Samantha King, PhD & Renukaradhya Gourapura, DVM, MS, PhD
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Evaluation of influenza titers during bacterial co-infection
The Center for Clinical and Translational Science awarded Ohio State and Nationwide Children’s Hospital collaborators Renukaradhya Gourapura, DVM, PhD, and Samantha King, PhD, a pilot grant for their research involving viral and bacterial co-infections.
One million influenza-related deaths occur each year, and 90 percent of these deaths are the result of a bacterial pathogen co-infection. The most common bacterial co-infecting pathogen is pneumococcus.
Despite the fact that the interaction between pneumococcus and influenza is clinically relevant, there have been limited scientific studies. “Not many people look at the interaction between them even though viral infections are known to make bacterial infections worse,” King said.
King and Gourapura aim to establish a model to study the interaction between pneumococcus and influenza to determine if pneumococcal colonization increases viral titers. They believe that such research could potentially lead to reduced morbidity and mortality rates due to co-infection. The research could also better prepare us for pandemic influenza viruses in the future.
The outcome of co-infection was tested using six different influenza viruses of both human and swine origin in epithelial cell lines derived from human, canine and pig. These cell lines were pretreated with live bacteria, washed, and then analyzed. This process allowed the researchers to see if the presence of pneumococci had an impact in the severity and replication of the influenza virus.
Surprisingly, no difference in influenza severity and replication was observed. “This may be due to the fact that these cell lines lack secreted host factors," Gourapura said. "Consequently, they are not a true representation of in vivo co-infections, wherein in the respiratory tract both bacteria and virus co-exist. Such studies are not possible in vitro.”
The work completed through the pilot grant resulted in a publication in PLOS ONE. In the article, investigators detailed their findings, which demonstrate that influenza virus replication is not effected by pneumococcus pre-exposure in cells studied in vitro.
The expected outcome was not observed; however the work completed through the team's CCTS pilot grant allowed these researchers to move towards investigating the interaction between influenza and pneumococcal co-infection in a higher model.
Next, King and Gourapura intend to apply for another grant that will allow them to establish a pig model that is more suitable for their investigation. Pigs have a similar immune system and airway anatomy to that of humans. Therefore, pigs are a better model for this investigation than other model systems, such as mice.
By Kasasha Arum, October 17, 2014
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