CCR5 and HIV-1 infection: For example, mutations of the C-C chemokine receptor type 5 gene (CCR5) confer resistance to HIV-1 infection, mutations of the Toll-like receptor 3 (TLR3) and UNC93B1 genes are associated with susceptibility to HSV-1 encephalitis, a polymorphism upstream of interleukin 28B (IL28B) is associated with HCV spontaneous clearance and response to treatment with IFN-α [2].