[Effect of heat inactivation of blood samples on the efficacy of three detection methods of SARS-CoV-2 antibodies]

Study on the Effect and Application Value of Heat-Inactivated Serum on the Detection of Thyroid Function, Tumor Markers, and Cytokines During the SARS-CoV-2 Pandemic

Purpose: The current explored the impact of heat inactivation of blood samples on the results of a particular clinical test and its potential application value during the SARS-CoV-2 pandemic. We have aimed at providing a reference for clinical testing methods during the pandemic. Methods: Blood samples were selected from our department's routine clinical examination between January 2021 and June 2021. The levels of these samples for quantitative detection of these indicators in each group (n = 90 cases/group) covered normal reference ranges and medically determined levels. For qualitative testing of the indicators, the specimens were additionally classified as negative, weakly positive, and positive (n = 20 cases/group). The specimens were then inactivated, and the differences in relevant indicators before and after inactivation were evaluated. Results: A statistically significant difference was evident between the levels of TSH, T3, FT4, FT3, AFP, NSE, CYFRA211, IRI, IL-1β, IL-6, IL-8, IL-10, IL-2R, and TNF-α in the non-inactivated group 1 and the inactivated group 1 (P < 0.05). Among them, there was a strong correlation between TSH, T3, FT4, FT3, CYFRA211, IRI, IL-1β, IL-6, IL-8, and IL-2R levels in the two groups (P < 0.05), however, there was no correlation between AFP (P = 0.256) and NSE (P = 0.352) levels between the two groups (P > 0.05). The detected values of low-level AFP (<4 ng/mL), IL-10, and TNF-α after inactivation were all lower than the detection limit. There was not any statistically significant difference in the levels of tumor markers, such as CEA, CA125, CA724, CA199, CA153, and the quantitative levels of T4, Vit. D, HCG, CPS, and five items of hepatitis B virus (P > 0.05). The positive rate of anti-nuclear antibodies after inactivation was not statistically different from the ones observed before inactivation (P > 0.05). Upon correction by the regression equation, the observed levels of TSH, T3, FT4, FT3, CYFRA211, IRI, IL-1β, IL-6, IL-8, and IL-2R were not significantly different from those before inactivation (P > 0.05). Conclusion: The heat inactivation of blood samples had different various effects on different test indicators, and some indicators could be corrected by employing regression equations. This detection method could potentially be employed during the SARS-CoV-2 pandemic, thereby effectively preventing iatrogenic infections.

Potential False-Positive and False-Negative Results for COVID-19 IgG/IgM Antibody Testing After Heat-Inactivation

Objectives: With the worldwide spread of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), various antibody detection kits have been developed to test for SARS-CoV-2– specific IgG, IgM, and total antibody. However, the use of different testing methods under various heat-inactivation conditions might affect the COVID-19 detection results.

Methods: Seven different antibody detection kits produced by four manufacturers for detection of SARS-CoV-2 IgG, IgM, and total antibody were tested at Wuhan Huoshenshan Hospital, China. Most of the kits used the indirect immunity, capture, and double-antigen sandwich methods. The effects of various heat-inactivation conditions on SARS-CoV-2-specific IgG, IgM, and total antibody detection were analyzed for the different test methods.

Results: Using the indirect immunity method, values for SARS-CoV-2 IgG antibody significantly increased and those for IgM antibody decreased with increasing temperature of heat-inactivation using indirect immunity method. However, values for SARS-CoV-2 IgM and total antibody showed no change when the capture and double-antigen sandwich methods were used. The changes in IgG and IgM antibody values with the indirect immunity method indicated that heat-inactivation could affect COVID-19 detection results obtained using this method. In particular, 18 (22.2%) SARS-CoV-2 IgM positive samples were detected as negative with heat-inactivation at 65°C for 30 min, and one (25%) IgG negative sample was detected as positive after heat-inactivation at 56°C for 60 min and 60°C for 30 min.

Conclusions: Heat-inactivation could increase SARS-CoV-2 IgG antibody values, and decrease IgM antibody values, causing potential false-positive or false-negative results for COVID-19 antibody detection using the indirect immunity method. Thus, before conducting antibody testing, the testing platforms should be evaluated in accordance with the relevant requirements to ensure accurate COVID-19 detection results.

Comparison of Five Serological Assays for the Detection of SARS-CoV-2 Antibodies

Serological assays can contribute to the estimation of population proportions with previous immunologically relevant contact with the Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) virus. In this study, we compared five commercially available diagnostic assays for the diagnostic identification of SARS-CoV-2-specific antibodies. Depending on the assessed immunoglobulin subclass, recorded sensitivity ranged from 17.0% to 81.9% with best results for immunoglobulin G. Specificity with blood donor sera ranged from 90.2% to 100%, with sera from EBV patients it ranged from 84.3% to 100%. Agreement from fair to nearly perfect was recorded depending on the immunoglobulin class between the assays, the with best results being found for immunoglobulin G. Only for this immunoglobulin class was the association between later sample acquisition times (about three weeks after first positive PCR results) and positive serological results in COVID-19 patients confirmed. In conclusion, acceptable and comparable reliability for the assessed immunoglobulin G-specific assays could be shown, while there is still room for improvement regarding the reliability of the assays targeting the other immunoglobulin classes.

Approaches towards fighting the COVID‑19 pandemic (Review)

The coronavirus disease 2019 (COVID‑19) outbreak, which has caused >46 millions confirmed infections and >1.2 million coronavirus related deaths, is one of the most devastating worldwide crises in recent years. Infection with COVID‑19 results in a fever, dry cough, general fatigue, respiratory symptoms, diarrhoea and a sore throat, similar to those of acute respiratory distress syndrome. The causative agent of COVID‑19, SARS‑CoV‑2, is a novel coronavirus strain. To date, remdesivir has been granted emergency use authorization for use in the management of infection. Additionally, several efficient diagnostic tools are being actively developed, and novel drugs and vaccines are being evaluated for their efficacy as therapeutic agents against COVID‑19, or in the prevention of infection. The present review highlights the prevalent clinical manifestations of COVID‑19, characterizes the SARS‑CoV‑2 viral genome sequence and life cycle, highlights the optimal methods for preventing viral transmission, and discusses possible molecular pharmacological mechanisms and approaches in the development of anti‑SARS‑CoV‑2 therapeutic agents. In addition, the use of traditional Chinese medicines for management of COVID‑19 is discussed. It is expected that novel anti‑viral agents, vaccines or an effective combination therapy for treatment/management of SARS‑CoV‑2 infection and spread therapy will be developed and implemented in 2021, and we would like to extend our best regards to the frontline health workers across the world in their fight against COVID‑19.

A high-throughput Anti-SARS-CoV-2 IgG testing platform for COVID-19

BACKGROUND

Serology tests for detecting the antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can identify previous infection and help to confirm the presence of current infection.

OBJECTIVE

The aim of this study was to evaluate the performances of a newly developed high throughput immunoassay for anti-SARS-CoV-2 IgG antibody detection.

RESULTS

Clinical agreement studies were performed in 107 COVID-19 patient serum samples and 226 negative donor serum/plasma samples. Positive percent agreement (PPA) was 46.15 % (95 % CI: 19.22 % ∼74.87 %), 61.54 % (95 % CI: 31.58 % ∼86.14 %), and 97.53 % (95 % CI: 91.36 % ∼99.70 %) for samples collected on 0-7 days, 8-14 days, and ≥15 days from symptom onset, respectively. Negative Percent Agreement (NPA) was 98.23 % (95 % CI: 95.53 % ∼99.52 %). No cross-reactivity was observed to patient samples positive for IgG antibodies against the following pathogens: HIV, HAV, HBV, RSV, CMV, EBV, Rubella, Influenza A, and Influenza B. Hemoglobin (200 mg/dL), bilirubin (2 mg/dL) and EDTA (10 mM) showed no significant interfering effect on this assay.

CONCLUSION

An anti-SARS-CoV-2 IgG antibody assay with high sensitivity and specificity has been developed. With the high throughput, this assay will speed up anti-SARS-CoV-2 IgG testing.

Preliminary Analysis of B- and T-Cell Responses to SARS-CoV-2

BACKGROUND AND OBJECTIVE

Without a specific antiviral treatment or vaccine, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic, affecting over 200 countries worldwide. A better understanding of B- and T-cell immunity is critical to the diagnosis, treatment and prevention of coronavirus disease 2019 (COVID-19).

METHODS

A cohort of 129 patients with COVID-19 and 20 suspected cases were enrolled in this study, and a lateral flow immunochromatographic assay (LFIA) and a magnetic chemiluminescence enzyme immunoassay (MCLIA) were evaluated for SARS-CoV-2 IgM/IgG detection. Additionally, 127 patients with COVID-19 were selected for the detection of IgM and IgG antibodies to SARS-CoV-2 to evaluate B-cell immunity, and peripheral blood lymphocyte subsets were quantified in 95 patients with COVID-19 to evaluate T-cell immunity.

RESULTS

The sensitivity and specificity of LFIA-IgM/IgG and MCLIA-IgM/IgG assays for detecting SARS-CoV infection were > 90%, comparable with reverse transcription polymerase chain reaction detection. IgM antibody levels peaked on day 13 and began to fall on day 21, while IgG antibody levels peaked on day 17 and were maintained until tracking ended. Lymphocyte and subset enumeration suggested that lymphocytopenia occurred in patients with COVID-19.

CONCLUSIONS

LFIA-IgM/IgG and MCLIA-IgM/IgG assays can indicate SARS-CoV-2 infection, which elicits an antibody response. Lymphocytopenia occurs in patients with COVID-19, which possibly weakens the T-cell response.

Anti-SARS-CoV-2 hyperimmune plasma workflow

Coronavirus disease 2019 (COVID-19) caused by the novel coronavirus has become a Public Health Emergency of International Concern. Among the various treatment proposals for COVID-19 infection, passive immunotherapy using plasma from recovering patients - "convalescent plasma" (CP)- could be a promising option in the treatment of SARS-CoV-2 infections. Immune (i.e. "convalescent") plasma refers to plasma that is collected from individuals, following resolution of infection and development of antibodies. Passive antibody administration through transfusion of convalescent plasma may offer the only short-term strategy to confer immediate immunity to susceptible individuals. According to the World Health Organization (WHO), the use of plasma therapy is permitted when faced with «serious diseases for which there are no effective pharmacological treatments». Several clinical trials are underway to test the effectiveness of hyperimmune plasma at various stages of SARS-CoV2.The Food and Drug Administration (FDA), the U.S. regulatory authority, has approved the use of CP for compassionate use in the treatment of patients with a critical COVID-19 infection. Below are the general indications for drawing up clinical protocols for the integral management of "COVID-19-convalescent plasma" for which the validation and approval of the Ethics Committees is still necessary.