Around 1.7 million children are estimated to live with HIV-1 worldwide, and about 160,000 infants are newly infected every year. Since adaptive immunity takes time to mature and develop in infants, and maternal antibodies provide limited antiviral activity, innate and intrinsic immunity against HIV-1 in the young is of critical importance. Intrinsic restriction factors are cellular proteins that effectively inhibit HIV-1 replication in vitro, but there is limited understanding of their role in vivo, and little to no data has been reported on the expression of host restriction factors in children. We hypothesized that restriction factor expression might be particularly important in children living with HIV-1 and correlate with disease progression.
We analyzed gene expression of APOBEC3A, APOBEC3C, APOBEC3G, APOBEC3H, SAMHD1, ISG15, CDKN1A, MX2, TRIM5, and SLFN11 by qPCR in 121 samples of CD4+ T cells from vertically infected children living with HIV-1. Cell surface expression of BST-2/tetherin and markers of CD4+ T-cell activation were analyzed by flow cytometry.
After adjusting for gender and age, BST-2/tetherin expression on CD4+ T cells showed significant positive correlation with viral load (P = 0.0006; ρ = 0.33), CD4+ T-cell activation (P < 0.0001; ρ = 0.53), CD8+ T-cell activation (P < 0.0001; ρ = 0.53), and a negative correlation with CD4+ T-cell counts (P = 0.0008; ρ = −0.33). The expression of SAMHD1 correlated negatively with markers of T-cell activation (P = 0.046; ρ = −0.22).
These results suggest an important role of some restriction factors in the pathogenesis of HIV-1 in children.