In conclusion, given the bountiful basic scientific data in animal models regarding the importance of the perforin-granzyme cytolytic pathway in protection from viral infections, and the strong circumstantial evidence in HIV-1 pathogenesis, it seems unreasonable to assume that these cytolytic effector molecules are not present for a key purpose, or that HIV-1 pathogenesis follows entirely different rules compared to other viruses. The gene discussed is PRF1; the disease is viral infectious disease.