Hepatitis B virus (HBV) reactivation during immunosuppression can lead to severe acute hepatitis, fulminant liver failure, and death. Here, we investigated hepatitis B surface antigen (HBsAg) genetic features underlying this phenomenon by analyzing 93 patients: 29 developing HBV reactivation and 64 consecutive patients with chronic HBV infection (as control). HBsAg genetic diversity was analyzed by population-based and ultradeep sequencing (UDS). Before HBV reactivation, 51.7% of patients were isolated hepatitis B core antibody (anti-HBc) positive, 31.0% inactive carriers, 6.9% anti-HBc/anti-HBs (hepatitis B surface antibody) positive, 6.9% isolated anti-HBs positive, and 3.4% had an overt HBV infection. Of HBV-reactivated patients, 51.7% were treated with rituximab, 34.5% with different chemotherapeutics, and 13.8% with corticosteroids only for inflammatory diseases. In total, 75.9% of HBV-reactivated patients (vs. 3.1% of control patients; P < 0.001) carried HBsAg mutations localized in immune-active HBsAg regions. Of the 13 HBsAg mutations found in these patients, 8 of 13 (M103I-L109I-T118K-P120A-Y134H-S143L-D144E-S171F) reside in a major hydrophilic loop (target of neutralizing antibodies [Abs]); some of them are already known to hamper HBsAg recognition by humoral response. The remaining five (C48G-V96A-L175S-G185E-V190A) are localized in class I/ II-restricted T-cell epitopes, suggesting a role in HBV escape from T-cell-mediated responses. By UDS, these mutations occurred in HBV-reactivated patients with a median intrapatient prevalence of 73.3% (range, 27.6%-100%) supporting their fixation in the viral population as a predominant species. In control patients carrying such mutations, their median intrapatient prevalence was 4.6% (range, 2.5%-11.3%; P < 0.001). Finally, additional N-linked glycosylation (NLG) sites within the major hydrophilic loop were found in 24.1% of HBV-reactivated patients (vs. 0% of chronic patients; P < 0.001); 5 of 7 patients carrying these sites remained HBsAg negative despite HBV reactivation. NLG can mask immunogenic epitopes, abrogating HBsAg recognition by Abs. Conclusion: HBV reactivation occurs in a wide variety of clinical settings requiring immune-suppressive therapy, and correlates with HBsAg mutations endowed with enhanced capability to evade immune response. This highlights the need for careful patient monitoring in all immunosuppressive settings at reactivation risk and of establishing a prompt therapy to prevent HBV-related clinical complications. (HEPATOLOGY 2015;61:823-833)

The activity of raltegravir and 4 other integrase inhibitors (MK-2048, L870,810, \ud IN2, and IN5) was investigated in primary human macrophages, PBMC and\ud C8166-lymphocytic T cells, in order to determine their relative potency and\ud efficacy in different cellular systems of HIV infection. Raltegravir showed\ud better protective efficacy in all cell types; MK-2048, L870,810 and IN5 showed a \ud potent anti-HIV-1 activity in macrophages, while in lymphocytes only MK-2048 and \ud L870,810 showed an inhibitory effect comparable to raltegravir. IN2 was a poorly \ud effective anti-HIV-1 compound in all cellular systems. All effective integrase\ud inhibitors exhibited a potent antiviral activity against both X4 and R5 HIV-1\ud strains. In general, raltegravir, MK-2048, L870,810 and IN5 showed anti HIV\ud activity similar or slightly higher in macrophages compared to PBMC and C8166 T\ud cells: for MK-2048, the EC(50) was 0.4, 0.9, 11.5nM in macrophages, in PBMCs and \ud T cells, respectively; for L870,810, the EC(50) was 1.5, 14.3, and 10.6nM,\ud respectively; for IN5 the EC(50) was 0.5, 13.7, and 5.7nM, respectively

Dolutegravir is effective in different HIV cellular targets and against raltegravir-resistant mutants. The high efficacy of dolutegravir in MDMs (cells with limited metabolism) has relevant clinical implications in light of the role of MDMs in the transmission of HIV infection and dissemination in different body compartments.

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APOBEC3G/F proteins are packaged into HIV-1 virions and associate with the reverse transcription (RT) complex. There, they deaminate cytosine residues to uracil in the single-stranded DNA minus strand, resulting in proviral guanosine-to-adenosine (Gto-A) nucleotide mutations in the plus-strand DNA (6, 7). These mutations predominantly occur in a GG or GA dinucleotide context, which are the preferential (but not exclusive) target sites for APOBEC3G and APOBEC3F, respectively (2, 6). Previous studies have shown that the frequency of G-to-A nucleotide mutations increases over the genome in the 5=-to-3= direction, with the lowest frequency in the 5= long terminal repeat and the highest in the 5= portion of the nef gene sequence (6). Beyond G-to-A mutations, C-to-T nucleotide mutations in plus-strand DNA have also been described (6).The activity of APOBEC3G/F is generally counteracted by the HIV-1 regulatory protein Vif by promoting proteasome-dependent APOBEC3G/F degradation (8) and inhibiting packaging in the producer cell (9). However, the activity of Vif against APOBEC3G/F is not absolute. Indeed, some Vif mutants fail (to different extents) to neutralize these enzymes (2, 10-13). For instance, previous in vitro studies showed that in the presence of the Vif amino acid substitution K22E, Vif completely loses the ability to neutralize APOBEC3G (implying APOBEC3G editing of the viral genome) and retains partial activity against APOBEC3F (implying less editing of APOBEC3F than APOBEC3G). In the presence of the Vif amino acid substitution E45G, Vif retained weak activity against APOBEC3G (implying a low rate of APOBEC3G editing) and completely neutralized APOBEC3F activity (implying no or limited APOBEC3F editing) (2).Previous studies have shown that these two Vif amino acid substitutions can facilitate the emergence of the G-to-A mutation