Table_1_Cross-Immunization Against Respiratory Coronaviruses May Protect Children From SARS-CoV2: More Than a Simple Hypothesis?.docx

In January 2020, a new coronavirus was identified as responsible for a pandemic acute respiratory syndrome. The virus demonstrated a high infectious capability and not-neglectable mortality in humans. However, similarly to previous SARS and MERS, the new disease COVID-19 caused by SARS-CoV-2 seemed to relatively spare children and younger adults. Some hypotheses have been proposed to explain the phenomenon, including lower ACE2 expression in children, cross-immunization from measles/rubella/mumps and BCG-vaccination, as well as the integrity of respiratory mucosa. Herein, we hypothesize that an additional mechanism might contribute to children's relative protection from SARS-CoV-2, the cross-immunization conferred by previous exposures to other common respiratory coronaviruses. To support our hypothesis, we show a statistically significant similarity in genomic and protein sequences, including epitopes for B- and T-cell immunity, of SARS-CoV-2 and the other beta coronaviruses. Since these coronaviruses are highly diffused across pediatric populations, cross-reactive immunity might reasonably induce an at least partial protection from SARS-CoV-2 in children.

2020年1月，一种新型冠状病毒被确定为引发大流行性急性呼吸综合征的病原体。该病毒具有高传染性，并对人类造成不可忽视的致死率。与此前的严重急性呼吸综合征（SARS）和中东呼吸综合征（MERS）类似，这种由严重急性呼吸综合征冠状病毒2型（SARS-CoV-2）引发的新型疾病COVID-19，似乎较少累及儿童与年轻群体。目前已有多项假说被提出以阐释该现象，包括儿童体内血管紧张素转换酶2（ACE2）表达水平较低、麻疹/风疹/腮腺炎与卡介苗（BCG）接种带来的交叉免疫，以及呼吸道黏膜完整性等。本文中，我们提出一种额外机制或可助力儿童获得对SARS-CoV-2的相对保护，即既往暴露于其他常见呼吸道冠状病毒所赋予的交叉免疫。为支撑这一假说，我们证实SARS-CoV-2与其他β冠状病毒在基因组与蛋白质序列（包括针对B细胞和T细胞免疫的表位）上存在统计学意义上的显著相似性。鉴于此类冠状病毒在儿童群体中广泛传播，交叉反应性免疫或可合理地使儿童获得至少部分针对SARS-CoV-2的保护力。