Diverse immune responses in vaccinated individuals with and without symptoms after omicron exposure during the recent outbreak in Guangzhou, China.

Objectives: During the recent wave of coronavirus disease 2019 (COVID-19) infections in China, most individuals have been vaccinated and exposed to the omicron variant. In the present study, two cohorts were observed in the vaccinated population: vaccinated individuals with symptoms (VIWS) and those without symptoms (VIWOS). Our study aimed to characterize the antibody response in two cohorts: VIWS and VIWOS. Methods: A questionnaire survey was conducted in the community. Blood and saliva samples were collected from 124 individuals in the VIWS and VIWOS cohorts. Capture enzyme-linked immunosorbent assay (ELISA) was performed to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) specific antibodies. Results: The questionnaire survey revealed that 30.0 % (302/1005) of individuals in the older adult group (≥65 years) experienced no symptoms, whereas the rate of individuals without symptoms in the younger group (<65 years) was 17.8 % (166/932). Nucleocapsid (N)-specific IgM (N-IgM) was detected in the blood samples at a rate of 69.2 % (54/78) in the VIWS cohort. The positivity rate for N-specific IgA (N-IgA) was 93.6 % (73/78). In addition, the positivity rates of spike (S)-specific IgA (S-IgA) and N-IgA detected in saliva samples were 42 % (21/50) and 54 % (27/50), respectively. Both N-IgA positivity and negativity were observed in the VIWOS cohort. The detection rate of N-IgM positivity was 57.1 % (12/21) in the N-IgA-positive group. In addition, 54.3 % (25/46) of the vaccinated individuals without symptoms were IgA-negative. Conclusions: Our study indicates that substantial N-specific antibodies were induced during omicron infection and that testing for N-IgA in both blood and saliva may aid in the diagnosis of SARS-CoV-2 infection in vaccinated populations.

Hemorrhagic fever with renal syndrome and reversible splenial lesion syndrome.

Hemorrhagic fever with renal syndrome (HFRS) and reversible splenial lesion syndrome are both considered uncommon conditions relatively rare. Fever, hemorrhage, and acute kidney injury are the prevailing symptoms frequently observed in cases of HFRS. We describe a case of a middle-aged man who had been hospitalized with fever and acute neurological symptoms. His main symptom was recurrent dizziness. Cranial computed tomography (CT) did not reveal any obvious lesions, such as encephalorrhagia or infarctions. The splenium of corpus callosum showed hyperintensity on brain magnetic resonance imaging (MRI), which is in line with the characteristic radiographic observations of reversible splenial lesion syndrome (RESLES). Further analyses revealed that the patient's platelet counts had decreased to 7×109/L while hemorrhagic fever antibodies were positive. Eventually, the patient was diagnosed with HFRS and exhibited clinical improvements after active treatment.

Patient-derived monoclonal antibodies to SARS-CoV-2 nucleocapsid protein N-terminal and C-terminal domains cross-react with their counterparts of SARS-CoV, but not other human betacoronaviruses.

Introduction: SARS-CoV-2 nucleocapsid (N) protein plays a key role in multiple stages of the viral life cycle such as viral replication and assembly. This protein is more conserved than the Spike protein of the virus and can induce both humoral and cell-mediated immune responses, thereby becoming a target for clinical diagnosis and vaccine development. However, the immunogenic characteristics of this protein during natural infection are still not completely understood. Methods: Patient-derived monoclonal antibodies (mAbs) against SARS-CoV-2 N protein were generated from memory B cells in the PBMCs using the antigen-specific B cell approach. For epitope mapping of the isolated hmAbs, a panel of series-truncated N proteins were used , which covered the N-terminal domain (NTD, aa 46-174 ) and C-terminal domain (CTD, aa 245-364 ), as well as the flanking regions of NTD and CTD. NTD- or CTD-specific Abs in the plasma from COVID-19 patients were also tested by ELISA method. Cross-binding of hmAbs or plasma Abs in COVID-19 patients to other human ß-CoV N proteins was determined using the capture ELISA. Results: We isolated five N-specific monoclonal antibodies (mAbs) from memory B cells in the peripheral blood of two convalescent COVID-19 patients. Epitope mapping revealed that three of the patient-derived mAbs (N3, N5 and N31) targeted the C-terminal domain (CTD), whereas two of the mAbs (N83 and 3B7) targeted the N-terminal domain (NTD) of SARS-CoV-2 N protein. All five patient-derived mAbs were cross-reactive to the N protein of SARS-CoV but showed little to no cross-reactivity to the N proteins of other human beta coronaviruses (ß-CoVs). We also tested 52 plasma samples collected from convalescent COVID-19 patients for Abs against the N proteins of human ß-CoVs and found that 78.8% of plasma samples showed detectable Abs against the N proteins of SARS-CoV-2 and SARS-CoV. No plasma sample had cross-reactive Abs to the N protein of MERS-CoV. Cross-reactive Abs to the N proteins of OC43 and HKU1 were detected in 36.5% (19/52) and 19.2% (10/52) of plasma samples, respectively. Discussion: These results suggest that natural SARS-CoV-2 infection elicits cross-reactive Abs to the N protein of SARS-CoV and that the five patient-derived mAbs to SARS-CoV-2 N protein NTD and CTD cross-react with their counterparts of SARS-CoV, but not other human ß-CoVs. Thus, these five patient-derived mAbs can potentially be used for developing the next generation of COVID-19 At-Home Test kits for rapid and specific screening of SARS-CoV-2 infection.

Risk Factors of Fatal Outcome of Hospitalized Patients with COVID-19.

BACKGROUND: Few studies reported the risk factors of fatal outcome of hospitalized patients with coronavirus disease 2019 (COVID-19). We aimed to identify the independent risk factors associated with fatal outcome of hospitalized COVID-19 patients. METHODS: The clinical data of 109 consecutive COVID-19 patients including 40 (36.7%) common cases and 69 (63.3%) severe cases were included and analyzed. RESULTS: Multivariate regression analysis indicated that platelets (PLT, OR, 0.988; 95% CI, 0.978-0.998; P=0.017) and C-reactive protein (CRP) (OR, 1.047; 95% CI, 1.026-1.068; P<0.001) levels were the independent risk factors of fatal outcome in COVID-19 patients. The optimal cut-off value of PLT counts for predicting fatal outcome was 161x109/L with the area under receiver operating characteristic curve (AUROC) of 0.824 (95% CI, 0.739-0.890). The optimal cut-off value of CRP for the prediction of fatal outcome was 46.2 mg/L with the AUROC of 0.954 (95% CI, 0.896-0.985). The CRP levels had higher predictive values for fatal outcome than PLT (P=0.016). The cumulative survival rate was significantly higher in patients with PLT>161x109/L compared with patients with PLT≤161x109/L (89.4% vs. 12.5%, log-rank test X2=72.17; P<0.001). Survival rate of COVID-19 patients was prominently higher in CRP≤46.2 mg/L patients compared with patients with CRP>46.2 mg/L (95.9% vs. 22.9%, log-rank test X2=77.85; P<0.001). CONCLUSIONS: PLT counts and CRP levels could predict fatal outcome of hospitalized COVID-19 patients with relatively high accuracy.

Electrodeposition of CdTe Thin Films for Solar Energy Water Splitting.

CdTe thin films have been prepared by electrochemical deposition. The morphological, structural, and optical properties of CdTe thin films deposited with different deposition time were investigated, and the influence of film thickness on the photoelectric characteristics of CdTe thin films was studied. At the deposition time of 1.5 h, CdTe thin films had good optical properties and the photocurrent reached 20 µAcm-2. Furthermore, the Pt/CdS/CdTe/FTO structure was prepared to improve its PEC stability and the photocurrent of 240 µAcm-2 had been achieved.

Activity of sitafloxacin against extracellular and intracellular Staphylococcus aureus in vitro and in vivo: comparison with levofloxacin and moxifloxacin.

Antibiotic activity can differ depending on whether the bacterial target is extracellular or intracellular. To determine extracellular and intracellular activities of sitafloxacin (STX) against Staphylococcus aureus in comparison with levofloxacin (LVX) and moxifloxacin (MXF) in vivo and in vitro, three S. aureus strains (ATCC25923, 29213, 43300) were evaluated. MIC, MBC and mutant prevention concentration (MPC) of the test quinolone for S. aureus were determined by microdilution in broth, and intracellular activity was determined in RAW264.7 cells after phagocytosis of bacteria. Cellular quinolone accumulation was determined by HPLC. The time- and concentration-kill relationships were examined in vitro (in broth and in RAW264.7 cells, respectively) and in vivo by use of a mouse peritonitis model. The results showed that the activity of STX in broth cultures, including the MIC, MBC, MPC and the time- and concentration-kill relationships, were greater for STX than those for LVX and MXF. In particular, STX exhibited the strongest activity against intramacrophage S. aureus. The intracellular effects could be ranked in the following order as the mean change in the log10 number of cfu ml(-1) (log10 cfu ml(-1)) between treated and untreated mice: STX>LVX>MXF. It also showed that the dominant factor of intracellular activity in vivo was the frequency of doses. There was a poor correlation between the intracellular accumulation of the three different quinolones and the actual intracellular effect. The results of the intracellular and extracellular time- and concentration-kill relationships indicated that STX has the potential to display useful activity against extracellular and intracellular S. aureus.