Persistent nucleic acids from endemic human coronaviruses in adenoids: Do they enhance children's immune response to SARS-CoV-2 infection?

Abstract

Introduction

Human Coronaviruses (HCoVs), including HCoV-OC43, HCoV-HKU1, HCoV-NL63, and HCoV-229E, are endemic viruses that circulate globally and infect humans. In contrast to SARS-CoV-2, which causes more severe symptoms, these endemic HCoVs typically induce mild cold symptoms and confer only temporary immunity [1,2]]. Understanding the presence and persistence of HCoVs in the human population, particularly in asymptomatic individuals, is crucial for understanding their potential role in immunity and viral dynamics.

Methods

This study aimed to investigate the presence of nucleic acids of endemic HCoVs (HCoV-OC43, HCoV-HKU1, HCoV-NL63, and HCoV-229E) in individuals without symptoms of acute respiratory infection. A total of 78 adenoid tissue samples were collected from children (up to 10 years old) without current symptoms of airway infection. The samples were analyzed using RT-nested PCR to detect viral RNA.

Results

Of the 78 adenoid samples, 24 (30,8 %) tested positive for at least one type of endemic HCoV. Additionally, throat swabs were collected from 56 participants immediately before surgery. Endemic HCoV RNA was rarely detected in these throat swabs, with only 3 out of 56 samples testing positive.

Discussion

Our findings suggest the frequent presence of endemic HCoV nucleic acids in the lymphatic tissue of Waldeyer's ring, especially in children. This observation supports the concept of these viruses acting as immune triggers. The persistence of viral remnants in the adenoid tissue may contribute to continuous immune surveillance, which could have implications for immunity to future infections and for understanding viral dynamics in asymptomatic individuals.