Plasma Viral Load Levels Research Articles

Neuroinvasion of Fluorescein-Positive Monocytes in Acute Simian Immunodeficiency Virus Infection

Monocytes and macrophages play a central role in the pathogenesis of human immunodeficiency virus (HIV)-associated dementia. They represent prominent targets for HIV infection and are thought to facilitate viral neuroinvasion and neuroinflammatory processes. However, many aspects regarding monocyte brain recruitment in HIV infection remain undefined. The nonhuman primate model of AIDS is uniquely suited for examination of the role of monocytes in the pathogenesis of AIDS-associated encephalitis. Nevertheless, an approach to monitor cell migration from peripheral blood into the central nervous system (CNS) in primates had been lacking. Here, upon autologous transfer of fluorescein dye-labeled leukocytes, we demonstrate the trafficking of dye-positive monocytes into the choroid plexus stromata and perivascular spaces in the cerebra of rhesus macaques acutely infected with simian immunodeficiency virus between days 12 and 14 postinfection (p.i.). Dye-positive cells that had migrated expressed the monocyte activation marker CD16 and the macrophage marker CD68. Monocyte neuroinvasion coincided with the presence of the virus in brain tissue and cerebrospinal fluid and with the induction of the proinflammatory mediators CXCL9/MIG and CCL2/MCP-1 in the CNS. Prior to neuroinfiltration, plasma viral load levels peaked on day 11 p.i. Furthermore, the numbers of peripheral blood monocytes rapidly increased between days 4 and 8 p.i., and circulating monocytes exhibited increased functional capacity to produce CCL2/MCP-1. Our findings demonstrate acute monocyte brain infiltration in an animal model of AIDS. Such studies facilitate future examinations of the migratory profile of CNS-homing monocytes, the role of monocytes in virus import into the brain, and the disruption of blood-cerebrospinal fluid and blood-brain barrier functions in primates.

Apricitabine: A Novel Deoxycytidine Analogue Nucleoside Reverse Transcriptase Inhibitor for the Treatment of Nucleoside-Resistant HIV Infection

Existing nucleoside reverse transcriptase inhibitors for HIV disease are limited by problems of resistance and, in some cases, long-term toxicity. Apricitabine (ATC; formerly BCH10618, SPD754 and AVX754) is a deoxycytidine analogue nucleoside reverse transcriptase inhibitor in clinical development. ATC retains substantial in vitro activity against HIV-1 containing many mutations associated with nucleoside reverse transcriptase inhibitor resistance, showing a less than twofold reduction in susceptibility in the presence of either up to five thymidine analogue mutations or the M184V mutation. ATC showed a low potential for cellular or mitochondrial toxicity in vitro. ATC is well absorbed orally, with a bioavailability of 65-80%. Its plasma elimination half-life (approximately 3 h), and the intracellular half-life of its triphosphate (TP) metabolite (6-7 h) support twice-daily dosing. Intracellular ATC-TP levels are markedly reduced in the presence of lamivudine or emtricitabine, indicating that clinical co-administration of ATC together with these agents will not be possible. The drug is renally eliminated, giving a low potential for hepatic drug interactions. In a double-blind, randomized, placebo-controlled Phase II monotherapy trial in antiretroviral-naive patients, ATC doses of 1,200 and 1,600 mg/day reduced plasma viral load levels by 1.65 and 1.58 log10 HIV RNA copies/ml, respectively, after 10 days of treatment (P<0.0001 versus placebo). ATC showed a low propensity to select for resistance mutants in vitro and during clinical monotherapy. ATC was well tolerated in volunteers and in HIV-infected patients. This promising profile suggests that ATC may be useful in treating patients who have failed previous lamivudine- or emtricitabine-containing regimens. Further studies to evaluate the long-term efficacy and tolerability of ATC are underway.

Impact of chloroquine on viral load in breast milk

The anti-malarial agent chloroquine has activity against HIV. We compared the effect of chloroquine (n = 18) to an anti-malarial agent without known anti-HIV-activity, sulfadoxine-pyrimethamine (n = 12), on breast milk HIV RNA levels among HIV-infected breastfeeding women in Zambia. After adjusting for CD4 count and plasma viral load, chloroquine was associated with a trend towards lower levels of HIV RNA in breast milk compared with sulfadoxine-pyrimethamine (P = 0.05). Higher breastmilk viral load was also observed among women receiving presumptive treatment for symptomatic malaria compared with asymptomatic controls and among controls reporting fever in the prior week. Further research is needed to determine the potential role of chloroquine in prevention of HIV transmission through breastfeeding.

Role of Lymphocyte Multidrug Resistance Protein 1 in HIV Infection

The multidrug resistance protein 1 (MRP1) is a drug transporter that protects cells from oxidative stress, which increases HIV-1 replication. The aim of this study was to characterize the expression, function, and role of lymphocyte MRP1 in HIV-1 infection and its modulation by antiretroviral drugs such as the protease inhibitors (PIs). Peripheral blood mononuclear cells (PBMCs) from HIV-positive individuals do not show significant alterations of MRP1 expression despite highly active antiretroviral therapy and HIV plasma viral load levels; however, they exhibit different intracellular MRP1 expression as compared with healthy subjects. By contrast, MRP efflux function is increased in subjects with primary HIV infection and becomes defective in later stages of the infection. PI- and probenecid (PBCD)-mediated inhibition of MRP lowers the in vitro stress-induced response of lymphoid cells by reducing the level of the specific reactive oxygen species superoxide anion and hydrogen peroxide. Finally, the blockade of MRP by PBCD and PIs down-modulates HIV-1 replication by a mechanism independent of inhibition of the HIV-1 protease. Our results are consistent with a model wherein HIV replication is favored by the MRP1-related oxidative stress and inhibition of MRP1 may contribute to the antiviral activity of PIs.

Mannose-binding lectin gene polymorphism and its impact on human immunodeficiency virus 1 infection

Mannose-binding lectin (MBL) is a serum protein whose low concentration is associated with the occurrence of allele variants named MBL* B, MBL* C and MBL* D. The present study investigated the association between MBL gene polymorphism and the susceptibility to HIV-1 infection. The study of 145 HIV-1-infected subjects and 99 healthy controls showed the presence of alleles MBL*A, MBL*B and MBL*D, whose frequencies were 69%, 22% and 09% among patients and 71%, 13% and 16% among healthy controls, respectively. The presence of the variant MBL*B was associated with higher plasma viral load levels, suggesting the importance of the MBL gene polymorphism in the clinical evolution of HIV-1-infected patients.

Nonfinancial Factors Associated With Decreased Plasma Viral Load Testing in Ontario, Canada

To examine whether individual characteristics were associated with differential use of viral load testing when testing is available without charge to all HIV-positive patients with provincial health insurance. Individuals enrolled in the HIV Ontario Observational Database with complete medication records and health insurance numbers for linkage were studied. Generalized estimating equation regression models were used to examine the relationship between time-varying covariates such as plasma viral load levels, CD4 counts, and antiretroviral regimen characteristics and the number of days between viral load tests and the occurrence of an interval of >or=6 or 9 months between tests. A total of 1032 individuals were included in the analysis with a median follow-up of 4.6 years and a median of 18 viral load tests. In multivariate analyses, clinically important gaps in viral load testing were more likely among injection drug users (odds ratio [OR]=1.86, P<0.0001), in more recent years (P<0.01) and for individuals not using antiretrovirals (OR=1.70, P<0.0001) and less likely among individuals using >4 antiretrovirals (OR=0.62, P<0.0001). Results were similar when the outcome was the number of days between tests. Injection drug users, younger individuals, and residents of Toronto used fewer viral load tests than other individuals, even when financial barriers to testing were removed.

Comprehensive comparison of the VERSANT ® HIV-1 RNA 3.0 (bDNA) and COBAS AMPLICOR HIV-1 MONITOR ® 1.5 assays on 1000 clinical specimens

Background Plasma human immunodeficiency virus type 1 (HIV-1) RNA level is an important parameter for patient management, yet viral load assays from different manufacturers are not standardized. Objectives and study design In this study, we evaluated the concordance between test results obtained for 1000 plasma specimens collected from HIV-1-infected individuals measured with the VERSANT ® HIV-1 RNA 3.0 assay (bDNA) and the COBAS AMPLICOR HIV-1 MONITOR ® 1.5 test (PCR). We compared viral load values obtained by each of these assays throughout their dynamic ranges, with particular focus on samples with low viral load (i.e. 50–250 copies/mL), and calculated the estimated distribution of distinct plasma viral load levels for the entire study population modeled from the data observed in the study. Results We found that these two assays show excellent agreement, with a correlation ( R 2) of 0.957 and a slope of 1.004. The mean difference in viral load values between the two assays was less than 0.10-log 10 throughout the dynamic range and 98.2% of all samples had bDNA and PCR results within 0.5-log 10 of each other, a difference that is within the range considered to be a minimal change in plasma viremia. Moreover, the two assays show very similar results across all assay ranges tested. The estimated prevalence of samples with results <50 copies/mL, 50–250 copies/mL, and 250–500,000 copies/mL were 41.6%, 7.7%, and 49.7%, respectively, by the bDNA assay, and 42.4%, 6.9%, and 50.7%, respectively, by the PCR assay. Conclusion Based on our findings from 1000 clinical specimens, we do not see the need to re-establish a baseline value or apply a conversion factor when switching from one assay to the other. Since the majority of our patient population likely is infected with subtype B virus, it is unclear if our findings will apply to other patient populations with a greater incidence of infection with non-B subtypes.

Therapeutic dendritic-cell vaccine for chronic HIV-1 infection

We present the results of a preliminary investigation of the efficacy of a therapeutic dendritic cell (DC)-based vaccine for HIV-1. We immunized 18 chronically HIV-1-infected and currently untreated individuals showing stable viral loads for at least 6 months with autologous monocyte-derived DCs loaded with autologous aldrithiol-2-inactivated HIV-1. Plasma viral load levels were decreased by 80% (median) over the first 112 d following immunization. Prolonged suppression of viral load of more than 90% was seen in 8 individuals for at least 1 year. The suppression of viral load was positively correlated with HIV-1-specific interleukin-2 or interferon-gamma-expressing CD4(+) T cells and with HIV-1 gag-specific perforin-expressing CD8(+) effector cells, suggesting that a robust virus-specific CD4(+) T-helper type 1 (T(H)1) response is required for inducing and maintaining virus-specific CD8(+) effectors to contain HIV-1 in vivo. The results suggest that inactivated whole virus-pulsed DC vaccines could be a promising strategy for treating people with chronic HIV-1 infection.

Impact of Highly Active Antiretroviral Therapy on CD4+ T Cells and Viral Load of Children with AIDS: A Population-Based Study

In this study, we sought to characterize the changes over time at the population level on CD4(+) T cells and plasma viral load (VL) levels of HIV-1-infected children with or without AIDS. We carried out a retrospective study in 114 HIV-infected children during the calendar period that a highly active antiretroviral therapy (HAART) protocol was used. The HAART protocol consisted of three drugs: nucleoside analogue HIV-1 reverse transcriptase inhibitors, and/or HIV protease inhibitors, and/or nonnucleoside analogue HIV-1 reverse transcriptase inhibitors. The mean of CD4(+) T cells percentage and log(10) VL per calendar year were stratified by AIDS diagnostic. As new HAART strategies become available, an increase of CD4(+) T cells and a decrease of VL were observed over time, in children with and without AIDS. In 2001, children with AIDS reached values of CD4(+) T cells and VL similar to children without AIDS. In conclusion, our study shows that the generalized use of HAART has permitted improvement in immunological and virological status of HIV-infected children without AIDS, and more importantly in children with AIDS.

NK cells as a reservoir for HIV-1

Introduction of highly active anti-retroviral therapy (HAART) for the treatment of HIV-1 has dramatically decreased plasma viral-load levels in many patients. However, the therapy can only eliminate circulating virus. Latently infected and long-living cells present a major hurdle in the eradication of HIV-1 in infected individuals. Initially, the reappearance of virus observed after discontinuation of therapy was proposed to be caused by quiescent CD4+ Tlymphocytes. The lack of genetic identity between the rebounding virus and the virus present in the latent T cell reservoir, observed in several patients, suggests that other sources of latently infected cells might be involved in viral rebound.

Normal CD95 (APO-1/Fas)-Induced T Cell Apoptosis Despite High Plasma Viral Load in HIV-1-Infected Children and Adolescents Receiving Highly Active Antiretroviral Therapy

Based on previous studies on the influence of antiretroviral treatment on CD95-induced T cell apoptosis cross-sectional data on T cell apoptosis and T cell homeostasis were analysed from 29 pediatric patients treated for more than 6 months either with 2 nucleosidic inhibitors of HIV-1 reverse transcriptase (group A, 20 observations) or HAART containing at least 1 inhibitor of HIV-1 protease (group B, 16 observations). Seven patients were studied twice. The relationship between specific anti-CD95-induced apoptosis of freshly isolated peripheral blood CD4 + and CD8 + T cells with the percentage of circulating CD4 + T cells, HIV-1 RNA plasma viral load levels and the proportion of circulating resting/naive and primed/memory CD4 + T cells was assessed. Seven patients in each group had HIV-1 plasma viral load levels ≤ 3.0 log RNA-copies per ml. In group A, CD95-sensitivity of T cells increased significantly with low CD4 counts, and tended to rise with low proportions of resting/naive CD4 cells and high HIV-1 plasma viral load levels. In group B, the sensitivity of peripheral blood T cells towards CD95-induced apoptosis was not increased compared to controls and was not correlated with CD4 + T cell counts and CD4 + T cell subpopulations or HIV-1 plasma viral load levels. These data indicate that treatment with HAART including HIV-1 protease inhibitors has an inhibitory effect on CD95-sensitivity of circulating T cells. This effect, which is independent of the reduction of HIV-1 plasma viral load levels by HAART, may contribute to the amelioration of CD4 + T cell homeostasis frequently seen in HAART-treated patients despite virological treatment failure.

Expression of CD69 on T-cells from HIV-1-infected children and adolescents increases with increasing viral load.

We evaluated the use of a whole-blood assay that measures spontaneous and activation-induced CD69 expression on peripheral blood T-cells in vitro for assessment of T-cell function in HIV-1-infected paediatric patients. Heparinized venous blood from 28 HIV-1 positive children and adolescents and 23 healthy controls was incubated for 4 h with or without 5 microg/ml phytohaemagglutinin (PHA). Thereafter, analysis of CD69 expression on CD4+ and CD8+ T-cells was done by flow cytometry; simultaneously we determined CD4+ T-cell counts and plasma HIV-1 viral load. Neither spontaneous nor PHA-induced CD69 expression differed significantly between HIV-1 positive patients and healthy controls. However, T-cells from HIV-1 positive patients with plasma HIV-1 viral load levels above 70x10(3) copies/ml showed a higher spontaneous CD69 expression than T-cells from patients with lower plasma viral load levels in different stages of the disease. Antiretroviral treatment in four patients reduced spontaneous CD69 expression in CD4+ T-cells and PHA-induced CD69 expression in CD4+ and CD8+ T-cells significantly after 8 weeks of therapy. Conclusion Spontaneous and activation-induced expression of the early (activation) antigen CD69 on peripheral blood T-cells does not distinguish HIV-1 positive patients from HIV-1 negative healthy controls and is not correlated with peripheral blood CD4+ T-cell counts. This test may not be a reliable marker for functional T-cell deficiency during early stages of HIV disease. Increased spontaneous as well as PHA-induced CD69 expression on T-cells from HIV-1-infected children and adolescents in vitro may rather reflect HIV-induced pre-activation of T-cells in vivo.

Weight gain associated with protease inhibitor therapy in HIV-infected patients

Weight loss and wasting are significant complications of HIV disease. HIV protease inhibitor therapy promotes clinical, immunologic and virologic improvement in HIV-infected patients. In this study, we sought to determine the specific effect of HIV protease inhibitors on patient weight. Ten consecutive HIV patients were treated with protease inhibitor-containing regimens over six months. CD4 T-cell counts, plasma viral load levels and bariatric changes were monitored during the study. Patients experienced a mean weight gain of 19 Pounds (P = 0.006). There was a significant increase in mean CD4 T-cell count (P = 0.008) and a significant decrease in mean viral load level (P = 0.004). The increase in CD4 T cells did not correlate with weight gain, whereas the decrease in viral load did show a significant correlation with the weight increase (P = 0.003). The mechanism of protease inhibitor-induced weight gain is discussed. The medications may also be useful for wasting diseases unrelated to HIV.

Correlation between plasma HIV-1 RNA levels and the rate of immunologic decline.

To determine the influence of HIV-1 replication on immunologic decline and clinical outcome, we quantified the HIV-1 plasma viral load in 20 patients at different times over a mean period of 10.8 months. Quantitation was performed by branched DNA signal amplification (bDNA) and p24 antigenemia. Immunologic status was assessed through beta 2-microglobulin and CD4+ cell count determinations. CD4+ cell decline was expressed as a slope of the regression line constructed by the logarithms of CD4+ cell count observations. Mean values of plasma viral load were correlated with CD4+ cell decline and mean beta 2-microglobulin levels. Significant correlation was observed between plasma viral load quantified by the bDNA technique and CD4+ cell decline. No significant correlation was observed between plasma viral load quantified by p24 antigenemia and CD4+ cell decline. A significant correlation was observed between plasma viral load and beta 2-microglobulin levels. Immunologic decline was better predicted from HIV-1 RNA levels than from the CD4+ cell count. Significantly higher plasma viral load was observed in patients who had clinical progression of HIV-1 infection. Thus, HIV-1 plasma viral load quantified by a highly reliable technique such as bDNA showed that the immunologic decline is closely related to HIV-1 RNA replication.