Saint Michael's Medical Center and The New Jersey Medical School, Newark, New Jersey 07102, USA. ssmith1824@aol.com
Recent data have established the HIV-1 and SIV escape CTL through epitope mutation. However, three novel studies prove that such escape comes at a "cost" to overall viral fitness. Understanding how HIV-1/SIV escape CTL and the impact of the escape mutations has tremendous importance in developing CTL based vaccines. Further, a CTL based HIV-1 vaccine is likely to have long-term protective effect against disease only if the escape virus is significantly weakened compared with wild type.