Duffy antigen as it relates to HIV
https://retrovirology.biomedcentral.com/articles/10.1186/1742-4690-10-S1-O31
The African-specific DARC null allele increases risk of HIV infection.
HIV-2 strains but not HIV-1 strains utilised DARC as an entry co-receptor. However, HIV-1 could bind to DARC on red cells and be delivered to activated CD4+ T-cells resulting in subsequent infection. GWAS analysis confirmed the link between DARC null genotype and African benign neutropenia. The DARC null phenotype with African benign neutropenia resulted in low CCL5 plasma levels and increased the relative risk of HIV-1 infection approximately 3-fold.
Researchers say the trait is extremely common because it used to have a beneficial effect; it protected people against a form of malaria that is now fairly rare.
Researchers aren’t yet clear on the mechanism by which the lack of Duffy antigens increases the risk of HIV infection, but they have a few theories. During an immune response, Duffy antigens create chemical messengers that summon white blood cells to fight an infection. Since those chemicals latch onto the same white blood cell proteins that are targeted by HIV, said Weiss, their absence in duffy-negative people may allow the virus to proceed unchecked [Wired News]. As for why HIV-infected patients with this genetic variant live longer, Weiss says it’s possible that since the white blood cells aren’t being summoned to the site of the infection, it may take longer for the HIV virus to spread throughout the body.