Ayhancı Tuğba, Toptan Hande, Özer Yunus Emre, Uzar Serdar, Enül Hakan, Adıay Cumhur, Sarac Fahriye, Dheir Hamad, Köroğlu Mehmet, Hasöksüz Mustafa, Altındiş Mustafa
Sakarya University Faculty of Medicine, Department of Medical Microbiology, Sakarya, Türkiye.
Ministry of Health Sakarya University Training and Research Hospital, Medical Microbiology Laboratory, Sakarya, Türkiye.
Mikrobiyol Bul. 2022 Jul;56(3):416-431. doi: 10.5578/mb.20229704.
The coronavirus disease 2019 (COVID-19) turned into a pandemic shortly after emerging in December 2019, in the city of Wuhan, China. In this study, it was aimed to investigate the presence of severe acute respiratory system coronavirus-2 (SARS-CoV-2) RNA in various clinical samples and the scattering profile of the virus and the variation of anti-SARS-CoV-2 IgG and neutralizing antibody levels over time in infected patients during and after the period of COVID-19 disease. The study included COVID-19 patients from the community (CCP) (n= 47) (May-June 2020) and healthcare workers (HCWP) (n= 30) (November-December 2020). To investigate the presence of SARS-CoV-2 in clinical samples, oropharynx (OF), nasopharynx (NF), sputum, stool, blood and urine samples were taken from the CCP group on days 0, 3, 7, 14 and 28. For the detection of anti SARS-CoV-2 IgG and neutralizing antibodies serum samples were taken from the CCP group on days 0, 3, 7, 14, 28, 60, 90 and 120 and on days 14, 28, 60, 90, 120 and 150 from HCWP group. Virus RNA was detected by reverse transcription polymerase chain reaction (RT-PCR), anti SARS-CoV-2 IgG antibody levels by enzyme-linked immunosorbent assay (ELISA), neutralizing antibody levels (NAb) by cell culture neutralization and representative neutralization test (sVNT) methods. With the onset of the vaccination program in our country, 11 of the HCWP group patients had SARS-CoV-2 vaccine after the second month serum samples were taken, the remaining HCWP group patients did not get vaccinated during the study period. SARS-CoV-2 RNA was detected with the highest rates in NF (100%), stool (65.8%), sputum (45.7%), OF (41.3%), blood (5.3%), and urine (2.2%) samples, respectively. It was found that viral shedding continued for 14 days in respiratory tract samples and up to 60 days in stool samples, and no virus was detected in blood samples after the third day. It was observed that the viral load was highest at the time of diagnosis in both upper and lower respiratory tract samples, peaking on the seventh day in stool samples and following an irregular course throughout the disease. Anti-SARS-CoV-2 IgG antibody positivity was found in 41.4% of CCP group patients on the first day of diagnosis, and seroconversion was observed in all patients at the fourth month. During the study period, seropositivity was detected in only 82.1% of the patients in the HCWP group. It was observed that the IgG antibody levels peaked at the 7th day in the CCP group patients and at the third month in the HCWP group patients (S/Co: 9.6 and 2.8, respectively). Anti-SARS-CoV-2 IgG antibody levels detected in the CCP group were found to be significantly higher than the HCWP group (p<0.05). At the end of the first month, NAb was detected in all (100%) patients in the CCP group. It was found that NAb titers peaked (1/256) on the 28th day and showed a decreasing trend from the second month. NAb median titers were observed to peak earlier in the severe HCWP group (14 days in the severe group, 28 days in the mild group, p> 0.05). It was observed that 6 (26.1%) of HCWP group patients had low, 11 (47.8%) moderate, 6 (26.1%) high titers of representative NAb. The distribution of representative NAb levels by vaccine status was examined and no statistically significant difference was found (p= 0.400, p= 0.077 and p= 0.830, respectively). As a result; SARS-CoV-2 RNA was detected in many samples such as sputum, stool, blood and urine, and it was observed that viral shedding in stool samples could continue for months. Anti-SARS-CoV-2 IgG antibody positivity was observed in most of the patients in the fourth month, and it was found that the antibody titers decreased after the third month. It was determined that protective antibody levels continued in the fourth month. These findings are important in vaccination strategies and in the fight against the pandemic. However, considering the emergence of new mutant forms of the virus in today's conditions where the pandemic continues, more detailed and comprehensive studies are needed for viral shedding and antibody titer studies.
2019年12月在中国武汉市出现后不久，新型冠状病毒肺炎（COVID-19）便演变成了一场大流行病。在本研究中，旨在调查各种临床样本中严重急性呼吸系统冠状病毒2（SARS-CoV-2）RNA的存在情况、病毒的传播情况以及COVID-19疾病期间及之后感染患者体内抗SARS-CoV-2 IgG和中和抗体水平随时间的变化。该研究纳入了社区COVID-19患者（CCP）（n = 47）（2020年5月至6月）和医护人员（HCWP）（n = 30）（2020年11月至12月）。为了调查临床样本中SARS-CoV-2的存在情况，在第0、3、7、14和28天从CCP组采集口咽（OF）、鼻咽（NF）、痰液、粪便、血液和尿液样本。为了检测抗SARS-CoV-2 IgG和中和抗体，在第0、3、7、14、28、60、90和120天从CCP组采集血清样本，并在第14、28、60、90、120和150天从HCWP组采集血清样本。通过逆转录聚合酶链反应（RT-PCR）检测病毒RNA，通过酶联免疫吸附测定（ELISA）检测抗SARS-CoV-2 IgG抗体水平，通过细胞培养中和及代表性中和试验（sVNT）方法检测中和抗体水平（NAb）。在我国开始实施疫苗接种计划后，HCWP组中的11名患者在采集第二个月血清样本后接种了SARS-CoV-2疫苗，其余HCWP组患者在研究期间未接种疫苗。SARS-CoV-2 RNA在NF（100%）、粪便（65.8%）、痰液（45.7%）、OF（41.3%）、血液（5.3%）和尿液（2.2%）样本中的检测率最高。发现呼吸道样本中的病毒脱落持续14天，粪便样本中长达60天，第三天后血液样本中未检测到病毒。观察到上下呼吸道样本在诊断时病毒载量最高，粪便样本在第7天达到峰值，并且在整个疾病过程中呈不规则变化。CCP组患者在诊断第一天抗SARS-CoV-2 IgG抗体阳性率为41.4%，所有患者在第四个月出现血清转化。在研究期间，HCWP组中仅82.1%的患者检测到血清阳性。观察到CCP组患者的IgG抗体水平在第7天达到峰值，HCWP组患者在第三个月达到峰值（S/Co分别为9.6和2.8）。发现CCP组检测到的抗SARS-CoV-2 IgG抗体水平显著高于HCWP组（p<0.05）。在第一个月末，CCP组所有（100%）患者检测到NAb。发现NAb滴度在第28天达到峰值（1/256），从第二个月开始呈下降趋势。观察到严重HCWP组中NAb中位数滴度峰值出现得更早（严重组为14天，轻症组为28天，p>0.05）。观察到HCWP组中有6名（26.1%）患者的代表性NAb滴度低，11名（47.8%）患者的滴度中等，6名（26.1%）患者的滴度高。检查了按疫苗接种状态划分的代表性NAb水平分布，未发现统计学显著差异（p分别为0.400、0.077和0.830）。结果；在痰液、粪便、血液和尿液等许多样本中检测到SARS-CoV-2 RNA，并且观察到粪便样本中的病毒脱落可能持续数月。大多数患者在第四个月观察到抗SARS-CoV-2 IgG抗体阳性，并且发现抗体滴度在第三个月后下降。确定在第四个月保护性抗体水平持续存在。这些发现对于疫苗接种策略和抗击大流行病具有重要意义。然而，考虑到在大流行病持续的当今情况下病毒新突变形式的出现，对于病毒脱落和抗体滴度研究需要更详细和全面的研究。
