Laboratory of Human Pathologies Biology, Faculty of Sciences, Mohammed V University in Rabat, Rabat, Morocco.
Mohammed VI Center for Research & Innovation, Rabat, Morocco and Mohammed VI University of Sciences and Health, Casablanca, Morocco.
Int J Immunopathol Pharmacol. 2024 Jan-Dec;38:3946320241260633. doi: 10.1177/03946320241260633.
This study aims to assess the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG antibodies against the spike (S) and nucleocapsid (NP) proteins, as well as neutralizing antibodies against the receptor-binding domain (RBD). Additionally, it aims to detect viral RNA of SARS-CoV-2 in pre-pandemic archival pediatric specimens collected before the announcement of the COVID-19 pandemic spread on March 20, 2020, in Morocco. The objective is to investigate the existence of pre-pandemic immunity to SARS-CoV-2.
We conducted a cross-sectional study, to analyze IgG antibody levels in a cohort of 106 pre-pandemic pediatric participants. Using an indirect enzyme-linked immunosorbent assay (ELISA), we measured the IgG levels against the S and NP proteins of SARS-CoV-2. Additionally, we staged a competitive ELISA assay to evaluate the neutralizing capability of these antibodies. We used reverse transcription polymerase chain reaction (rRT-PCR) to detect viral NP and ORF1ab genes of SARS-CoV-2 in oropharyngeal swabs. Moreover, we conducted on the same specimens a multiplexed RT-PCR to detect RNA of the most common 27 pathogens involved in lower respiratory tract infections.
Among the 106 serum samples, 13% (n = =14) tested positive for SARS-CoV-2 IgG antibodies using ELISA. Temporal analysis indicated varying IgG positivity levels across 2019. Neutralizing antibodies were found in 21% of the 28 samples analyzed, including two with high inhibition rates (93%). The SARS-CoV-2 RNA was detected using rRT-PCR in 14 samples. None of the samples tested positive for the other 27 pathogens associated with lower respiratory tract infections, using multiplexed RT-PCR.
Our study addresses the possibility, that COVID-19 infections occurred in Morocco before the recognized outbreak. On the other hand, some of the cases might reflect cross-reactivity with other coronaviruses or be influenced by previous viral exposures or vaccinations. Understanding these factors is crucial to comprehending pediatric immune responses to newly emerging infectious diseases.
本研究旨在评估针对严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）刺突（S）和核衣壳（NP）蛋白的 IgG 抗体以及针对受体结合域（RBD）的中和抗体的血清阳性率。此外，还旨在检测 SARS-CoV-2 在摩洛哥 2020 年 3 月 20 日宣布 COVID-19 大流行传播之前收集的档案儿科标本中的病毒 RNA，以调查是否存在针对 SARS-CoV-2 的大流行前免疫。
我们进行了一项横断面研究，以分析 106 例大流行前儿科参与者的 IgG 抗体水平。使用间接酶联免疫吸附试验（ELISA），我们测量了针对 SARS-CoV-2 的 S 和 NP 蛋白的 IgG 水平。此外，我们进行了竞争性 ELISA 试验以评估这些抗体的中和能力。我们使用逆转录聚合酶链反应（rRT-PCR）检测 SARS-CoV-2 的咽拭子中的 NP 和 ORF1ab 基因。此外，我们对同一标本进行了多重 RT-PCR 检测以检测涉及下呼吸道感染的 27 种常见病原体的 RNA。
在 106 份血清样本中，使用 ELISA 检测到 13%（n=14）的 SARS-CoV-2 IgG 抗体呈阳性。时间分析表明，2019 年 IgG 阳性率存在差异。在分析的 28 个样本中发现了 21%的中和抗体，其中两个样本的抑制率很高（93%）。rRT-PCR 检测到 14 个样本中存在 SARS-CoV-2 RNA。使用多重 RT-PCR 检测未在其他与下呼吸道感染相关的 27 种病原体的样本中检测到阳性。
我们的研究表明，摩洛哥可能在公认的 COVID-19 爆发之前就发生了 COVID-19 感染。另一方面，某些病例可能反映了与其他冠状病毒的交叉反应，或者受到先前病毒暴露或疫苗接种的影响。了解这些因素对于理解儿科对新出现的传染病的免疫反应至关重要。
