Effect of adherence to newly initiated antiretroviral therapy on plasma viral load.

OBJECTIVE: To determine whether differences in adherence to newly initiated antiretroviral therapy exist between subjects who do and do not achieve undetectable plasma viral loads. DESIGN: Observational cohort study monitoring adherence and virological and immunological parameters over the initial 4 months of therapy with nelfinavir. Adherence was measured using the microelectronic monitoring system (MEMS; APREX Corporation, Menlo Park, California, USA). SETTING: General Clinical Research Center at a tertiary care center. PARTICIPANTS: Forty-one protease inhibitor-naive subjects with viral loads > 10 000 copies/ml newly starting a regimen including nelfinavir, referred from HIV clinics in Philadelphia. MAIN OUTCOME MEASURES: The primary outcome was undetectable viral load (< 50 copies/ml) after 4 months. Secondary measures included changes in viral load and CD4 cell counts. We hypothesized that adherence would be greater in subjects who achieved undetectable viral loads. RESULTS: Adherence was greater in undetectable subjects, who took a median of 93% of prescribed doses [interquartile range (IQR) 84-96%], whereas detectable subjects took a median of 70% (IQR 46-93%). Adherence correlated with viral load decrease (Spearman's rho = 0.38, P < 0.01) and CD4 cell count increase (Spearman's rho = 0.25, P = 0.06). Despite differences between the groups over 4 months of therapy, there were no adherence differences over the first month [undetectables, 95% (IQR 88-98%) versus detectables, 94% (IQR 87-98%), P > 0.50]. CONCLUSIONS: Adherence is important in determining whether or not individuals achieve suppression with a newly initiated antiretroviral regimen. Adherence begins to wane after the first month of therapy. Therefore, closer assessment of adherence particularly after this first month is important.     

Effect of influenza vaccination on viral replication and immune response in persons infected with human immunodeficiency virus receiving potent antiretroviral therapy

Nineteen patients infected with human immunodeficiency virus (HIV) with varying levels of viral suppression achieved with antiretroviral therapy were evaluated to determine whether trivalent influenza vaccine activated HIV replication. Humoral immune responses and CD4+ lymphocyte subsets were compared in 5 HIV-uninfected vaccinated subjects. Transient elevations of plasma HIV RNA levels (76-89 copies/mL) appeared within 2 weeks in 3 of 11 patients with <50 copies/mL at baseline. Sustained elevation in HIV plasma RNA was observed in 7 of 8 patients with baseline HIV RNA of >50 copies/mL. HIV DNA decreased in patients with <400 RNA copies/mL at baseline and showed an HIV RNA increase after vaccination (n=8) when compared with 8 patients with <50 copies/mL at baseline who lacked viral response to vaccination. Concurrent decreases in proviral DNA and memory phenotype CD4+ cells in association with increased plasma HIV RNA after vaccination in patients with <400 RNA copies/mL at baseline suggest that in vivo mobilization of the latently infected cell reservoir may occur during potent antiretroviral therapy.     

Lymphoid tissue viral burden and duration of viral suppression in plasma

OBJECTIVES: To assess virological response in lymphoid tissue and its impact on the durability of response in plasma in HIV-1-infected persons who achieved sustained suppression of plasma viraemia with different antiretroviral regimens. METHODS: Consecutive patients on first-line antiretroviral therapy were included if they had a plasma HIV-1 RNA viraemia < 20 copies/ml within the last 6 months and tonsillar tissue accessible for biopsy. First-line therapy contained two nucleoside analogues: alone (2NRTI group, n = 3); plus a HIV-1 protease inhibitor (PI group, n = 11) or plus nevirapine (NVP group; n = 16). Patients were followed until virus was detectable in plasma, they changed therapy or were lost to follow-up. RESULTS: Tonsillar HIV-1 RNA could be detected (> 100 copies/mg) in 10 patients: one in the PI group (9%), six (38%) in the NVP group and in all three patients in the 2NRTI group. Primary resistance mutations could be detected in only 2 of these 10 patients. After a median of 9 months after the biopsies, viral suppression in plasma had failed in 6 of these 10 patients whereas failure had only occurred in 1 out of 20 with initially undetectable viral load in lymphoid tissue (P = 0.01; log rank test). CONCLUSIONS: In patients with sustained viral suppression in plasma, triple therapy including a HIV-1 protease inhibitor was more potent than triple therapy containing nevirapine or dual therapy with nucleoside analogues to reduce viral burden in lymphoid tissue. A worse response in lymphoid tissue could not be explained by local selection of resistance and was associated with a less durable virological response in plasma.     

Virological response to protease inhibitor therapy in an HIV clinic cohort

OBJECTIVE: New antiretroviral strategies aim to reduce plasma HIV RNA (viral load) to below the limits of detectability of assays with the objective of reducing viral replication in order to stop or reverse the pathogenic process and prevent development of drug resistance. First use of a protease inhibitor might offer the most realistic chance of achieving this aim. Our objective was to study the virological response to protease inhibitors in patients taking them for the first time. METHODS: A total of 901 patients from a large outpatient clinic were followed a mean of 15 months from the time of starting a protease inhibitor until 1 May 1998. Viral load and CD4 cell count measurements were made on average every 34 days. RESULTS: Overall there was a 79% [95% confidence interval (CI), 76-82] probability of the patients achieving a viral load < 500 copies/ml by 24 weeks after starting the protease inhibitor. In a multiple Cox regression model, those with lower initial viral load [relative hazard (RH), 0.72; P < 0.0001], higher CD4 cell count (RH, 1.07; P = 0.002), those starting other new drugs at same time as the protease inhibitor (RH, 1.46 for two versus none; P = 0.003), those who were antiretroviral-naive, and those using indinavir or nelfinavir were more likely to achieve such levels. In those 651 patients achieving viral load < 500 copies/ml within 24 weeks, there was an estimated 53% (95% CI, 51-55) probability of rebound of viral load to > 500 copies/ml by 52 weeks from the first undetectable value. Again, those who had started other new drugs at the same time as the protease inhibitor (RH, 0.57; P = 0.003 for starting two versus none) tended to experience a lower probability of viral load rebound, as did those with higher initial CD4 cell count (RH, 0.87 per 100 x 10(6)/l higher; P = 0.0007). Those who took saquinavir achieved less durable virological responses than those who took other protease inhibitors. CONCLUSIONS: Starting protease inhibitor therapy with two other new antiretroviral drugs simultaneously with protease inhibitor therapy offers a better best chance of achieving sustained viral load < 500 copies/ml than starting fewer new drugs.     

HIV-1耐药性基因型检测法在临床治疗随访中的应用

目的 探索HIV-1耐药性基因型检测法在高效抗逆转录病毒疗法（HAART）治疗组中监测HIV-1耐药性病毒株的临床应用。方法 从接受HAART的HIV-1感染者血浆中抽提病毒RNA,采用套式RT-PCR方法扩增HIV-1的PR和RT基因片段,并对扩增片段进行序列测定和分析。结果HIV-1耐药性基因型检测法能够从血浆病毒载量在 1000拷贝/ml以上的样本中得到扩增产物。在 16例接受 HAART的 HIV-1感染者中,发现 1例感染者 DP31的 PR和 RT基因出现了突变,这些突变为L63P、T215F、K219Q和M184V。所有突变均与公开报道的结果一致,并被证明与HIV-1的耐药性有关。另外,DP31在接受HAART前已出现T215F、K219Q的耐药性突变,究其原因,还有待进一步研究。结论HIV-1耐药性基因型检测法能有效地监测接受HAART的HIV-1感染者血浆中耐药性病毒株的存在。该方法提供的结果准确、可靠,并且为临床医生评价HAART效果,合理选择和及时优化药物组合方案提供了可靠的依据。     

Duration and predictors of CD4 T-cell gains in patients who continue combination therapy despite detectable plasma viremia.

BACKGROUND: Sustained elevations in CD4 cell counts commonly occur despite incomplete viral suppression with protease inhibitor-based antiretroviral therapy. OBJECTIVES: To determine the incidence and risk factors associated with return of CD4 cell count to pre-therapy levels in patients experiencing virologic failure of protease inhibitor therapy. DESIGN: This is a clinic-based cohort study of HIV-infected adults who failed to maintain durable viral suppression on a protease inhibitor-based regimen. MAIN OUTCOME MEASURES: Virologic failure was defined as persistent plasma HIV RNA level > 500 copies/ml. Immunologic failure was defined as return of CD4 cell count to pre-therapy levels. RESULTS: A total of 291 patients experienced virologic failure on a protease inhibitor-based regimen and had a treatment-mediated CD4 cell increase above pre-therapy levels at the time of virologic failure. If patient data were censored at the time a successful salvage regimen was initiated, then the median time to immunologic failure after the onset of virologic failure was 3 years. If patient data were also censored at the time therapy was discontinued, then 36.8% of the cohort experienced immunologic failure after 3 years of continuous virologic failure. The change in viral load from a pre-treatment baseline, and not the absolute level of viremia achieved, was a strong and independent predictor of immunologic failure. Discontinuing therapy was associated with immunologic failure independent of viral load changes. CONCLUSION: Reduction in T CD4+ cell numbers may eventually occur during prolonged virologic failure of a protease inhibitor-based regimen and is predicted by the degree of virologic suppression below a pre-therapy 'set-point'.     

Clinical cross-resistance between the HIV-1 protease inhibitors saquinavir and indinavir and correlations with genotypic mutations

OBJECTIVES: To determine the clinical efficacy of the HIV-1 protease inhibitor indinavir (IDV) in saquinavir (SQV)-experienced patients and delineate the developing drug-resistance patterns. DESIGN: Open-label prospective clinical trial. SETTING: University hospital research center. PATIENTS: Ten patients who had completed a SQV monotherapy study in which they had received SQV at a dose of 3600 or 7200 mg daily (two and fourfold the standard dose). INTERVENTIONS: At enrollment patients received IDV for 4 weeks as monotherapy, after which zidovudine (ZDV) and lamivudine (3TC) were added to their drug regimen. Patients then received combination therapy (IDV-ZDV-3TC) for an additional 20 weeks to complete a total of 24 weeks of therapy. MAIN OUTCOME MEASURES: Plasma HIV RNA viral load and CD4+ T-cell counts were monitored. Sequencing of the HIV protease gene was performed to determine the development of resistance mutations. Plasma samples for sequencing were taken before initial SQV therapy, after SQV therapy before starting IDV, and after 24 weeks of IDV therapy. RESULTS: The average duration of high-dose SQV before starting IDV was 58+/-29.2 weeks. A 0.58 log10 RNA copies/ml increase was noted during the 3-week washout phase followed by a mean reduction in plasma HIV RNA viral load of 1.2 log10 RNA copies/ml after 4 weeks of IDV. After the addition of ZDV and 3TC at week 4, HIV RNA continued to fall reaching a mean reduction of 1.96 log10 RNA copies/ml at week 24. Plasma HIV RNA was below 400 RNA copies/ml in six out of nine patients at week 24. CD4+ T-cell counts showed a gradual rise from 328 x 10(6)/l to 453 x 10(6)/l by week 24. SQV therapy had resulted in multiple mutations in the protease gene. Six of the patients had developed five or more mutations: L90M in two, G48V in four (of which three also contained L101), and V82A in three. Patients in whom plasma HIV RNA was not durably suppressed by subsequent IDV combination therapy developed multiple (up to four) additional mutations within 24 weeks, including codons 54, 82 and 93 amongst others. No clear correlation was found between the mutations that had developed in individual patients after SQV and the subsequent efficacy of IDV. CONCLUSION: Prolonged use of SQV at potent doses in the presence of elevated viral load levels resulted in the development of multiple resistance mutations. Individual resistance patterns varied greatly between patients, as did their virological response to therapy. Resistance assays may be useful in identifying which patients will benefit from salvage therapy with a second protease inhibitor.