The greening of virology: Plant Virology Satellite Symposium, American Society for Virology, UC-Davis, July 12, 2003.
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Virological and pharmacological factors associated with virological response to salvage therapy after an 8-week of treatment interruption in a context of very advanced HIV disease (GigHAART ANRS 097).
Both highly potent antiretroviral drug rescue multi therapy and treatment interruption (TI) have been suggested to be effective in HIV-1 infected-patients with multiple treatment failure. GigHAART-ANRS 097 was the only randomized trial during which an 8-week TI was beneficial in heavily pre-treated patients with multi-drug resistant virus on resuming a multiple-drug salvage regimen. The aim of this study was to analyze virological and pharmacological factors associated with a virological response. Clonal resistance analysis showed that although the viral population was highly mutated and nearly monoclonal at baseline, the 8-week interruption therapy allowed the re-emergence of more susceptible quasispecies to the subsequent salvage therapy, which were not detected by classical genotypic resistance testing. The fact that not every viral clone harbored all resistance viral mutations could explain a part of the virological response to a six to eight drug regimen for patients enrolled in the TI group. This phenomenon was associated with a transient virological response after the use of a GigHAART therapy, but was followed by the re-emergence of baseline resistance pattern and acquisition of additional mutations in patients failing this strategy. A combined factor of protease inhibitor (PI) concentration and genotypic score, expressed as a genotypic inhibitory quotient (GIQ), was used to assess the importance of genotypic resistance and plasma drug levels in the rate of response to multiple PI combination. The GIQ of each PI used in the regimen was not associated with virological success. However, the sum of PI GIQs was predictive of a virological response. These results suggest that pharmacological enhancement might overcome viral resistance and that there is some benefit in adding the activity of several boosted-PIs to improve the response to a salvage regimen.
Anti-HIV Agents↗
Does an increase in nevirapine plasma levels cause complete virologic suppression in patients experiencing early virologic failure?
BACKGROUND: Patients on two nucleoside analogs plus nevirapine (NVP) who show low-level plasma HIV RNA might have insufficient NVP plasma levels and therefore might benefit from an increase in NVP dosing. METHOD: The dose of NVP was increased from 400 mg/day to 600 mg/day in 25 participants taking NVP-containing triple combinations for at least 3 months and experiencing a first virological failure (>50 HIV RNA copies/mL). The levels of NVP were measured in plasma samples taken prior to and 3 months after the intervention. HIV genotyping was performed at the time of dose increase. A control group of 25 participants who showed early virological failure with NVP continued with standard doses of the drug for 3 months. RESULTS: The median HIV RNA and CD4 cell counts were 100 copies/mL and 635 cells/mm(3), respectively. Similar figures were recorded in the control arm. Mean NVP plasma levels that were reached with a dose of 600 mg/day were significantly higher than those with 400 mg/day (7.4 microg/mL [95% CI, 6.4-8.4] vs. 3.4 microg/mL [95% CI, 2.9-3.9]; p <.0001). Thirteen (52%) participants reached <50 HIV RNA copies/mL after the intervention. The greater levels of NVP were relatively well tolerated, with no development of rashes and only mild elevations in transaminase levels. NVP-associated mutations were recognized in 9 of 10 participants who did not respond but only in 3 of 9 responders (p =.019). More frequent mutations appeared at positions 181, 103, 106, and 190. The levels of NVP did not change significantly in participants who were included in the control arm, and only one reached complete virological suppression after continuing treatment for 3 additional months. CONCLUSION: An increase of one pill of NVP per day led to a significant rise in NVP plasma levels. A greater virologic response was noticed among participants with higher NVP plasma levels. Major resistance mutations that conferred resistance to NVP were recognized in all participants who failed to regain virological suppression after increasing NVP dose.
Adult↗
Immunological and virological features of HIV-infected patients with increasing CD4 cell numbers despite virological failure during protease inhibitor-based therapy.
OBJECTIVES: To investigate the extent of functional T cell recovery and to characterize plasma virus and virus producing cells in patients with increasing CD4 cell counts despite virological failure during protease inhibitor (PI) based therapy. METHODS: The study group included 13 patients who were treated for at least 12 months with a PI based regimen and were selected on the basis of a sustained immunological response (increase of > 70 CD4 cells/microL) despite virological failure (< 1 log10 copies/mL decrease in HIV-1 RNA plasma levels). RESULTS: Compared to a historical series of 11 complete responders with less advanced disease, the proportion of memory CD4 T cells was significantly higher (67.8+/-17.8 vs. 52.8+/-11.0; P=0.045) and the proportion of naive CD4 T cells significantly lower (30.5+/-14.8 vs. 45.0+/-10.4, P=0.021) in patients who were immunological responders/virological nonresponders. In those patients, ongoing viral replication was associated with a strong activation of circulating CD8 T lymphocytes; interleukin-2 production remained decreased. CD4 T cell reactivity to cytomegalovirus proteins was observed in nine of 11 patients tested. In the study group, the proportion of infectious virus present in plasma as well as the levels of intracellular viral replication were similar to those measured in untreated patients. Virological failure in this group of patients probably resulted from pre-existing mutations in the reverse transcriptase gene. CONCLUSIONS: This study of patients with increasing CD4 cell numbers despite virological failure shows the persistence of immune activation and partial immune restoration with no evidence of specific viral dynamics in vivo.
Adult↗
Virologic outcome and predictors of virologic failure of highly active antiretroviral therapy containing protease inhibitors.
In this observational single-center cohort study outside the clinical trial setting, outcome and predictors of virologic failure of highly active antiretroviral therapy (HAART) containing a protease inhibitor were evaluated in human immunodeficiency (HIV)-infected persons. The study population consisted of 807 protease inhibitor-naive HIV-seropositive patients who initiated antiretroviral therapy with reverse transcriptase inhibitors and protease inhibitors (indinavir, nelfinavir, ritonavir) between January 1997 and January 1999. Demographic variable, plasma HIV-1 RNA levels, CD4+ T-cell count, adverse drug reactions, and adherence to HAART were assessed. Virologic treatment response was defined as a decrease in plasma HIV-1 RNA load from baseline to below 500 copies per milliliter after 12 months of therapy. Levels of HIV-1 RNA were undetectable in 43% of patients at 12 months. Factors associated with failure to suppress viral load included age 40 years or younger, baseline CD4+ T cell count less than 200 x 10(6) per liter baseline viral load greater than 4.3 log(10) per milliliter, and non-adherence to HAART. After adjustment by logistic regression, non-adherence was the only statistically significant variable associated with virologic failure (odds ratio 0.38, 95% confidence interval 0.21 to 0.67). Unselected patients in whom protease inhibitor is started in a usual clinical setting achieve viral suppression less frequently than do patients in controlled clinical trials. Failure to adherence to HAART was the strongest predictor of virologic failure.
Adult↗
Plasma levels of indinavir and nelfinavir at time of virologic response may have a different impact on the risk of further virologic failure in HIV-infected patients.
Indinavir and nelfinavir plasma levels were studied in 407 patients having plasma HIV RNA <500 copies/mL after 4 months of treatment with these drugs. For each drug, an observed/predicted (O/P) ratio was calculated between individual and mean time-adjusted population plasma drug levels. The relationship between the O/P ratio and the risk of rebound of plasma HIV RNA >500 copies/mL beyond month 4 was studied using Cox proportional hazard models. Median follow-up was 20 months. There was no association between indinavir plasma levels and risk of virologic rebound, whereas low nelfinavir + M8 (active nelfinavir metabolite) plasma levels were associated with a higher risk of virologic rebound. In multivariate analysis, the adjusted relative hazard of virologic rebound for patients with an O/P ratio of nelfinavir + M8 metabolite <0.8 compared with others was 2.2 (P = 0.01). In some patients, plasma levels of nelfinavir sufficient to achieve early viral response may not be sufficient to maintain it in the long term. This may be related to insufficient compliance with dietary recommendations. Monitoring of nelfinavir plasma levels thus seems useful, even in patients having early virologic response.
Biotransformation↗
Baseline resistance and virological outcome in patients with virological failure who start a regimen containing abacavir: EuroSIDA study.
OBJECTIVES: To investigate the ability of several HIV-1 drug-resistance interpretation systems, as well as the number of pre-specified combinations of abacavir-related mutations, to predict virological response to abacavir-containing regimens in antiretroviral therapy-experienced, abacavir-naive patients starting an abacavir-containing regimen in the EuroSIDA cohort. PATIENTS AND METHODS: A total of 100 HIV-infected patients with viral load (VL) >500 copies/ml who had a plasma sample available at the time of starting abacavir (baseline) were included. Resistance to abacavir was interpreted by using eight different commonly used systems that consisted of rules-based algorithms or tables of mutations. Correlation between baseline abacavir-resistance mutations and month 6 virological response was performed on this population using a multivariable linear regression model accounting for censored data. RESULTS: The baseline VL was 4.36 log10 RNA copies/ml [interquartile range (IQR): 3.65-4.99 log10 RNA copies/ml] and the median CD4 cell count was 210 cells/microl (IQR: 67-305 cells/microl). Our patients were pre-exposed to a median of seven antiretrovirals (2-12) before starting abacavir therapy. The median (range) number of abacavir mutations (according to the International AIDS Society-USA) detected at baseline was 3.5 (0-8). Overall, the Kaplan-Meier estimate of the median month 6 VL decline was 0.86 log10 RNA copies/ml [95% confidence intervals (95% CI): 0.45-1.24]. The VL in those patients (n=31) who intensified treatment by adding only abacavir decreased by a median 0.20 log10 RNA copies/ml (95% CI: -0.18; +0.94). The proportion of patients who harboured viruses fully resistant to abacavir among the eight genotypic resistance interpretation algorithms ranged from 12% [Agence Nationale de Recherches sur le SIDA (ANRS)] to 79% [Stanford HIV RT and PR Sequence Database (HIVdb)]. Some interpretation systems showed statistically significant associations between the predicted resistance status and the virological response while others showed no consistent association. The number of active drugs in the regimen was associated with greater virological suppression (additional month 6 VL reduction per additional sensitive drug=0.51, 95% CI: 0.15-0.88, P=0.006); baseline VL was also weakly associated (additional month 6 VL reduction per log10 higher=0.30, 95% CI: -0.02; +0.62, P=0.06). In contrast, the number of drugs previously received was associated with diminished viral reduction (additional month 6 VL reduction per additional drug=-0.14, 95% CI: -0.28; 0.00, P=0.05). CONCLUSIONS: Our results revealed a high degree of variability among several genotypic resistance interpretation algorithms currently in use for abacavir. Therefore, the interpretation of genotypic resistance for predicting response to regimens containing abacavir remains a major challenge.
Adult↗
[Early virologic response value as predictive factor of sustained virologic response to treatment with interferon alpha-2b plus ribavirin in chronic hepatitis C patients with or without HIV coinfection].
BACKGROUND AND OBJECTIVE: The most effective currently available therapy for chronic hepatitis C virus infection is the combination of interferon alpha-2b plus ribavirin both, in patients with human immunodeficiency virus (HIV) coinfection and in patients without coinfection. In an attempt to avoid morbidity and health costs we searched for an indicator of early virologic response (EVR). We evaluated the EVR efficiency at 4 and 12-weeks after the initiation of antiviral combination therapy. PATIENTS AND METHOD: A total of consecutive 127 patients with chronic hepatitis C virus infection treated with combination therapy for 12 months in genotypes 1 and 4 and for 6 months in genotypes 2 and 3, were studied, 62 HIV-coinfected and 65 non-coinfected. They were evaluated for sustained virologic response and EVR at 4 and 12-weeks to initial therapy. RESULTS: Sustained virologic response was greater in the non-coinfected group than coinfected group; these differences were significant for genotypes 1 and 4. In both groups EVR had a 100% predictive negative value at 12-weeks after the initiation of therapy in genotypes 1 and 4, however came down in 79% at 4-weeks. CONCLUSIONS: The EVR at 12-weeks after the initiation of therapy has a 100% predictive negative value in coinfected and non-coinfected patients. Patient adherence to prescribed antiviral therapy is a predictive value of response.
Adult↗
Long-term virological outcome and resistance mutations at virological rebound in HIV-infected adults on protease inhibitor-sparing highly active antiretroviral therapy.
OBJECTIVE: To assess the durability of the undetectability of HIV plasma viraemia (pV) and to determine the factors associated with virological rebound (VR) in HIV-infected adults on protease inhibitor (PI)-sparing highly active antiretroviral therapy (HAART). The development of resistance mutations during virologically successful therapy and VR was also analysed. MATERIALS AND METHODS: One hundred and twenty-six HIV-infected adults on PI-sparing HAART were prospectively followed from April 1998 to December 2002: Group 1, naive for antiretroviral drugs (n = 26); Group 2, previously PI-HAART-exposed patients (n = 19); Group 3, previously exposed to suboptimal therapy (n = 81). Genotypic resistance tests on peripheral blood mononuclear cells or on plasma RNA (when feasible) were carried out when undetectable HIV pV was demonstrated for at least 48 weeks. Additionally, patients showing a therapy adherence >95% developing VR were also tested at rebound, at simplification and during previous suboptimal therapy exposure. RESULTS: The median follow-up time was 630 [329-903] days. VR was considered as two consecutive pV levels >50 copies/mL. Twenty-two (17.5%) patients developed VR. Only therapy adherence <95% was independently associated with VR (adjusted hazard ratio: 8.42; 95% CI: 3.33-21.27). Twenty (40%) of the 50 patients with pV < 50 copies/mL for at least 48 weeks showed at least one thymidine-associated mutation (TAM) but none had NNRTI-resistance mutations. Ten (83.3%) of 12 available adherent patients showing VR harboured NNRTI-resistance-associated mutations; 50% of them were considered as wild-type strains at simplification time. However, the TAM number and resistance mutations profile found on suboptimal exposure were very similar to those found at VR on simplification therapy. CONCLUSIONS: PI-sparing HAART allows maintenance of successful long-term control of HIV replication, adherence to therapy being the main factor associated with VR. However, a small proportion of patients on simplification regimen may develop VR regardless of therapy compliance. VR on PI-sparing HAART is characterized by the emergence of NNRTI cross-resistance mutations. Finally, TAMs 'archived' during previous suboptimal exposures are partially involved in subsequent VR on simplification HAART.
Adult↗
HIV-1 reverse transcriptase codon 215 mutation in plasma RNA: immunologic and virologic responses to zidovudine. The AIDS Clinical Trials Group Study 175 Virology Team.
Treatment of HIV infection with zidovudine (ZDV) may select for changes in the genetic sequence of the viral reverse transcriptase (RT) that imparts drug resistance. The presence of a 2-bp mutation at codon 215 of RT (from threonine to phenylalanine or tyrosine) was assessed in plasma viral RNA in 85 subjects treated with ZDV in the AIDS Clinical Trials Group (ACTG) 175 virology substudy. Median CD4 cell numbers, HIV plasma RNA levels, and infectious titers of virus were significantly different over 56 weeks of treatment among 58 subjects with the wild-type threonine at codon 215 virus at study entry compared with the 27 subjects with mutations to phenylalanine or tyrosine (MUT) virus. Thirty percent (13 of 44 subjects) with wild-type virus at study entry developed a new codon 215 mutation. Genotypic resistance at codon 215 in plasma HIV RNA is associated with the subsequent immunologic and virologic failure of ZDV monotherapy in subjects with 200 to 500 CD4 cells/mm3.
Anti-HIV Agents↗
[Role of Semen Mykytovych Moskovets' in the foundation and development of plant virology at the Institute of Microbiology and Virology of the National Academy of Sciences of Ukraine (1960-1971)].
The historical events in the Zabolotny Institute of Microbiology and Virology of the NAS of Ukraine that were connected with professor's S.M. Moskovets work activity as director and organizer of plant virology investigations are analyzed.
Academies and Institutes↗
Virological and immunological response to antiretroviral therapy in HIV-1 infected children: genotypic and phenotypic assays in monitoring virological failure.
Children differ from adults in both natural history of HIV-1 infection and their response to anti-retroviral therapy (ART). ART appears to be less successful in children than in adults at reducing HIV-1 RNA to below the level of detection of current assays. Nonetheless, children receiving ART frequently experience rises in CD4 cell counts, even in the absence of full virological suppression in plasma (discordant response). This immune repopulation in the presence of viral replication may increase the risk of emergence of drug-resistant viral variants. While the rationale for resistance testing is to optimise therapy, particularly when drugs are being changed following virological failure, it should be pointed out that currently available genotypic and phenotypic assays fail to detect drug resistance in about one third of viremic ART-treated children. This cannot be fully explained by the limitation of assays in detecting minor variants; factors other than resistance might be involved in the failure of therapy. Reduced fitness of drug-resistant viral variants is also unlikely to fully explain the discordant response to therapy, since immunological recovery is often observed even in the absence of detectable drug resistance. Rather, restoration of thymic function and higher thymic output may play a critical role in sustaining peripheral CD4 cell increases despite the persistence of viral replication. Such immune recovery might also drive the evolution of the replicating viruses.
Anti-HIV Agents↗
[Viral myocarditis and classical virology. Clinico-virologic and experimental data].
A viral etiology of myocarditis has been proven stringently only in a few cases and mostly enteroviruses have been shown to be involved. In fact, a virological diagnosis of viral myocarditis is still rarely possible today. Virus isolation from heart-tissue is hard to achieve and biopsies, if at all, are often performed too late. Successful virus isolation from other materials (e.g. faeces, throat swab) or a serological diagnosis of acute virus infection cannot easily be correlated etiologically with cardial symptoms, depending of course also on the kind of virus infection diagnosed. To prove an acute infection serologically a fourfold rise in antibody titer or for some viruses specific IgM has to be detected. A group specific diagnosis of "acute enterovirus infection" is not reliably possible at the moment. The neutralization test is the only relatively type specific test in enterovirus serology. Intraserotypic virus variants cannot be detected by normal serology. Even when determining neutralizing IgM-antibodies, interpretation of results raises problems due to long persistence and possible cross reactivity. In case of suspected viral myocarditis clinicians should institute early and broad virological diagnostic measures. Virologists have to establish methods for virus or antigen determinations by molecular biological means. Furthermore, a fast and easy serological method for the diagnosis of an "acute enterovirus infection' would be very helpful. For research on the pathogenesis established animal models have to be used.
Animals↗
HIV-1 viral load, phenotype, and resistance in a subset of drug-naive participants from the Delta trial. The National Virology Groups. Delta Virology Working Group and Coordinating Committee.
BACKGROUND: The Delta trial showed that combination therapy (zidovudine plus didanosine and zidovudine plus zalcitabine) substantially lengthened life and reduced disease progression compared with zidovudine monotherapy. We did a nested virological study in three countries (France, the Netherlands, and the UK) to investigate changes in markers for viral load and antiretroviral-drug resistance during therapy. METHODS: 240 zidovudine-naive HIV-1-infected patients were randomly assigned zidovudine only (n = 87), zidovudine plus didanosine (n = 80), or zidovudine plus zalcitabine (n = 73). Viral load in peripheral-blood mononuclear cells and plasma was measured by quantitative culture. Plasma HIV-1 RNA was measured by reverse-transcriptase PCR amplification, and serum p24 antigen by ELISA. Resistance to antiretroviral drugs was measured phenotypically by culture and genotypically by detection and quantification of drug-related point mutations in the pol gene. Analyses were done by intention to treat. FINDINGS: The reduction in viral load was greatest 4-12 weeks after the start of therapy and was most pronounced in the combination-therapy study groups (median reductions of RNA at 4 weeks 1.58, 1.28, and 0.49 log10 copies/mL for zidovudine plus didanosine, zidovudine plus zalcitabine, and zidovudine only, respectively). RNA levels at 8 weeks were predictive of disease progression and death after allowance for baseline values. At 48 weeks, the proportion of participants with phenotypic zidovudine resistance was similar in all three groups: didanosine and zalcitabine resistance were rare; zidovudine genomic resistance correlated with phenotypic resistance (r = 0.54, p < 0.0001) and developed earlier in the combined-therapy groups. However, participants in the zidovudine monotherapy group had higher circulating loads of resistant virus than those in the combined-therapy groups. INTERPRETATION: Combined antiretroviral therapy was more efficient at lowering virus load than monotherapy. Although zidovudine resistance was common in monotherapy and combined-therapy groups, circulating concentrations of resistant virus were substantially lower in the combination groups, which is likely to be a result of the continued antiviral activity of didanosine or zalcitabine.
Anti-HIV Agents↗
Drug resistance and heterogeneous long-term virologic responses of human immunodeficiency virus type 1-infected subjects to zidovudine and didanosine combination therapy. The AIDS Clinical Trials Group 143 Virology Team.
Plasma human immunodeficiency virus (HIV) type 1 RNA levels, CD4 lymphocyte changes, and drug resistance were studied in HIV-infected patients with 200-500 CD4 lymphocytes/microL who received zidovudine and didanosine combination therapy for 2 years. Among 35 patients, 10 had sustained and 16 had transient > 10-fold reductions in HIV RNA: 9 did not have 10-fold HIV RNA reductions. Only patients with sustained HIV suppression maintained increased CD4 cell counts for 2 years (370 to 501 cells/microL; P = .006). Patients with transient HIV suppression were more likely to develop drug-resistant HIV strains (12/16 vs. 5/19, P = .01) and reverse transcriptase (RT) mutations (4.5 vs. 2.5/strain; P = .02) than were patients with sustained or no HIV suppression. Zidovudine resistance occurred with RT mutations at codons 41, 67, 70, 215, and 219. Multidrug resistance occurred with mutations at codons 62, 75, 77, 116, and 151. Mutations occurred at codons 60, 68, 118, 210, and 228 in > or = 4 patients each. Heterogeneity exists among individual virologic responses to zidovudine and didanosine combination therapy. HIV resistance mechanisms during combination therapy appear more complex than reported with monotherapy.
Amino Acid Sequence↗
When two is better than one: thoughts on three decades of interaction between Virology and the Journal of Virology.
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History, 20th Century↗
Papers resulting from presentations made at the 1998 European Society for Clinical Virology meeting: Progress in Clinical Virology IV, held in Hamburg, Germany.
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Animals↗
[Memorable dates in the history of Russian medical science and virology: establishment, on June 30th 1944, of the Academy of Medical Sciences of the USSR and of the Institute of Virology].
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Academies and Institutes↗