ERAP2 and HIV-1 infection: Our results suggest that the viral stimulus triggers the expression of antiviral factors known playing a role in resistance to HIV-1 infection such as ERAP2, MX2, TRIM22, and APOBEC3G (Figure 3), suggesting that the frequent viral exposure in HESNs could induce higher levels of these molecules as particularly observed for APOBEC3G and MX2 in several cohorts of HESNs (5, 9, 37).