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Center for Nonlinear Studies |
Secondary bacterial infections associated with influenza are a leading cause of death in the United States. These bacterial infections, mainly caused by Streptococcus pneumoniae, capitalize on the environment in the respiratory tract created by the Influenza virus. Experiments suggest a lethal synergism between these pathogens, but the precise mechanisms involved are unknown. However, some hypotheses attribute the interaction to specific viral properties, dysfunctional immune responses, and/or accelerated cell regeneration. In addition, an interesting and surprising observation is the change in viral levels following the bacterial challenge suggesting a truly dual effect. While the kinetics and interactions of these two pathogens are not well understood, we are developing ordinary differential equation models of the following three infections: (i) influenza, (ii) S. pneumoniae, and (iii) influenza followed by S. pneumoniae 7 days later. Using experimental mouse lung data, we are fitting the models, estimating parameters, and investigating synergistic mechanisms. So far, we have good candidates for control models of influenza and S. pneumoniae; however, choosing functional forms for the interaction between the two pathogens presents extreme difficulty. Since the equations are highly coupled, obtaining a fit that accurately represents both viral and bacterial data sets in addition to having biological meaning is not trivial. Therefore, we are continuing to explore possible mechanisms as well as the functional forms involved in these models.
Host: T-CNLS