Diagnostic value and characteristic analysis of serum nucleocapsid antigen in COVID-19 patients.

Background: To date, several types of laboratory tests for coronavirus disease 2019 (COVID-19) diagnosis have been developed. However, the clinical importance of serum severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid antigen (N-Ag) remains to be fully elucidated. In this study, we sought to investigate the value of serum SARS-CoV-2 N-Ag for COVID-19 diagnosis and to analyze N-Ag characteristics in COVID-19 individuals. Methods: Serum samples collected from 215 COVID-19 patients and 65 non-COVID-19 individuals were used to quantitatively detect N-Ag via chemiluminescent immunoassay according to the manufacturer's instructions. Results: The sensitivity and specificity of the N-Ag assay were 64.75% (95% confidence interval (95% CI) [55.94-72.66%]) and 100% (95% CI [93.05-100.00%]), respectively, according to the cut-off value recommended by the manufacturer. The receiver operating characteristic (ROC) curve showed a sensitivity of 100.00% (95% CI [94.42-100.00%]) and a specificity of 71.31% (95% CI [62.73-78.59%]). The positive rates and levels of serum SARS-CoV-2 N-Ag were not related to sex, comorbidity status or disease severity of COVID-19 (all P < 0.001). Compared with RT‒PCR, there was a lower positive rate of serum N-Ag for acute COVID-19 patients (P < 0.001). The positive rate and levels of serum SARS-CoV-2 N-Ag in acute patients were significantly higher than those in convalescent patients (all P < 0.001). In addition, the positive rate of serum SARS-CoV-2 N-Ag in acute COVID-19 patients was higher than that of serum antibodies (IgM, IgG, IgA and neutralizing antibodies (Nab)) against SARS-CoV-2 (all P < 0.001). However, the positive rate of serum SARS-CoV-2 N-Ag in convalescent COVID-19 patients was significantly lower than that of antibodies (all P < 0.001). Conclusion: Serum N-Ag can be used as a biomarker for early COVID-19 diagnosis based on appropriate cut-off values. In addition, our study also demonstrated the relationship between serum N-Ag and clinical characteristics.

CESSAT: A chemical additive-enhanced single-step accurate CRISPR/Cas13 testing system for field-deployable ultrasensitive detection and genotyping of SARS-CoV-2 variants of concern.

The continued emergence of SARS-CoV-2 variants of concern (VOCs) has raised great challenges for epidemic prevention and control. A rapid, sensitive, and on-site SARS-CoV-2 genotyping technique is urgently needed for individual diagnosis and routine surveillance. Here, a field-deployable ultrasensitive CRISPR-based diagnostics system, called Chemical additive-Enhanced Single-Step Accurate CRISPR/Cas13 Testing system (CESSAT), for simultaneous screening of SARS-CoV-2 and its five VOCs (Alpha, Beta, Gamma, Delta, and Omicron) within 40 min was reported. In this system, a single-step reverse transcription recombinase polymerase amplification-CRISPR/Cas13a assay was incorporated with optimized extraction-free viral lysis and reagent lyophilization, which could eliminate complicated sample processing steps and rigorous reagent storage conditions. Remarkably, 10% glycine as a chemical additive could improve the assay sensitivity by 10 times, making the limit of detection as low as 1 copy/µL (5 copies/reaction). A compact optic fiber-integrated smartphone-based device was developed for sample lysis, assay incubation, fluorescence imaging, and result interpretation. CESSAT could specifically differentiate the synthetic pseudovirus of SARS-CoV-2 and its five VOCs. The genotyping results for 40 clinical samples were in 100% concordance with standard method. We believe this simple but efficient enhancement strategy can be widely incorporated with existing Cas13a-based assays, thus leading a substantial progress in the development and application of rapid, ultrasensitive, and accurate nucleic acid analysis technology.

Booster shot of inactivated SARS-CoV-2 vaccine induces potent immune responses in people living with HIV.

This study aimed to investigate the immunogenicity to SARS-CoV-2 and evasive subvariants BA.4/5 in people living with HIV (PLWH) following a third booster shot of inactivated SARS-CoV-2 vaccine. We conducted a cross-sectional study in 318 PLWH and 241 healthy controls (HC) using SARS-CoV-2 immunoassays. Vaccine-induced immunological responses were compared before and after the third dose. Serum levels of IgG anti-RBD and inhibition rate of NAb were significantly elevated at the "post-third dose" sampling time compared with the pre-third dose in PLWH, but were relatively decreased in contrast with those of HCs. Induced humoral and cellular responses attenuated over time after triple-dose vaccination. The neutralizing capacity against BA.4/5 was also intensified but remained below the positive inhibition threshold. Seropositivity of SARS-CoV-2-specific antibodies in PLWH was prominently lower than that in HC. We also identified age, CD4 cell counts, time after the last vaccination, and WHO staging type of PLWH as independent factors associated with the seropositivity of antibodies. PLWH receiving booster shot of inactivated vaccines generate higher antibody responses than the second dose, but lower than that in HCs. Decreased anti-BA.4/5 responses than that of WT impede the protective effect of the third dose on Omicron prevalence.

Application of 2019 Novel Coronavirus (2019-nCoV) specific antibody detection for suspected cases screening

Comparing the accuracy of antibody detection reagents which based on different principles by the diagnosis of suspected cases of new crown, propose an efficient screening plan for suspected cases, and further provide a scientific basis for establishing a clinical screening path for high-risk populations. For 76 suspected cases of COVID-19 that were transferred to designated hospitals for isolation and observation due to the initial IgM antibody test, nasopharyngeal swab nucleic acid tests, serum trace virus neutralizing antibodies and three commercially available antibody test reagents with different principles were tested, combined with lung CT and the examination and clinical symptoms or other information, comprehensively judge the diagnosis or exclusion of the new crown, and compare the three kinds of serological antibody detection reagents with the clinical judgment results to compare the detection rates of the three detection methods. Through comprehensive judgment, 3 suspected cases are confirmed cases, and 73 suspected cases are excluded cases. Compared with the clinical diagnosis/exclusion results, among the three serological antibody detection methods, the chemiluminescence total antibody kit detect positive for all the 9 serums collected from the 3 confirmed cases in different time points, the detection specificity is 97.26% for 73 excluded cases, it's significantly higher than that of the chemiluminescence method IgM/IgG and the colloidal gold method IgM/IgG Separate testing (the specificity is 73.97% on the first day of admission). The chemiluminescence method for the detection of total antibodies to the 2019-nCoV has high sensitivity and high specificity, and can be used for preliminary screening of antibody detection in suspected cases. For the screening of target populations, the 2019-nCoV nucleic acid test should be performed first. If the nucleic acid test is negative, the screening path with the detection of serum total antibodies as the main indicator should be adopted.

Single-cell immune profiling reveals distinct immune response in asymptomatic COVID-19 patients.

While some individuals infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) present mild-to-severe disease, many SARS-CoV-2-infected individuals are asymptomatic. We sought to identify the distinction of immune response between asymptomatic and moderate patients. We performed single-cell transcriptome and T-cell/B-cell receptor (TCR/BCR) sequencing in 37 longitudinal collected peripheral blood mononuclear cell samples from asymptomatic, moderate, and severe patients with healthy controls. Asymptomatic patients displayed increased CD56briCD16- natural killer (NK) cells and upregulation of interferon-gamma in effector CD4+ and CD8+ T cells and NK cells. They showed more robust TCR clonal expansion, especially in effector CD4+ T cells, but lack strong BCR clonal expansion compared to moderate patients. Moreover, asymptomatic patients have lower interferon-stimulated genes (ISGs) expression in general but large interpatient variability, whereas moderate patients showed various magnitude and temporal dynamics of the ISGs expression across multiple cell populations but lower than a patient with severe disease. Our data provide evidence of different immune signatures to SARS-CoV-2 in asymptomatic infections.

A digital single-molecule nanopillar SERS platform for predicting and monitoring immune toxicities in immunotherapy.

The introduction of immune checkpoint inhibitors has demonstrated significant improvements in survival for subsets of cancer patients. However, they carry significant and sometimes life-threatening toxicities. Prompt prediction and monitoring of immune toxicities have the potential to maximise the benefits of immune checkpoint therapy. Herein, we develop a digital nanopillar SERS platform that achieves real-time single cytokine counting and enables dynamic tracking of immune toxicities in cancer patients receiving immune checkpoint inhibitor treatment - broader applications are anticipated in other disease indications. By analysing four prospective cytokine biomarkers that initiate inflammatory responses, the digital nanopillar SERS assay achieves both highly specific and highly sensitive cytokine detection down to attomolar level. Significantly, we report the capability of the assay to longitudinally monitor 10 melanoma patients during immune inhibitor blockade treatment. Here, we show that elevated cytokine concentrations predict for higher risk of developing severe immune toxicities in our pilot cohort of patients.

Serum IP-10 and IL-7 levels are associated with disease severity of coronavirus disease 2019.

We quantified the serum levels of 34 cytokines/chemokines in 30 patients with SARS-CoV-2 infection. Elevated levels of IP-10 and IL-7 were detected in the acute and convalescent stages of the infection and were highly associated with disease severity.

The immunodominant and neutralization linear epitopes for SARS-CoV-2.

Although vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are under development, the antigen epitopes on the virus and their immunogenicity are poorly understood. Here, we simulate the 3D structures and predict the B cell epitopes on the spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins of SARS-CoV-2 using structure-based approaches and validate epitope immunogenicity by immunizing mice. Almost all 33 predicted epitopes effectively induce antibody production, six of these are immunodominant epitopes in individuals, and 23 are conserved within SARS-CoV-2, SARS-CoV, and bat coronavirus RaTG13. We find that the immunodominant epitopes of individuals with domestic (China) SARS-CoV-2 are different from those of individuals with imported (Europe) SARS-CoV-2, which may be caused by mutations on the S (G614D) and N proteins. Importantly, we find several epitopes on the S protein that elicit neutralizing antibodies against D614 and G614 SARS-CoV-2, which can contribute to vaccine design against coronaviruses.

The clinical feature and imaging analysis of patients with new coronavirus infection in Shijiazhuang

Objective: To investigate clinical features and imaging manifestation of patients with the COVID-19 infection in Shijiazhuang.