Dynamic changes of IgM and IgG antibodies in asymptomatic patients as an effective way to detect SARS-CoV-2 infection.

BACKGROUND: COVID-19 has become a global pandemic, and close contacts and asymptomatic patients are worthy of attention. METHODS: A total of 1844 people in close contacts with 76 COVID-19 patients were investigated, and nasopharyngeal swabs and venous blood were collected for centralized medical quarantine observation. Real-time fluorescence was used to detect SARS-CoV-2 nucleic acid in nasopharyngeal swabs of all close contacts, and the colloidal gold method was used to detect serum-specific antibodies. Levels of IgM- and IgG-specific antibodies were detected quantitatively through chemiluminescence from the first nucleic acid turned negative date (0 week) and on weekly intervals of ≤1 week, 1-2 weeks, 2-3 weeks, 3-4 weeks, 4-5 weeks, 5-6 weeks, and 6-7 weeks. RESULTS: The total positive rate of the colloidal gold method (88.5%, 23/26) was significantly higher (χ2  = 59.182, p < 0.001) than that of the healthy control group (2.0%, 1/50). There was significant difference in IgG concentration at different time points (0-7 weeks) after negative nucleic acid conversion (χ2  = 14.034, p = 0.029). Serum IgG levels were significantly higher at weekly time points of 4-5 weeks (Z = -2.399, p = 0.016), 5-6 weeks (Z = -2.049, p = 0.040), and 6-7 weeks (Z = -2.197, p = 0.028) compared with 1-2 weeks after negative nucleic acid conversion. However, there was no significant difference (χ2  = 4.936, p = 0.552) in IgM concentration between time points tested (0-7 weeks) after negative nucleic acid conversion. The positive rates of IgM and IgG in asymptomatic patients (χ2  = 84.660, p < 0.001) were significantly higher than those in the healthy control group (χ2  = 9.201, p = 0.002) within 7 weeks of negative nucleic acid conversion. CONCLUSIONS: The IgG concentration in asymptomatic cases remained at a high level after nucleic acid turned negative. Nucleic acid detection combined with IgM and IgG antibody detection is an effective way to screen asymptomatic infections.

Changes of serum IL-10, IL-1ß, IL-6, MCP-1, TNF-α, IP-10 and IL-4 in COVID-19 patients.

BACKGROUND AND PURPOSE: Studies have shown that some cytokines in COVID-19 patients were elevated. This study aims to assess whether IL-10, IL-1ß, IL-6, MCP-1, TNF-α, IP-10 and IL-4 serve as potential diagnostic biomarkers of COVID-19. METHODS: The above serum cytokines in COVID-19 patients and non-COVID-19 patients were detected by ELISA and SARS-CoV-2 IgM and IgG were detected by the chemiluminescence method. The independent-sample Mann-Whitney U test was utilised to compare cytokine levels in different groups and courses, the Levene T-test and T'-test were utilised to compare they in different genders and the Spearman correlation test was utilised to analyse the correlation between the cytokine levels with ages and SARS-CoV-2 IgG and IgM. RESULTS: Serum levels of IL-10, IL-1ß, MCP-1, TNF-α and IL-4 in COVID-19 patients were significantly higher than those in non-COVID-19 patients, while IL-6 were only significantly higher than in healthy people, IP-10 were significantly lower than in other diseases patients. AUCs of COVID-19 diagnosed by IL-10, IL-1ß, IL-6, MCP-1, TNF-α, IP-10 and IL-4 were 0.735, 0.775, 0.595, 0.821, 0.848, 0.38 and 0.682, respectively. In the COVID-19 patients' serum, the levels of IL-10 and MCP-1 of male were noticeably higher than those of female, and all cytokines were significantly positively correlated with age, IL-1ß and IL-4 were significantly negatively correlated with SARS-CoV-2 IgM, while IL-10, IL-1ß, IL-6, TNF- and IP-10 were significantly negatively correlated with SARS-CoV-2 IgG. IL-10 on 43-56 days was significantly lower than at 29-42 days, TNF-α at 15-42 days was significantly higher than at 0-14 days, IP-10 at 0-14 days was the highest and IL-4 at 29-42 days was significantly higher than at 0-14 days. CONCLUSIONS: The detection of IL-10, IL-1 ß, IL-6, MCP-1, TNF-α and IL-4 would assist the clinical study of COVID-19, and IP-10 may be the cytokine of early elevation in COVID-19 patients.

Matrix metalloproteinase 3 as a valuable marker for patients with COVID-19.

The situation of the coronavirus disease 2019 (COVID-19) continues to evolve, our study explored the significance of serum levels of matrix metalloproteinase 3 (MMP3) as a marker for patients with COVID-19. Sixty-two COVID-19 patients in the First Hospital of Hunan University of Chinese Medicine and Loudi Center for Diseases Prevention and Control, from January to March 2020, were sampled as the novel coronavirus pneumonia infected group. One hundred and thirty-one cases from the First Hospital of Hunan University of Chinese Medicine, including 67 healthy individuals and 64 non-COVID-19 inpatients, served as the noninfected group. Approximately every 5 days, sera from 20 cases were collected and analyzed three times, using an automatic biochemical analyzer, to detect serum MMP3 concentrations. Correlation was analyzed between MMP3 and other proinflammatory cytokines. Following normality tests, differences in serum MMP3 levels between the infected and noninfected group were analyzed via SPSS (version 25.0) software, using the Wilcoxon rank sum test. The MMP3 concentration was 44.44 (23.46 ~ 72.12) ng/mL in the infected group and 32.42 (28.16 ~ 41.21) ng/mL in the noninfected group. The difference between the two groups was statistically significant (Z = -2.799, P = .005 < .05). A positive correlation was found between MMP3 and interleukin 1ß (IL-1ß; r = .681, P = .000 < .05), and IL-6 (r = .529, P = .002 < .05). Serum MMP3 concentration, measured over three separate time points, were 55.98 (30.80 ~ 75.97) ng/mL, 34.84 (0.00 ~ 51.84) ng/mL, and 5.71 (0.00 ~ 40.46) ng/mL, respectively. Detection of serum MMP3 levels may play an important role in the development of therapeutic approaches for COVID-19 and may indicate the severity of disease.