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Background: Numerous studies have shown that baseline drug resistance patterns may influence the outcome of antiretroviral therapy. Therefore, guidelines recommend drug resistance testing to guide the choice of initial regimen. In addition to optimizing individual patient management, these baseline resistance data enable transmitted drug resistance (TDR) to be surveyed for public health purposes. The SPREAD program systematically collects data to gain insight into TDR occurring in Europe since 2001., Methods: Demographic, clinical, and virological data from 4140 antiretroviral-naive human immunodeficiency virus (HIV)-infected individuals from 26 countries who were newly diagnosed between 2008 and 2010 were analyzed. Evidence of TDR was defined using the WHO list for surveillance of drug resistance mutations. Prevalence of TDR was assessed over time by comparing the results to SPREAD data from 2002 to 2007. Baseline susceptibility to antiretroviral drugs was predicted using the Stanford HIVdb program version 7.0., Results: The overall prevalence of TDR did not change significantly over time and was 8.3% (95% confidence interval, 7.2%-9.5%) in 2008-2010. The most frequent indicators of TDR were nucleoside reverse transcriptase inhibitor (NRTI) mutations (4.5%), followed by nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations (2.9%) and protease inhibitor mutations (2.0%). Baseline mutations were most predictive of reduced susceptibility to initial NNRTI-based regimens: 4.5% and 6.5% of patient isolates were predicted to have resistance to regimens containing efavirenz or rilpivirine, respectively, independent of current NRTI backbones., Conclusions: Although TDR was highest for NRTIs, the impact of baseline drug resistance patterns on susceptibility was largest for NNRTIs. The prevalence of TDR assessed by epidemiological surveys does not clearly indicate to what degree susceptibility to different drug classes is affected., (© The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America.)

Background: One out of ten newly diagnosed patients in Europe was infected with a virus carrying a drug resistant mutation. We analysed the patterns over time for transmitted drug resistance mutations (TDRM) using data from the European Spread program., Methods: Clinical, epidemiological and virological data from 4317 patients newly diagnosed with HIV-1 infection between 2002 and 2007 were analysed. Patients were enrolled using a pre-defined sampling strategy., Results: The overall prevalence of TDRM in this period was 8.9% (95% CI: 8.1-9.8). Interestingly, significant changes over time in TDRM caused by the different drug classes were found. Whereas nucleoside resistance mutations remained constant at 5%, a significant decline in protease inhibitors resistance mutations was observed, from 3.9% in 2002 to 1.6% in 2007 (p = 0.001). In contrast, resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs) doubled from 2.0% in 2002 to 4.1% in 2007 (p = 0.004) with 58% of viral strains carrying a K103N mutation. Phylogenetic analysis showed that these temporal changes could not be explained by large clusters of TDRM., Conclusion: During the years 2002 to 2007 transmitted resistance to NNRTI has doubled to 4% in Europe. The frequent use of NNRTI in first-line regimens and the clinical impact of NNRTI mutations warrants continued monitoring.

Background: In Europe, a continuous programme (SPREAD) has been in place for ten years to study transmission of drug resistant HIV. We analysed time trends of transmitted drug resistance mutations (TDRM) in relation to the risk behaviour reported., Methods: HIV-1 patients newly diagnosed in 27 countries from 2002 through 2007 were included. Inclusion was representative for risk group and geographical distribution in the participating countries in Europe. Trends over time were calculated by logistic regression., Results: From the 4317 patients included, the majority was men-having-sex-with-men -MSM (2084, 48%), followed by heterosexuals (1501, 35%) and injection drug users (IDU) (355, 8%). MSM were more often from Western Europe origin, infected with subtype B virus, and recently infected (<1 year) (p<0.001). The prevalence of TDRM was highest in MSM (prevalence of 11.1%), followed by heterosexuals (6.6%) and IDU (5.1%, p<0.001). TDRM was predominantly ascribed to nucleoside reverse transcriptase inhibitors (NRTI) with a prevalence of 6.6% in MSM, 3.3% in heterosexuals and 2.0% in IDU (p = 0.001). A significant increase in resistance to non- nucleoside reverse transcriptase inhibitors (NNRTIs) and a decrease in resistance to protease inhibitors was observed in MSM (p = 0.008 and p = 0.006, respectively), but not in heterosexual patients (p = 0.68 and p = 0.14, respectively)., Conclusions: MSM showed to have significantly higher TDRM prevalence compared to heterosexuals and IDU. The increasing NNRTI resistance in MSM is likely to negatively influence the therapy response of first-line therapy, as most include NNRTI drugs.

Introduction: Clinically evaluating genotypic interpretation systems is essential to provide optimal guidance in designing potent individualized HIV-regimens. This study aimed at investigating the ability of the latest Rega algorithm to predict virological response on a short and longer period., Materials Methods: 9231 treatment changes episodes were extracted from an integrated patient database. The virological response after 8, 24 and 48 weeks was dichotomized to success and failure. Success was defined as a viral load below 50 copies/ml or alternatively, a 2 log decrease from the baseline viral load at 8 weeks. The predictive ability of Rega version 8 was analysed in comparison with that of previous evaluated version Rega 5 and two other algorithms (ANRS v2011.05 and Stanford HIVdb v6.0.11). A logistic model based on the genotypic susceptibility score was used to predict virological response, and additionally, confounding factors were added to the model. Performance of the models was compared using the area under the ROC curve (AUC) and a Wilcoxon signed-rank test., Results: Per unit increase of the GSS reported by Rega 8, the odds on having a successful therapy response on week 8 increased significantly by 81% (OR = 1.81, CI = [1.76-1.86]), on week 24 by 73% (OR = 1.73, CI = [1.69-1.78]) and on week 48 by 85% (OR = 1.85, CI = [1.80-1.91]). No significant differences in AUC were found between the performance of Rega 8 and Rega 5, ANRS v2011.05 and Stanford HIVdb v6.0.11, however Rega 8 had the highest sensitivity: 76.9%, 76.5% and 77.2% on 8, 24 and 48 weeks respectively. Inclusion of additional factors increased the performance significantly., Conclusion: Rega 8 is a significant predictor for virological response with a better sensitivity than previously, and with rules for recently approved drugs. Additional variables should be taken into account to ensure an effective regimen.

Background: The effect of drug resistance transmission on disease progression in the newly infected patient is not well understood. Major drug resistance mutations severely impair viral fitness in a drug free environment, and therefore are expected to revert quickly. Compensatory mutations, often already polymorphic in wild-type viruses, do not tend to revert after transmission. While compensatory mutations increase fitness during treatment, their presence may also modulate viral fitness and virulence in absence of therapy and major resistance mutations. We previously designed a modeling technique that quantifies genotypic footprints of in vivo treatment selective pressure, including both drug resistance mutations and polymorphic compensatory mutations, through the quantitative description of a fitness landscape from virus genetic sequences., Results: Genotypic correlates of viral load and CD4 cell count were evaluated in subtype B sequences from recently diagnosed treatment-naive patients enrolled in the SPREAD programme. The association of surveillance drug resistance mutations, reported compensatory mutations and fitness estimated from drug selective pressure fitness landscapes with baseline viral load and CD4 cell count was evaluated using regression techniques. Protease genotypic variability estimated to increase fitness during treatment was associated with higher viral load and lower CD4 cell counts also in treatment-naive patients, which could primarily be attributed to well-known compensatory mutations at highly polymorphic positions. By contrast, treatment-related mutations in reverse transcriptase could not explain viral load or CD4 cell count variability., Conclusions: These results suggest that polymorphic compensatory mutations in protease, reported to be selected during treatment, may improve the replicative capacity of HIV-1 even in absence of drug selective pressure or major resistance mutations. The presence of this polymorphic variation may either reflect a history of drug selective pressure, i.e. transmission from a treated patient, or merely be a result of diversity in wild-type virus. Our findings suggest that transmitted drug resistance has the potential to contribute to faster disease progression in the newly infected host and to shape the HIV-1 epidemic at a population level.

Saliva may provide interesting advantages as matrix for compliance measurements, pharmacokinetic studies and therapeutic drug monitoring in resource limited countries. We investigated the feasibility of using saliva for compliance monitoring of zidovudine (ZDV), lamivudine (3TC) and nevirapine (NVP) in 29 HIV-1 infected patients from Rwanda. ZDV, 3TC and NVP drug levels were quantified by an LC/MS-MS method in plasma and stimulated saliva samples and compared using Bland-Altman analysis. Seven patients demonstrated undetectable saliva ZDV levels while five out of these seven also showed no 3TC salivary concentrations. For the other samples, we observed a good agreement between salivary and plasma concentrations of each antiretroviral drug. A significant relation between the difference in saliva and plasma ZDV concentrations and the average ZDV concentration in the two matrices was deduced as follow: y = -380.15 + 1.79 x. The log saliva and plasma concentration difference of both 3TC and NVP was consistent across the range of average log concentration. Overall, we showed large agreement limits suggesting a wide inter patient variability that may result to non-reliable plasma level predictions from saliva drug measurements. Therefore, our results indicate that saliva may serve as a valuable tool only for NVP compliance testing because of its high salivary concentration.

The European HIV Drug Resistance Guidelines Panel, established to make recommendations to clinicians and virologists, felt that sufficient new information has become available to warrant an update of its recommendations, explained in both pocket guidelines and this full paper. The Panel makes the following recommendations concerning the indications for resistance testing: for HIV-1 (i) test earliest sample for protease and reverse transcriptase drug resistance in drug-naive patients with acute or chronic infection; (ii) test protease and reverse transcriptase drug resistance at virologic failure, and other drug targets (integrase and envelope) if such drugs were part of the failing regimen; (iii) consider testing for CCR5 tropism at virologic failure or when a change of therapy has to be made in absence of detectable viral load, and in the latter case test DNA or last detectable plasma RNA; (iv) consider testing earliest detectable plasma RNA when a successful nonnucleoside reverse transcriptase inhibitor-containing therapy was inappropriately interrupted; (v) genotype source patient when postexposure prophylaxis is considered; for HIV-2, (vi) consider resistance testing where treatment change is needed after treatment failure. The Panel recommends genotyping in most situations, using updated and clinically evaluated interpretation systems. It is mandatory that laboratories performing HIV resistance tests take part regularly in external quality assurance programs, and that they consider storing samples in situations where resistance testing cannot be performed as recommended. Similarly, it is necessary that HIV clinicians and virologists take part in continuous education and discuss problematic clinical cases. Indeed, resistance test results should be used in the context of all other clinically relevant information for predicting therapy response.

Background: Human Immunodeficiency Virus type 2 is naturally resistant to some antiretroviral drugs, restricting therapeutic options for patients infected with HIV-2. Regimens including integrase inhibitors (INI) seem to be effective, but little data on HIV-2 integrase (IN) polymorphisms and resistance pathways are available., Materials and Methods: The integrase coding sequence from 45 HIV-2-infected, INI-naïve, patients was sequenced and aligned against the ROD (group A) or EHO (group B) reference strains and polymorphic or conserved positions were analyzed.To select for raltegravir (RAL)-resistant variants in vitro, the ROD strain was cultured under increasing sub-optimal RAL concentrations for successive rounds. The phenotype of the selected variants was assessed using an MTT assay., Results: We describe integrase gene polymorphisms in HIV-2 clinical isolates from 45 patients. Sixty-seven percent of the integrase residues were conserved. The HHCC Zinc coordination motif, the catalytic triad DDE motif, and AA involved in IN-DNA binding and correct positioning were highly conserved and unchanged with respect to HIV-1 whereas the connecting residues of the N-terminal domain, the dimer interface and C-terminal LEDGF binding domain were highly conserved but differed from HIV-1. The N155 H INI resistance-associated mutation (RAM) was detected in the virus population from one ARV-treated, INI-naïve patient, and the 72I and 201I polymorphisms were detected in samples from 36 and 38 patients respectively. No other known INI RAM was detected.Under RAL selective pressure in vitro, a ROD variant carrying the Q91R+I175M mutations was selected. The Q91R and I175M mutations emerged simultaneously and conferred phenotypic resistance (13-fold increase in IC50). The Q91R+I175M combination was absent from all clinical isolates. Three-dimensional modeling indicated that residue 91 lies on the enzyme surface, at the entry of a pocket containing the DDE catalytic triad and that adding a positive charge (Gln to Arg) might compromise IN-RAL affinity., Conclusions: HIV-2 polymorphisms from 45 INI-naïve patients are described. Conserved regions as well as frequencies of HIV-2 IN polymorphisms were comparable to HIV-1. Two new mutations (Q91R and I175M) that conferred high resistance to RAL were selected in vitro, which might affect therapeutic outcome.

This study was conducted among individuals taking first-line antiretroviral treatment (ART) for at least 12 months under programme conditions in Maputo, Mozambique in order to report on the level of detectable viraemia and the proportion and types of drug resistance mutations among those with detectable viral loads. HIV-1 RNA viral load levels (lower detection limit <50 copies/ml) were measured, and resistance mutations were sequenced. One hundred and forty-nine consecutive patients (69% females, median age 36 years) were included after a mean follow-up time of 23 months. One hundred and seven (72%; 95% CI 64-79) had undetectable viral load, while in 42 (28%, 95% CI 21-36) viral load was detectable (range 50-58884 copies/ml). From 15 patients with viral load >1000 copies/ml, 12 viruses were sequenced: eight were C subtypes and four were circulating recombinant forms (CRF08). Eight (5%; 95% CI 2-9) patients with detectable viral load had one or more major resistance mutations. Nucleoside reverse transcriptase inhibitor (NRTI) and non-NRTI mutations were observed. There were no major mutations for resistance to protease inhibitors. In Maputo, the level of detectable viraemia is reassuringly low. While embarking on ART scale-up, wider surveillance is warranted to monitor programme quality and limit the development of drug resistance, which remains a major potential challenge for the future of ART in Africa.

Objective: Drug resistance interpretation systems are used to select the optimal antiretroviral therapy in HIV-infected patients. It is unclear how the systems perform in predicting therapy success and failure and in how far the interpretations are affected by insufficient drug levels., Methods: The accuracy of nine different interpretation systems in predicting therapy outcomes was evaluated using virological, immunological, pharmacological, and clinical data of 130 patients treated at 13 outpatient centers. Individual susceptibility scores of the interpretation systems were converted into active drug scores (ADS) and correlated with therapy success and failure, defined as viral load reduction of equal to or more (n=66) and less than 1 log10 copies/ml (n=64) at three months after drug resistance testing., Results: Three interpretation systems considered the respective therapies as more active compared to the other interpretation systems (p<0.01). These systems predicted therapy success better than the other systems, while the others performed better in predicting therapy failure. Thus, the overall rate of correctly predicted treatment outcomes was comparable between the different systems (73.1-80.0 %). Univariate and multivariate regression analysis revealed significant correlations between the ADS of all interpretation systems and virological therapy outcomes (p<0.0001). In contrast, only three interpretation systems were significantly correlated with immunological therapy outcomes in univariate and just one in multivariate models (p<0.05). Among 128 determinations of drug levels in 64 patient samples, 19.4 % revealed no detectable drug levels. The consideration of insufficient drug levels significantly improved the prediction accuracy of all interpretation systems (p<0.005)., Conclusion: Differences between interpretation systems in predicting therapy failures and success need to be considered for future consensus algorithms. The prediction accuracy of interpretation systems can be improved by consideration of plasma drug levels.

Our study aimed to complete the published data on ARV therapy in Africa by describing the baseline situation in Rwanda before the launch of a large ARV programme (ESTHER). Prescription habits, frequency and reasons for treatment interruptions but also antiviral efficay, resistance to ARVs and genotypic variability of the viruses present in Rwanda were analysed. Among the 233 patients included in the study, it appeared that a vast majority (91%) were under triple therapy and that half of them had experienced at least one treatment interruption caused mainly by drug shortage or financial difficulties. Among 60 blood samples analysed, 26 were in virological failure with a viral load above 1000 RNA copies/ml and 11 presented major drug resistance mutations. Finally, virological failure could mainly be explained by the high frequency of treatment interruptions but also by the emergence of drug resistance mutations. Consequently the major objective for the ESTHER programme to improve the situation in Rwanda will be to reduce the drug shortage and facilitate the financial accessibility of the treatments.

Background: Resistance testing is increasingly accepted as a tool in guiding the selection of human immunodeficiency virus type 1 (HIV-1) antiretroviral therapy in HIV-1 infected individuals who fail their current regimen., Objectives: To descriptively compare the correlation between virologic treatment response and results using three genotypic HIV-1 drug resistance interpretation systems: the VERSANT HIV-1 Resistance Assay (LiPA) system and two sequence-based interpretation systems., Study Design: Specimens from 213 HIV-1-infected subjects, either starting (n=104) or switching to (n=109) a regimen of three or four antiretroviral drugs, were collected retrospectively at baseline and after 3 months of uninterrupted therapy. The correlation between viral load change and the number of predicted active drugs in the treatment regimen was assessed. An interpretation algorithm was recently developed to process VERSANT HIV-1 Resistance Assay (LiPA) data. The number of active drugs predicted using this algorithm was rank correlated with the viral load change over a 3-month treatment period. For comparison, a similar calculation was made using two sequence-based algorithms (REGA version 5.5 and VGI GuideLines Rules 4.0), both applied on the same sequences., Results: Statistically significant (p<0.05) correlation coefficients for each of the three HIV-1 drug resistance interpretation systems were observed in the treatment-experienced subjects on a 3-drug regimen (-0.39, -0.38, and -0.42, respectively) as well as on a 4-drug regimen (-0.33, -0.31, and -0.37, respectively). However, no significant correlation was observed in treatment-naive subjects, probably due to the very low frequency of drug resistance in these subjects., Conclusion: All three genotypic drug resistance interpretation systems (LiPA version 1, REGA version 5.5, and VGI GuideLines Rules 4.0) were statistically significantly correlated with virologic therapy response as measured by viral load testing.

In most European countries, HIV drug resistance testing has become a routine clinical tool. However, its practical implementation in a clinical context is demanding. The European HIV Drug Resistance Panel was established to make recommendations to clinicians and virologists on this topic and to propose quality control measures. The panel recommends resistance testing for the following indications: i) drug-naive patients with acute or recent infection; ii) therapy failure, including suboptimal treatment response, when treatment change is considered; iii) pregnant HIV-1-infected women and paediatric patients with detectable viral load when treatment initiation or change is considered; and iv) genotype source patient when post-exposure prophylaxis is considered. In addition, for drug-naive patients with chronic infection in whom treatment is to be started, the panel suggests that resistance testing should be strongly considered and recommends testing the earliest sample for drug resistance if suspicion of resistance is high or prevalence of resistance in this population exceeds 10%. The panel does not favour genotyping over phenotype, however it is anticipated that genotyping will be used more often because of its greater accessibility, lower cost and faster turnaround time. For the interpretation of resistance data, clinically validated systems should be used to the greatest extent possible. It is mandatory that laboratories performing HIV resistance tests take regular part in quality assurance programs. Similarly, it is necessary that HIV clinicians and virologists take part in continuous education and meet regularly to discuss problematic clinical cases. Indeed, resistance test results should be used in the context of all other clinically relevant information for predicting therapy response. The panel also encourages the timely collection of epidemiological information to estimate the impact of transmission of resistant HIV and the prevalence of HIV-1 non-B subtypes in the different European countries.

Enfuvirtide (T-20) is the lead compound of the new class of antiretroviral drugs called fusion inhibitors. T-20 resistance-associated mutations located in the heptad repeat 1 (HR-1) domain of gp41 have been described in vitro and in clinical trials. In this study, the authors investigated the primary genotypic T-20 resistance in subtype B and non-B HIV-1 strains from patients at the beginning of their follow-up in the Luxembourg HIV Cohort as well as the emergence of primary resistance to T-20 in patients who had long-term infection with subtype B HIV-1 strains. HR-1 fragments including the gp41 amino acid 36-45, T-20-sensitive region were screened for amino acid variation. No classic T-20 resistance-associated mutations were identified in subtype B or non-B isolates. However, several uncommon mutations were found at residues 37, 39, and 42 for subtype B isolates and at residue 42 for a subtype non-B isolate. The results indicate that primary genotypic T-20 resistance seems to be rare in HIV-1, regardless of subtype or prior antiretroviral therapy (excluding fusion inhibitors). However, episodic variation within HR-1 can occur and needs further phenotypic evaluation in accurate fusion inhibitor resistance assays.

The emergence of HIV strains that are resistant to antiretroviral drugs is a major cause of treatment failure. Two sets of mutations: the Q151 M complex and the 69 insert, cause resistance to multiple nucleoside analogues. We report the response to treatment in 12 patients with multiple NRTI-resistant HIV-1 strains. Seven of 12 patients (58%) were able to maintain a viral load below 200 copies/ml at week 48. The patients most likely to obtain therapeutic success were those having no or low-level resistance to non-nucleoside reverse transcriptase inhibitors and/or protease inhibitors. New and more effective drugs are needed for patients with HIV-1 that is resistant to more than one of the current three classes of HIV drugs.

Background: The efficacy of treatment containing nonnucleoside reverse transcriptase inhibitors (NNRTIs) could be compromised in NNRTI-naïve patients already harboring a virus resistant to NNRTIs. On the contrary, hypersusceptibility to NNRTIs in patients having failed nucleoside reverse transcriptase inhibitor (NRTI)-containing regimens has been described and has been associated with improved outcome., Method: We assessed the prevalence of NNRTI resistance-associated mutations or polymorphisms in 146 antiretroviral-naïve patients and in 181 HIV-infected patients who were given an NNRTI-based regimen. We phenotypically evaluated the NNRTI susceptibility of 41 strains presenting with amino acid substitutions at positions involved in NNRTI resistance., Results: In the 268 genotypically analyzable samples, the overall prevalence of NNRTI resistance-associated mutations was 2% (6/268 patients). The prevalence of strains with amino acid substitutions at reverse transcriptase (RT) gene positions (A98, K101, K103, V106, V108, V179) involved in NNRTI resistance was 15%. Hypersusceptibility to NNRTI was rare (2%, 1/41) in those samples. RT substitutions at positions involved in NNRTI resistance were not associated with a significantly worse virologic outcome in NNRTI-treated patients. Our understanding of small shifts in IC50 values (higher or lower) toward NNRTI is very limited. The significance of many RT mutations on NNRTI susceptibility is not clear., Conclusion: In contrast to resistance mutations, RT substitutions at positions involved in NNRTI resistance are frequent. They are not associated with a worse virologic outcome or with decreased phenotypic susceptibility to NNRTIs. It may be prudent not to rule out the use of NNRTIs in patients with small shifts in IC50 values or poorly understood mutations.

Objectives: To investigate the genotypic and phenotypic effects of in vitro resistance selection with lamivudine and/or the second generation non-nucleoside reverse transcriptase inhibitor (NNRTI) quinoxaline HBY097 using HIV-1 isolates carrying the multi-nucleoside resistance pattern linked to the Q151M mutation., Methods: Virus strains were selected in C8166 cells in the presence of increasing concentrations of lamivudine or HBY097. In parallel control experiments, the virus was cultured in C8166 cells in the absence of drugs. The entire reverse transcriptase encoding region was amplified using polymerase chain reaction and was subsequently sequenced. Antiviral activities of drugs were evaluated in C8166 cells., Results: High-level resistant viruses were selected rapidly in the presence of lamivudine and quinoxaline (less than 10 passages). The multi-nucleoside resistance mutations were stable during in vitro resistance selection. Lamivudine elicited the acquisition of the M184I mutation. Phenotypic resistance to all nucleoside-analog reverse transcriptase inhibitors (NRTIs) was increased when M184I was added to the multi-nucleoside resistance background in the absence of NNRTI-resistance mutations. In most cases of HBY097 resistance selection, at least two mutations associated with NNRTI resistance resulted in high-level NNRTI resistance. The NNRTI resistance-related mutations partially reversed the phenotypic resistance to most NRTIs, except to abacavir. The addition of the M184I mutation to the NNRTI-multi-nucleoside resistance set abolished this antagonizing effect for didanosine, zalcitabine and lamivudine, but further potentiated the phenotypic reversal for zidovudine and stavudine., Conclusion: Changes in the non-nucleoside binding pocket must affect the conformation of residues at the dNTP binding site, and can result in a partial phenotypic reversal of the multi-nucleoside resistance phenotype.

Background: Azodicarbonamide (ADA), a HIV-1 zinc finger inhibitor, targets a new step in viral replication and cell infectivity., Objective: A first phase I/II clinical study of ADA., Methods: ADA was administered at escalating doses concomitantly with current antiviral therapy during a 3-month open-label period in patients with advanced AIDS and documented virological failure. After 3 months, patients were randomized in a double-blind placebo-controlled withdrawal, ADA being given at the highest tolerated dosage., Results: Fifteen patients with advanced disease failing on combined antiretroviral therapy, 75% of them with proven phenotypic resistance, had a median baseline CD4 cell count of 85 x 10(6) cells/l, CD4/CD8 cell ratio of 0.09 and median plasma RNA viral load of 4.2 log10 copies/ml. Tolerance to ADA was dose dependent and some patients developed nephrolithiasis, glucose intolerance or showed an ADA-related cytotoxicity towards CD4 cells at higher dosages. No patient died during the study period. ADA increased CD4 cell percentage, increased the CD4/CD8 cell ratio and decreased plasma RNA viral load from baseline. At the end of the double-blind period, the ADA group, but not the placebo group, showed a significant response (P < 0.05). No phenotypic resistance to ADA was observed. Overall, 3/11 patients (27%) had consistent viral load reductions > 0.5 log10 copies/ml compared with baseline and 5/ 11 (45%) showed a CD4 cell recovery from baseline > 33%. In responders, ADA induced a median peak increase in CD4 cell percentage change from baseline of 65% (range 47-243%), and viral load decrease of 1.04 log10 copies/ml (range 0.52-1.23)., Conclusions: The maximal tolerated dosage of ADA appears to be 2 g (three times daily). This study provides safety results that will allow larger clinical trials to confirm the preliminary efficacy data.

The prevalence and the genotypic and phenotypic characteristics of multinucleoside-resistant (MNR) human immunodeficiency virus type 1 (HIV-1) variants in Europe were investigated in a multicenter study that involved centers in nine European countries. Study samples (n = 363) collected between 1991 and 1997 from patients exposed to two or more nucleoside analogue reverse transcriptase inhibitors (NRTIs) and 274 control samples from patients exposed to no or one NRTI were screened for two marker mutations of multinucleoside resistance (the Q151M mutation and a mutation with a 2-amino-acid insertion at codon 69, T69S-XX). Q151M was identified in six of the study samples (1. 6%), and T69S-XX was identified in two of the study samples (0.5%; both of them T69S-SS), but both patterns were absent among control samples. Non-NRTI (NNRTI)-related changes were observed in viral strains from two patients, which displayed the Q151M resistance pattern, although the patients were NNRTI naive. The patients whose isolates displayed multinucleoside resistance had received treatment with zidovudine and either didanosine, zalcitabine, or stavudine. Both resistance patterns conferred broad cross-resistance to NRTIs in vitro and a poor response to treatment in vivo. MNR HIV-1 is found only among multinucleoside-experienced patients. Its prevalence is low in Europe, but it should be closely monitored since it seriously limits treatment options.

HIV-1 samples from six patients undergoing diverse anti-HIV therapies possessed the E138A mutation in their reverse transcriptase (RT) genome. Patients were receiving the following therapies: TIBO monotherapy (one patient); zidovudine plus didanosine combination therapy (one); zidovudine monotherapy (one); sequential therapy with zidovudine, then stavudine and finally zalcitabine plus didanosine (one); and two were drug naive. E138K, not E138A, is a known TSAO-specific resistance mutation, emerging under selective pressure in vitro. Our phenotypic data on the patient isolates, confirmed by data on an E138A mutant acquired through in vitro mutagenesis, indicated that an alanine substitution for glutamate at codon 138 of the HIV-1 RT renders the virus TSAO resistant, confirming the importance of this amino acid residue in the activity of TSAO derivatives. In addition, we have demonstrated through phenotypic analysis of the E138A and A98S mutants (after in vitro mutagenesis) that the mutation A98S, found in one of these patients, could be partially responsible for the phenotypic reversal of TSAO resistance. This reversal could be explained by the restoration of a hydrogen bond between 98S and the main-chain residue L349, which compensates for the loss of the E138-G99 main-chain hydrogen bond. As TSAO derivatives have not been used in the clinical setting, the presence of the E138A mutation at a frequency of 6.7% in our study of 90 TSAO-inexperienced HIV-seropositive individuals implies that 138A of the RT must be a natural variant and that the mutant virus is replication competent. Our observations suggest that the E138A mutation may likely arise in patients under the selective pressure of TSAO or related compounds that show a decreased antiviral potency toward the E138A variant.

Objective: To study the prevalence of multiple dideoxynucleoside (ddN)-resistant (MddNR) HIV-1 in European patients under treatment with multiple ddN analogues, and to characterize MddNR strains genotypically and phenotypically., Design and Methods: Blood samples from patients after > or = 6 months of treatment with multiple ddN were screened for the MddNR mutation Q151M. After confirmation of MddNR in 15 patients from five European countries, genotypic resistance was evaluated by DNA sequencing of the reverse transcriptase (RT) gene. Phenotypic resistance was measured by the recombinant virus assay. Results were compared with the clinical evolution of the patients., Results: The prevalence of MddNR strains in European patients treated with multiple ddN analogues was 3.5%. Viruses typically contained amino acid substitutions V75F, F77L, F116Y and Q151M in the RT gene. A new mutation, S68G, was frequently associated with MddNR. Phenotypically, viruses displayed high-level resistance to zidovudine (ZDV), didanosine (ddl), zalcitabine (ddC), stavudine (d4T) and partial resistance to lamivudine (3TC) once multiple mutations were present. Under in-vivo treatment pressure, some MddNR strains additionally developed resistance to protease inhibitors or non-nucleoside RT inhibitors (NNRTI). Clinically, most patients had advanced HIV disease with low CD4 cell counts, high viral loads and a rapid progression, but two patients harbouring MddNR virus responded well to dual protease inhibitor associations., Conclusions: MddNR resistant HIV-1 can be found in European patients. MddNR is characterized by a specific set of drug resistance mutations, cross-resistance to most ddN analogues and a fast clinical progression. MddNR can be associated with protease inhibitor or NNRTI resistance.

The performance to detect drug resistance mutations in the reverse transcriptase gene of HIV-1 was compared for direct solid phase sequencing, selective polymerase chain reaction (PCR) using the amplification refractory mutation system (ARMS) and the new line probe assay (LIPA) HIV-1 RT. The three tests were undertaken on 50 plasma samples from 25 treatment-experienced patients under combination therapy with dideoxynucleoside analogues. LiPA HIV-1 RT gave interpretable results in 80 to 96% of the samples depending on the codon of interest. In 2% of the samples a failure to amplify resulted in uninterpretable results for sequencing. ARMS gave no result in seven samples (14%). Overall, there was a 73 to 100% concordance between the three methods. In this study, LiPA HIV-1 RT proved to be an accurate and reliable alternative to DNA sequencing for the detection of drug resistance mutations in patient samples.

We report the development of a new group of nonnucleoside reverse transcriptase inhibitors (NNRTIs). One of the most active congeners of this series of 1,1,3-trioxo-2H,4H-thieno[3,4-e] [1,2,4]thiadiazine (TTD) derivatives, i.e., 2-(3-fluorobenzyl)-4-cyanomethylen-l,1,3-trioxo-2H,4H- thieno [3,4-e] [1,2,4] thiadiazine) (QM96639) was found to inhibit human immunodeficiency virus (HIV) type 1 [HIV-1 (IIIB)] replication in MT-4 cells at a concentration of 0.09 microM. This compound was toxic for the host cells only at a 1,400-fold higher concentration. The TTD derivatives proved effective against a variety of HIV-1 strains, including those that are resistant to 3'-azido-3'-deoxythymidine (AZT), but not against HIV-2 (ROD) or simian immunodeficiency virus (SIV/ MAC251). HIV-1 strains containing the L100I, K103N, V106A, E138K, Y181C, or Y188H mutations in their reverse transcriptase (RT) displayed reduced sensitivity to the compounds. Their cross-resistance patterns correlated with that of nevirapine. 2-Benzyl-4-cyanomethylen-1,1,3-trioxo-2H,4H-thieno[3,4-e] [1,2,4]thiadiazine (QM96521) enhanced the anti-HIV-1 activity of AZT and didanosine in a subsynergistic manner. HIV-1-resistant virus containing the V179D mutation in the RT was selected after approximately six passages of HIV-1 (IIIB) in CEM cells in the presence of different concentrations of QM96521. From structure-activity relationship analysis of a wide variety of TTD derivatives, a number of restrictions appeared as to the chemical modifications that were compatible with anti-HIV activity. Modelling studies suggest that in contrast to most other NNRTIs, but akin to nevirapine, QM96521 does not act as a hydrogen bond donor in the RT-drug complex.

From a series of macrocyclic diamides possessing the disulfide linkage, only SRR-SB3, a compound that complexes with zinc, was found to inhibit human immunodeficiency virus type 1 (HIV-1; strain IIIB) replication at a concentration of 1.8 to 6.5 micrograms/ml in MT-4, CEM, and peripheral blood mononuclear cells. SRR-SB3 was toxic to MT-4 cells at a concentration of 15.9 micrograms/ml, resulting in a selectivity index of 9 in these cells. This macrolide was also effective against various other HIV-1 strains, including clinical isolates and HIV-1 strains resistant to protease inhibitors and nucleoside and nonnucleoside reverse transcriptase inhibitors. It was also active against various HIV-2 strains, simian immunodeficiency virus (strain MAC251), and Moloney murine sarcoma virus, but not against viruses other than retroviruses. In addition, the compound was found to inhibit chronic HIV-1 infections in vitro. The compound in combination with other antiviral agents, such as zidovudine, zalcitabine, and stavudine, showed an effect that was between additive and synergistic. Time-of-addition experiments indicated that SRR-SB3 acts at a late stage of the HIV-1 replicative cycle.

Sodium valproate (VPA), a simple branched-chain fatty acid that has anticonvulsant activity and is used in the treatment of many forms of epilepsy, has been reported to stimulate human immunodeficiency virus (HIV) type 1 replication in acutely infected CEM and chronically infected U1 cells (Chemico-Biological Interactions 1994;91:111-121). When attempting to reproduce and extend these findings, we confirmed that VPA is able to stimulate HIV-1(IIIB) replication in acutely infected CEM and C8166 T lymphocytic cell lines and chronically infected ACH-2 and U937/IIIB/LAI cells in a concentration-dependent manner. The stimulatory effect of VPA on HIV replication in CEM cells was not increased by pretreatment of the cells with VPA for 24 hr before infection. However, we could not detect any stimulatory effect of VPA on HIV-1(IIIB) replication in acutely infected peripheral blood mononuclear cells (PBMCs), MT-4, MT-2, HUT-78, and MOLT-4 (clone 8) cells and in chronically infected HUT-78/IIIB/LAI cells. The stimulatory effect by VPA under certain conditions (see above) may be ascribed to an enhanced HIV transcription, as VPA was found to enhance the HIV long terminal repeat (LTR)-directed expression of beta-galactosidase in transiently transfected HLtat, P4, and COS7 cells. VPA did not enhance beta-galactoside expression mediated by the cytomegalovirus (CMV) promoter. VPA did not affect HIV-induced syncytium formation. Nor had VPA any direct inactivating effect on HIV.

Objective: To evaluate the immunological and virological efficacy of triple combination therapy with zidovudine (ZDV) plus zalcitabine (ddC) plus lamivudine (3TC) and a double (ZDV+3TC) combination therapy in patients previously treated with ZDV plus ddC., Design: A 6-month follow-up open-label randomized study was undertaken in 46 HIV-1-infected patients previously treated for at least 6 months with ZDV plus ddC, who were allocated to receive either ZDV/ddC/3TC (n = 15) or ZDV/3TC (n = 15) or to continue with the ZDV/ddC regimen (control group; n = 16)., Methods: Changes in CD4+ cell counts and plasma viral load (VL) were analysed with analysis of variance. Sequencing of the reverse transcriptase gene was performed in a subset of 3TC-treated patients., Results: Mean CD4+ cell counts increased significantly above baseline in both 3TC regimens whereas counts decreased in the control group. Significant plasma VL reduction was achieved in both 3TC combination therapy groups at weeks 4 and 24 compared with the control group. Coexistence of mutations conferring resistance to ZDV and 3TC were found in patients from both 3TC treatment groups., Conclusions: Both therapy strategies, switching ddC to 3TC or adding 3TC, significantly improved the virological and immunological efficacy compared with continuing ZDV/ddC. Our results support the use of 3TC in patients previously treated with the ZDV/ddC combination.