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PubMed2003

Response to systemic HIV viral load suppression correlates with psychomotor speed performance.

The authors evaluated the association of a virologic response to highly active antiretroviral therapy, or a subsequent rebound, with performance on two measures of psychomotor speed in HIV-positive subjects. Virologic suppression was associated with improved performance on measures of psychomotor speed, and virologic rebound was associated with psychomotor speed performance decline. Changes in plasma HIV viral load in HIV-positive individuals with cognitive slowing correlate with performance on tests of psychomotor speed.

AIDS Dementia Complex↗

PubMed2002

Effects of age and human papilloma viral load on colposcopy triage: data from the randomized Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study (ALTS).

BACKGROUND: Testing for oncogenic human papillomavirus (HPV) DNA at a 1.0-pg/mL threshold represents a promising approach for colposcopy triage of atypical squamous cells of undetermined significance (ASCUS), but not for low-grade squamous intraepithelial lesions (LSIL). Considering age or viral load could improve colposcopy triage. METHODS: We determined the sensitivity for detecting Cervical Intraepithelial Neoplasia 3 (CIN3) and cancer and the percentage of referrals for colposcopy using HPV testing and repeat thin-layer cytopathology in 2198 women with ASCUS and in 848 women with LSIL enrolled in ALTS from November 1996 through December 1998. We analyzed results by age and at two thresholds for HPV load and repeat cytopathology. RESULTS: For ASCUS, the overall sensitivity of HPV testing at 1.0 pg/mL was 96.1% (95% confidence interval [CI] = 92.8 to 99.5%) and varied minimally with age (range, 93.9% to 97.8%). HPV testing at this threshold would refer 31.2% (95% CI = 28.0% to 34.3%) of women aged 29 years or older as compared with more than 65% of younger women. Among women aged 29 years or older with ASCUS, referral for repeat cytopathology of ASCUS had a sensitivity of 90.9% (95% CI = 81.1% to 100.0%) and would refer 50.1% (95% CI = 46.7 to 53.5%). Among all ASCUS, HPV testing using a 10.0-pg/mL threshold decreased sensitivity to 91.5% and referrals to 41.7%. More than 63% of LSIL would have been referred using any strategy achieving 90% sensitivity. CONCLUSION: For women with ASCUS, HPV testing was highly sensitive for detecting CIN3 and cancer with dramatically fewer referrals of older women. Neither a single HPV test nor repeat cytopathology provides useful triage for women with LSIL.

Adult↗

PubMed2004

Double-step PCR assay to quantify Epstein-Barr viral load in peripheral blood.

Posttransplant lymphoproliferative disorders (PTLD) are a severe complication arising in solid organ transplant patients. A strong correlation between Epstein-Barr virus (EBV) infection, the grade and type of immunosuppression, and the development of PTLD has been recognized. This article describes the development of a double-step polymerase chain reaction (PCR) assay for the quantification of EBV-deoxyribonucleic acid (DNA) to monitor EBV infection. Screening of samples containing >/=10(3) viral genomes/10(5) peripheral blood mononuclear cells (PBMC) or 100 micro L serum by a semiquantitative PCR assay is followed by quantification of the samples containing a high number of viral genomes in a quantitative-competitive (QC)-PCR assay. Screening by semiquantitative PCR selects samples with a high number of viral genomes for use in the more labor-intensive and expensive QC-PCR assay and thus provides a handy means for quantitative DNA analysis of large numbers of samples. Our double-step PCR assay can be employed in EBV viral load measurement in PBMC and serum samples to monitor transplanted patients at risk to develop PTLD.

Cells, Cultured↗

PubMed2006

Multiple polyexponentials and quasipolynomials as empirical nonlinear regression models: a case study with HIV viral load data.

Measurements of HIV1-RNA plasma concentrations are an important method of assessing patient response to anti-HIV1 treatment, and in most clinical trials of such treatments HIV1-RNA levels are assessed at regular intervals of time. HIV1-RNA levels in successfully treated patients tend to follow a standard pattern of biphasic decline-a rapid early decline in viral load, followed by a period of slower decline or a steady level. Fitting nonlinear regression models to these patterns of declining HIV1-RNA levels can be of value in comparing different treatment regimes and in predicting treatment outcome. Simple exponential-decline models can give an adequate fit to the typical pattern of HIV1-RNA decline, but we have explored the extent to which curve-fitting can be improved by using two novel nonlinear model forms. Specifically, we describe the fitting of multiple polyexponential and quasipolynomial forms to longitudinal HIV1-RNA plasma data collected in two recent trials of the novel anti-HIV1 treatment Fuzeon. We comment on the practicalities of fitting these nonlinear models, and compare the fit using various criteria.

Data Interpretation, Statistical↗

PubMed2006

Evaluation of HIV-1 p24 antigenemia and level of CD8+CD38+ T cells as surrogate markers of HIV-1 RNA viral load in HIV-1-infected patients in Dakar, Senegal.

Alternative, affordable, and simple assays to monitor antiretroviral therapy (ART) in resource-poor settings are needed. We have evaluated and compared a heat-denatured (HD) HIV p24 amplified enzyme-linked immunosorbent assay from Perkin-Elmer and CD38CD8 T-cell levels, determined by flow cytometry, for their capacity to predict viral load (VL) in HIV-1-infected patients from Senegal. Median fluorescence intensity (MFI) of CD38 expression on memory (CD45RO) CD8 T cells correlated better with RNA VL than HD p24 antigenemia (R = 0.576, P < 0.0001 vs R = 0.548, P < 0.0001). MFI of CD38 expression on memory CD8 T cells could predict detectable RNA VL (VL = 2.6 log10) with a sensitivity of 87% and a specificity of 74%. A comparable sensitivity (89%) could be reached for HD p24 assay, but only to predict RNA VL of more than 5 logs, which might lead to unacceptable delays in clinical decision making. The clinical use of the HD p24 assay to monitor ART in Senegal would require more comparative data about the kinetics of p24 antigen and HIV RNA in peripheral blood as well as further evaluation regarding its sensitivity toward subtype A and CRF02. MFI of CD38 expression on memory CD8 T cells appeared to be a better alternative to monitor ART in HIV-infected patients from Senegal.

ADP-ribosyl Cyclase 1↗

PubMed2003

A Gag-Pol/Env-Rev SIV239 DNA vaccine improves CD4 counts, and reduce viral loads after pathogenic intrarectal SIV(mac)251 challenge in rhesus Macaques.

DNA vaccines are an important vaccine approach for many infectious diseases including human immunodeficiency virus (HIV). Recently, there have been exciting results reported for plasmid vaccination in pathogenic SHIV model systems. In these studies, plasmid vaccines supplemented by IL-2 Ig cytokine gene adjuvants or boosted by recombinant MVA vectors expressing relevant SIV and HIV antigens prevented CD4(+) T-cell loss and lowered viral loads following pathogenic challenge. However, similar results have not been reported in a direct pathogenic macaque challenge model. Here we report on a study of the ability of a multiplasmid SIV DNA vaccine in a pathogenic SIV251 rhesus mucosal challenge study. We observed that pGag/Pol+pEnv/Rev plasmid vaccines could not prevent SIV infection; however, vaccinated animals exhibited significant improvement in control of viral challenge compared to control animals. Furthermore, vaccinated animals exhibited protection against CD4(+) T-cell loss.

Animals↗

PubMed2006

Lack of agreement between cervicography and cytology and the effect of human papillomavirus infection and viral load.

OBJECTIVE: Cohort studies of the natural history of human papillomavirus (HPV) infection and cervical squamous intraepithelial lesions with repeated screening allow the comparison of different macroscopic and microscopic diagnostic methods. MATERIALS AND METHODS: Concurrent visual inspection using cervicography and conventional Pap cytology tests were performed during multiple visits in a cohort of women attending a maternal and child health clinic in São Paulo, Brazil. HPV infection status at the same visits was determined by polymerase chain reaction followed by typing with specific oligonucleotide probing and viral load quantification. Information on reproductive health and hygiene habits was also collected at each visit. RESULTS: Overall agreement between cervicography and cytology was low (kappa = 0.046), which increased only slightly when high oncogenic-risk HPV types (kappa = 0.120) or high viral burden (>100 copies/cell) (kappa = 0.170) was present. Analysis of reproductive health and hygiene habits revealed somewhat different risk factors for cervical lesions detected by these tests. However, presence of oncogenic HPV DNA (odds ratio = 36.0, 95% CI = 16.6-77.8) and high viral burden (odds ratio = 67.34; 95% CI = 27.1-167.0) were strongly associated with lesions detected by cytology but not by cervicography. CONCLUSIONS: Although changes in the cervix (because of age, gravidity, or hormonal effects) may influence the performance of morphology-based screening tests, the lack of agreement and the different degrees of association with HPV infection measures indicate that a visual inspection method such as cervicography may detect different cervical abnormalities relative to cytology.

Adolescent↗

PubMed2002

Stochastic processes defining sensitivity and variability of internally calibrated quantitative NASBA-based viral load assays.

For quantitative assessment of virus particles in patient plasma samples various assays are commercially available. Typical performance characteristics for such assays are sensitivity, precision and the range of linearity. In order to assess these properties it is common practice to divide the range of inputs into subranges in order to apply different statistical models to evaluate these properties separately. We developed a general statistical model for internally calibrated amplification based viral load assays that combines these statistical properties in one powerful analysis. Based on the model an unambiguous definition of the lower limit of the linear range can be given. The proposed method of analysis was illustrated by a successful application to data generated by the NucliSens EasyQ HIV-1 assay.

HIV-1↗

PubMed1999

Viral load and CD69 molecule expression on freshly isolated and cultured mitogen-stimulated lymphocytes of children with perinatal HIV-1 infection.

HIV-1 in adults changes the proportion of mitogen-stimulated lymphocytes expressing the CD69 activation molecule, but little is known about this molecule expression on lymphocytes of HIV-1-infected (HIV-1+) children. Freshly isolated CD3+, CD4+, CD8+ and CD19+ and phytohaemagglutinin (PHA)-stimulated CD3+, CD4+ and CD8+ lymphocytes co-expressing CD69 were investigated cross-sectionally (adopting a MoAb double-staining technique) in 24 HIV-1+ children with severe disease and given anti-retroviral therapy and in 24 age-matched healthy children. CD69 results in HIV-1+ children were correlated with plasma HIV-1 RNA load prospectively determined. HIV-1+ compared with healthy children had higher frequencies of freshly isolated CD3+CD69+ (2.4 +/- 2.2% versus 0.9 +/- 0.5%; P = 0.002) and CD8+CD69+ (1.5 +/- 1.1% versus 0. 5 +/- 0.2%; P < 0.0001) lymphocytes. The frequencies of CD4+CD69+ and CD19+CD69+ lymphocytes were similar. High viral load correlated with an elevated proportion of freshly isolated CD3+CD69+ and CD8+CD69+ lymphocytes. HIV-1+ children showed reduced frequencies of PHA-stimulated CD3+CD69+ (60.7 +/- 7.6% versus 86.1 +/- 7.6%; P < 0. 001), CD4+CD69+ (73.6 +/- 18.2% versus 92.6 +/- 5.1%; P < 0.001), and CD8+CD69+ (51.0 +/- 19.1% versus 65.3 +/- 15.4%; P = 0.007) lymphocytes. Virologic worsening within 6 months correlated with a low proportion of PHA-stimulated CD3+CD69+ and CD8+CD69+ lymphocytes. CD69 molecule expression reflected the coexistence of immune activation and immune deficiency in HIV-1 infection. Changes partly differed from those observed in HIV-1+ adults. CD8+CD69+ (but not CD4+CD69+) lymphocyte proportion correlated with virologic course, and an impaired ability of CD8+ lymphocytes to express CD69 upon PHA stimulation preceded a virologic worsening.

Antigens, CD↗

PubMed2001

Quantitation of viral load using real-time amplification techniques.

Real-time PCR amplification techniques are currently used to determine the viral load in clinical samples for an increasing number of targets. Real-time PCR reduces the time necessary to generate results after amplification. In-house developed PCR and nucleic acid sequence-based amplification (NASBA)-based systems combined with several detection strategies are being employed in a clinical diagnostic setting. The importance of these assays in disease management is still in an exploration phase. Although these technologies have the implicit capability of accurately measuring DNA and RNA in clinical samples, issues related to standardization and quality control must be resolved to enable routine implementation of these technologies in molecular diagnostics.

Calibration↗

PubMed2002

Racial/ethnic differences in CD4 T cell count and viral load at presentation for medical care and in follow-up after HIV-1 infection.

The baseline characteristics of antiretroviral-naive patients were compared by ethnic/racial groups. First CD4 T cell counts were lower for Latino (P = 0.0004) and black patients (P = 0.10) when compared with white patients. First HIV-1-RNA levels were higher in Latino patients (P = 0.08), who were also more likely to present with major opportunistic infections (P < 0.004). Once in care, changes in CD4 T cell counts and viral loads over time did not differ significantly between groups.

Academic Medical Centers↗

PubMed2003

[Effect of HAART on HCV viral load in the first three years of follow-up].

BACKGROUND AND OBJECTIVE: Highly active antiretroviral therapy (HAART) has been considered to be ineffective in controlling hepatitis C viremia in the first year of treatment. The present study evaluates the effect of prolonged HAART upon HCV-VL. PATIENTS AND METHOD: We selected those cases with positive serology for HCV, never been treated with protease inhibitors (PIs) at baseline, which after the introduction of HAART maintained undetectable HIV viral loads (HIV-VL) uninterruptedly for at least three years. Determinations were made of HCV-VL at baseline and after two and three years of HIV-VL suppression. Spearman coefficient and Friedman test were used. RESULTS: Of these patients, 21 satisfied the inclusion criteria. HCV-VL remained without significant changes and with relatively stable levels throughout the three-year follow-up period. However, two patients showed HCV-VL negative conversion after two years, that persisted after three years. CONCLUSIONS: Patients who respond to HAART maintain stable HCV-VL. Some subjects may exhibit HCV RNA clearance in the first two years of treatment, maintaining this situation after three years.

Antiretroviral Therapy, Highly Active↗

PubMed1999

Decreasing levels of anti-Nef antibody correlate with increasing HIV type 1 viral loads and AIDS disease progression.

To study the association between anti-Gag and anti-Nef antibody reactivities and their correlations with disease progression, 174 HIV-1/AIDS patients were followed up for 1 year after they received triple therapy. The antibody reactivities were analyzed using a Western blot test with recombinant Gag and Nef proteins. The results showed that decreasing levels of anti-Gag or anti-Nef antibody correlate with disease progression defined by HIV-1 viral loads or T4 cell counts. After receiving triple treatment for 1 year, 8 of 38 (21.1%) Nef antibody-negative patients became positive, while only 9 of 125 (7.2%) Nef antibody-positive persons lost the antibody reactivity (p < 0.01). Therefore, HIV-1 Nef may serve as a clinical marker of disease progression.

Blotting, Western↗

PubMed2000

Plasma RNA viral load predicts the rate of CD4 T cell decline and death in HIV-2-infected patients in West Africa.

OBJECTIVE: To examine whether the levels of plasma RNA and DNA provirus predict the rate of CD4 cell decline and patient death. DESIGN: Retrospective analysis of HIV-2 cohort subjects. METHODS: Fifty-two subjects were recruited between January 1991 and December 1992. HIV-2 RNA levels in plasma and DNA levels in peripheral blood mononuclear cells (PBMC) were measured using in-house quantitative PCR assays. The annual rate of CD4 cell decline was calculated using the least-squares method. The survival data on 31 December 1997 were used. RESULTS: The mean percentage of CD4 cells at baseline was 30.7 (SD, 9.5). In a linear regression model, the annual rate of CD4 cell decline was 1.76 CD4% faster for every increase in one log10 RNA copies/ml [95% confidence interval (CI), 0.81-2.7; P = 0.0006; r = 0.46; n = 52] and 1.76 CD4% faster for every increase in log10 DNA copies/10(5) PBMC (95% CI 0.46-3.1; P = 0.01; r = 0.33; n = 42). In a multiple linear regression model, RNA load was related to CD4 decline independently of DNA load (P = 0.02). The overall mortality rate was 7.29/100 person-years. In a Cox regression model, the hazard rate increased by 2.12 for each log10 increase in RNA load (95% CI, 1.3-3.5; P = 0.0023) but only by 1.09 for each log10 increase in DNA load (95% CI, 0.64-1.87; P = 0.8). CONCLUSION: This longitudinal study shows for the first time that a baseline HIV-2 RNA load predicts the rate of disease progression. HIV-2-infected patients with a high viral load may need to be treated as vigorously as HIV-1 patients.

Adolescent↗

PubMedDate not supplied

Hepatitis C viral load does not predict disease outcome: going beyond numbers.

The analysis of 58 patients with chronic hepatitis C without cirrhosis and treated with interferon-alpha demonstrated that hepatitis C viral (HCV) load does not correlate with the histological evolution of the disease (p = 0.6559 for architectural alterations and p = 0.6271 for the histological activity index). Therefore, the use of viral RNA quantification as an evolutive predictor or determinant of the severity of hepatitis C is incorrect and of relative value. A review of the literature provided fundamental and interdependent HCV (genotype, heterogeneity and mutants, specific proteins), host (sex, age, weight, etc) and treatment variables (dosage, time of treatment, type of interferon) within the broader context of viral kinetics, interferon-mediated immunological response (in addition to natural immunity against HCV) and the role of interferon as a modulator of fibrogenesis. Therefore, viral load implies much more than numbers and the correct interpretation of these data should consider a broader context depending on multiple factors that are more complex than the simple value obtained upon quantification.

Adult↗

PubMed2002

Exacerbation of HIV viral load simultaneous with asymptomatic reactivation of chronic Chagas' disease.

Chronic Trypanosoma cruzi infection can reactivate in patients with immunosuppression related to human immunodeficiency virus (HIV) infection, resulting in severe meningoencephalitis or myocarditis and high parasitemia. The effects of T. cruzi on HIV infection are unknown. We describe an HIV-infected patient with chronic Chagas' disease who experienced an asymptomatic T. cruzi reactivation characterized by the finding of the parasite in direct microscopic examination of blood. The patient's HIV viral load had increased simultaneously with the exacerbation of T. cruzi parasitemia and decreased to previous levels after successful antiparasitic treatment. This otherwise unexplained finding suggests that T. cruzi infection might up-regulate HIV replication, which may affect HIV disease progression. Asymptomatic reactivation of Chagas' disease has not been reported before. This could mean that the severe clinical manifestations related to the reactivation of trypanosomiasis are just the tip of the iceberg.

Adult↗

PubMed2003

Greater reversal of CD4+ cell abnormalities and viral load reduction after initiation of antiretroviral therapy with zidovudine, lamivudine, and nelfinavir before complete HIV type 1 seroconversion.

In a prospective open-label study, 41 male subjects received nelfinavir, zidovudine, and lamivudine stratified as either: early stage (ES; negative/indeterminate Western blot; n = 19) or late stage (LS; positive Western blot; n = 22) primary HIV-1 infection. Despite higher median baseline HIV-1 RNA levels and lower CD4(+) cell numbers in the ES subjects, a significantly greater decline in viral load (-3.46 vs. -2.83 log(10) copies/ml; p = 0.023) and increase in CD4(+) cell number (+85 vs. +41 cells/month increase, p = 0.01) were observed over the first 3 months of therapy such that both groups had comparable results at 1 year. The proportion with HIV-1 RNA < 50 copies/mL at 1 year was similar (9 of 19 ES subjects and 11 of 22 LS subjects by intention-to-treat analysis). Memory CD4(+) cell numbers, and activated CD4(+) percentages, were also significantly improved in ES subjects. Despite poorer prognostic markers at baseline ES subjects achieved responses similar to those of LS subjects after 1 year of treatment.

Anti-HIV Agents↗

PubMed2000

Early intervention in post-transplant lymphoproliferative disorders based on Epstein-Barr viral load.

Using a real-time quantitative PCR assay, we identified two patients with EBV-related lymphoproliferative disorders at a very early stage. Both had received an unmanipulated bone marrow transplant with anti-thymocyte globulin for conditioning. To estimate virus-specific immunity, the frequencies of EBV-specific CD8+ T cells were measured using an enzyme-linked immunospot assay. The frequencies of EBV-specific CD8+ T cells of the two were 3.2 and 7.7%, respectively, which had possibly expanded in vivo. After withdrawing the immunosuppressive agents or administering donor lymphocytes transfusion, their symptoms regressed in parallel with the viral load.

Adult↗