The characteristics of the cell-mediated immune response identify different profiles of occult hepatitis B virus infection.

BACKGROUND & AIMS: Hepatitis B virus (HBV) DNA detection in serum and/or in the liver of hepatitis B surface antigen (HBsAg)-negative patients with or without serologic markers of previous viral exposure is defined as occult HBV infection. Because the role of the adaptive response in keeping HBV replication under control in occult infection still is undefined, this study was performed to characterize the features of the HBV-specific T-cell response in this condition. METHODS: HBV-specific T-cell frequency and function were tested ex vivo and after in vitro expansion in 32 HBsAg-negative patients undergoing diagnostic liver biopsy for chronic hepatitis C: 18 with occult HBV infection (11 anti-HBc-negative and 7 anti-HBc-positive patients) defined by the detection of intrahepatic HBV DNA by polymerase chain reaction; 14 without detectable intrahepatic HBV DNA (5 anti-HBc-positive and 9 anti-HBc-negative patients). Six patients with chronic hepatitis B and 7 HBsAg-inactive carriers were studied for comparison. RESULTS: The presence or absence of serologic HBV markers defined 2 profiles of HBV-specific T-cell responses in occult infection. Anti-HBc-positive patients showed a T-cell response typical of protective memory, suggesting that this condition represents a resolved infection with immune-mediated virus control. In contrast, HBV-specific T cells in anti-HBc-negative patients did not readily expand and produce interferon-gamma in vitro, suggesting the possibility of a low-dose infection insufficient to allow maturation of protective memory. CONCLUSIONS: Our results suggest different mechanisms of control of viral replication in seropositive and seronegative occult infections. Additional studies aimed at understanding possible different clinical implications are needed.

Evolution of the HIV-1 protease region in heavily pretreated HIV-1 infected patients receiving Atazanavir.

BACKGROUND: Previous in vitro studies indicated that Atazanavir (ATV) has a distinct resistance profile than other protease inhibitors (PIs). In treatment-experienced patients ATV resistance is characterised by the accumulation of at least four mutations among those that confer cross-resistance to the PIs. OBJECTIVE: We studied the evolution of PIs resistance mutations in 10 HAART-failed patients undergoing ATV enrolled in an early access program. STUDY DESIGN: Virus genotypic resistance was determined from plasma collected at baseline and during treatment. HIV-RNA was extracted and the pol region amplified and sequenced. Genotypic data were used to determine drug susceptibility. Phylogenetic analysis was performed. RESULTS: At baseline, genotypic data showed cross-resistance patterns to approved PIs in 6 patients. In two of these subjects new mutations (I54V and A71V) conferring cross-resistance emerged after 3 months of therapy. The I50L mutation was evidenced in one subject after 12 months of treatment. The "virtual" phenotype analysis mirrored the resistance profiles to ATV and other PIs and evidenced differences with tipranavir and darunavir. CONCLUSION: Genotype evolution within the protease region did not emerge at significant levels during salvage therapy of multidrug-experienced patients. ATV exhibited certain/same virologic effect on the majority of our patients.

Does GSS still maintain relevance on HAART outcome after the introduction of newest active antiretroviral drugs? 48 weeks results.

BACKGROUND: Since recent observations demonstrated that extended resistance to protease inhibitors, nucleosidic and non - nucleosidic retrotranscriptase inhibitors (PI, NRTI, NNRTI) is a marker of disease progression and death, it is a matter of the greatest importance that experienced human immunodeficiency virus (HIV) - infected patients with limited therapeutic options receive a suppressive therapy pending the availability of at least two new antiretroviral drugs. Aim of the present study is to evaluate if the GSS score, calculated by analyzing the resistance to historical antiretroviral drugs and drug classes, is still relevant since several new potent drugs and drug classes entered the current clinical use. METHODS: Taking into account patients without suppression of HIV replication for ≥ 6 months from October 2008 and October 2009, we analyzed viroimmunological and resistance data of 38 outpatients starting their last antiretroviral regimen including at least one of the following: maraviroc, enfuvirtide, raltegravir, etravirine, darunavir/ritonavir or tipranavir/ritonavir. Mutations present in all available genotypic resistance tests were recorded for each patient and then correlated to GSS value, assessed using the last genotypic ribonucleic acid (RNA) resistance test. GSS was studied as predictor of virological treatment outcome by univariate and multivariate logistic regression. RESULTS: At 48 weeks, undetectable viral load was obtained in 80% of patients without difference between GSS classes (HIV-RNA median < 50 copies/ml); 95.8% of patients with baseline HIV-RNA < 50,000 copies/ml obtained virological suppression (p=0.003). 48 weeks CD4+ median value was 412 cells/µl considering GSS1 and 300 cells/µl for combined GSS2 and GSS3 scores. Data also showed a > 60% recurrence of specific mutations for NRTI: M41L, M184IV, L210W, T215FY, K219EQ and 75% for D67N. K103N and Y181CIV mutations for NNRTI persisted in 35% of cases and their prevalence incresed in parallel with the number of GRTs. About 60% of tests reported L10FIRVC, M36ILV, M46IL, I54VLAMTS, V82AFTSLI, and L90M mutations in the protease region. 63P mutation was found in a total number of GRTs close to 80%. This percentages, when correlated to GSS, revealed a distinct pattern for most mutations, that showed a greater prevalence for GSS = 2. Conversely, only NNRTI 181CIV and NRTI 210W showed larger numbers in GSS1 and GSS3. CONCLUSIONS: Single drugs belonging to new antiretroviral classes did not correlate to viroimmunological success for any GSS. High frequency and recurrence over GRTs for specific mutations confirm their key role following the exposure to ARVs classes. A baseline HIV-RNA < 50,000 cp/ml is a predictor of therapeutic success and a carefully selected HAART based upon the evaluation of GRTs can favorably influence the immunovirologic response.

Characterization of hepatitis B virus (HBV)-specific T-cell dysfunction in chronic HBV infection.

Dysfunctional CD8+ T cells present in chronic virus infections can express programmed death 1 (PD-1) molecules, and the inhibition of the engagement of PD-1 with its ligand (PD-L1) has been reported to enhance the antiviral function of these T cells. We took advantage of the wide fluctuations in levels of viremia which are typical of chronic hepatitis B virus (HBV) infection to comprehensively analyze the impact of prolonged exposure to different virus quantities on virus-specific T-cell dysfunction and on its reversibility through the blocking of the PD-1/PD-L1 pathway. We confirm that chronic HBV infection has a profound effect on the HBV-specific T-cell repertoire. Despite the use of a comprehensive panel of peptides covering all HBV proteins, HBV-specific T cells were rarely observed directly ex vivo in samples from patients with chronic infection, in contrast to those from patients with acute HBV infection. In chronic HBV infection, virus-specific T cells were detected mainly in patients with lower levels of viremia. These HBV-specific CD8+ T cells expressed PD-1, and their function was improved by the blocking of PD-1/PD-L1 engagement. Thus, a broad spectrum of anti-HBV immunity is expressed by patients with chronic HBV infection and this spectrum is proportional to HBV replication levels and can be improved by blocking the PD-1/PD-L1 pathway. This information may be useful for the design of immunotherapeutic strategies to complement and optimize available antiviral therapies.