The cold virus ‘hides’ and multiplies in the tonsils and adenoids, even in people without symptoms A study conducted at the University of São Paulo (USP) in Brazil reveals that tissues such as the tonsils and adenoids can serve as hiding places for the rhinovirus, which causes the common cold and is responsible for most respiratory infections worldwide. Using samples from 293 children who underwent surgery to remove these tissues, the study showed that the pathogen can infect immune cells known as lymphocytes and remain there for long periods without causing symptoms. This allows the virus to potentially be transmitted to others without warning. “The virus has a ‘date’ with the child population. Every year, about two or three weeks after school starts in temperate regions, there’s a rhinovirus outbreak. And children pass it on to their parents, and grandparents. We’ve always wondered: What does the start of school have to do with it? Well, children gather in closed spaces, and some of them with the virus in their throats can spark an outbreak at school, even if they’re asymptomatic,” comments rhinovirologist Eurico de Arruda Neto, a professor at the Ribeirão Preto School of Medicine (FMRP-USP) and coordinator of the research, supported by FAPESP (projects 13/06380‐0, 13/16349‐2 and 17/25654‐4). As the researcher explains, it was already known that the rhinovirus infects the epithelium (the outermost layer of the mucosa) of the nose and throat, hijacks the cellular machinery to multiply, and causes the host cell to rupture once this process is complete, releasing progeny capable of generating new infections. Scientists consider it a lytic virus, one that causes cell lysis, or rupture. This rapid and destructive cycle quickly draws the attention of the immune system, which, in most cases, eliminates the virus from the body within about five to seven days. The rhinovirus can infect B lymphocytes, which produce antibodies, and CD4 T cells, which conduct the local immune response. This ability to persist in immune cells within the tonsils and adenoids provides a mechanism for the virus to evade immediate detection and clearance, contributing to its seasonal patterns of transmission. Previous studies by Arruda’s team had detected adenovirus (another cause of the common cold), influenza A (flu), and SARS-CoV-2 (COVID-19) in samples of tonsils and adenoids from children who had undergone surgery. The latter two are known to cause longer-lasting infections in some patients. This research highlights the role of lymphoid tissues in the upper respiratory tract as reservoirs for respiratory viruses, with implications for understanding disease transmission dynamics and potentially informing public health strategies aimed at reducing the spread of the common cold, particularly in settings like schools where children are in close contact.
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