Did smallpox lead to HIV-1 resistance?
The entry of HIV-1 into lymphocytes requires two cellular proteins, the receptor CD4, and a co-receptor, either CXCR4 or CCR5. Individuals who carry a mutation in the gene encoding CCR5, called delta 32, are resistant to HIV-1 infection. This observation was the basis for giving an AIDS patient a bone marrow transplant from a donor …