Like a lizard that lets go of its tail to escape from predators, research has found that there are various ways how HIV mutates and evolves in response to the pressure from the human immune system.  One of the observations shows that people with the rare ability of "beating" HIV for years tend to have HLA genes that help the immune system recognize and fight HIV more efficiently. 

According to the report published in the Journal of Experimental Medicine, a team of researchers from Emory Vaccine Center studied how the virus mutates and evolves in response to immune pressure among HIV-infected people with such effective HLA genes called HLA-B*5703.

The HLA genes encode molecules that display bits of viral proteins called epitopes on the surface of HIV-infected cells.  When certain white blood cells, called cytotoxic T lymphocytes, spot certain combinations of HLA molecules and viral epitopes, they end up attacking the infected cells.

Meanwhile, researchers have found that a set of three mutations within the HIV’s Gag protein, which consists the viral core, could slow down the replication of the virus.  In cell culture, the virus with triple mutations replicate 20 times slower than usual.  However, these same mutations could eliminate the ability of white blood cells to detect the virus.

This means that if a patient lacked the HLA-B*5703 gene, the virus loses the mutations because doing so would not be useful in evading the new and different immune system.  However, people with that particular gene and the triple-mutated HIV get sick.

This situation has been compared by researchers as the HIV resembling a thief picking a lock.  When all three mutations are in place, the lock is picked and the virus can thrive.