Original Antigenic Sin - in Cytotoxic T Cells

In Cytotoxic T Cells

A similar phenomenon has been described in cytotoxic T cells (CTL). Several groups have attempted to design vaccines for HIV and hepatitis C based on induction of cytotoxic (CTL) responses. The finding that CTL may be biased by original antigenic sin, may help to explain the limited effectiveness of these vaccines. Viruses like HIV are highly variable and undergo mutation frequently, and thus, due to original antigenic sin, HIV infection induced by viruses that express slightly different epitopes (than those in a viral vaccine) would fail to be controlled by the vaccine. In fact, the vaccine might make the infection even worse, by "trapping" the immune response into the first, ineffective, response it made against the virus.