Bortlik M, Copertino DC, Brailey PM, et al. - Innate and intrinsic immunity against HIV-1 in the young is considered to be of critical importance as in infants, adaptive immunity takes time to mature and develop, and maternal antibodies provide limited antiviral activity. Intrinsic restriction factors result in effective inhibition of HIV-1 replication in vitro, however, their role in vivo has not been ascertained completely and there is little to no data on the expression of host restriction factors in children. Researchers here examined 121 samples of CD4+ T cells from vertically infected children living with HIV-1 by qPCR for gene expression of APOBEC3A, APOBEC3C, APOBEC3G, APOBEC3H, SAMHD1, ISG15, CDKN1A, MX2, TRIM5, and SLFN11. Flow cytometry was used to determine cell surface expression of BST-2/tetherin and markers of CD4+ T-cell activation. They identified a significant positive correlation of BST-2/tetherin expression on CD4+ T cells with viral load, CD4+ T-cell activation, CD8+ T-cell activation, and its negative correlation with CD4+ T-cell counts. Negative correlation of the expression of SAMHD1 with markers of T-cell activation was noted. Overall findings suggest that some restriction factors play an important role in the pathogenesis of HIV-1 in children.