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Results for “Viral Load”

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PubMed2006

Determination of HPV type 16 and 18 viral load in cervical smears of women referred to colposcopy.

It has been recognized that human papillomavirus infection is the major causal factor for high-grade cervical lesions. The aim of the study was to evaluate the relationship between HPV 16 and 18 viral loads and cervical status in different age strata. A duplex real time PCR method was devised to determine HPV 16 and 18 viral load per million of human cells using an in house plasmidic construct as a standard of quantification. The 151 cervical scrapes were collected before colposcopic examination from either abnormal cervico-vaginal smear (group 1, 97 patients) or from post treatment clinical follow-up (group 2, 54 patients). In women aged 30-40, the HPV16 viral loads were significantly higher in high-grade squamous intraepithelial lesion than in low-grade squamous intraepithelial lesion in both groups and HPV18 in group 1. In women aged 20-30 of group 1, high HPV viral load was associated in few cases with high-grade squamous intraepithelial lesion or low-grade squamous intraepithelial lesion, and surprisingly in some patients with normal cervix. HPV 16 and 18 viral loads are related to the severity of cervical lesion, and may be useful in the clinical management of cervical lesions. A specific follow-up may be useful for those with high viral load despite normal cervix.

Adolescent↗

PubMed2001

Analytic validation of a competitive polymerase chain reaction assay for measuring Epstein-Barr viral load.

Epstein-Barr virus (EBV) is associated with several benign and malignant diseases, and blood tests for EBV viral load show promise as markers of disease burden in affected patients. A commercial quantitative PCR method (BioSource International) was recently introduced to facilitate measuring viral load. It relies on coamplification of EBV DNA and a spiked competitor in plasma or serum, followed by semiautomated product detection on enzyme-linked immunosorbent assay (ELISA) plates. In the current study, analytic performance characteristics were assessed, and the authors describe several methodologic improvements to facilitate laboratory implementation. Rapid DNA extraction was accomplished using commercial silica spin columns, heat-labile uracil-N-glycosylase was used to inhibit amplicon contamination, and inexpensive agarose gels were used to screen for polymerase chain reaction products requiring ELISA plate quantitation. Accuracy and precision were verified using EBV DNA standards derived from two cell lines and plasmid containing viral sequences. The assay was sensitive to as few as five template copies per polymerase chain reaction and was linear across four orders of magnitude (correlation coefficient 0.995). When applied to matched plasma and serum samples from 15 patients with nasopharyngeal carcinoma, both sample types yielded similar viral load results. This commercial EBV viral load assay provides sensitive and quantitative detection of EBV DNA using equipment already available in many molecular diagnostic laboratories.

DNA, Viral↗

PubMed1998

[Viral load quantification for the early diagnosis of perinatal human immunodeficiency virus 1 (HIV-1) infection].

OBJECTIVE: The aim of this study was to compare the sensitivity and specificity of polymerase chain reaction (DNA-PCR) and virus cultures with HIV-RNA assays (viral load) in the early diagnosis of vertically transmitted HIV-1 infection. PATIENTS AND METHODS: One hundred and six infants born to HIV-1 seropositive mothers were divided into three groups: A) Nineteen newborns (24-26 hours of age): B) Twenty-three infants between 1 and 2 months of age; and C) Sixty-four infants older than 2 months. HIV-1 RNA was measured in plasma and HIV proviral DNA was determined in peripheral blood mononuclear cells after amplification by DNA-PCR. The HIV was isolated by a microculture technique. RESULTS: In the samples obtained during the neonatal period (less than 96 hours of age), 75% of the infants were positive by viral load analysis, 50% by proviral DNA-PCR and only 25% by culture assay. In group B, 100% of the infants were positive by viral load analysis and 85.7% by proviral DNA-PCR and culture assays. Viral load, proviral DNA-PCR and cultures were positive in all infants older than 2 months of age. CONCLUSIONS: Our results indicate that the 3 techniques, viral load, DNA-PCR and culture, have 100% sensitivity after 2 months of age. However, the viral load technique, which is not routinely used, was found to have a higher sensitivity than proviral DNA-PCR and viral culture in infants younger than 2 months. We conclude that viral load is a useful technique to diagnose HIV infection in newborns.

DNA, Viral↗

PubMed2026

The effect of antiretroviral therapy adherence on viral load suppression rate among people living with HIV in Ethiopia: A systematic review and meta-analysis.

BACKGROUND: Antiretroviral therapy (ART) adherence is a key determinant of viral load suppression among people living with HIV (PLHIV). In Ethiopia, evidence on the magnitude of ART adherence and its effect on virological outcomes remains fragmented. This systematic review and meta-analysis aimed to estimate the pooled prevalence of ART adherence and viral load suppression, and to measure the association between adherence and viral suppression among PLHIV in Ethiopia. METHODS: This systematic review and meta-analysis used the PRISMA checklist for systematic reviews and meta-analyses. The review protocol has been registered onPROSPERO:(CRD420251125899). PubMed, ScienceDirect, Scopus, Epistemonikos, and Google Scholar were searched. The quality of included articles has been evaluated with a Newcastle-Ottawa Scale (NOS), adapted for observational studies. A random-effects model using restricted maximum likelihood (REML) with Knapp-Hartung adjustment was used to estimate pooled prevalence and odds ratio. Heterogeneity was assessed using I2, τ2, and Cochran's Q test. RESULTS: A total of 39 studies were included in the final analysis. The pooled prevalence of good ART adherence was 79.4% (95% CI: 74.8%-83.4%), while the pooled viral load suppression rate was 77.5% (95% CI: 72.5%-81.8%). The pooled odds ratio showed that good ART adherence was strongly associated with viral load suppression (OR = 6.30, 95% CI: 4.84-8.19). Substantial heterogeneity was observed across studies for both adherence and viral suppression outcomes (I2 > 90%). CONCLUSIONS: ART adherence and viral load suppression among PLHIV in Ethiopia are relatively high but remain below global targets. Good adherence was significantly associated with virologic suppression, highlighting adherence as a critical modifiable factor for achieving optimal treatment outcomes. Strengthening adherence support interventions is essential to improve virological success and advance progress toward HIV epidemic control.

Humans↗

PubMed1998

Co-Infection by HTLV-I/II is Associated With Increased Viral Load in PBMC of HIV-1 Infected Patients in Bahia, Brazil.

To evaluate the viral load in peripheral blood mononucler cells (PBMC) of patients infected by HIV-1 we performed 96 quantitative cultures in 74 patients infected by HIV-1, using the co-culture method. The viral load was expressed in tissue culture infectious doses (TCID), and the results were analyzed according to gender, age and clinical stage of patients, duration of previous antiretroviral therapy, detectable p24 antigenemia, CD4(+)/CD8(+) cell counts, co-infection by HTLV-I/II and viral subtype. We detected a statistically significant association between co-infection by HTLV-I/II and viral load higher than >50 TCID (p=0.003). We also found a significant association between co-infection by HTLV-I/II and p24 antigenemia (p=0.028). CD4(+) cell counts were significantly higher for patients presenting negative cultures, but there was no detectable association between lower CD4(+) cell counts and higher TCID. The majority of patients were infected by subtype B virus. The observation in this study that co-infection with HTLV-I/II was significantly associated with higher viral load raises the possibility that these agents act as co-factors of AIDS progression, in doubly-infected patients.

Journal Article↗

PubMed2003

Antiretroviral therapy in HIV-2-infected patients: changes in plasma viral load, CD4+ cell counts, and drug resistance profiles of patients treated in Abidjan, Côte d'Ivoire.

OBJECTIVE: To describe changes in plasma viral load, CD4+ cell counts, and drug resistance profiles of HIV-2-infected patients receiving antiretroviral (ARV) therapy in Abidjan, Côte d'Ivoire. METHODS: Consecutive blood samples were collected from 18 HIV-2-infected ARV-naive patients who had received ARV therapy in the UNAIDS drug access initiative (UNAIDS-DAI) in Abidjan between August 1998 and July 2000. Changes in HIV-2 plasma viral load, CD4+ cell counts, and genotypic and phenotypic drug resistance testing were determined. RESULTS: At baseline, 11 (61%) of the 18 patients initiated highly active antiretroviral therapy (HAART) and seven (39%) received dual therapy. No significant change in median viral load was observed at 2 months (P = 0.09), at 6 months (P = 0.06), and at 12 months of therapy (P = 0.26). No significant increase in CD4+ cell counts was observed at 12 months (P = 0.10). All four patients on indinavir-containing HAART had undetectable viral loads at 2-4 months of therapy. However, none of seven patients on nelfinavir-containing HAART had a substantial decrease in viral load. Viruses from 14 patients were analyzed, 12 of which (86%) had at least one primary resistance mutation that is known to confer resistance to HIV-1 virus. Three patients had the multi-drug-resistant mutation, Q151M, two of whom showed reduced susceptibility to zidovudine, didanosine, stavudine and zalcitabine. CONCLUSION: Our limited findings show that nelfinavir-containing regimens may have limited virologic benefit to HIV-2-infected patients.

Adult↗

PubMed2006

Scarce influence of corticosteroid boluses on long-term viral load and liver histology in transplanted patients with recurrent hepatitis C.

Corticosteroid boluses, which are the treatment for acute rejection episodes, have been shown to produce transient increases in viremia. However, their effect on long-term viral load, histological activity index (HAI), and fibrosis has not been well established. The aim of our study was to compare late viral load, HAI, and fibrosis in patients with versus without steroid boluses in the immediate posttransplant period. We analyzed patients transplanted due to hepatitis C virus. Inclusion criteria were: no change in immunosuppression (cyclosporine or tacrolimus with/without mycophenolate); no steroids in the previous 4 months; no antiviral treatment; liver biopsy and viral load determination >12 months after transplantation. Exclusion criteria were HIV, hepatitis B, and active cytomegalovirus infection. Nonparametric tests were used to compare viral load, HAI, and fibrosis (Ishak-score) among patients who received steroid boluses for an acute rejection episode (group 1) versus those who did not (group 2). Among the 48 selected patients were 38 men with the overall mean age of the entire group of 55.6 +/- 10.9 years. The mean period from liver transplantation was 53.25 +/- 33.4 months. Thirty-four (70.1%) were treated with tacrolimus and the rest, cyclosporine. Eleven (22.9%) had and 37 (77.1%) had not received corticosteroid boluses. The viral load was similar in groups 1 and 2 (5.74 +/- 0.54 vs 5.98 +/- 0.53 Log(10) IU per mL, P = .32). Fibrosis was also similar (2.5 +/- 1.6 vs 2.2 +/- 1.7, P = .56). However, HAI was higher in group 1 (7.5 +/- 1.7 vs 6.0 +/- 1.7, P = .026). In conclusion, although long-term viral load was similar in patients who had versus had not received one cycle of steroid boluses, the HAI was significantly higher in the former cohort, but had not resulted in greater fibrosis during the study follow-up.

Adrenal Cortex Hormones↗

PubMed2004

Initial viral load and the outcomes of SARS.

BACKGROUND: Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus. It may progress to respiratory failure, and a significant proportion of patients die. Preliminary data suggest that a high viral load of the SARS coronavirus is associated with adverse outcomes in the intensive care unit, but the relation of viral load to survival is unclear. METHODS: We prospectively studied an inception cohort of 133 patients with virologically confirmed SARS who were admitted to 2 general acute care hospitals in Hong Kong from Mar. 24 to May 4, 2003. The patients were followed until death or for a minimum of 90 days. We used Cox proportional hazard modelling to analyze potential predictors of survival recorded at the time of presentation, including viral load from nasopharyngeal specimens (measured by quantitative reverse transcriptase polymerase chain reaction [PCR] of the SARS-associated coronavirus). RESULTS: Thirty-two patients (24.1%) met the criteria for acute respiratory distress syndrome, and 24 patients (18.0%) died. The following baseline factors were independently associated with worse survival: older age (61-80 years) (adjusted hazard ratio [HR] 5.24, 95% confidence interval [CI] 2.03-13.53), presence of an active comorbid condition (adjusted HR 3.36, 95% CI 1.44-7.82) and higher initial viral load of SARS coronavirus, according to quantitative PCR of nasopharyngeal specimens (adjusted HR 1.21 per log10 increase in number of RNA copies per millilitre, 95% CI 1.06-1.39). INTERPRETATION: We found preliminary evidence that higher initial viral load is independently associated with worse prognosis in SARS. Mortality data for patients with SARS should be interpreted in light of age, comorbidity and viral load. These considerations will be important in future studies of SARS.

Adult↗

PubMed2006

Effects of drug resistance on viral load in patients failing antiretroviral therapy.

Previous studies on patients who develop drug resistant HIV-1 variants have shown that continued use of failing regimens might provide clinical benefit. However, the effect of long-term exposure to drug resistant variants may lead to emergence of compensatory mutations that may jeopardize this effect. In this study, we assess associations among type and number of drug resistant mutations, viral load and disease progression in patients with long-term follow up. Patients with genotypic testing performed at the time of treatment failure were enrolled. Comparison of viral load and CD4 cell count between different resistance groups was performed using analysis of variance. Multiple linear regression analysis was performed to assess the simultaneous effects of the presence of particular mutations and their accumulation on viral load. Data from 475 patients who were followed for a median of 43 months from October 1999 to July 2005 were studied. A "V shape" relationship was observed between the number of mutations and viral load. Specifically, in patients harboring up to five mutations, viral load was reduced by 0.8 log/copies when compared to wild-type variants. However, with more than six mutations viral load progressively increased. Certain reverse transcriptase mutations such as M184V/I, K70R, V108I, and protease mutations such as L33FIV, M84V, and M36I were associated with reduced viral load. Together, these findings suggest that long-term maintenance of a sub-optimal antiretroviral regimen may have deleterious consequences for the patient.

Adult↗

PubMed2005

Use of quantitative real-time PCR (qRT-PCR) to measure cytokine transcription and viral load in murine cytomegalovirus infection.

A quantitative real-time PCR (qRT-PCR) assay was developed to measure cytokine transcription profiles and viral load during sub-clinical and clinical infection with murine cytomegalovirus (MCMV). Primers/fluorogenic probes specific for mouse cytokines and for the immediate early gene 1 (IE1) of MCMV were used to quantitate cytokine responses and viral load in various organs of MCMV infected mice. Increased mRNA levels of TNF-alpha, INF-gamma and IL-10 were detected in the spleens, lungs and livers of clinically infected mice at 5 days post-infection. Transcription of these cytokines was 2-5-fold lower (p=0.07 for each cytokine) in the spleens and 10-100-fold lower in the lungs (p=0.03 for INFgamma, not significant for IL-10 and TNFalpha) and livers (p<0.05 for each cytokine) of sub-clinically infected mice. Clinical MCMV infection induced high levels of IL-6 in the lungs and spleens of infected animals, while no significant transcription of IL-6 was detected in any organ during sub-clinical infection (p<0.05). The timing of peak amounts of INF-gamma, IL-10 and IL-6 observed in the spleens of clinically infected mice correlated with high viral loads in these organs. Cytokine expression rose in the salivary glands later, at day 15, corresponding to the increase in salivary gland viral load. The qRT-PCR demonstrates that infection with MCMV induces an organ-specific cytokine response characterized by the production of TNF-alpha, INF-gamma, IL-6 and IL-10 which correlates with severity of the disease (sub-clinical versus clinical) and with viral load. In summary, qRT-PCR is a sensitive and accurate method to study MCMV infection and host responses to the virus.

Animals↗

PubMed2005

Can viral load, semi-quantitatively evaluated, of human papillomavirus predict cytological or histological outcome in women with atypical squamous or glandular cells of undetermined significance cytology?

OBJECTIVE: 1) To assess the regression to normal cytology in women with cervical smears diagnosed as atypical squamous or glandular cells of undetermined significance (ASCUS/AGUS) and absence or clearance of human papillomavirus (HPV) infection; 2) To evaluate the association between viral load, semi-quantitatively evaluated, and cytological or histological outcome. MATERIAL AND METHODS: In this cohort study HPV test and biopsy was taken in 148 women with ASCUS/AGUS cytology. After 12-18 months a HPV test and cervical smear were repeated in 121 women. RESULTS: Absence or clearance of HPV showed significantly more regression to normal cytology than persistent or newly acquired infected women, odds ratio 27 (95% confidence interval; 7-103). The viral load of the HPV test at enrollment was not correlated with the follow-up cytological outcome (Spearman correlation coefficient 0.2, p = 0.2). A marked association between viral load and histological outcome at enrollment was shown (Spearman correlation coefficient 0.43, p < 0.0001). CONCLUSION: Absence or clearance of HPV can predict regression to normal cytology. Viral load at enrollment cannot predict cytological regression. There was a marked association between viral load and the underlying CIN at enrollment. However, there was large overlapping of viral loads among the grades of CIN. Therefore, viral load is not a useful parameter to predict high-grade lesions in women with ASCUS/AGUS cytology.

Adolescent↗

PubMed2003

Plasma viral load, CD4 cell percentage, HLA and survival of HIV-1, HIV-2, and dually infected Gambian patients.

OBJECTIVE: To examine baseline plasma viral loads according to the CD4 cell percentage (CD4%) in HIV-1, HIV-2 and dually infected patients (HIV-D), and to relate these measurements to survival. PATIENTS AND METHODS: A total of 119 HIV-1, 137 HIV-2 and 81 HIV-D-infected patients attending the Medical Research Council clinic in The Gambia were recruited from 1991 according to baseline CD4%, and followed until death or the end of December 2000. HIV-1 and HIV-2 RNA levels were measured by in-house reverse transcriptase polymerase chain reaction assays. RESULTS: The plasma viral load, which varied inversely with CD4%, was similar in HIV-1 singly and dually infected patients, but was significantly higher in HIV-1 than in HIV-2 singly infected patients, except in those with a CD4% less than 14%. HIV-2 plasma viral load in dually infected patients did not vary significantly with CD4%, but was significantly lower than in HIV-2 singly infected patients with CD4% less than 14%. Multivariate analysis showed that only CD4% was independently associated with survival in HIV-1 and HIV-D infections; whereas both CD4% and plasma viral load were independently associated with survival in HIV-2 infections. The mortality rate of HIV-D-infected patients was not significantly different from that of HIV-1-infected patients, but was significantly higher in the absence of HLA B58. CONCLUSION: HIV-2 infection does not alter HIV-1 replication or prolong survival in dually infected patients. In a clinical setting in Africa, where many patients present with advanced disease, CD4% may be a more important predictor of prognosis than plasma viral load.

Adolescent↗

PubMedDate not supplied

RT-PCR comparative study of viral load levels in the HIV positive population in Puerto Rico before and after protease inhibitor regimen implanted.

Ponce School of Medicine AIDS Research Program conducted a large scale viral load assessment of Puerto Ricans who are infected by human immunodeficiency virus type 1 (HIV-1) during the summer of 1996 through the Roche ACCESS program before general implementation of combination therapy. Since January 1997, it has monitored those HIV-1 patients who are under treatments at most HIV-1 health care clinics, including both public and private. The present study was conducted to evaluate how the new treatment has generally impacted on the HIV-1 disease status of HIV-1 infected population in the eight Immunology Clinics. Assessment was made by consecutively monitoring the changes in HIV-1 viral load profiles of the population from January to September, 1997. A large majority of samples were delivered for viral load assessment without information of their treatment status, and only a small number of samples were identifiable either as baseline or followup. Despite the paucity of individual information, remarkable improvements of HIV-1 (+) population at large were evident. For example, in the summer of 1996 (ACCESS), population median viral load was 51,842; only 9% of the population had viral load less than 500 viral RNA copies/ml plasma and 72% had over 10,000 copies/ml. By July-September, 1997, the population median dropped to 8,679 (83%); 23% were below 500 copies/ml (+156%) and the proportion of patients who had over 10,000 copies/ml was reduced to 48% (-33%). The group of individuals who were positively identified as "follow-up" (i.e., under active treatment) had a median of 37128 copies/ml (-94%); 28% were below 500 copies/ml (+211%) and only 40% had more than 10,000 copies/ml (-44%). It is obvious that the implementation of triple combination therapy by PASET in 1997, has very markedly improve the HIV-1 disease status of HIV-1 (+) population in Puerto Rico.

HIV Infections↗

PubMedDate not supplied

TTV viral load as a marker for immune reconstitution after initiation of HAART in HIV-infected patients.

PURPOSE: To investigate whether TT virus (TTV) viral load may be used as a surrogate marker for functional immune reconstitution in HIV-infected patients receiving highly active antiretroviral therapy (HAART). METHOD: Fifteen protease inhibitor-naïve HIV-infected patients were included in a longitudinal study. From each patient, three serum samples taken before HAART initiation and three samples taken during HAART were analyzed. TTV was detected by polymerase chain reaction (PCR) and was quantitated by competitive PCR. TTV viral heterogeneity was determined by restriction fragment length polymorphisms (RFLPs) and sequencing. RESULTS: All 15 HIV-infected patients were TTV positive. No significant change in HIV RNA or TTV viral load was observed at the three time points before HAART initiation. Even though HAART lead to an immediate and significant reduction in HIV RNA (p =.0001), a significant reduction in TTV viral load (p =.0002) was not observed until after 3-5 months of HAART. Four patients did not have an increase in CD4+ T cell count after 1 year of HAART; however, a decrease in TTV viral load was still observed, and three of these patients had a reduction in HIV RNA. RFLPs and sequencing revealed that TTV is represented as a heterogeneous population of virus in HIV-infected patients. CONCLUSION: This pilot study suggests that HAART leads to improved immunological responses, even in patients who do not have an increase in CD4+ T cell counts. We propose that the change in TTV viral load may be useful in the evaluation of cellular immune response at a functional level in HIV-infected patients who receive HAART.

Adult↗

PubMed2004

Hierarchical targeting of subtype C human immunodeficiency virus type 1 proteins by CD8+ T cells: correlation with viral load.

An understanding of the relationship between the breadth and magnitude of T-cell epitope responses and viral loads is important for the design of effective vaccines. For this study, we screened a cohort of 46 subtype C human immunodeficiency virus type 1 (HIV-1)-infected individuals for T-cell responses against a panel of peptides corresponding to the complete subtype C genome. We used a gamma interferon ELISPOT assay to explore the hypothesis that patterns of T-cell responses across the expressed HIV-1 genome correlate with viral control. The estimated median time from seroconversion to response for the cohort was 13 months, and the order of cumulative T-cell responses against HIV proteins was as follows: Nef > Gag > Pol > Env > Vif > Rev > Vpr > Tat > Vpu. Nef was the most intensely targeted protein, with 97.5% of the epitopes being clustered within 119 amino acids, constituting almost one-third of the responses across the expressed genome. The second most targeted region was p24, comprising 17% of the responses. There was no correlation between viral load and the breadth of responses, but there was a weak positive correlation (r = 0.297; P = 0.034) between viral load and the total magnitude of responses, implying that the magnitude of T-cell recognition did not contribute to viral control. When hierarchical patterns of recognition were correlated with the viral load, preferential targeting of Gag was significantly (r = 0.445; P = 0.0025) associated with viral control. These data suggest that preferential targeting of Gag epitopes, rather than the breadth or magnitude of the response across the genome, may be an important marker of immune efficacy. These data have significance for the design of vaccines and for interpretation of vaccine-induced responses.

Amino Acid Sequence↗

PubMed1999

Presence of genotypic resistance in nucleoside analogue-treated HIV-1-infected patients with undetectable viral load.

Patients harbouring drug-resistance viruses usually suffer a rise in serum viraemia after a variable period of time. We have investigated the relationship between the appearance of resistant genotypes and the viral load of each patient after treatment. Our objective was to assess the association between human immunodeficiency virus (HIV) RNA plasma levels and the number of drug resistance-associated point mutations after treatment. A total of 150 patients from three reference centres in Spain (Madrid, Barcelona and Seville) from a previous study (Erase Study) were included. Patients had at that time undergone antiretroviral treatment with nucleoside analogues for at least 1 year (zidovudine/didanosine; zidovudine/zalcitabine; zidovudine/zalcitabine/lamivudine; zidovudine/didanosine/lamivudine). In this study, plasma viraemia in these patients was quantified and a line probe assay was used to determine the genotype of the virus. Viral load was significantly higher in patients harbouring virus with more than three mutations than in those individuals who harboured wild-type strains (P < 0.05). Surprisingly, when patients with viral load < 500 copies/ml (13/150) were analysed, only two carried wild-type strains, whereas three had virus with more than three point mutations. The viral load of six samples was assayed using an ultrasensitive test (detection limit < 20 copies/ml). Of the three samples where viral load was < 20 copies/ml, one patient harboured wild-type virus, whereas two carried mutant virus strains. These results suggest that even in patients with undetectable viral loads by conventional methods, viral replication may continue and mutations develop. Therefore, standard values of plasma viraemia for measuring the effectiveness of the treatment should be reconsidered when patients are on antiviral regimens of just two or three nucleoside analogues.

Acquired Immunodeficiency Syndrome↗

PubMed2006

Reverse transcriptase viral load correlates with RNA in SIV/SHIV-infected macaques.

Monitoring of viral load in macaques has usually been carried out using in-house PCR-based methods. A novel viral load (VL) kit (ExaVir Load) based on the measurement of lentivirus reverse transcriptase (RT) activity provides a potential alternative to methods that measure plasma viral RNA. RT is a fundamental and conserved activity of all retroviruses and the method should theoretically detect RT from all lentiviruses. To test this we compared VL measured by a commercially available RT kit with an in-house QC RT-PCR in macaques infected with SIV and SHIV. Both RT and RNA levels were measured over time in both sets of macaques. Results indicated that the relationship between both tests was strong for SIV and SHIV (r = 0.95 and r = 0.92, p < 0.0001, respectively). The VL trends also followed each other, indicating that both techniques measured the same process of viral replication. Furthermore, the RT load obtained using standardized control plasma samples supplied by NIBSC gave values close to the designated VL. However, when comparing RT load with QC RT-PCR a consistently three to five time higher level was obtained with the RT assay, highlighting potential differences in assay calibration. Even so, the data suggest that the RT assay is both sensitive and robust for use in the SIV/SHIV macaque model, particularly where molecular-based assays for SIV VL determinations are not easily available. The assay is also a commercially available kit and hence has the potential to reduce the variability seen between laboratories using in-house PCR.

Animals↗

PubMed2000

Cerebrospinal fluid and plasma viral load in HIV-1-infected patients with various anti-retroviral treatment regimens.

Highly active anti-retroviral therapy (HAART) effectively decreases HIV-1 RNA in cerebrospinal fluid (CSF) and plasma in controlled clinical trials. To study the virological effect in CSF and plasma achieved in routine practice, HIV-1 RNA levels were analysed retrospectively in 27 patients on mono-nucleoside reversed transcriptase inhibitor (NRTI) treatment, 27 on dual-NRTI-treatment and 45 on HAART using a Roche Amplicor HIV-1 monitor quantitative PCR. A significant difference was found in the proportion of patients with a CSF viral load below 20 copies/ml between patients treated with 1 (0%) and 2 NRTIs (41%) as well as between those treated with 2 NRTIs and HAART (69%). The proportion of patients with plasma viral load below 20 copies/ml differed significantly between patients on HAART (47%) and those on 2 NRTIs (0%), but not between those with 1 (0%) or 2 NRTIs. In multivariate regression analysis, treatment regimen and prior anti-retroviral experience (but not treatment time) were independently associated with the CSF viral load. Plasma viral load was independently associated with treatment regimen and treatment time, but not with anti-retroviral experience. Dual-NRTI-treatment affects the CSF viral load substantially, while HAART is required to achieve an essential decline in plasma viral load.

Acquired Immunodeficiency Syndrome↗