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PubMed2002

TT virus is distributed in various leukocyte subpopulations at distinct levels, with the highest viral load in granulocytes.

When TT virus (TTV) DNA was quantitated in whole blood and plasma aliquots from 27 viremic individuals by real-time detection PCR that can detect essentially all TTV genotypes, the TTV load was 6.9 +/- 3.5 (mean +/- standard deviation)-fold higher in the whole blood than in the plasma samples [P < 0.002 (paired t test)]. To clarify the reason for this difference, peripheral blood cells of various types including red blood cells, granulocytes (CD15+), B cells (CD19+), T cells (CD3+), monocytes (CD14+), and NK cells (CD3-/CD56+) were separated at a purity of 95.4-99.5% from each of three infected individuals with relatively high TTV viremia, and their TTV viral loads were determined. Red blood cells were uniformly negative, but the other cell types were positive for TTV DNA at various titers. In all three patients, the highest TTV load was found in granulocytes (4.2 x 10(4)-3.1 x 10(5) copies/10(6) cells), followed by monocytes (1.4-2.2 x 10(4) copies/10(6) cells) and NK cells (5.4-6.5 x 10(3) copies/10(6) cells); B and T cells were positive, with a low viral load (6.7 x 10(1)-2.7 x 10(3) copies/10(6) cells). These results indicate that TTV is distributed in various peripheral blood cell types at distinct levels, with the highest viral load in granulocytes, and that a significant proportion of the TTV DNA in peripheral blood is not identified by the standard plasma/serum DNA detection methods.

Adult↗

PubMed2007

Crack cocaine: effect modifier of RNA viral load and CD4 count in HIV infected African American women.

This study reports on the role of cocaine as effect modifier of the association of CD4+ cell counts and RNA viral load. HIV-1 seropositive (n = 80) and seronegative (n = 42) African American women (AAW) crack cocaine smokers were recruited. Increasing cocaine use, based on self-reports and laboratory values, significantly exacerbates the immunopathology of HIV-1 in a dose-response manner, confirmed by a non-linear drop in CD4+ cell number for a given viral load in HIV+ AAW. This report supports a view of deleterious effects due to cocaine use in humans.

Adult↗

PubMed2001

Area under the viraemia curve versus absolute viral load: utility for predicting symptomatic cytomegalovirus infections in kidney transplant patients.

A novel approach to predicting symptomatic cytomegalovirus (CMV) infections combines the level and the duration of viraemia in a single parameter. Sixty-four kidney transplant recipients were monitored by quantitative shell vial culture, pp65 antigenaemia, and polymerase chain reaction (PCR) of leucocytes. The area under the curve (AUC) of each parameter was determined from the onset of viraemia to the beginning of antiviral treatment. The AUC values were significantly higher in symptomatic than in asymptomatic patients. For antigenaemia and PCR, optimal AUC thresholds for predicting symptomatic CMV infections were determined. They were superior to standard cutoff levels of absolute viral load in sensitivity, specificity, and positive and negative predictive value. In 8 of the 23 patients who became symptomatic, impending clinical features were indicated earlier by the AUC thresholds than by standard viral load. In conclusion, the concept of the AUC should facilitate identification of patients at risk of symptomatic CMV infection.

Area Under Curve↗

PubMed2003

HIV-1 viral load determination based on reverse transcriptase activity recovered from human plasma.

We describe a procedure (ExaVir Load) to carry out human immunodeficiency virus-1 (HIV-1) viral load testing using reverse transcriptase (RT) recovered from HIV-1 virions in plasma. Samples from individuals infected with HIV-1 were treated with a sulphydryl-reactive agent to inactivate endogenous polymerases. Virions were then immobilised on a gel and washed in individual mini columns to remove RT-inhibiting antibodies, antiviral drugs, and other RT inhibitors. Immobilised virions were lysed finally, and the viral RT eluted. The amount of RT recovered was quantified by a sensitive RT activity assay using either colorimetry or fluorimetry to detect DNA produced by RT. The "RT load" values of 390 samples from 302 HIV-1 patients living in Sweden were compared to results obtained with an HIV-1 RNA viral load assay. The correlation between the two tests was r = 0.90, P < 0.0001. Four of 202 samples from healthy blood donors gave low positive values in the RT test. All samples in a panel with 10 HIV-1 subtypes were positive by the RT load. The RT load test provides a technically less demanding and cost-effective alternative to methods based on nucleic acid amplification. Being insensitive to genetic drift occurring in HIV, the assay should be of particular use in resource-limited settings, where different subtypes and recombinant HIV strains occur.

Animals↗

PubMed1998

Prognostic significance of plasma markers of immune activation, HIV viral load and CD4 T-cell measurements.

OBJECTIVE: To evaluate the prognostic significance for AIDS occurrence of plasma levels of immune activation markers in comparison with and in conjunction with HIV viral load and CD4 T-cell measurements. DESIGN: A retrospective analysis was conducted of three plasma activation markers, the soluble tumor necrosis factor (TNF) receptor II (TNF-RII), neopterin and soluble interleukin-2 receptor levels, and of CD4 T-cell levels and plasma HIV viral load. SUBJECTS: The participants were 659 men taking part in the University of California Los Angeles Multicenter AIDS Cohort Study who were HIV-seropositive but AIDS-free in 1985. MAIN OUTCOME MEASURE: Clinically defined AIDS within 3 years. Failure time statistical regression models for the time to development of AIDS were used to assess prognostic capacity of the parameters alone and in combination. RESULTS: All the markers had prognostic capability. The levels of the three plasma activation markers correlated well with each other (median r = 0.61). They related less well with HIV RNA plasma levels (median r = 0.50) and least well with CD4 cell levels (median r = 0.36). Furthermore, plasma marker levels were shown to be able to stratify patients for prognosis within all the major categories of CD4 T-cell and HIV RNA levels. CONCLUSIONS: Plasma levels of soluble TNF-RII and other soluble markers of immune activation have prognostic capabilities which are different from HIV and CD4 T-cell levels. Combination of a single plasma activation marker measurement (such as soluble TNF-RII) with CD4 T-cell levels improved the prognostic capability of each. A new graphic technique for presenting prognostic capability indicated that plasma soluble TNF-RII and CD4 cell levels are better prognostic factors than HIV plasma level with CD4 cells < 200 x 10(6)/l. Inexpensive tests for one of the plasma activation markers, such as soluble TNF-RII or neopterin, can be useful for evaluations of HIV disease course, especially when expensive equipment, technical expertise and funding required for flow cytometry and for HIV load measurements are not readily available.

Antigens, CD↗

PubMed1998

Quantification of viral load: clinical relevance for human immunodeficiency virus, hepatitis B virus and hepatitis C virus infection.

Quantitative determination of viral load using nucleic acid amplification techniques represents the most accurate prognostic marker for human immunodeficiency virus type 1 (HIV-1) infection, independently of CD4+ cell count. Overall, the different methods for HIV-1 RNA determination (RT-PCR, nucleic acid sequence-based amplification, branched DNA) show a good reproducibility (0.5 log), however for low copy numbers and in HIV-1-infected children the variability may exceed 0.7 log. In non-HIV-1 subtype B infections the copy number is underestimated. While serology permits an accurate follow-up of hepatitis B virus (HBV) infection, HBV DNA quantification is used for monitoring of antiviral therapy, determination of infectiosity and in combination with serological markers for the resolution of unusual profiles, i.e. isolated anti-HBc reactivity. The prognostic relevance of hepatitis C virus (HCV) RNA determination is of limited value for the long-term prognosis of chronic hepatitis C, however the viral load may predict the outcome of antiviral therapy. Genetic diversity represents a challenge for HCV RNA quantification.

Acquired Immunodeficiency Syndrome↗

PubMed2003

Association of amino acid substitution pattern in nonstructural protein 5A of hepatitis C virus genotype2a low viral load and response to interferon monotherapy.

Patients with low titer (<0.5 mEq/ml) of hepatitis C virus (HCV) genotype 2a achieve high and sustained response (SR) rates to interferon (IFN) monotherapy, but we also encounter patients who are resistant to therapy. We explored the relationship between response to IFN and virological differences in such patients. We evaluated 159 consecutive naive patients with low titer of HCV genotype 2a who received IFN monotherapy. A case-control study matched for age, sex, and viral load was conducted to examine the substitution patterns in amino acid positions (amino acids) 2163-2254 of nonstructural (NS) 5A between nonresponders to ideal IFN dose (>/=500 million units) (nonresponders; NR) and responder to less than ideal dose. Overall, 82.4% achieved SR. The substitution numbers in amino acids 2193-2254 were higher in SR than NR patients (P < 0.05). High proportions of patients with substitution at amino acid 2205 (mainly threonine [T] instead of alanine [A]), dual amino acids 2169 and 2205 (mainly A-T instead of T-A), and those without substitution at amino acids 2227 were NR (P < 0.05). Four of 7 NR patients achieved SR after receiving a second course of IFN. Their amino acids patterns at positions probably associated with sensitivity to IFN did not change at the start of initial and second therapies except for one patient, and they had lower viral load and were treated with higher IFN dose in the second course compared with the initial course. Our results suggest that substitution patterns in NS5A in patients with low titer of HCV genotype 2a may affect their response to IFN, but the response to therapy may be affected by mechanisms other than substitutions in this region.

Adult↗

PubMed2005

Mechanisms involved in the low-level regeneration of CD4+ cells in HIV-1-infected patients receiving highly active antiretroviral therapy who have prolonged undetectable plasma viral loads.

BACKGROUND: Persistent low CD4(+) cell counts are observed in 5%-27% of patients treated for human immunodeficiency virus (HIV)-1 infection despite their having prolonged undetectable plasma viral loads. METHODS: To understand the possible mechanisms of this discordant immunological situation, a prospective transsectional case-control study was designed. HIV-1-infected subjects who had a plasma viral load <200 copies/mL for >1 year were considered to be case patients if their CD4(+) cell count was <250/mm(3); control patients had CD4(+) cell counts >500/mm(3) and were matched by sex, age, and nadir CD4(+) cell count to case patients. T cell proliferation after stimulation with various antigens, T cell subset counts, T cell rearrangement excision circles (TRECs), T cells undergoing apoptosis, cytokines influencing apoptosis, and cellular proviral DNA and plasma viral RNA persistence were assessed. RESULTS: Compared with the 19 control patients, the 19 case patients had undistinguishable lymphoproliferative responses to candidin and cytomegalovirus, fewer naive CD4(+) cells (CD45RA(+)62L(+), 23%+/-13% vs. 47%+/-14%; P<.0001), lower thymic output (1.28 vs. 3.95 TRECs/microL of blood; P=.0015), increased cell death by apoptosis (spontaneous, 23.2%+/-8.3% vs. 11.9%+/-8.4% [P=.02]; Fas induced, 38.6%+/-13.7% vs. 16.4%+/-8.0% [P=.004]), higher levels of plasma soluble tumor necrosis factor receptor II (9.6 vs. 5.3 ng/mL; P=.0058), and undistinguishable plasma HIV-1 and cellular proviral DNA loads. CONCLUSIONS: The mechanisms responsible for the low-level regeneration of CD4(+) cells involve, at least, deficiency in the regeneration of central CD4(+) cells and excessive apoptosis.

Adult↗

PubMed2004

Hepatitis C virus population analysis of a single-source nosocomial outbreak reveals an inverse correlation between viral load and quasispecies complexity.

The features of Hepatitis C virus (HCV) quasispecies within an envelope segment including the hypervariable region 1 were analysed at an early time point post-infection in seven patients that acquired HCV from a single common donor during a nosocomial outbreak. The grouping of patients according to viral load was reflected in the structure of the quasispecies. A higher viral load correlated with the presence of a predominant HCV genome and a corresponding lower quasispecies complexity. The quasispecies complexity itself was not correlated with HCV clearance or persistence. Thus, the relationship between an intrapatient HCV quasispecies and the clinical outcome of an HCV infection is more complex than previously anticipated.

Amino Acid Sequence↗

PubMed2003

Comparison of human immunodeficiency virus type 1 viral loads in Kenyan women, men, and infants during primary and early infection.

Steady-state levels of human immunodeficiency virus type 1 (HIV-1) RNA in plasma reached at approximately 4 months postinfection are highly predictive of disease progression. Several studies have investigated viral levels in adults or infants during primary and early infection. However, no studies have directly compared these groups. We compared differences in peak and set point plasma HIV-1 RNA viral loads among antiretrovirus-naive Kenyan infants and adults for whom the timing of infection was well defined. Peak and set point viral loads were significantly higher in infants than in adults. We did not observe any gender-specific differences in viral set point in either adults or infants. However, infants who acquired HIV-1 in the first 2 months of life, either in utero, intrapartum, or through early breast milk transmission, had significantly higher set point HIV-1 RNA levels than infants who were infected after 2 months of age through late breast milk transmission or adults who were infected through heterosexual transmission.

Acute Disease↗

PubMed2006

Communication of HIV viral load to guide sexual risk decisions with serodiscordant partners among San Francisco men who have sex with men.

The objective of this study was to estimate frequency and correlates of discussing HIV viral load (VL) with serodiscordant sex partners to guide decisions about sexual activities among men who have sex with men (MSM). We conducted a cross-sectional survey of 573 San Francisco MSM. Among 507 who knew their HIV status, 397 (78%) were familiar with the term 'viral load', and half (n=199) had a serodiscordant partner in the prior year. These 199 respondents (n=130 [65%] HIV-positive; n=69 [35%] HIV-negative) were the focus of this analysis. A majority (n=111, 56%) discussed VL in the prior year with serodiscordant partners specifically to guide decisions about sexual risk behaviour. Discussion was more common among HIV-positive than HIV-negative participants (adjusted odds ratio [AOR], 3.5; 95% confidence interval [CI], 1.6-7.6), and African Americans compared to whites (AOR, 3.7; 95% CI, 1.5-9.5). HIV-negative men who discussed VL were more concerned about becoming infected, but also more willing to engage in risky behaviour with a partner whose VL is undetectable, than men not discussing VL. Some HIV-negative men may be discussing VL to engage in higher risk behaviour upon learning of an HIV-positive partner's undetectable VL. Interventions targeting MSM should explain that while risk of transmission is likely reduced with a low blood plasma VL, it is not necessarily eliminated.

Adult↗

PubMed2005

Are in vitro hepatitis B core promoter mutations important for clinical alterations in viral load?

In vitro studies of HBV core promoter mutations in hepatoma cell lines suggest that some mutations in core promoter transcription factor binding sites result in reduced core promoter activity and viral replication. We sought to validate this hypothesis using clinical samples with viral load differences before and after HBeAg seroconversion. A consensus sequence for transcription factor binding sites/regulatory regions was constructed based on published studies. Serum from two time points in 33 seroconverters and 10 interferon non-responders (controls) were utilized. Genotyping, HBV DNA quantification and direct sequencing of core promoter were performed. There were 216 new mutations following HBeAg seroconversion but few in controls. Mutations or mismatches to consensus transcription factor/regulatory region sequences clustered at nucleotide positions appeared genotype-specific, non-group specific or baseline mismatches and were discounted as having significant impact on viral replication. Only a few mutations in three seroconverters (9.1%) were specific, while 39.4% had no new mutations that could be attributed to reduction in viral load following HBeAg seroconversion. In 51.5% of patients, mutations were of uncertain significance because they occurred in demonstrated non-critical clustered nucleotide positions. Core promoter mutations post-seroconversion did not correlate with in vitro induced mutations that reduced the promoter activity.

Adult↗

PubMed2005

Relationship of neurological manifestations, CD4+ lymphocyte count and plasma viral load in HIV infected patients.

The aim of the study was to assess the relationship between the neurological manifestations of HIV infection, CD4+ lymphocyte count and the levels of HIV-1 RNA (viral load) in plasma. A total of 62 adult antiretroviral naïve HIV infected patients were enrolled in the study. Among them 26 had neurological complications of HIV infection (1st group), 16 patients had symptomatic disease without neurological involvements (2nd group) and 20 were asymptomatic patients (control group). Measurement of CD4 count was performed by indirect immunofluorescent assay by using the monoclonal antibodies and viral load (VL) in plasma--by RT PCR method. CD4 count was significantly lower in the 1st and 2nd group compared to the control group. There was correlation between the level of CD4 count and type of neurological manifestation. VL was comparable between the 1st and 2nd groups and was higher than in control group. There is a significant correlation between the level of CD4 count and type of neurological manifestation of HIV infection. Presence of neurological complication as well as other clinical manifestations is associated with decreased CD4 count and increased VL. Level of CD4 count can serve as an indicator for initiation of prophylaxis treatment of certain opportunistic pathogens.

Adult↗

PubMedDate not supplied

Actual medication pill burden and dosing frequency in HIV-infected patients with undetectable viral loads.

Studies have shown equivalent or improved outcomes with once-daily antiretroviral (ARV) regimens, but have failed to quantify the true daily dosing frequency and pill burden of HIV-infected patients, by not considering concomitant medications. This study was conducted to describe the total daily number (pill burden) and dosing frequency for all oral medicines, and not just ARV medications in HIV-infected patients with undetectable viral loads. A retrospective chart review of patients with undetectable viral loads in an HIV primary care clinic identified dosing frequency and pill burden for all prescribed medications. These patients were divided into those with concomitant medications (WITH) and those only on ARV medications (WITHOUT). One hundred and seventeen patients qualified for the evaluation. Ninety-three were in the WITH group and 24 were in the WITHOUT group. WITH patients were older (p < 0.05), and had advanced US Centers for Disease Control and Prevention (CDC)-defined HIV disease stage (p< 0.05), a longer duration of HIV infection (p= 0.03), and a longer duration of AIDS (p= 0.02). WITH patients had a significantly greater total pill burden (p<0.01) and dosing frequency (p<0.001) when considering all medications. Assessing only ARV medications, a significant difference existed only in pill burden (mean +/- SD) (WITH = 9.91 +/- 2.1 versus WITHOUT = 6.6 +/- 1; p < 0.01), and no difference existed in ARV dosing frequency of 2.09 +/- 1.9 and 1.83 +/- 1.7, respectively (p = 0.07). Higher dosing frequencies and pill burdens were present in patients with co-morbid conditions. All patients were on more than once-daily therapies. Dosing requirements for non-ARV medications should also be considered when optimizing or simplifying ARV regimens.

Adult↗

PubMed2005

Type distribution, viral load and integration status of high-risk human papillomaviruses in pre-stages of cervical cancer (CIN).

A series of 176 archival cervical intraepithelial neoplasia (CIN) was analysed for the presence, viral load and integration status of 'high-risk' types of human papillomavirus (HR-HPV). The samples were assayed using newly developed methods based on real-time PCR. Two methods for the extraction of DNA from the paraffin-embedded biopsies were compared: a protocol based on the MagNA pure system (Roche) and a Qiagen spin column kit (Qiagen). It was possible to amplify 94% (166) of the samples. Of these, 36, 63 and 80% of the CIN I, II and III cases contained HR-HPV. HPV 16 was the most prevalent, and was found in 20, 28 and 46% of the CIN I, II and III cases, respectively. The second most frequent HR-HPV was type 33 group, and in CIN II it was as prevalent as HPV 16. The median number of copies of HR-HPV per cell was not significantly different in the CIN I, II and III cases, but there was a wide range of viral load values over several magnitudes, regardless of the grade of CIN. All samples were found to contain integrated forms of HPV 16, frequently mixed with an episomal form.

DNA, Viral↗

PubMed2004

Outpatient pharmacy care and HIV viral load response among patients on HAART.

Adherence to highly active antiretroviral therapy (HAART) is necessary to achieve long-term effectiveness. The impact of HIV/AIDS-specific pharmacy services on patient adherence and HIV viral suppression is currently not well described. This study aimed to compare the impact of differing levels of HIV-pharmacy care on adherence and time to HIV viral suppression among participants on HAART enrolled in a population-based HIV/AIDS drug treatment programme in British Columbia. We performed a retrospective observational study of 788 treatment-naïve patients who started HAART between August 1997 and July 2000 and were followed until 31 March 2002. The degree of outpatient pharmacy care was defined according to pharmacy dispensing site for the participants' first prescription of HAART: highest at the AIDS-tertiary care hospital outpatient pharmacies, intermediate at HIV/AIDS drug treatment programme funded off-site pharmacies and lowest at family physician's offices. Cox-proportional hazard models examined the independent effect of pharmacy dispensing site on time to two consecutive HIV viral suppressions controlling for other prognostic factors including physicians' experience, age, gender, injection drug use, use of therapy containing NNRTI versus PI, adherence >90%, AIDS diagnosis at baseline, baseline CD4 cell count and HIV viral load. The median time on antiretrovirals was 28 months (IQR=14-38). There were 489 (62.1%) participants who obtained their medications from the AIDS-tertiary care outpatient pharmacies; 98 (12.4%) from off-site pharmacies and 201 (25.5%) from their physicians' offices. The proportion of patients exhibiting >90% adherence to treatment was observed to be higher among patients receiving their HAART at the AIDS-tertiary care pharmacies compared to off-site pharmacies and to physicians' offices (70.4, 59.2 and 55.7%, respectively; p=0.0001). After adjusting for other prognostic factors, subjects who were first dispensed medications from the AIDS-tertiary care pharmacy were 1.42 times (CI: 1.10-1.84) more likely to achieve HIV viral suppression than those getting their medications from off-site pharmacies and physicians' offices. Providing regular outpatient pharmacy care is independently associated with improved HIV viral load response through enhanced adherence to HAART. Standardization of pharmacy practices for dispensing HAART may improve outcomes for patients who receive their HIV medications from other non-tertiary care pharmacy sites.

Adolescent↗

PubMed2002

Positive association between beta-chemokine-producing T cells and HIV type 1 viral load in HIV-infected subjects in Abidjan, Côte d'Ivoire.

The role of beta-chemokines in controlling HIV replication in vivo is still controversial. Therefore, the association between HIV-1 plasma viral load and the capacity of CD4(+) and CD8(+) T cells to produce beta-chemokines was studied in 28 antiretroviral drug-naïve HIV-1-infected female sex workers in Abidjan, Côte d'Ivoire. Percentages of beta-chemokine-positive T cells were measured in peripheral blood mononuclear cells by flow cytometry after intracellular staining for RANTES (regulated on activation, normal T expressed and secreted), macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta. HIV-1-infected subjects had higher percentages of MIP-1alpha- and MIP-1beta-positive CD4(+) and CD8(+) T cells (p < 0.02) and of RANTES-positive CD8(+) T cells (p = 0.054) than uninfected controls. Percentages of RANTES- and MIP-1beta-positive CD8(+) T cells correlated directly with HIV-1 plasma viral load (p < 0.02). Percentages of beta-chemokine-positive CD4(+) and CD8(+) T cells correlated directly with percentages of HLA-DR-positive T cells (p < 0.02) and inversely (except RANTES in CD4(+) T cells) with absolute numbers of CD4(+) T cells (p < 0.05) in peripheral blood. These data indicate that increased percentages of beta-chemokine-producing T cells in HIV-1-infected subjects correlate with disease progression and are a sign of viremia-driven chronic T cell activation.

Adult↗

PubMed2006

Relationship between viral load and genotypes of hepatitis B virus in children with chronic hepatitis B.

OBJECTIVE: We evaluated the prevalence and clinical significance of hepatitis B virus (HBV) genotypes in children with chronic hepatitis B. METHODS: Hepatitis B virus genomes of 249 hepatitis Be antigen-positive chronic hepatitis B surface antigen carriers were genotyped based on restriction fragment length polymorphism. Genotypes were correlated with corresponding values for alanine aminotransferase levels, quantitative HBV DNA and histological findings. RESULTS: One hundred and sixty-two boys and 87 girls (mean age, 7.2 years) were studied. Ninety-six percent were attributed to HBV genotypes A (32.5%) or D (63.5%). The remaining were classified as genotypes B, C, E and F. There was no significant difference in both alanine aminotransferase levels and histological findings among different genotypes. However, there was a clear association between very high HBV DNA levels and individuals with genotype D (P = 0.006). Mean time follow-up of 3.6 years showed later anti-HBe seroconversion in patients with genotype D than in those with genotype A (58% vs 37%). CONCLUSIONS: Compared with children with genotype A, children with genotype D showed a significantly higher viral load. Inasmuch as a relationship exists between viral load and response to treatment in children infected through vertical transmission, children with genotype D have to be carefully monitored. Long-term studies are needed to determine whether these patients are at risk of a poorer outcome.

Adolescent↗