- The high genetic variability of HCV is caused by the rapid and inaccurate replication of the virus. It promotes pathogen adaptation, in particular, the avoidance of an immune response. The acquired immune response associated with T cell activity plays a very important role in the fight against the infection - writes Kamila Caraballo Cortés, MD, PhD, from the Department of Immunopathology of Infectious and Parasitic Diseases MUW.