- Rhinovirus infections may ramp up genes that help the lung airway defend itself against SARS-CoV-2.
- In this study, participants with a rhinovirus infection in the previous 30 days had a 48% lower risk of subsequent SARS-CoV-2 infection.
- Children were more likely than adults to have rhinovirus infections, which may explain why they experience milder SARS-CoV-2 infections.
The family of viruses responsible for the common cold was linked to a lower risk of SARS-CoV-2 infection, according to a prospective analysis of the Human Epidemiology and Response to SARS-CoV-2 (HEROS) cohort.
Among 1,394 U.S. households, family members who had a rhinovirus infection in the previous 30 days had a 48% lower risk of subsequent SARS-CoV-2 infection (adjusted HR 0.52, 95% CI 0.29-0.95, P=0.034), reported Camille Moore, PhD, of National Jewish Health in Denver, and colleagues.
For those with SARS-CoV-2 infection, a recent rhinovirus infection was also associated with a 9.6-fold lower SARS-CoV-2 viral load (0.98 log10 lower, P=0.0031), they noted in the Journal of Infectious Diseases.
Because children are most likely to have rhinovirus infections -- with an estimated 63.4% of kids in this study having one or more infections during the study period compared with 37% of teenagers and 35.6% of adults -- this may partially explain why they experience milder SARS-CoV-2 infections versus adults, Moore and team said.
Rhinovirus infections trigger an immune response in respiratory airway epithelium that may make children more resistant than adults to subsequent symptomatic SARS-CoV-2 infection. While kids' risk of one or more SARS-CoV-2 infections was the same as adults' -- with 14% each experiencing one or more infections during the study period -- their odds of having an asymptomatic infection were 6.02-fold greater.
"These findings strongly suggest that frequent HRV [human rhinovirus] infections in children lead to increased expression of our protective gene set in the airway, resulting in reduced risk of SARS-CoV-2 infection, lower viral loads among those infected, and less severe SARS-CoV-2 infections," Moore and colleagues wrote.
Genes may be why rhinovirus causes viral interference, making it tougher for SARS-CoV-2 to find an airway home after rhinovirus.
"We identified a set of genes that, if they were expressed at higher levels in people's airways, they experienced much lower SARS-CoV-2 infection levels," co-author Max Seibold, PhD, also of National Jewish Health, told MedPage Today. "Those are genes that are stimulated by rhinovirus."
Rhinovirus infections appear to ramp up genes that help the lung airway defend itself against viral attack. The researchers found that a rhinovirus infection upregulated 22 antiviral genes in airway epithelium, potentially priming the immune response against later infections by SARS-CoV-2. Even in uninfected family members, 13 of those 22 genes were already significantly more highly expressed in children than in adults.
Infections' timing appeared to matter. Family members with concurrent rhinovirus and SARS-CoV-2 infections saw no protective benefit from their cold. In fact, their SARS-CoV-2 viral loads were similar to those of family members infected by SARS-CoV-2 without a prior rhinovirus infection.
Rhinovirus Points to a Therapeutic Opening
That collection of protective genes in airway epithelium could offer an antiviral therapeutic opportunity.
"We've identified multiple genes that might be really important in preventing the development of respiratory infections -- not just SARS-CoV-2, but likely other viruses as well," Seibold said. That knowledge could lead to development of recombinant therapies based on the proteins expressed by those genes, he added, perhaps as an intranasal therapy that people could use to block infections.
The HEROS study included 4,160 members of 1,394 U.S. households from May 2020 to February 2021. Participants self-collected and returned nasal swabs every 2 weeks for SARS-CoV-2 testing.
Moore and colleagues assessed how respiratory virus circulation affected SARS-CoV-2 infection risk by analyzing data from 1,000 randomly selected HEROS participants (mean age 25.9, 63.7% white, 19.4% Black, and 10.1% Hispanic), plus all additional SARS-CoV-2 cases in HEROS. Of this subcohort, 30.8% were younger than 13 years, 20.3% were teens and young adults ages 13 to 21 years, and 48.9% were adults ages 22 and up.
The researchers compared respiratory viral infection rates during the 30 days before a household's first SARS-CoV-2 infection. Tests showed that most non-SARS-CoV-2 respiratory infections were caused by either a rhinovirus or an enterovirus (86.5%), with 97.9% of those infections caused by rhinovirus. Non-SARS-CoV-2 viruses were found more frequently than SARS-CoV-2 viruses (6.7% vs 1% of tested nasal swabs).
Study limitations included potential underestimation of SARS-CoV-2 and rhinovirus cases, given the 2-week interval for nasal swab collection. In addition, the effect of rhinovirus viral loads on SARS-CoV-2 infection could not be calculated.
Disclosures
The study was supported by the NIH.
Moore reported no disclosures.
Seibold reported a relationship with Escient Pharmaceuticals.
Co-authors reported relationships with numerous companies.
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.