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ObjectiveTo investigate the performance of serological test and dynamics of serum antibody with the progress of SARS-CoV-2 infections. MethodsA total of 419 patients were enrolled including 19 confirmed cases and 400 patients from fever clinics. Their serial serum samples collected during the hospitalization were menstruated for IgM and IgG against SARS-CoV-2 using gold immunochromatographic assay and chemiluminescence immunoassay. We investigated whether thermal inactivation could affect the results of antibody detection. The dynamics of antibodies with the disease progress and false positive factors for antibody testing were also analyzed. ResultsThe positive rate of IgG detection was 91.67% and 83.33% using two CLIA, respectively. However, the IgM positive rate was dramatically declined might due to the lack of blood samples at early stages of the disease. The chemiluminescence immunoassay had a favorable but narrow linear range. Our work showed increased IgG values in serums from virus-negative patients and four negative samples were IgG weak-positive after thermal incubation. Our data showed the specificity of viral N+S proteins was higher than single antigen. Unlike generally thought that IgM appeared earlier than IgG, there is no certain chronological order of IgM and IgG seroconversion in COVID-19 patients. It was difficult to detect antibodies in asymptomatic patients suggesting that their low viral loads were not enough to cause immune response. Analysis of common interferent in three IgG false-positive patients, such as rheumatoid factor, proved that false positives were not caused by these interfering substances and antigenic cross-reaction. ConclusionsViral serological test is an effective means for SARS-CoV-2 infect detection using both chemiluminescence immunoassay and gold immunochromatographic assay. Chemiluminescence immunoassay against multi-antigens has obvious advantages but still need improve in reducing false positives.
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Objective@#To investigate the expression levels of serum miR-638 in the patients with breast cancer and its clinical value. @*Methods@#One hundred and fifty-two patients with breast cancer were selected as the disease group, and 102 healthy persons as the control group. The expression levels of miR-638 in their serum samples were detected by the quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and the expression levels of serum miR-638 in the patients with different pathological stages, before and after operation, and before and after chemotherapy were compared. The diagnosis efficacy of serum miR-638 alone and in combination with CEA, CA125, CA15-3 for breast cancer was analyzed by the ROC curve and Z test. @*Results@#The expression levels of serum miR-638 in the breast cancer group (3.6 [1.3～10.5]) were significantly lower than that in the control group (79.0 [52.5～120.8],P＜0.01). The linear regression analysis showed that chemotherapy and pathological staging were the main factors influencing the expression levels of serum miR-638. The area under the ROC curve (AUC ROC ) of serum miR-638 in the diagnosis of breast cancer was 0.954. When the cut-off value of serum miR-638 was 27.47, its sensitivity and specificity for the diagnosis of breast cancer were 94% and 86.2%, respectively. The area under the ROC curve (AUC ROC ) of serum miR-638 combined with CEA, CA125 and CA15-3 in the diagnosis of breast cancer was 0.978 8. When the combined cut-off value was 0.29, their sensitivity and specificity for the diagnosis of breast cancer were 95.4% and 89.5%, respectively. There was no significant difference in the AUC ROC between miR-638 alone and combined screening (Z=1.68,P=0.091). @*Conclusion@#Serum miR-638 may be a potential molecular marker for the screening of breast cancer.
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The sodium hydrogen exchanger 1 (NHE1), which functions in maintaining the ratio of Na+ and H+ ions, is widely distributed in cell plasma membranes. It plays a prominent role in pH balancing, cell proliferation, differentiation, adhesion, and migration. However, its exact subcellular location and biological functions in Toxoplasma gondii are largely unclear. In this study, we cloned the C-terminal sequence of T. gondii NHE1 (TgNHE1) incorporating the C-terminal peptide of NHE1 (C-NHE1) into the pGEX4T-1 expression plasmid. The peptide sequence was predicted to have good antigenicity based on the information obtained from an immune epitope database. After induction of heterologous gene expression with isopropyl-b-D-thiogalactoside, the recombinant C-NHE1 protein successfully expressed in a soluble form was purified by glutathione sepharose beads as an immunogen for production of a rabbit polyclonal antiserum. The specificity of this antiserum was confirmed by western blotting and immunofluorescence. The antiserum could reduce T. gondii invasion into host cells, indicated by the decreased TgNHE1 expression in T. gondii parasites that were pre-incubated with antiserum in the process of cell entry. Furthermore, the antiserum reduced the virulence of T. gondii parasites to host cells in vitro, possibly by blocking the release of Ca2+. In this regard, this antiserum has potential to be a valuable tool for further studies of TgNHE1.
