CCR5 and infectious disease: Well-known examples of partial resistance to infectious disease include sickle cell trait and resistance to malaria (Allison, 1954), and the common deletion of 32 nucleotides within the CCR5 gene (CCR5-Delta32 allele; rs333), which confers complete resistance to the Human Immunodeficiency Virus 1 (HIV-1) (Dean et al., 1996).