Synergism and Antagonism of Bacterial-Viral Coinfection in the Upper Respiratory Tract
Sam Manna, Julie McAuley, Jonathan Jacobson, Cattram Nguyen, Md Ashik Ullah, Ismail Sebina, Victoria Williamson, E. Kim Mulholland, Odilia Wijburg, Simon Phipps, Catherine Satzke
Abstract
Respiratory bacterial-viral coinfections (such as pneumococci and influenza virus) are often synergistic, resulting in enhanced disease severity. Although colonization of the nasopharynx is the precursor to disease and transmission, little is known about bacterial-viral interactions that occur within this niche. In this study, we developed a novel mouse model to examine pneumococcal-viral interactions in the nasopharynx with pneumonia virus of mice (PVM) and influenza. We found that PVM infection benefits pneumococci by increasing their numbers in the nasopharynx and shedding of these bacteria in respiratory secretions. In contrast, we discovered that pneumococci decrease PVM numbers by accelerating viral clearance. We also report a similar effect of pneumococci on influenza. By showing that coinfections lead to both synergistic and antagonistic outcomes, our findings challenge the existing dogma in the field. Our work has important applications and implications for bacterial and viral vaccines that target these microbes.