Tracing the HIV-1 subtype B mobility in Europe: a phylogeographic approach.

BACKGROUND: The prevalence and the origin of HIV-1 subtype B, the most prevalent circulating clade among the long-term residents in Europe, have been studied extensively. However the spatial diffusion of the epidemic from the perspective of the virus has not previously been traced. RESULTS: In the current study we inferred the migration history of HIV-1 subtype B by way of a phylogeography of viral sequences sampled from 16 European countries and Israel. Migration events were inferred from viral phylogenies by character reconstruction using parsimony. With regard to the spatial dispersal of the HIV subtype B sequences across viral phylogenies, in most of the countries in Europe the epidemic was introduced by multiple sources and subsequently spread within local networks. Poland provides an exception where most of the infections were the result of a single point introduction. According to the significant migratory pathways, we show that there are considerable differences across Europe. Specifically, Greece, Portugal, Serbia and Spain, provide sources shedding HIV-1; Austria, Belgium and Luxembourg, on the other hand, are migratory targets, while for Denmark, Germany, Italy, Israel, Norway, the Netherlands, Sweden, Switzerland and the UK we inferred significant bidirectional migration. For Poland no significant migratory pathways were inferred. CONCLUSION: Subtype B phylogeographies provide a new insight about the geographical distribution of viral lineages, as well as the significant pathways of virus dispersal across Europe, suggesting that intervention strategies should also address tourists, travellers and migrants.

HIV-1 coreceptor usage and CXCR4-specific viral load predict clinical disease progression during combination antiretroviral therapy.

BACKGROUND: Although combination antiretroviral therapy (cART) dramatically reduces rates of AIDS and death, a minority of patients experience clinical disease progression during treatment. OBJECTIVE: To investigate whether detection of CXCR4(X4)-specific strains or quantification of X4-specific HIV-1 load predict clinical outcome. METHODS: From the Swiss HIV Cohort Study, 96 participants who initiated cART yet subsequently progressed to AIDS or death were compared with 84 contemporaneous, treated nonprogressors. A sensitive heteroduplex tracking assay was developed to quantify plasma X4 and CCR5 variants and resolve HIV-1 load into coreceptor-specific components. Measurements were analyzed as cofactors of progression in multivariable Cox models adjusted for concurrent CD4 cell count and total viral load, applying inverse probability weights to adjust for sampling bias. RESULTS: Patients with X4 variants at baseline displayed reduced CD4 cell responses compared with those without X4 strains (40 versus 82 cells/microl; P = 0.012). The adjusted multivariable hazard ratio (HR) for clinical progression was 4.8 [95% confidence interval (CI) 2.3-10.0] for those demonstrating X4 strains at baseline. The X4-specific HIV-1 load was a similarly independent predictor, with HR values of 3.7 (95% CI, 1.2-11.3) and 5.9 (95% CI, 2.2-15.0) for baseline loads of 2.2-4.3 and > 4.3 log10 copies/ml, respectively, compared with < 2.2 log10 copies/ml. CONCLUSIONS: HIV-1 coreceptor usage and X4-specific viral loads strongly predicted disease progression during cART, independent of and in addition to CD4 cell count or total viral load. Detection and quantification of X4 strains promise to be clinically useful biomarkers to guide patient management and study HIV-1 pathogenesis.

Transmission of HIV-1 drug resistance in Switzerland: a 10-year molecular epidemiology survey.

OBJECTIVES: Representative prevalence data of transmitted drug-resistant HIV-1 are essential to establish accurate guidelines addressing resistance testing and first-line treatments. METHODS: Systematic resistance testing was carried out in individuals in Switzerland with documented HIV-1 seroconversion during 1996-2005 and available samples with RNA > 1000 copies/ml obtained within 1 year of estimated seroconversion. Resistance interpretation used the Stanford list of mutations for surveillance of transmitted drug resistance and the French National Agency for AIDS Research algorithm. RESULTS: Viral sequences from 822 individuals were available. Risk groups were men having sex with men (42%), heterosexual contacts (32%) and intravenous drug users (20%); 30% were infected with non-B subtype viruses. Overall, prevalence of transmitted resistance was 7.7% [95% confidence interval (CI), 5.9-9.5] for any drug, 5.5% (95% CI, 3.9-7.1) for nucleoside reverse transcriptase inhibitors, 1.9% (95% CI, 1.0-2.8) for non-nucleoside reverse transcriptase inhibitors and 2.7% (95% CI, 1.6-3.8) for protease inhibitors. Dual- or triple-class resistance was observed in 2% (95% CI, 0.8-2.5). No significant trend in prevalence of transmitted resistance was observed over years. There were no differences according to ethnicity, risk groups or gender, but prevalence of transmitted resistance was highest among individuals infected with subtype B virus. CONCLUSIONS: The transmission rate of drug-resistant HIV-1 has been stable since 1996, with very rare transmission of dual- or triple-class resistance. These data suggest that transmission of drug resistance in the setting of easy access to antiretroviral treatment can remain stable and be kept at a low level.

Emergence of HIV-1 drug resistance in previously untreated patients initiating combination antiretroviral treatment: a comparison of different regimen types.

BACKGROUND: Standard first-line combination antiretroviral treatment (cART) against human immunodeficiency virus 1 (HIV-1) contains either a nonnucleoside reverse transcriptase inhibitor (NNRTI) or a ritonavir-boosted protease inhibitor (PI/r). Differences between these regimen types in the extent of the emergence of drug resistance on virological failure and the implications for further treatment options have rarely been assessed. METHODS: We investigated virological outcomes in patients from the Swiss HIV Cohort Study initiating cART between January 1, 1999, and December 31, 2005, with an unboosted PI, a PI/r, or an NNRTI and compared genotypic drug resistance patterns among these groups at treatment failure. RESULTS: A total of 489 patients started cART with a PI, 518 with a PI/r, and 805 with an NNRTI. A total of 177 virological failures were observed (108 [22%] PI failures, 24 [5%] PI/r failures, and 45 [6%] NNRTI failures). The failure rate was highest in the PI group (10.3 per 100 person-years; 95% confidence interval [CI], 8.5-12.4). No difference was seen between patients taking a PI/r (2.7; 95% CI, 1.8-4.0) and those taking an NNRTI (2.4; 95% CI, 1.8-3.3). Genotypic test results were available for 142 (80%) of the patients with a virological treatment failure. Resistance mutations were found in 84% (95% CI, 75%-92%) of patients taking a PI, 30% (95% CI, 12%-54%) of patients taking a PI/r, and 66% (95% CI, 49%-80%) of patients taking an NNRTI (P < .001). Multidrug resistance occurred almost exclusively as resistance against lamivudine-emtricitabine and the group-specific third drug and was observed in 17% (95% CI, 9%-26%) of patients taking a PI, 10% (95% CI, 0.1%-32%) of patients taking a PI/r, and 50% (95% CI, 33%-67%) of patients taking an NNRTI (P < .001). CONCLUSIONS: Regimens that contained a PI/r or an NNRTI exhibited similar potency as first-line regimens. However, the use of a PI/r led to less resistance in case of virological failure, preserving more drug options for the future.

New complete genome sequences of human rhinoviruses shed light on their phylogeny and genomic features.

BACKGROUND: Human rhinoviruses (HRV), the most frequent cause of respiratory infections, include 99 different serotypes segregating into two species, A and B. Rhinoviruses share extensive genomic sequence similarity with enteroviruses and both are part of the picornavirus family. Nevertheless they differ significantly at the phenotypic level. The lack of HRV full-length genome sequences and the absence of analysis comparing picornaviruses at the whole genome level limit our knowledge of the genomic features supporting these differences. RESULTS: Here we report complete genome sequences of 12 HRV-A and HRV-B serotypes, more than doubling the current number of available HRV sequences. The whole-genome maximum-likelihood phylogenetic analysis suggests that HRV-B and human enteroviruses (HEV) diverged from the last common ancestor after their separation from HRV-A. On the other hand, compared to HEV, HRV-B are more related to HRV-A in the capsid and 3B-C regions. We also identified the presence of a 2C cis-acting replication element (cre) in HRV-B that is not present in HRV-A, and that had been previously characterized only in HEV. In contrast to HEV viruses, HRV-A and HRV-B share also markedly lower GC content along the whole genome length. CONCLUSION: Our findings provide basis to speculate about both the biological similarities and the differences (e.g. tissue tropism, temperature adaptation or acid lability) of these three groups of viruses.

Predictors of virological outcome and safety in primary HIV type 1-infected patients initiating quadruple antiretroviral therapy: QUEST GW PROB3005.

BACKGROUND: Initiation of antiretroviral therapy during primary human immunodeficiency virus (HIV)-1 infection may confer long-term benefit. METHODS: After initiation of zidovudine, lamivudine, abacavir, and amprenavir therapy in patients in the QUEST cohort, predictors of virological outcome, virological and immunological changes, and adverse events were evaluated over 48 weeks. RESULTS: One hundred forty-eight patients started antiretroviral therapy during primary HIV-1 infection with < or =3 bands on Western Blot (median plasma HIV-1 RNA load, 5.4 log copies/mL; median CD4 cell count, 517 cells/mm(3)). By week 48, 36% of patients had stopped treatment or were lost to follow-up. Among the 115 patients receiving follow-up care at week 48 (102 of whom were receiving antiretroviral therapy), the median viral load decrease was -5.4 log copies/mL (interquartile range [IQR], -6.4 to -3.9 log copies/mL), and the median increase in CD4 cell count was 147 cells/mm(3) (IQR, -1 to 283 cells/mm(3)); 84.2% of patients had a viral load < or =50 copies/mL, and 44.7% of patients had a viral load < or =3 copies/mL. The median cell-associated RNA level decreased from 3.4 log copies/million PBMCs (IQR, 2.9-4.1 log copies/million PBMCs) to 0.8 log copies/million PBMCs (IQR, 0.5-1.4 log copies/million PBMCs), and the median cell-associated DNA level decreased from 2.8 log copies/million PBMCs (IQR, 2.4-3.0 log copies/million PBMCs) to 1.6 log copies/million PBMCs (IQR, 1.2-1.9 log copies/million PBMCs); 33.3% of patients had an undetectable RNA level, and 9.5% of patients had an undetectable cell-associated DNA level. The median CD8(+)/CD38(++) T cell count decreased from 459 cells/mm(3) (IQR, 208-974 cells/mm(3)) to 33 cells/mm(3) (IQR, 19-75 cells/mm(3)). Baseline CD8(+)/CD38(++) T cell count and cell-associated DNA level were independent inverse predictors for reaching a viral load < or =3 copies/mL. Eighty-three patients experienced a serious adverse event (median duration of an adverse event, 15 days).Conclusions. Initiation of antiretroviral therapy during primary HIV-1 infection was associated with very significant antiretroviral activity and a decrease in immune activation. Lower baseline CD8(+)/CD38(++) T cell count and cell-associated DNA level were predictive of achieving a viral load < or =3 copies/mL.

Cytomegalovirus quantification in plasma by an automated real-time PCR assay.

BACKGROUND: Sensitive quantitation of cytomegalovirus (CMV) DNA in blood is helpful for the diagnosis of CMV infection or reactivation and the monitoring of transplanted patients. OBJECTIVES: We compared a new PCR assay coupled with an automated extraction system (CMV real-time PCR, Abbott Molecular, Des Plaines, IL, USA) to a previously validated method (ultrasensitive Cobas Amplicor CMV DNA Monitor, Roche Molecular, Indianapolis, IN, USA). RESULTS: Using limiting dilutions of CMV DNA positive plasma, the two assays had a similar detection threshold ranging between 20 and 45 copies/ml. Coefficients of variation of CMV real-time PCR assay varied from 1 to 12% for CMV DNA levels between 10,000 and 20 copies/ml. Viral loads assessed by the two methods on 179 clinical samples showed an overall concordance of 89% and an excellent correlation (R=0.94). Discrepancies were only observed for samples with low CMV DNA levels (<300 copies/ml); 18 samples were positive by CMV real-time PCR only, and 2 samples by ultrasensitive Cobas CMV only. Values obtained by CMV real-time PCR were on average 0.4 log higher than those of ultrasensitive Cobas CMV. Successive samples of transplanted patients with evidence of CMV infection/reactivation revealed that CMV real-time PCR assay was positive earlier and for a longer period of time after treatment initiation. CONCLUSIONS: Although both assays had similar analytical performances, the CMV real-time PCR assay has the advantages of automated extraction and higher dynamic range, and shows a trend for an improved sensitivity that might impact on clinical decisions.

HIV viral load monitoring in resource-limited regions: optional or necessary?

Although it is a standard practice in high-income countries, determination of the human immunodeficiency virus (HIV) load is not recommended in developing countries because of the costs and technical constraints. As more and more countries establish capacity to provide second-line therapy, and as costs and technological constraints associated with viral load testing decrease, the question of whether determination of the viral load is necessary deserves attention. Viral load testing could increase in importance as a guide for clinical decisions on when to switch to second-line treatment and on how to optimize the duration of the first-line treatment regimen. In addition, the viral load is a particularly useful tool for monitoring adherence to treatment, performing sentinel surveillance, and diagnosing HIV infection in children aged <18 months. Rather than considering viral load data to be an unaffordable luxury, efforts should be made to ensure that viral load testing becomes affordable, simple, and easy to use in resource-limited settings.

Molecular epidemiology: HIV-1 and HCV sequences from Libyan outbreak.

In 1998, outbreaks of human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) infection were reported in children attending Al-Fateh Hospital in Benghazi, Libya. Here we use molecular phylogenetic techniques to analyse new virus sequences from these outbreaks. We find that the HIV-1 and HCV strains were already circulating and prevalent in this hospital and its environs before the arrival in March 1998 of the foreign medical staff (five Bulgarian nurses and a Palestinian doctor) who stand accused of transmitting the HIV strain to the children.

Chronic rhinoviral infection in lung transplant recipients.

RATIONALE: Lung transplant recipients are particularly at risk of complications from rhinovirus, the most frequent respiratory virus circulating in the community. OBJECTIVES: To determine whether lung transplant recipients can be chronically infected by rhinovirus and the potential clinical impact. METHODS: We first identified an index case, in which rhinovirus was isolated repeatedly, and conducted detailed molecular analysis to determine whether this was related to a unique strain or to re-infection episodes. Transbronchial biopsies were used to assess the presence of rhinovirus in the lung parenchyma. The incidence of chronic rhinoviral infections and potential clinical impact was assessed prospectively in a cohort of 68 lung transplant recipients during 19 mo by screening of bronchoalveolar lavages. MEASUREMENTS AND MAIN RESULTS: We describe 3 lung transplant recipients with graft dysfunctions in whom rhinovirus was identified by reverse transcriptase-polymerase chain reaction in upper and lower respiratory specimens over a 12-mo period. In two cases, rhinovirus was repeatedly isolated in culture. The persistence of a unique strain in each case was confirmed by sequence analysis of the 5'NCR and VP1 gene. In the index case, rhinovirus was detected in the lower respiratory parenchyma. In the cohort of lung transplant recipients, rhinoviral infections were documented in bronchoalveolar lavage specimens of 10 recipients, and 2 presented with a persistent infection. CONCLUSIONS: Rhinoviral infection can be persistent in lung transplant recipients with graft dysfunction, and the virus can be detected in the lung parenchyma. Given the potential clinical impact, chronic rhinoviral infection needs to be considered in lung transplant recipients.

CD4-guided scheduled treatment interruptions compared with continuous therapy for patients infected with HIV-1: results of the Staccato randomised trial.

BACKGROUND: Stopping antiretroviral therapy in patients with HIV-1 infection can reduce costs and side-effects, but carries the risk of increased immune suppression and emergence of resistance. METHODS: 430 patients with CD4-positive T-lymphocyte (CD4) counts greater than 350 cells per muL, and viral load less than 50 copies per mL were randomised to continued therapy (n=146) or scheduled treatment interruptions (n=284). Median time on randomised treatment was 21.9 months (range 16.4-25.3). Primary endpoints were proportion of patients with viral load less than 50 copies per mL at the end of the trial, and amount of drugs used. Analysis was intention-to-treat. This study is registered at ClinicalTrials.gov with the identifier NCT00113126. FINDINGS: Drug savings in the scheduled treatment interruption group, compared with continuous treatment, amounted to 61.5%. 257 of 284 (90.5%) patients in the scheduled treatment interruption group reached a viral load less than 50 copies per mL, compared with 134 of 146 (91.8%) in the continued treatment group (difference 1.3%, 95% CI-4.3 to 6.9, p=0.90). No AIDS-defining events occurred. Diarrhoea and neuropathy were more frequent with continuous treatment; candidiasis was more frequent with scheduled treatment interruption. Ten patients (2.3%) had resistance mutations, with no significant differences between groups. INTERPRETATION: Drug savings with scheduled treatment interruption were substantial, and no evidence of increased treatment resistance emerged. Treatment-related adverse events were more frequent with continuous treatment, but low CD4 counts and minor manifestations of HIV infection were more frequent with scheduled treatment interruption.

Efficacy of nelfinavir-based treatment in the central nervous system of HIV-1 infected patients.

We studied the HIV-1 load and nelfinavir (NFV) concentrations in cerebrospinal fluid (CSF) after long-term successful NFV-based therapy, using ultrasensitive methods of detection. 19 patients without virological failure in plasma, who had been treated with 2 nucleoside analogue reverse transcripaste inhibitors (NRTI) and NFV for a minimum of 18 months were included. HIV-RNA was determined in plasma and CSF using an ultrasensitive method (<2 copies/ml). Total and free concentrations of NFV were analysed using high liquid chromatography with UV-light detection. 12 out of 19 (63%) patients had <2 copies HIV-RNA/ml in CSF. Seven subjects ranged between 3 and 39 copies/ml, 2 of whom had a slightly higher viral load in CSF than in plasma. NFV was detected in CSF in 16 out of 18 patients analysed and was quantifiable in 8 patients, at concentrations ranging from 6 to 29 nM. There was no correlation between NFV concentration and HIV-RNA levels. Long-term therapy with NFV + 2 NRTI showed no increased rate of virological treatment failure within the central nervous system (CNS) in compliant patients, despite earlier reports of lack of NFV penetration to CNS. Using a highly sensitive method, NFV was detected and quantified in the CSF, although at low values, which could have contributed to the high anti-HIV-1 efficacy of the therapy seen in our subjects.

The calculated genetic barrier for antiretroviral drug resistance substitutions is largely similar for different HIV-1 subtypes.

BACKGROUND: The genetic barrier, defined as the number of mutations required to overcome drug-selective pressure, is an important factor for the development of HIV drug resistance. Because of high variability between subtypes, particular HIV-1 subtypes could have different genetic barriers for drug resistance substitutions. This study compared the genetic barrier between subtypes using some 2000 HIV-1 sequences (>600 of non-B subtype) isolated from anti-retroviral-naive patients in Europe. METHODS: The genetic barrier was calculated as the sum of transitions (scored as 1) and/or transversions (2.5) required for evolution to any major drug resistance substitution. In addition, the number of minor protease substitutions was determined for every subtype. RESULTS: Few dissimilarities were found. An increased genetic barrier was calculated for I82A (subtypes C and G), V108I (subtype G), V118I (subtype G), Q151M (subtypes D and F), L210W (subtypes C, F, G, and CRF02_AG), and P225H (subtype A) (P < 0.001 compared with subtype B). A decreased genetic barrier was found for I82T (subtypes C and G) and V106M (subtype C) (P < 0.001 vs subtype B). Conversely, minor protease substitutions differed extensively between subtypes. CONCLUSIONS: Based on the calculated genetic barrier, the rate of drug resistance development may be similar for different HIV-1 subtypes. Because of differences in minor protease substitutions, protease inhibitor resistance could be enhanced in particular subtypes once the relevant major substitutions are selected.

Stable virulence levels in the HIV epidemic of Switzerland over two decades.

OBJECTIVE: To determine whether the virulence of HIV-1 has been changing since its introduction into Switzerland. DESIGN: A prospective cohort study of HIV-1 infected individuals with well-characterized pre-therapy disease history. METHODS: To minimize the effect of recently imported viruses and ethnicity-associated host factors, the analysis was restricted to the white, north-west-European majority population of the cohort. Virulence was characterized by the decline slope of the CD4 cell count (n = 817 patients), the decline slope of the CD4:CD8 ratio (n = 815 patients) and the viral setpoint (n = 549 patients) in untreated patients with sufficient data points. Linear regression models were used to detect correlations between the date of diagnosis (ranging between 1984 and 2003) and the virulence markers, controlling for gender, exposure category, age and CD4 cell count at entry. RESULTS: We found no correlation between any of the virulence markers and the date of diagnosis. Inspection of short-term trends confirmed that virulence has fluctuated around a stable level over time. CONCLUSIONS: The lack of long-term time trends in the virulence markers indicates that HIV-1 is not evolving towards increasing or decreasing virulence at a perceptible rate. Both highly virulent and attenuated strains have apparently been unable to spread at the population level. This result suggests that either the evolution of virulence may be slow or inhibited due to evolutionary constraints, or HIV-1 may have already evolved to optimal virulence in the human host.

Early induction of leukemia inhibitor factor (LIF) in acute HIV-1 infection.

BACKGROUND: Leukemia inhibitor factor (LIF) is thought to play a substantial role in protecting CD4 T cells in lymphoid tissues (LT) from infection by HIV-1. OBJECTIVE: To investigate whether primary HIV-1 infected subjects with sustained virological control (< 1000 HIV-1 RNA copies/ml plasma) post-cessation antiretroviral therapy (ART) had a higher initial LIF response during primary HIV-1 infection (PHI) as compared with those individuals who did not achieve a similar control (> 9000 HIV-1 RNA copies/ml plasma) of HIV-1 replication. MATERIAL AND METHODS: Consecutively obtained HIV plasma samples were collected from primary HIV-1 infected subjects. A group of acutely Epstein-Barr virus-infected subjects and a group of HIV-1-seronegative healthy individuals served as controls. All samples were tested by ELISA for LIF and sgp130, the soluble form of LIF's signalling receptor. RESULTS: LIF and sgp130 plasma levels were significantly increased in primary HIV-1-infected subjects as compared with HIV-1-seronegative controls. Peak plasma levels of LIF occurred during the first week of PHI whereas sgp130 peaked between 2 and 4 weeks after the onset of PHI. Furthermore a positive correlation was found between viral load and plasma levels of LIF during PHI. Both LIF and sgp130 plasma concentrations were significantly lower during the viral rebound phase after treatment interruption as compared with the PHI phase. CONCLUSIONS: LIF induction occurred in the initial stages of viral dissemination during PHI. It may be a part of the virally induced generalized pro-inflammatory response. LIF levels at PHI did not predict low levels of HIV viraemia after discontinuation of ART. LIF was not increased following ART interruption in this early treated population.

Clinical validation of atazanavir/ritonavir genotypic resistance score in protease inhibitor-experienced patients.

OBJECTIVE: To develop a clinically relevant genotypic resistance score for boosted atazanavir (ATV) in protease inhibitor-experienced patients. METHODS: At baseline, 62 patients with HIV-1 RNA > 1000 copies/ml switched to a boosted ATV regimen (300 mg ATV, 100 mg ritonavir once daily); two were excluded from analysis at 3 months as they had undetectable plasma ATV. The impact of baseline protease mutations on virological response (> 1 log10 copies/ml plasma HIV RNA decrease) at 3 months was analysed using Fisher's exact test. Mutations with prevalence > 8% and P < 0.2 were retained. Cochran-Armitage's test was used to select the combination of mutations most strongly associated with reduced virological response. Robustness of the score was investigated using bootstrap resampling. RESULTS: At 3 months, 82% of patients had a virological response and 56% had RNA < 50 copies/ml. Eight mutations (10F/I/V, 16E, 33I/F/V, 46I/L, 60E, 84V, 85V and 90M) were retained in the genotypic resistance score (P = 8.67 x 10) and virological response was observed in 100%, 100%, 80%, 42%, and 0% of patients with none, one, two, three, and four/five mutations, respectively. There was 100% response in patients with a score < 2 independently of the number of active drugs, whereas in patients with a score > or = 3 there was a gradient of response according to the number of active drugs (0%, 29% and 60% with none, one and two/three active drugs, respectively). CONCLUSIONS: The occurrence of three of the eight mutations in the ATV/RTV genotypic resistance score predicted a clinically identifiable reduced response in patients.

HIV-1 p24 may persist during long-term highly active antiretroviral therapy, increases little during short treatment breaks, and its rebound after treatment stop correlates with CD4(+) T cell loss.

The dynamics of HIV-1 RNA during structured treatment interruptions (STIs) are well established, but little is known about viral proteins like p24. We studied 65 participants of an STI trial. Before the trial, continuous highly active antiretroviral therapy (HAART) had suppressed their viral load to <50 copies/mL during 6 months. They then interrupted HAART during weeks 1 through 2, 11 through 12, 21 through 22, 31 through 32, and 41 through 52. The p24 was measured by boosted enzyme-linked immunosorbent assay of plasma pretreated by efficient virus disruption and heat denaturation. At time point 0, p24 was measurable in 22 patients (34%), who had maintained a viral load <50 copies/mL for 25.4 months (median, range: 6.2-38.9 months) under HAART. Viral rebounds during 2-week STIs led to a mean p24 increase of only 0.08 to 0.19 log10 (ie, 20%-60%). Pre-HAART viral load and p24 at time 0 independently predicted p24 rebounds during the 4 2-week STIs. The p24 at time 0 and HIV-1 RNA rebound during weeks 41 through 52 independently determined the concomitant p24 rebound. An increase of p24 but not viral load during the first 8 weeks of the long STI correlated significantly with concomitant CD4(+) T cell loss. Persisting p24 despite successful HAART may reflect virus replication in reservoirs not represented by plasma viral load and has implications for the concept of therapeutic vaccination.

Prevalence of drug-resistant HIV-1 variants in untreated individuals in Europe: implications for clinical management.

BACKGROUND: Infection with drug-resistant human immunodeficiency virus type 1 (HIV-1) can impair the response to combination therapy. Widespread transmission of drug-resistant variants has the disturbing potential of limiting future therapy options and affecting the efficacy of postexposure prophylaxis. METHODS: We determined the baseline rate of drug resistance in 2208 therapy-naive patients recently and chronically infected with HIV-1 from 19 European countries during 1996-2002. RESULTS: In Europe, 1 of 10 antiretroviral-naive patients carried viruses with > or = 1 drug-resistance mutation. Recently infected patients harbored resistant variants more often than did chronically infected patients (13.5% vs. 8.7%; P=.006). Non-B viruses (30%) less frequently carried resistance mutations than did subtype B viruses (4.8% vs. 12.9%; P<.01). Baseline resistance increased over time in newly diagnosed cases of non-B infection: from 2.0% (1/49) in 1996-1998 to 8.2% (16/194) in 2000-2001. CONCLUSIONS: Drug-resistant variants are frequently present in both recently and chronically infected therapy-naive patients. Drug-resistant variants are most commonly seen in patients infected with subtype B virus, probably because of longer exposure of these viruses to drugs. However, an increase in baseline resistance in non-B viruses is observed. These data argue for testing all drug-naive patients and are of relevance when guidelines for management of postexposure prophylaxis and first-line therapy are updated.