Investigating Streptococcus pneumoniae and Adenovirus Co-infections of Lung Epithelial Cells

Co-infection is common among viruses and bacteria in the human respiratory system. Adenovirus (AdV) and Streptococcus pneumoniae are clinically relevant respiratory pathogens that cause morbidity and mortality in a variety of patient populations with the highest morbidity occurring among immunocompromised individuals, but also prevalent in infants and the elderly. Acute respiratory distress syndrome may become severe in healthy individuals when co-infection with S. pneumoniae and AdV occurs due to synergistic effects of the pathogens on the host. I hypothesized that S. pneumoniae infection decreases AdV transduction of airway epithelia. To test this hypothesis, we utilized the polarized immortalized airway epithelial cell line Calu-3. Calu-3 cells were inoculated with S. pneumoniae followed by the addition of recombinant adenovirus, AdVLacZ. Then, the effect of bacteria on AdV transduction into Calu-3 cells was determined by quantifying β-galactosidase. Cell-associated viral genomes were measured by quantitative polymerase chain reaction. These results showed that S. pneumoniae infection decreased significantly AdV transduction in Calu-3 cells, but there was no significant difference in quantity of cell-associated AdV genomes.