HIV-1 subtype F integrase polymorphisms external to the catalytic core domain contribute to severe loss of replication capacity in context of the integrase inhibitor resistance mutation Q148H.

BACKGROUND: In prior studies, HIV-1 BF recombinants with subtype F integrases failed to develop resistance to raltegravir through the Q148H mutational pathway. We aimed to determine the role of subtype-specific polymorphisms in integrase on drug susceptibility, viral replication and integration. METHODS: Integrase sequences were retrieved from the Los Alamos Database or obtained from the Garrahan HIV cohort. HIV-1 infectious molecular clones with or without Q148H (+ G140S) resistance mutations were constructed using integrases of subtype B (NL4-3) or F1(BF) ARMA159 and URTR23. Integrase chimeras were generated by reciprocal exchanges of a 200 bp fragment spanning amino acids 85-150 of the catalytic core domain (CCD) of NL4-3-Q148H and either ARMA159-Q148H or URTR23-Q148H. Viral infections were quantified by p24 ELISA and Alu-gag integration PCR assay. RESULTS: At least 18 different polymorphisms distinguish subtype B from F1(BF) recombinant integrases. In phenotypic experiments, p24 at Day 15 post-infection was high (105-106 pg/mL) for WT and NL4-3-Q148H; by contrast, it was low (102-104 pg/mL) for both F1(BF)-Q148H + G140S viruses, and undetectable for the Q148H mutants. Compared with WT viruses, integrated DNA was reduced by 5-fold for NL4-3-Q148H (P = 0.05), 9-fold for URTR23-Q148H (P = 0.01) and 16000-fold for ARMA159-Q148H (P = 0.01). Reciprocal exchange between B and F1(BF) of an integrase CCD region failed to rescue the replicative defect of F1(BF) integrase mutants. CONCLUSIONS: The functional impairment of Q148H in the context of subtype F integrases from BF recombinants explains the lack of selection of this pathway in vivo. Non-B polymorphisms external to the integrase CCD may influence the pathway to integrase strand transfer inhibitor resistance.

HIV-1 pretreatment drug resistance in vertically infected children is associated with poor virological response to protease inhibitor (PI)-based first-line antiretroviral therapy (ART): results from a cohort study in Argentina.

BACKGROUND: Increasing evidence from adult cohorts suggests an important role of HIV-1 pretreatment drug resistance (PDR) in ART failure, in spite of treatment being fully active according to baseline genotyping tests. Whether this is also true for children is unknown. METHODS: Virological and immunological parameters were longitudinally assessed in a group of 39 HIV-1 vertically infected children starting first-line lopinavir/ritonavir-based ART at a median of 5.0 months (IQR = 3.0-9.0). Evolution of viral load (VL) over time was compared between children with and without baseline PDR, as defined by the WHO mutation list. RESULTS: Resistance-associated mutations (RAMs) in the HIV-1 pol gene were present in nine HIV-1-infected children (23%) before initiation of first-line ART (PDR group). Of them, six carried RAMs associated with NNRTIs (NNRTI-PDR subgroup). At 4-8 weeks after ART initiation, the proportion of children achieving ≥1 log VL reduction was 87% for the no-PDR group versus 33% and 16.7% for the PDR group and the NNRTI-PDR subgroup, respectively. During follow-up, children with no PDR reached virological suppression almost four times faster than children with PDR or NNRTI-PDR [no-PDR = 631 days and PDR = 2134 days (P = 0.1249) and NNRTI-PDR = 2134 days (P = 0.0447)]. CD4 T cells remained similar between the study groups over time. CONCLUSIONS: HIV-1 baseline genotyping at diagnosis in vertically infected children is important for improved personalized medicine. While the mechanism is unclear, cases with PDR (particularly to NNRTIs) require closer monitoring of their first-line ART regimens in order to avoid early virological failures and prevent further accumulation of resistance.

DMT1 iron uptake in the PNS: bridging the gap between injury and regeneration.

Previous studies by our group demonstrated the key role of iron in Schwann cell maturation through an increase in cAMP, PKA activation and CREB phosphorylation. These studies opened the door to further research on non-transferrin-bound iron uptake, which revealed the presence of DMT1 mRNA all along SC progeny, hinting at a constitutive role of DMT1 in ensuring the provision of iron in the PNS. In light of these previous results, the present work evaluates the participation of DMT1 in the remyelination process following a demyelinating lesion promoted by sciatic nerve crush--a reversible model of Wallerian degeneration. DMT1 was observed to colocalize with a SC marker S100ß at all survival times analyzed. In turn, the assessment of DMT1 mRNA expression exhibited an increase 7 days post-injury, while DMT1 protein levels showed an increase 14 days after crush at the lesion site and distal stump; finally, an increase in iron levels became evident as from 14 days post-injury, in parallel with DMT1 values. To sum up, the present work unveils the role of DMT1 in mediating the neuroregenerative action of iron.