Diagnostic Virology Group, ICMR-National Institute of Virology, Pune, Maharashtra, India.
Dengue and Chikungunya Group, ICMR-National Institute of Virology, Pune, Maharashtra, India.
Indian J Med Res. 2022 May-Jun;155(5&6):565-569. doi: 10.4103/ijmr.IJMR_675_21.
BACKGROUND & OBJECTIVES: The pandemic caused by the SARS-CoV-2 has been a threat to humankind due to the rapid spread of infection and appearance of multiple new variants. In the present study, we report the dynamics and persistence of immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies in asymptomatic and symptomatic COVID-19 patients by chemiluminescent assay.
A total of 463 serum samples from 218 SARS-CoV-2 PCR-positive patients were collected over a period of 124 days post-onset of disease (POD). Antibody levels were measured by chemiluminescence bioanalyzer. Neutralizing antibody titres were assessed by plaque reduction neutralization test (PRNT) for SARS-CoV-2.
Both IgM and IgG started appearing from day five post-infection in symptomatic and asymptomatic patients. IgM antibody response peaked around day 35 POD and rapidly diminished thereafter, with the last IgM-positive sample observed at 90 days POD. IgG antibody response peaked around 45 days POD and persisted till 124 days. The chemiluminescence immunoassay (CLIA) results showed a moderate correlation (R=0.5846, P<0.001) compared with PRNT. Additional analysis indicated a neutralizing titre of 250 corresponded to 12.948 AU/ml of YHLO iFlash SARS-CoV-2 IgG units.
INTERPRETATION & CONCLUSIONS: Both symptomatic and asymptomatic COVID-19 patients seem to initiate production of antibody responses from day five of onset of disease. Although the CLIA gives high sensitivity and specificity and also its binding IgG antibody titres may correlate moderately with protective immunity, our results indicate that the values of binding antibody alone may not be a perfect guide to represent virus neutralization titre during donor selection for plasma therapy. However, IgM and IgG antibody detection may help in monitoring the status of disease progression and burden in the community.
由 SARS-CoV-2 引起的大流行对人类构成了威胁，因为其感染迅速传播，并出现了多种新变种。在本研究中，我们通过化学发光法报告了无症状和有症状 COVID-19 患者中免疫球蛋白 G（IgG）和免疫球蛋白 M（IgM）抗体的动态变化和持久性。
共收集了 218 例 SARS-CoV-2 PCR 阳性患者的 463 份血清样本，这些样本是在发病后 124 天内采集的。通过化学发光生物分析仪测量抗体水平。通过 SARS-CoV-2 蚀斑减少中和试验（PRNT）评估中和抗体滴度。
有症状和无症状患者均从感染后第五天开始出现 IgM 和 IgG。IgM 抗体反应在发病后第 35 天达到峰值，此后迅速下降，最后一个 IgM 阳性样本出现在发病后第 90 天。IgG 抗体反应在发病后第 45 天达到峰值，并持续到第 124 天。化学发光免疫分析（CLIA）结果与 PRNT 相比显示出中度相关性（R=0.5846，P<0.001）。进一步分析表明，中和效价为 250 时相当于 YHLO iFlash SARS-CoV-2 IgG 单位的 12.948 AU/ml。
有症状和无症状 COVID-19 患者似乎在发病后第五天开始产生抗体反应。虽然 CLIA 具有高灵敏度和特异性，并且其结合 IgG 抗体滴度与保护性免疫可能呈中度相关，但我们的结果表明，单独的结合抗体值可能无法成为代表血浆治疗中供体选择时病毒中和效价的完美指标。然而，IgM 和 IgG 抗体检测可能有助于监测疾病进展和社区中疾病负担的状况。
