C-C chemokine receptor type 5, also known as CCR5 or CD195, is a protein on the surface of white blood cells that is involved in the immune system as it acts as a receptor for chemokines. In humans, the CCR5 gene that encodes the CCR5 protein is located on the short (p) arm at position 21 on chromosome 3. Certain populations have inherited the Delta 32 mutation, resulting in the genetic deletion of a portion of the CCR5 gene. Homozygous carriers of this mutation are resistant to M-tropic strains of HIV-1 infection.