Tracing Immunity

In the year 3021, after a massive pandemic, humanity has become immune to all known diseases. However, a new deadly virus has emerged, and the only way to create a cure is by tracing the immunity of a rare surviving test subject who has combatants of the virus in his T cell receptors. You are a top-notch medical detective who has been brought on board to extract rare 4-residue long strips of Atchley numbers from the test subject’s T-cell receptors, and solve the mystery of immunity to develop a cure.