Bortlik M, Copertino DC, Brailey P, et al. - In infants, adaptive immunity takes time to mature and develop, and maternal antibodies yield limited antiviral activity, which suggest the critical importance of innate and intrinsic immunity against HIV-1 in the young. In in vitro studies, HIV-1 replication is effectively inhibited by intrinsic restriction factors, which are cellular proteins. Researchers here hypothesized that in children living with HIV-1, restriction factor expression might be especially important and correlate with disease progression. They examined 121 samples of CD4+ T cells from vertically infected children living with HIV-1 for gene expression of APOBEC3A, APOBEC3C, APOBEC3G, APOBEC3H, SAMHD1, ISG15, CDKN1A, MX2, TRIM5, and SLFN11 by qPCR. After adjusting for gender and age, cell surface expression of BST-2/tetherin on CD4+ T cells exhibited a significant positive correlation with viral load, CD4+ T-cell activation, CD8+ T-cell activation, and a negative correlation with CD4+ T-cell counts. Negative correlation of the expression of SAMHD1 with markers of T-cell activation. Results are thereby suggestive of a significant role of some restriction factors in the pathogenesis of HIV-1 in children.