Sneeze on your health
The "cold virus" was called a way to protect against Covid-19
Maria Azarova, Naked Science
Given the prevalence of the so-called common cold, this effect is likely to help reduce the number of new Covid-19 cases.
Rhinoviruses (HRV) are pathogens of acute respiratory diseases transmitted by airborne droplets or contact, in everyday life they are also called colds (common cold). These small RNA-containing viruses from the genus of enteroviruses, which are familiar to us, enter the body through the mucous membrane of the nose and eyes. Previous studies have shown that interactions between HRV and other respiratory viruses can affect the type and severity of infections, as well as how they spread among people. For example, it was recently found out that rhinoviruses provide protection against influenza.
Over the past year, experts have made many assumptions about how the Covid-19 pathogen will fit into the world of viral interactions, but social distancing measures, lockdowns and other restrictions have slowed down the spread of other pathogens, thereby complicating their study. However, the authors of the new study – virologists from the University of Glasgow (UK) – managed to find that HRV causes an immune response, which, apparently, is able to block the reproduction of SARS-CoV-2 in the cells of the respiratory tract. The findings are presented in an article for the Journal of Infectious Diseases (Dee et al., Human rhinovirus infection blocks SARS-CoV-2 replication within the respiratory epithelium: implications for COVID-19 epidemiology).
Scientists took copies of the epithelial cells of the human bronchi and infected them with either coronavirus, rhinovirus, or their "mixture". "To assess the effect of coinfections on the replication of each virus, the titers were determined at different times after infection and compared with the corresponding titers from single viral infections. SARS-CoV-2 showed very contrasting replication kinetics in single and coinfections. Its titers slowly increased from 24 hours after infection and further to 96 hours with a single infection, whereas with co-infection with HRV, coronavirus titers decreased rapidly and were not determined after 48 hours. On the contrary, rhinovirus titers showed the same kinetics in single and coinfection: they rose rapidly in the first 24 hours, then there was a gradual and steady decline. Since coinfections occur infrequently in real life, we performed the experiment as follows: the cells were infected with HRV, and after 24 hours with coronavirus. The process was repeated in reverse order (first SARS-CoV-2, then rhinovirus). As with simultaneous coinfections, the replication of SARS-CoV2 was seriously disrupted in both cases, while the presence of coronavirus did not affect HRV," the authors of the study write.
That is, throughout the experiment, the causative agent Covid-19 was suppressed by rhinovirus. From this, scientists concluded that the so-called cold can provide a certain level of protection against coronavirus. Mathematical modeling has shown that such interaction of two viruses can reduce the number of new Covid-19 cases in the population.
"Rhinovirus causes an immune response in respiratory epithelial cells that blocks the replication of SARS-CoV-2. Consequently, the immune response caused by mild colds viral infections can provide some level of temporary protection against coronavirus, potentially blocking its transmission and reducing the severity of coronavirus disease. <...> Now we plan to understand what happens at the molecular level during these virus-virus interactions. Then we will be able to use this knowledge to develop new strategies and measures to combat Covid-19," added Professor Pablo Murcia.
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