Background We aim to investigate the profile of acute antibody response in COVID-19 patients, and provide proposals for the usage of antibody test in clinical practice.Methods A multi-center cross-section study (285 patients) and a single-center follow-up study (63 patients) were performed to investigate the feature of acute antibody response to SARS-CoV-2. A cohort of 52 COVID-19 suspects and 64 close contacts were enrolled to evaluate the potentiality of the antibody test. ResultsThe positive rate for IgG reached 100% around 20 days after symptoms onset.The median day of seroconversion for both lgG and IgM was 13 days after symptoms onset. Seroconversion of IgM occurred at the same time, or earlier, or later than that of IgG. IgG levels in 100% patients (19/19) entered a platform within 6 days after seroconversion. The criteria of "IgG seroconversion" and "≥ 4-fold increase in the IgG titers in sequential samples" together diagnosed 82.9% (34/41) of the patients.Antibody test aided to confirm 4 patients with COVID-19 from 52 suspects who failed to be confirmed by RT-PCR and 7 patients from 148 close contacts with negative RT-PCR. ConclusionIgM and IgG should be detected simultaneously at the early phase of infection. The serological diagnosis criterion of seroconversion or the "≥ 4-fold increase in the IgG titer" is suitable for a majority of COVID-19 patients. Serologic test is helpful for the diagnosis of SARS-CoV-2 infection in suspects and close contacts.
SARS-CoV-2, a novel ß-coronavirus, cause severe pneumonia and has spread throughout the globe rapidly. The disease associated with SARS-CoV-2 infection is named COVID-19. To date, real-time RT-PCR is the only test able to confirm this infection. However, the accuracy of RT-PCR depends on several factors; variations in these factors might significantly lower the sensitivity of detection. Here, we developed a peptide-based luminescent immunoassay that detected immunoglobulin G (IgG) and IgM. The assay cut-off value was determined by evaluating the sera from healthy and infected patients for pathogens other than SARS-CoV-2. To evaluate assay performance, we detected IgG and IgM in the sera from confirmed patients. The positive rate of IgG and IgM was 71.4% and 57.2%, respectively. Therefore, combining our immunoassay with real-time RT-PCR might enhance the diagnostic accuracy of COVID-19.
A respiratory illness has been spreading rapidly in China, since its outbreak in Wuhan city, Hubei province in December 2019. The illness was caused by a novel coronavirus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Clinical manifestations related to SARS-CoV-2 infection ranged from no symptom to fatal pneumonia. World Health Organization (WHO) named the diseases associated with SARS-CoV-2 infection as COVID-19. Real time RT-PCR is the only laboratory test available till now to confirm the infection. However, the accuracy of real time RT-PCR depends on many factors, including sampling location and of methods, quality of RNA extraction and training of operators etc. Variations in these factors might significantly lower the sensitivity of the detection. We developed a peptide-based luminescent immunoassay to detect IgG and IgM. Cut-off value of this assay was determined by the detection of 200 healthy sera and 167 sera from patients infected with other pathogens than SARS-CoV-2. To evaluate the performance of this assay, we detected IgG and IgM in the 276 sera from confirmed patients. The positive rate of IgG and IgM were 71.4% (197/276) and 57.2% (158/276) respectively. By combining with real time RT-PCR detection, this assay might help to enhance the accuracy of diagnosis of SARS-CoV-2 infection.
Background Insulin sensitivity and inflammation can be affected by juxtaposition with another zinc finger gene 1 ( JAZF1 ), but its precise role in chronic inflammation is unclear. In this study, JAZF1 -overexpression adenovirus plasmids were transfected into macrophages, CD4 + T cells, and C57BL/6J mice to assess the role of JAZF1 in chronic inflammation. Material/Methods JAZF1 was cloned into an adenovirus skeleton plasmid and transfected in HEK293 cells to package and enrich the virus particles. In vitro , the JAZF1 overexpression adenovirus vector (PAD-JAZF1) was cultured with peritoneal macrophages and peripheral blood CD4 + T cells of C57BL/6J mice, and samples were evaluated using flow cytometry. In vivo , PAD-JAZF1 was introduced into C57BL/6J mice, and livers were collected to evaluate factors related to inflammation by hematoxylin & eosin and immunohistochemical staining. Results In vitro , PAD-JAZF1 decreased total macrophages, CD11c + macrophages, and the secretion of proinflammatory cytokines, but increased CD206 + macrophages. It also decreased total CD4 + T cells, active T cells, memory T cells, and the secretion of IL-6, IL-10, and IFN-γ, but increased Treg cells and restrictive T cells. In vivo , compared to those in the control group transfected with the adenovirus skeleton vector, mice transfected with the PAD-JAZF1 recombinant adenovirus had fewer CD11c + ATMs and CD4 + T cells, lower levels of TNF-α and IL-6, and higher IL-10 concentrations in the liver. Conclusions These findings indicate that JAZF1 limits chronic inflammation by reducing macrophage and CD4 + T cell populations, altering subtype differentiation, and regulating the secretion of immune-related factors.
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