A new longitudinal study by Columbia University researchers of symptomatic, asymptomatic, and mild infections sheds light on how our bodies respond to viral respiratory infections on a molecular level.
They report the discovery of a gene expression signature capable of differentiating both between symptomatic and asymptomatic infections and between positive asymptomatic individuals and negative individuals.
The study presents a complex picture of how several common respiratory viruses interact with the human body, and with each other, as well as with common respiratory bacteria. The results are available as an interactive web tool for scientists to generate and test new hypotheses and are described in a new peer-reviewed article in the journal PLOS Biology.
Over 19 months, 214 volunteers enrolled in the Virome of Manhattan study provided nasal swab samples, which were analyzed by molecular testing (RNA-seq and qPCR) along with daily individual reports of symptoms and demographic information. The majority of the infections were caused by rhinoviruses and coronaviruses. Only 8 percent of positive samples contained evidence of multiple viral coinfections (one case was positive for five different viruses). The study found that influenza leads to greater changes in gene expression than other viruses, such as coronavirus or rhinovirus. Their findings were also suggestive of a possible link between repeat exposure to pathogens and host responses.
An earlier study using data from the same cohort found that reinfections with endemic coronaviruses are not uncommon, even within a year of prior infection. The study found that when reinfection occurred, it was not associated with less severe symptoms. Instead, genetic factors may be a greater determinant of the severity of an infection.
