3.5. Resistance to HIV
Scientists have carefully studied people who have the CCR5-delta32 mutation that prevents a particular type of HIV-1 from binding to the CD4 cells. This occurs in about 1% of mostly Caucasian people.
As it is well-known, the virus enters CD4 cells using interaction of the HIV protein with a co-receptor CCR5 (R5) or CXCR4 (x 4). We distinguish between three types of viruses entering the cell via co-receptor CCR5 (R5), CXCR4 (x 4) or both (R5X4). This phenomenon is called HIV affinity to co-receptors data.
Thus, people with the mutated CCR5 gene only have natural resistance to HIV strains with affinity to co-receptor R5. The CCR5 gene mutation arose about two thousand years ago and gradually spread throughout Europe, especially among northern peoples. The scientists associate occurrence of this mutation with the West Nile virus (WNV). Despite the relatively low prevalence of the disease in the world and a stable immunity which emerged in the course of evolution, the probability of WNV infection is increased in people with the CCR5 delta32gene mutation.
There is also a small number of people (about 10%) who have a virus in the blood, but HIV symptoms manifest themselves over a long period of time, and the viral load and immune system stays within the normal range. Such people are called nonprogressors or elite controllers.