New research offers an explanation for how influenza A infection, followed by S. pneumoniae infection, causes severe pneumonia and a high death rate.

This new mechanism had been missed in the past because it facilitates bacterial adherence only to dead or dying lung epithelial cells, not to living cells. Heretofore, researchers typically used healthy lung cell monolayers to search for bacterial adhesins that aid infection. Virus killing of lung cells during flu was found to set the stage for S. pneumonia attachment to the airway, thereby worsening disease and pneumonia.

The research, published in the journal Cell Reports, was led by Carlos Orihuela, Ph.D., and David Briles, Ph.D., professor and professor emeritus in the University of Alabama at Birmingham Department of Microbiology.

Orihuela and Briles say their findings provide further explanation for how an infection by influenza A flu virus — followed by S. pneumoniae superinfection — causes severe pneumonia and a high death rate. The mechanism also points to possible improvements for disease treatment and vaccination.

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