The following is a summary of “Influenza A and Respiratory Syncytial Virus Trigger a Cellular Response That Blocks Severe Acute Respiratory Syndrome Virus 2 Infection in the Respiratory Tract,” published in the June 2023 issue of Infectious Diseases by Dee, et al.

Respiratory diseases are caused by multiple viruses that coexist and contribute to the overall disease burden. Interactions between different viruses can lead to decreased susceptibility to infection, and understanding these interactions is important for epidemiological purposes. Since humans are regularly exposed to a community of respiratory viruses, experimental studies involving coinfection are necessary to comprehend the mechanisms underlying diseases caused by multiple pathogens. For a study, researchers sought to investigate the interactions between severe acute respiratory syndrome virus 2 (SARS-CoV-2) and two prominent respiratory viruses, influenza A virus (IAV) and respiratory syncytial virus (RSV), within the respiratory tract.

They conducted single infections and coinfections using SARS-CoV-2 and IAV or RSV in cultures of human bronchial epithelial cells. They employed a combination of microscopy and viral replication quantification, both in the presence and absence of an innate immune inhibitor, to assess changes in virus-induced pathology, virus spread, and viral replication.

The findings demonstrated that both IAV and RSV can inhibit the replication of SARS-CoV-2. This inhibition relies on a functional antiviral response, and the degree of inhibition is proportional to the timing of the secondary viral infection.

Infections with other respiratory viruses can confer temporary resistance to SARS-CoV-2. Consequently, it was expected that the incidence of coronavirus disease 2019 (COVID-19) might decrease during periods when IAV and RSV are highly prevalent.

Source: academic.oup.com/jid/article/227/12/1396/6957417