 into training and testing sets. The quantitative CT radiomics features were extracted and screened sequentially by correlation analysis, Mann-Whitney U test, the least absolute shrinkage and selection operator (LASSO) logistic regression (LR) and backward stepwise LR with minimum AIC methods. The selected features were used to construct the LR model for differentiating COVID-19 from NC. Meanwhile, the differentiation performance of traditional quantitative CT features such as lesion volume ratio, ground glass opacity (GGO) or consolidation volume ratio were also considered and compared with Radiomics-based method. The receiver operating characteristic curve (ROC) analysis were conducted to evaluate the predicting performance. RESULTS: Compared with traditional CT quantitative features, radiomics features performed best with the highest Area Under Curve (AUC), sensitivity, specificity and accuracy in the training (0.994, 0.942, 1.0 and 0.965) and testing sets (0.977, 0.944, 0.870, 0.915) (Delong test, P < 0.001). Among CT volume-ratio based models using lesion or GGO component ratio, the model combining CT lesion score and component ratio performed better than others, with the AUC, sensitivity, specificity and accuracy of 0.84, 0.692, 0.853, 0.756 in the training set and 0.779, 0.667, 0.826, 0.729 in the testing set. The significant difference of the most selected wavelet transformed radiomics features between COVID-19 and NC might well reflect the CT signs. CONCLUSIONS: The differentiation between COVID-19 and NC could be well improved by using radiomics features, compared with traditional CT quantitative values.

Study of the inhibitory effect of STAT1 on PDCoV infection.

Porcine deltacoronavirus (PDCoV) is an enteropathogen found in many pig producing countries. It can cause acute diarrhea, vomiting, dehydration, and death in newborn piglets, seriously affecting the development of pig breeding industries. To date, our knowledge of the pathogenesis of PDCoV and its interactions with host cell factors remains incomplete. Using Co-IP coupled with LC/MS-MS, we identified 67 proteins that potentially interact with PDCoV in LLC-PK1 cells; five of the identified proteins were chosen for further evaluation (IMMT, STAT1, XPO5, PIK3AP1, and TMPRSS11E). Five LLC-PK1 cell lines, each with one of the genes of interest knocked down, were constructed using CRISPR/cas9. In these knockdown cells lines, only STAT1KD resulted in a significantly greater virus yield. Knockdown of the remaining four genes resulted, to varying degrees, in a lower virus yield that wild-type LLC-PK1 cells. The absence of STAT1 did not significantly affect the attachment of PDCoV to cells, but did result in increased viral internalization. Additionally, PDCoV infection stimulated expression of interferon stimulated genes (ISGs) downstream of STAT1 (IFIT1, IFIT2, RADS2, ISG15, MX1, and OAS1) while knockdown of STAT1 resulted in a greater than 80 % decrease in the expression of all six ISGs. Our findings show that STAT1 interacts with PDCoV, and plays a negative regulatory role in PDCoV infection.

Retrospective Study of Critically Ill COVID-19 Patients With and Without Extracorporeal Membrane Oxygenation Support in Wuhan, China.

Background: Extracorporeal membrane oxygenation (ECMO) might benefit critically ill COVID-19 patients. But the considerations besides indications guiding ECMO initiation under extreme pressure during the COVID-19 epidemic was not clear. We aimed to analyze the clinical characteristics and in-hospital mortality of severe critically ill COVID-19 patients supported with ECMO and without ECMO, exploring potential parameters for guiding the initiation during the COVID-19 epidemic. Methods: Observational cohort study of all the critically ill patients indicated for ECMO support from January 1 to May 1, 2020, in all 62 authorized hospitals in Wuhan, China. Results: Among the 168 patients enrolled, 74 patients actually received ECMO support and 94 not were analyzed. The in-hospital mortality of the ECMO supported patients was significantly lower than non-ECMO ones (71.6 vs. 85.1%, P = 0.033), but the role of ECMO was affected by patients' age (Logistic regression OR 0.62, P = 0.24). As for the ECMO patients, the median age was 58 (47-66) years old and 62.2% (46/74) were male. The 28-day, 60-day, and 90-day mortality of these ECMO supported patients were 32.4, 68.9, and 74.3% respectively. Patients survived to discharge were younger (49 vs. 62 years, P = 0.042), demonstrated higher lymphocyte count (886 vs. 638 cells/uL, P = 0.022), and better CO2 removal (PaCO2 immediately after ECMO initiation 39.7 vs. 46.9 mmHg, P = 0.041). Age was an independent risk factor for in-hospital mortality of the ECMO supported patients, and a cutoff age of 51 years enabled prediction of in-hospital mortality with a sensitivity of 84.3% and specificity of 55%. The surviving ECMO supported patients had longer ICU and hospital stays (26 vs. 18 days, P = 0.018; 49 vs. 29 days, P = 0.001 respectively), and ECMO procedure was widely carried out after the supplement of medical resources after February 15 (67.6%, 50/74). Conclusions: ECMO might be a benefit for severe critically ill COVID-19 patients at the early stage of epidemic, although the in-hospital mortality was still high. To initiate ECMO therapy under tremendous pressure, patients' age, lymphocyte count, and adequacy of medical resources should be fully considered.

The Implementation of Patient-Centered Humanistic Care for COVID-19 Closely Contacted Hemodialysis Patients Under the Hospital-Based Group Medical Quarantine: A Brief Research Report.

In February 2020, an inpatient in Peking University People's Hospital (PKUPH), China, was confirmed positive for the novel coronavirus. In this case, 143 hemodialysis patients were labeled as close contacts and required to be placed under the hospital-based group medical quarantine (HB-GMQ) for 2 weeks by the authorities. After the case was reported, false or misleading information about the case flourished on social media platforms, which led to infodemic. Under this context, PKUPH adopted patient-centered humanistic care to implement the HB-GMQ, through the synergy of administrative, healthcare, logistical, and other measures under the model of patient-centered care of the Massachusetts Medical Society (MMS). As a result, all the patients tided over the HB-GMQ with no COVID-19 infection and no unanticipated adverse events, and all met the criteria for lifting the HB-GMQ. According to the questionnaires taken during the HB-GMQ, a high level of satisfaction was found among the quarantined and no symptomatic increase of anxiety and depression in the patients before and during the HB-GMQ, by comparing the Zung self-rating anxiety scale (SAS) and self-rating depression scale (SDS) conducted in December 2019 and on the 12th day of the HB-GMQ. This article is to brief on PKUPH's experience in implementing patient-centered humanistic care tailored to hemodialysis patients under the HB-GMQ, and to validate the hypothesis that patient-centered humanistic care is effective and helpful to help them tide over the HB-GMQ, so as to shed light on how to implement the HB-GMQ and cope with the HB-GMQ-induced problems in other hospitals.

Predictors for Fear of Cancer Recurrence in Breast Cancer Patients Referred to Radiation Therapy During the COVID-19 Pandemic: A Multi-Center Cross-Section Survey.

OBJECTIVE: The outbreak of COVID-19 pandemic has greatly impacted on radiotherapy (RT) strategy for breast cancer patients, which might lead to increased distressing psychological symptoms. We performed a multi-center cross-section survey to investigate prevalence of fear of cancer recurrence (FCR) and predictors for FCR in patients referred to RT during pandemic. METHODS: 542 patients were consecutively enrolled from three regions in China including Yangtze Delta River Region, Guangdong and Shanxi province. Patients' characteristics were collected using an information sheet, Fear of progression questionnaire-short form, Hospital Anxiety/Depression Scale and EORTC QLQ-C30. The hierarchical multiple regression models were performed. RESULTS: 488 patients with complete data were eligible. The RT strategy was affected in 265 (54.3%) patients, including 143 with delayed RT initiation, 66 believing to have delayed RT initiation but actually not, 24 with RT interruptions, 19 shifting to local hospitals for RT and the remaining 13 influenced on both RT schedule and hospital level. The model explained 59.7% of observed variances in FCR (p<0.001) and showed that influence of RT strategy had significantly impacted on FCR (△R2 = 0.01, △F=2.966, p=0.019). Hospitals in Shanxi province (ß=-0.117, p=0.001), emotional function (ß=-0.19, p<0.001), social function (ß=-0.111, p=0.006), anxiety (ß=0.434, p<0.001) and RT interruption (ß=0.071, p=0.035) were independent predictors. CONCLUSIONS: RT strategy for breast cancer patients was greatly influenced during pandemic. RT interruption is an independent predictor for high FCR. Our findings emphasize the necessity to ensure continuum of RT, and efforts should be taken to alleviate FCR through psychological interventions.

Hydrogen: A Potential New Adjuvant Therapy for COVID-19 Patients.

Hydrogen has been shown to have antioxidant, anti-inflammatory, hormone-regulating, and apoptosis-resistance properties, among others. Based on a review of the research, the use of hydrogen might reduce the destructive cytokine storm and lung injury caused by SARS-CoV-2 during COVID-19 (Corona Virus Disease 2019) in the early stage, stimulating ropy sputum drainage, and ultimately reducing the incidence of severe disease. Molecular hydrogen treatment has the potential to become a new adjuvant therapy for COVID-19, but its efficacy and safety require large clinical trials and further confirmation.

[Clinical characteristics of liver damage in 30 patients with severe coronavirus disease 2019 in Sichuan area].

OBJECTIVE: To describe the characteristics of liver damage in severe coronavirus disease 2019 (COVID-19) patients in Sichuan area and the effect of antiviral drugs on liver function. METHODS: The clinical data of severe COVID-19 patients admitted to Chengdu Public Health Clinical Medical Center from January 21 to February 24, 2020 were retrospectively collected, including demographic data, clinical manifestations and liver function changes within 1 week after admission to intensive care unit (ICU). The changes of liver function during the course of disease in severe COVID-19 patients were analyzed and summarized, and group analysis was performed. RESULTS: A total of 30 COVID-19 patients with complete clinical data were enrolled. The incidence of severe COVID-19 in elderly men was higher (60.0%), with median age of 61 (47, 79) years old, and those aged 80 or above accounted for 23.3%. The severe COVID-19 patients mainly presented with respiratory symptoms such as fever (96.7%), cough (80.0%) and dyspnea (66.7%). The alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBil) and prothrombin time (PT) of 30 patients were increased to various degrees within 1 week after ICU admission, and albumin (ALB) was decreased. (1) The patients were divided into two groups according to whether to take lopinavir/ritonavir (kaletra). It was shown that the incidence of liver dysfunction in patients taking kaletra was significantly higher than those who did not take kaletra (7-day abnormal rate of ALT was 54% vs. 33%, the abnormal rate of AST was 38% vs. 33%, the abnormal rate of TBil was 8% vs. 0%), but there were no statistical differences (all P > 0.05). (2) The patients were divided into normal dose group (500 mg, twice a day, n = 19) and reduced dose group (250 mg, twice a day, n = 5) according to the dosage of kaletra. It was shown that patients taking low-dose kaletra had a smaller effect on liver function within 1 week after ICU admission than those receiving normal dosage, and ALB, TBil in the reduced dose group were significantly lower than those in the normal dose group on the 2nd day after ICU admission [ALB (g/L): 33.3±2.0 vs. 37.5±4.0, TBil (µmol/L): 6.3±3.3 vs. 11.3±4.8, both P < 0.05]. CONCLUSIONS: Severe COVID-19 patients in Sichuan area suffered obvious liver damage in the early course of the disease and have a slower recovery. It is important to pay attention to avoid using drugs that can aggravate liver damage while treating the disease. If there is no alternative drug, liver protection treatment should be considered appropriately.