Impact of the HIV-1 genetic background and HIV-1 population size on the evolution of raltegravir resistance.

BACKGROUND: Emergence of resistance against integrase inhibitor raltegravir in human immunodeficiency virus type 1 (HIV-1) patients is generally associated with selection of one of three signature mutations: Y143C/R, Q148K/H/R or N155H, representing three distinct resistance pathways. The mechanisms that drive selection of a specific pathway are still poorly understood. We investigated the impact of the HIV-1 genetic background and population dynamics on the emergence of raltegravir resistance. Using deep sequencing we analyzed the integrase coding sequence (CDS) in longitudinal samples from five patients who initiated raltegravir plus optimized background therapy at viral loads > 5000 copies/ml. To investigate the role of the HIV-1 genetic background we created recombinant viruses containing the viral integrase coding region from pre-raltegravir samples from two patients in whom raltegravir resistance developed through different pathways. The in vitro selections performed with these recombinant viruses were designed to mimic natural population bottlenecks. RESULTS: Deep sequencing analysis of the viral integrase CDS revealed that the virological response to raltegravir containing therapy inversely correlated with the relative amount of unique sequence variants that emerged suggesting diversifying selection during drug pressure. In 4/5 patients multiple signature mutations representing different resistance pathways were observed. Interestingly, the resistant population can consist of a single resistant variant that completely dominates the population but also of multiple variants from different resistance pathways that coexist in the viral population. We also found evidence for increased diversification after stronger bottlenecks. In vitro selections with low viral titers, mimicking population bottlenecks, revealed that both recombinant viruses and HXB2 reference virus were able to select mutations from different resistance pathways, although typically only one resistance pathway emerged in each individual culture. CONCLUSIONS: The generation of a specific raltegravir resistant variant is not predisposed in the genetic background of the viral integrase CDS. Typically, in the early phases of therapy failure the sequence space is explored and multiple resistance pathways emerge and then compete for dominance which frequently results in a switch of the dominant population over time towards the fittest variant or even multiple variants of similar fitness that can coexist in the viral population.

Lower Ribavirin Plasma Concentrations in HCV/HIV-Coinfected Patients Than in HCV-Monoinfected Patients Despite Similar Dosage.

BACKGROUND: Hepatitis C virus (HCV)/HIV-coinfected patients respond worse to dual therapy with ribavirin (RBV)/peginterferon compared with HCV-monoinfected patients. Several trials found that lower RBV plasma concentrations are associated with impaired virological response rates. The aim of this study was to determine RBV plasma concentrations in a cohort of HCV-monoinfected and HCV/HIV-coinfected patients. Our hypothesis is that HCV/HIV-coinfected patients have lower RBV plasma concentrations, which may in part explain their inferior response to dual therapy. METHODS: A retrospective cohort study was performed in chronic HCV-monoinfected and HCV/HIV-coinfected patients who received peginterferon and weight-based RBV. Plasma RBV concentrations were determined at weeks 4 and 12 by a validated high-performance liquid chromatography assay. RBV concentrations were compared between monoinfected and coinfected patients. We calculated the proportion of patients with a subtherapeutic RBV plasma concentration defined as <2.0 mg/L. RESULTS: A total of 61 HCV-infected patients were included, of whom 21 (34%) were coinfected with HIV. Although there was no difference in the weight-based dose of RBV between monoinfected and coinfected patients, RBV exposure was significantly lower in HCV/HIV-coinfected patients than in HCV-monoinfected patients: the mean ± SD RBV plasma concentrations were 1.82 ± 0.63 mg/L versus 2.25 ± 0.80 mg/L (P = 0.04) at week 4 and 2.14 ± 0.65 mg/L versus 2.62 ± 0.81 mg/L (P = 0.05) at week 12, respectively. The percentage of patients with subtherapeutic plasma concentrations of RBV in coinfected patients versus monoinfected patients was 62% versus 46% (P = 0.240) at week 4 and 50% versus 16% (P = 0.01) at week 12 of treatment, respectively. CONCLUSIONS: HIV/HCV-coinfected patients yield significantly lower plasma concentrations of RBV than HCV-monoinfected patients. This puts them at an increased risk of not achieving sustained virological response.

Predictors and correlates of adherence to combination antiretroviral therapy (ART) for chronic HIV infection: a meta-analysis.

BACKGROUND: Adherence to combination antiretroviral therapy (ART) is a key predictor of the success of human immunodeficiency virus (HIV) treatment, and is potentially amenable to intervention. Insight into predictors or correlates of non-adherence to ART may help guide targets for the development of adherence-enhancing interventions. Our objective was to review evidence on predictors/correlates of adherence to ART, and to aggregate findings into quantitative estimates of their impact on adherence. METHODS: We searched PubMed for original English-language papers, published between 1996 and June 2014, and the reference lists of all relevant articles found. Studies reporting on predictors/correlates of adherence of adults prescribed ART for chronic HIV infection were included without restriction to adherence assessment method, study design or geographical location. Two researchers independently extracted the data from the same papers. Random effects models with inverse variance weights were used to aggregate findings into pooled effects estimates with 95% confidence intervals. The standardized mean difference (SMD) was used as the common effect size. The impact of study design features (adherence assessment method, study design, and the United Nations Human Development Index (HDI) of the country in which the study was set) was investigated using categorical mixed effects meta-regression. RESULTS: In total, 207 studies were included. The following predictors/correlates were most strongly associated with adherence: adherence self-efficacy (SMD = 0.603, P = 0.001), current substance use (SMD = -0.395, P = 0.001), concerns about ART (SMD = -0.388, P = 0.001), beliefs about the necessity/utility of ART (SMD = 0.357, P = 0.001), trust/satisfaction with the HIV care provider (SMD = 0.377, P = 0.001), depressive symptoms (SMD = -0.305, P = 0.001), stigma about HIV (SMD = -0.282, P = 0.001), and social support (SMD = 0.237, P = 0.001). Smaller but significant associations were observed for the following being prescribed a protease inhibitor-containing regimen (SMD = -0.196, P = 0.001), daily dosing frequency (SMD = -0.193, P = 0.001), financial constraints (SMD -0.187, P = 0.001) and pill burden (SMD = -0.124, P = 0.001). Higher trust/satisfaction with the HIV care provider, a lower daily dosing frequency, and fewer depressive symptoms were more strongly related with higher adherence in low and medium HDI countries than in high HDI countries. CONCLUSIONS: These findings suggest that adherence-enhancing interventions should particularly target psychological factors such as self-efficacy and concerns/beliefs about the efficacy and safety of ART. Moreover, these findings suggest that simplification of regimens might have smaller but significant effects.

A case suspected for yellow fever vaccine-associated viscerotropic disease in the Netherlands.

Yellow fever (YF) 17D vaccine is one of the most successful vaccines ever developed. Since 2001, 56 cases of yellow fever vaccine-associated viscerotropic disease (YEL-AVD) have been published in the peer-reviewed literature. Here, we report a new case suspected for YEL-AVD in the Netherlands. Further research is needed to determine the true incidence of YEL-AVD and to clarify host and vaccine-associated factors in the pathogenesis of YEL-AVD. Because of the potential adverse events, healthcare providers should carefully consider vaccination only in people who are truly at risk for YF infection, especially in primary vaccine recipients.

Seroprotection after hepatitis a vaccination in patients with drug-induced immunosuppression.

BACKGROUND: Increasing numbers of travelers using immunosuppressive drugs visit hepatitis A endemic countries. Data on protection rates after hepatitis A vaccination in this group are scarce. METHODS: In this retrospective study, records of subjects with hepatitis A serology taken after vaccination were searched for in travel clinic databases. Relation between immunosuppressive drug use, age, gender, and time between vaccination and serology was evaluated. RESULTS: Seroprotection rates within 4 weeks after primary vaccination (50%) are lower than after 4 weeks (64%). After the complete series of two vaccinations seroprotection rates reach 95% although success depends on the immunosuppressive drug being used. Subjects under anti-TNF alpha treatment have significantly lower seroprotection rates than subjects using classical immunosuppressive drugs after the second vaccination. There is no influence of age or gender on seroprotection rates. CONCLUSIONS: Last-minute vaccination in subjects using immunosuppressive medication is not reliable, only 60% of our subjects had a protective antibody level after a single vaccination. When serology was done within 4 weeks after a single vaccination, seroprotection rates were only 50%, after 4 weeks this number rose to 64%. When persons visit a travel clinic in time for a complete vaccination series, satisfactory seroprotection rates can be reached. Seroprotection rate depends on the drug being used, persons using anti-TNF alpha are less protected.