PROGNOSTIC FITNESS. “Translated into clinical practice, it means that the evolutionary history of HCV in infected patients may influence the response to treatments. In particular, long-term replication of HCV during prolonged chronicity may increase viral fitness to the detriment of treatment efficacy, as observed in clinical practice. These observations render essential to develop methods to define fitness values in vivo and to explore the fitness landscape in viral populations.”
http://www.sciencedirect.com/science/article/pii/S0042682215001580