Plasma Viral Load Levels Research Articles

Stable HIV decoy receptor expression after in vivo HSC transduction in mice and NHPs: Safety and efficacy in protection from SHIV

We aim to develop an invivo hematopoietic stem cell (HSC) gene therapy approach for persistent control/protection of HIV-1 infection based on the stable expression of a secreted decoy protein for HIV receptors CD4 and CCR5 (eCD4-Ig) from blood cells. HSCs in mice and a rhesus macaque were mobilized from the bone marrow and transduced by an intravenous injection of HSC-tropic, integrating HDAd5/35++ vectors expressing rhesus eCD4-Ig. Invivo HSC transduction/selection resulted in stable serum eCD4-Ig levels of ∼100μg/mL (mice) and >20μg/mL (rhesus) with half maximal inhibitory concentrations (IC50s) of 1μg/mL measured by an HIV neutralization assay. After simian-human-immunodeficiency virus D (SHIV.D) challenge of rhesus macaques injected with HDAd-eCD4-Ig or a control HDAd5/35++ vector, peak plasma viral load levels were ∼50-fold lower in the eCD4-Ig-expressing animal. Furthermore, the viral load was lower in tissues with the highest eCD4-Ig expression, specifically the spleen and lymph nodes. SHIV.D challenge triggered a selective expansion of transduced CD4+CCR5+ cells, thereby increasing serum eCD4-Ig levels. The latter, however, broke immune tolerance and triggered anti-eCD4-Ig antibody responses, which could have contributed to the inability to eliminate SHIV.D. Our data will guide us in the improvement of the invivo approach. Clearly, our conclusions need to be validated in larger animal cohorts.

Surrogate Biomarkers of Disease Progression in Human Pegivirus Seropositive Human Immunodeficiency Virus-Infected Individuals.

Scientific observations indicate that an actively prevailing systemic condition could alleviate the pathology of another disease. Human pegivirus (HPgV), a highly ubiquitous flavivirus is believed to be associated with slow human immunodeficiency virus (HIV) disease progression, and has seldom been linked to hepatic pathology. In this study, we investigated whether HPgV seropositivity had any impact on surrogate markers of HIV disease progression in a cohort of HIV-infected HPgV seropositive (n = 28) and seronegative (n = 12) individuals who were prospectively evaluated for absolute CD4+ T cell counts, plasma viral load (PVL), liver enzymes, and plasma cytokine levels. The HIV PVL was relatively lower in HPgV seropositive than in HPgV seronegative HIV-infected subjects. Clinical markers of hepatic injury were significantly low among HPgV seropositive HIV-infected participants. HPgV seropositive individuals showed significantly higher levels of interleukin-7 (IL-7), and although not significant, the levels of IL-6 were lower among HPgV seropositive subjects. Spearman correlation analysis showed that the absolute CD4+T cell count was inversely correlated with HIV PVL. Exposure to HPgV appears to have a positive prognostic impact on the levels of surrogate biomarkers of HIV disease progression.

Levels of Total Antioxidant Capacity, sCD14, and TGF-β2 in Breast Milk Plasma of HIV-Infected and HIV-Uninfected Lactating Women.

Introduction: Breast milk provides nourishment for infants and nonnutritive bioactive factors, which possess key protective and developmental benefits essential in shaping the infant immune system. However, the impact of human immunodeficiency virus (HIV) and universal antiretroviral therapy (ART) on breast milk nutritional composition and immunity status is not well documented. Objective: The study aimed to compare breast milk immune factors; total antioxidant capacity (TAC), soluble cluster of differentiation 14 (sCD14), and transcription growth factor-beta 2 (TGF-β2) levels between HIV-infected and HIV-uninfected lactating mothers and determine the association between breast milk parameters with HIV disease progression and duration of ART. Methods: Breast milk sCD14, TAC, and TGF-β2 were quantified using enzyme-linked immunosorbent assays and spectrophotometric techniques in 57 HIV-infected breast feeding mothers on option B+ therapy for prevention of vertical transmission of HIV and 57 HIV-uninfected mothers at 6 weeks postpartum. The plasma HIV viral load was measured on enrollment and demographic data were recorded. Results: Mean breast milk plasma TAC levels were significantly lower in HIV-infected mothers (1,250.5 ± 280.4 μmolTE/L) compared to the HIV-uninfected participants (1,915.4 ± 326 μmolTE/L; p < 0.001). Soluble CD14 levels in HIV-infected mothers were significantly higher (7,059.3 ± 1,604.7 ng/mL) compared to the HIV-uninfected group (5,670.7 ± 1,268.3 pg/mL; p < 0.001). Similarly, TGF-β2 concentration was also significantly elevated in the HIV-infected mothers (1,426.1 ± 695.4 pg/mL) compared to the HIV-uninfected counterparts (709.2 ± 196.8 pg/mL; p < 0.001). A positive correlation was observed between breast milk plasma sCD14 concentration and the plasma viral load (r = 0.576, p < 0.001), while a significant negative correlation was observed with the duration of ART (r = -0.285, p = 0.032). TAC and TGF-β2 concentrations were inversely correlated with plasma viral load levels. Conclusion: HIV-infected mothers are at risk of oxidative stress. Nutritional intervention with antioxidant rich foods is recommended for this vulnerable group during breastfeeding.

Methylation regulation of Antiviral host factors, Interferon Stimulated Genes (ISGs) and T-cell responses associated with natural HIV control.

GWAS, immune analyses and biomarker screenings have identified host factors associated with in vivo HIV-1 control. However, there is a gap in the knowledge about the mechanisms that regulate the expression of such host factors. Here, we aimed to assess DNA methylation impact on host genome in natural HIV-1 control. To this end, whole DNA methylome in 70 untreated HIV-1 infected individuals with either high (>50,000 HIV-1-RNA copies/ml, n = 29) or low (<10,000 HIV-1-RNA copies/ml, n = 41) plasma viral load (pVL) levels were compared and identified 2,649 differentially methylated positions (DMPs). Of these, a classification random forest model selected 55 DMPs that correlated with virologic (pVL and proviral levels) and HIV-1 specific adaptive immunity parameters (IFNg-T cell responses and neutralizing antibodies capacity). Then, cluster and functional analyses identified two DMP clusters: cluster 1 contained hypo-methylated genes involved in antiviral and interferon response (e.g. PARP9, MX1, and USP18) in individuals with high viral loads while in cluster 2, genes related to T follicular helper cell (Tfh) commitment (e.g. CXCR5 and TCF7) were hyper-methylated in the same group of individuals with uncontrolled infection. For selected genes, mRNA levels negatively correlated with DNA methylation, confirming an epigenetic regulation of gene expression. Further, these gene expression signatures were also confirmed in early and chronic stages of infection, including untreated, cART treated and elite controllers HIV-1 infected individuals (n = 37). These data provide the first evidence that host genes critically involved in immune control of the virus are under methylation regulation in HIV-1 infection. These insights may offer new opportunities to identify novel mechanisms of in vivo virus control and may prove crucial for the development of future therapeutic interventions aimed at HIV-1 cure.

Very high pre-therapy viral load is a predictor of virological rebound in HIV-1-infected patients starting a modern first-line regimen.

Pre-cART (combined antiretroviral therapy) plasma viral load >500,000 copies/ml has been associated with a lower probability of achieving virological suppression, while few data about its role on maintenance of virological suppression are available. In this study we aimed to clarify whether high levels of pre-cART viraemia are associated with virological rebound (VR) after virological suppression. HIV-infected individuals who achieved virological suppression after first-line cART were included. VR was defined as the first of two consecutive viraemia >50 copies/ml (VR50) or, in an alternative analysis, >200 copies/ml (VR200). The impact of pre-cART viraemia on the risk of VR was evaluated by survival analyses. Among 5,766 patients included, 59.2%, 31.4%, 5.2% and 4.2% had pre-cART viraemia ≤100,000, 100,001-500,000, 500,001-1,000,000 and >1,000,000 copies/ml, respectively. Patients with pre-cART viraemia levels >1,000,000 copies/ml had the highest probability of VR (>1,000,000; 500,000-1,000,000; 100,000-500,000; <100,000 copies/ml; VR50: 28.4%; 24.3%; 17.6%; 13.8%, P<0.0001; VR200: 14.4%; 11.1%; 7.2%; 7.6%; P=0.009). By Cox multivariable analyses, patients with pre-cART viraemia >500,000 and >1,000,000 copies/ml showed a significantly higher risk of VR regardless of the VR end point used. No difference in the risk of VR was found between patients with pre-cART viraemia ranging 500,000-1,000,000 copies/ml and those with pre-cART viraemia >1,000,000 copies/ml, regardless of the VR end point used. Pre-cART plasma viral load levels >500,000 copies/ml can identify fragile patients with poorer chance of maintaining virological control after an initial response. An effort in defining effective treatment strategies is mandatory for these patients that remain difficult to treat.

Mucocutaneous Disorders of Pediatric HIV in South West Nigeria

Nigeria has the world's highest burden of pediatric HIV. In the face of paucity of monitoring tests in Nigeria, we studied the spectrum of pediatric mucocutaneous manifestations and evaluated their clinical utility as surrogate markers for immunodeficiency and plasma viral load levels. Cross-sectional study comparing mucocutaneous manifestations in 155 HIV-positive children aged 12 weeks to 14 years with 155 HIV-negative children. Relationships between mucocutaneous manifestations in HIV-infected patients and their immunologic and virologic indices were analyzed. Mucocutaneous lesions were seen in 53.5% of HIV-infected children compared with 18.1% of the controls. Prevalence of lesions increased with worsening levels of immunodeficiency and increasing viral loads (P < .01). Oral candidiasis, angular stomatitis, and fluffy hair were associated with more severe degrees of immunodeficiency. Mucocutaneous disorders are common in HIV-infected children. Oral candidiasis and nutritional dermatoses can be used as surrogates for advanced or severe immunodeficiency.

Oral Mucosal Changes in Patients of HIV /AIDS Taking Antiretroviral Therapy in Pakistan

Background: This study was designed to describe different oral mucosal changes present in HIV/AIDS patients taking antiretroviral therapy (ART) in Pakistan and to compare these changes with CD4+ lymphocyte count and plasma viral load. Methods: Oral smears, from n=35 patients taking antiretroviral therapy, were prepared and examined microscopically using routine and special stains. CD4+ lymphocyte count was determined using flow cytometry. Latest plasma viral load levels were recorded from the patient`s updated laboratory record and patients were clinically examined and staged according to WHO clinical staging system. Results: Oral lesions were present in 63% of the patients with oral pigmentation in 45.7%, chronic periodontitis in 20%, linear gingival erythema in 2.9%, pseudomembranous candidiasis, oral ulcers and xerostomia each in 5.7% cases while mucositis, oral hairy leukoplakia and oral wart each in 2.9% cases. On cytological examination, fungi were detected in 48.5% smears. Inflammation was seen in 65.7% smears, micronuclei in 51.4%, nuclear atypia in 37.1% and dysplastic changes in 17.1% (grade 1 in 83.3% and grade 2 in 17%) smears. Most of the oral mucosal changes were seen with low CD4+ lymphocyte count but no association was seen with high viral load. Conclusions: This study describes different oral mucosal changes present in HIV/AIDS patients taking antiretroviral therapy (ART) in Pakistan and highlights their importance as a marker of immunosuppression and disease progression as these changes have strong association with low CD4+ lymphocyte count.

Cellular HIV Type 1 DNA Levels Are Equivalent Among Drug-Sensitive and Drug-Resistant Strains in Newly Diagnosed and Antiretroviral Naive Patients

The emergence of resistance against current antiretroviral drugs to human immunodeficiency virus type 1 (HIV-1) is an increasingly important concern to the continuous success of antiretroviral therapy to HIV-1-infected patients. In the past decade, a number of studies reported that the prevalence of transmitted drug resistance among newly diagnosed patients has reached an overall 9% prevalence worldwide. Also, a number of studies using longitudinal HIV-1 patient study cohorts demonstrated that the cellular HIV-1 DNA level in peripheral blood mononuclear cells (PBMCs) has a prognostic value for the progression of HIV-1 disease independently of plasma HIV-1 RNA load and CD4 count. Using a previously established molecular-beacon-based real-time PCR methodology, cellular HIV-1 DNA levels were quantified in newly diagnosed and antiretroviral-naive patients in Northern Greece recruited between 2009 and 2010 using a predefined enrolling strategy, in an effort to investigate whether there is any relationship between cellular HIV-1 DNA levels and HIV-1 transmitted drug resistance. As part of the same study, DNA sequences encoding the env (C2-C5 region of gp120) were also amplified from PBMC-extracted DNA in order to determine the genotypic coreceptor tropism and genetic subtype. Cellular HIV-1 DNA levels had a median of 3.309 log10 HIV-1 copies per 10(6) PBMCs and demonstrated no correlation between cellular HIV-1 DNA levels and HIV-1 transmitted drug resistance. An absence of association between cellular HIV-1 DNA levels with plasma viral HIV-1 RNA load and CD4 levels was also found reconfirming the previously published study. Genotypic analysis of coreceptor tropism indicated that 96% of samples, independently of the presence or not of genotypic drug resistance, were CCR5-tropic. Overall, the findings reconfirmed the previously proposed proposition that transmitted drug resistance does not have an impact on disease progression in HIV-1-infected individuals. Also, CCR5 coreceptor tropism dominance suggests that both drug-resistant and drug-sensitive strains behave similarly in early infection in newly diagnosed patients.

HPV-Genotype Distribution and Oncogene Expression in HIV-Positive Adults and the Underlying Risk Factors for Anal, Oral and Genital Malignancy: An Atlantic Canada Prospective Cohort Study

HPV-Genotype Distribution and Oncogene Expression in HIV-Positive Adults and the Underlying Risk Factors for Anal, Oral and Genital Malignancy: An Atlantic Canada Prospective Cohort Study

Early immunologic and virologic predictors of clinical HIV-1 disease progression

To identify early determinants of HIV-1 disease progression, which could potentially enable individualized patient treatment, and provide correlates of progression applicable as reference phenotypes to evaluate breakthrough infections in vaccine development. High-throughput technologies were employed to interrogate multiple parameters on cryopreserved, retrospective peripheral blood mononuclear cell (PBMC) samples from 51 individuals from São Paulo, Brazil, obtained within 1 year of diagnosing early Clade B HIV-1 infection. Fast Progressors, Slow Progressors, and Controllers were identified based on a 2-year clinical follow-up. Phenotypic and functional T-cell parameters were tested by flow cytometry and qPCR to identify potential early determinants of subsequent HIV-1 disease progression. Major differences were observed between Controllers and Progressors, especially in cell-associated viral load (CAVL), the differentiation pattern and CD38 expression of CD8 T cells, and the cytokine pattern and activation phenotype of HIV-1-specific CD8 T cells. Despite remarkably few other differences between the two Progressor groups, the CAVL had predictive power independent of plasma viral load. Analysis of three parameters (% CD38 CD8 T cells, total CAVL, % CCR5 CD8 T cells) was sufficient to predict subsequent disease progression (P < 0.001). Use of such prognostic correlates may be crucial when early CD4 T-cell counts and plasma viral load levels fail to discriminate among groups with differing subsequent clinical progression.

Distribution of parvovirus B19 DNA in blood compartments and persistence of virus in blood donors.

Because the receptor for parvovirus B19 (B19V) is on red blood cells (RBCs), we investigated B19V distribution in blood by in vitro spiking experiments and evaluated viral compartmentalization and persistence in natural infection. Two whole blood (WB) protocols (ultracentrifugation and a rapid RBC lysis and removal protocol) were evaluated using quantitative real-time polymerase chain reaction. WB was spiked with known concentrations of B19V and recovery in various blood fractions was determined. The rapid RBC lysis and removal protocol was then used to compare B19V concentrations in 104 paired WB and plasma samples collected longitudinally from 43 B19V-infected donors with frozen specimens in the REDS Allogeneic Donor and Recipient Repository (RADAR). In B19V spiking experiments, approximately one-third of viral DNA was recovered in plasma and two-thirds was loosely bound to RBCs. In the immunoglobulin (Ig)M-positive stage of infection in blood donors when plasma B19V DNA concentrations were greater than 100 IU/mL, median DNA concentrations were approximately 30-fold higher in WB than in plasma. In contrast, when IgM was absent and when the B19V DNA concentration was lower, the median WB-to-plasma ratio was approximately 1. Analysis of longitudinal samples demonstrated persistent detection of B19V in WB but declining ratios of WB to plasma B19V with declining plasma viral load levels and loss of IgM reactivity. The WB-to-plasma B19V DNA ratio varies by stage of infection, with 30-fold higher concentrations of B19V DNA in WB relative to plasma during the IgM-positive stage of infection followed by comparable levels during persistent infection when only IgG is present. Further study is required to determine if this is related to the presence of circulating DNA-positive RBCs derived from B19V-infected erythroblasts, B19V-specific IgM-mediated binding of virus to cells, or other factors.

Characterization of mannose-binding lectin plasma levels and genetic polymorphisms in HIV-1-infected individuals

The present study investigated the association between mannose-binding lectin (MBL) gene polymorphism and serum levels with infection by HIV-1. Blood samples (5 mL) were collected from 97 HIV-1-infected individuals resident in Belém, State of Pará, Brazil, who attended the Special Outpatient Unit for Infections and Parasitic Diseases (URE-DIPE). CD4+ T-lymphocyte count and plasma viral load were quantified. A 349bp fragment of exon 1 of the MBL was amplified via PCR, using genomic DNA extracted from controls and HIV-1-infected individuals, following established protocols. MBL plasma levels of the patients were quantified using an enzyme immunoassay kit. Two alleles were observed: MBL*O, with a frequency of 26.3% in HIV-1-infected individuals; and the wild allele MBL*A (73.7%). Similar frequencies were observed in the control group (p > 0.05). Genotype frequencies were distributed according to the Hardy-Weinberg equilibrium in both groups. Mean MBL plasma levels varied by genotype, with statistically significant differences between the AA and AO (p < 0.0001), and AA and OO (p < 0.001) genotypes, but not AO and OO (p = 0.17). Additionally, CD4+ T-lymphocytes and plasma viral load levels did not differ significantly by genotype (p > 0.05). The results of this study do not support the hypothesis that MBL gene polymorphism or low plasma MBL concentrations might have a direct influence on HIV-1 infection, although a broader study involving a large number of patients is needed.

Elevated frequency of CD1c+ myeloid dendritic cells in the peripheral blood mononuclear cells of simian/human immunodeficiency virus (SHIV) and simian immunodeficiency virus (SIV) repeatedly infected Chinese rhesus macaques

CD1c+ myeloid dendritic cells (mDCs) in the peripheral blood of 30 SHIV-SF162p4 and SIVmac251 sequentially infected Chinese rhesus macaques were examined by flow cytometry to obtain further insight into mDC alterations in HIV/AIDS. The CD1c+ cells were found to be mononuclear leukocytes rather than granulocytes, and most of them expressed CD20. CD1c+mDCs (CD1c+CD20−) consisted of two morphological subsets: the granular and the large CD1c+mDCs. The expression of HLA-DR, CD86, and CD11b, but no CCR7, CD83 and CD123, together with their endocytotic capacity indicated that they were immature mDCs. Their frequency at weeks 10 and 12 post-infection was significantly higher than that of un-infected ones; the large CD1c+mDC level was significantly different between time points and almost absent from un-infected rhesus monkeys; significant correlations between CD1c+mDCs and plasma viral load levels were also observed. These data indicated a possible role for CD1c+mDCs in the pathophysiological process of SIV/HIV infection.

Activation and maturation of peripheral blood T cells in HIV‐1‐infected and HIV‐1‐uninfected adults in Burkina Faso: a cross‐sectional study

BackgroundWe wanted to explore to what extent environmental exposure to immune stimulants, which is expected to be more present in rural than in urban settings, influences T cell activation and maturation in healthy and in HIV-1-infected individuals in Burkina Faso in west Africa.MethodsThe proportion of circulating naïve T cells and the expression of the T cell activation markers, CD95 and CD38, were analyzed by immunophenotyping and three-colour flow cytometry in 63 healthy individuals and 137 treatment-naïve HIV-1-infected subjects from Ouagadougou (urban setting) and 26 healthy adults and 61 treatment-naïve patients from Nouna (rural).ResultsA slightly higher activation level of CD4+ and CD8+ peripheral blood T cells was seen in healthy adults living in Nouna than in those living in Ouagadougou. The percentages of naïve CD45RAbright CCR7+ T cells were not significantly different between both study sites. Taking into consideration that relatively more HIV-1-infected patients in Nouna were in an advanced disease stage, no relevant differences were seen in T cell activation and maturation between patients at both study sites. As expected, the percentage of CD95+ CD4+ and CD38+ CD8+ T cells and the respective antigen density on these cells was significantly higher in patients than in controls in both settings. The percentage of naïve CD8+ T cells was lower in HIV-1-infected subjects than in healthy controls irrespective of the study site, while a lower proportion of naïve CD4+ T cells in patients compared with controls was seen only in Nouna.ConclusionsEnvironmentally triggered immune activation may contribute to the increased expression of the activation markers CD95 and CD38 on peripheral blood T cells from healthy adults living in rural versus urban settings in Burkina Faso. T cell activation is further increased in HIV-1-infected individuals due to T cell loss and high plasma viral load levels. The observed variations in T cell activation levels or the proportion of naïve T cells in our study patients, however, are not explained by differences in CD4+ T cell counts or HIV-1 plasma viral load levels alone.

A conceptual model of interventions to increase diagnosis of acute HIV infection and reduce forward transmission.

Approximately 56,000 individuals in the US acquire HIV annually [1, 2]. Newly-infected persons are highly infectious during the first 2–4 months following HIV acquisition—a period known as acute HIV infection (AHI)—and consequently contribute disproportionately to HIV transmissions. In this paper, we discuss a conceptual model that incorporates interventions specifically targeting AHI that have the potential to greatly decrease new HIV infections. Two important properties distinguish acute HIV infection from the later, chronic stage of HIV infection. First, AHI is characterized by exceptionally high levels of virus circulating in the blood and in the genital tract [3–9]. Plasma and genital tract viral load levels are positively correlated with the risk of sexual transmission [4, 5, 10]. The high-level viremia observed during acute infection results in greatly increased risks of HIV transmission during sexual or syringe-sharing activities. The risk of transmission during acute HIV infection is approximately 8–22 times greater, on a per-act basis, than it is during the subsequent period of chronic infection [5, 11]. Consequently, and despite the relatively brief period during which persons are acutely-infected, the acute period of infection plays a disproportionate role in fueling nascent epidemics and sustaining more mature epidemics [12–16]. Simulation and mathematical models of the mature epidemics in the UK and US suggest that between 10 and 20% of sexually-transmitted infections can be attributed to acute-phase transmission [12, 17]. Moreover, phylogenetic analyses of persons with recent infection in England and Quebec suggest that 25–50% of recently-acquired infections are due to transmission during the early or acute-phase of HIV infection [13, 16]. The second distinguishing characteristic of AHI is that antibodies against HIV are not detectable during much of the acute period of infection. Formation of HIV antibodies usually occurs 2–4 weeks after HIV is acquired [7, 18]. Antibody levels detectable by standard enzyme-linked immunoassay (EIA, ELISA) screening tests are not reliably present until 4–8 weeks after infection. As a consequence, acutely-infected individuals usually have negative or indeterminate antibody test results [3, 18]. Current HIV screening strategies mainly rely on HIV antibody tests. Unfortunately, even the most aggressive antibody-based testing strategy will fail to identify HIV-infected individuals during AHI, when the risk of onward transmission is greatest. The annual incidence of new HIV infections in the US has remained relatively constant for more than a decade [1]. To reduce HIV incidence below the current plateau, innovative HIV prevention strategies are needed, including interventions to increase AHI diagnoses and prevent transmission of the virus during AHI. Currently, accurate diagnosis of AHI requires the use of HIV nucleic acid amplification tests that detect the presence of HIV RNA, rather than antibodies against the virus. We have developed a conceptual model of potential targets of AHI-specific interventions to increase AHI diagnoses and to reduce HIV transmission through a combination of increased RNA testing in both public health and clinical settings; education of at-risk individuals, health care providers, and HIV counselors; and implementation of timely and efficient partner notification programs.

The Interplay between Sexually Transmitted Infections and HIV: An Evolving Story.

The Interplay between Sexually Transmitted Infections and HIV: An Evolving Story.

Inflammatory control in AIDS-resistant non human primates

African non human primates are natural hosts of SIV. The infection is non-pathogenic despite plasma viral load levels similar to those in HIV-1 infected humans and SIVmac-infected macaques (MAC) progressing towards AIDS. The most striking difference between non-pathogenic SIV and pathogenic HIV-1/SIVmac infections is the lack of chronic T cell activation in natural hosts. In HIV and SIVmac infections, chronic T cell activation is known to drive CD4+T cell depletion. Intense research efforts are worldwide put on the search of the mechanisms that can control chronic T cell activation in HIV/SIV infections. Innate immune responses play a determinant role in the regulation of T cell activation profiles. Type I interferons (IFN-I) are part of the first-wave response of the innate immune system in viral infections. We compared the IFN-I responses between pathogenic (MAC) and non-pathogenic SIV infections (African Green monkey, AGM) at the level of blood and lymph nodes (LN) during the early and chronic stage of infection. During the acute SIVagm infection, we detected high amounts of IFN-α in the plasma of AGMs, although the mean levels at the peak were three times lower than in MAC. The microarray data revealed a rapid and strong up-regulation of type I Interferon-Stimulated Genes (ISG) in AGMs during acute SIVagm infection. ISGs denote the in vivo activity of IFN-I. Using a functional assay, we demonstrated that low IFN-α concentrations (50 times lower than the IFN-α levels in plasma at the peak) were sufficient to induce strong ISG responses in AGM and MAC cells. Surprisingly, our direct comparison of blood and LNs showed that ISG induction was broader in blood of AGMs than in MAC, while in LN, it was the contrary. Thus, in AGMs, less ISG were induced in LNs as compared to MAC already during the acute phase of infection. Moreover, our tight kinetic analysis showed that this ISG expression was efficiently controlled after day 28 post-infection in AGMs, while in MAC the ISGs expression remained uncontrolled. Finally, we identified genes that were differentially expressed between the two species and which might be involved in the discriminating responses. Altogether, this shows that AGMs are capable to mount a well coordinated and efficient regulative response to innate immune activation.

Higher Homologous and Lower Cross-Reactive Gag-Specific T-Cell Responses in Human Immunodeficiency Virus Type 2 (HIV-2) Than in HIV-1 Infection

Human immunodeficiency virus type 2 (HIV-2) infection results in slower CD4(+) T-cell decline, lower plasma viral load levels, and hence slower progression of the disease than does HIV-1 infection. Although the reasons for this are not clear, it is possible that HIV-2 replication is more effectively controlled by host responses. We used aligned pools of overlapping HIV-1 and HIV-2 Gag peptides in an enhanced gamma interferon enzyme-linked immunospot assay to compare the levels of homologous and cross-reactive Gag-specific T-cell responses between HIV-1- and HIV-2-infected patients. HIV-2-infected patients showed broader and stronger homologous Gag-specific T-cell responses than HIV-1-infected patients. In contrast, the cross-reactive T-cell responses in HIV-2-infected patients were both narrower and weaker than those in HIV-1-infected patients, in line with overall weaker correlations between homologous and heterologous T-cell responses among HIV-2-infected patients than among HIV-1-infected patients. Cross-reactive responses in HIV-2-infected patients tended to correlate directly with HIV-1/HIV-2 Gag sequence similarities; this was not found in HIV-1-infected patients. The CD4(+) T-cell counts of HIV-2-infected patients correlated directly with homologous responses and inversely with cross-reactive responses; this was not found in HIV-1-infected patients. Our data support a model whereby high-level HIV-2-specific T-cell responses control the replication of HIV-2, thus limiting viral diversification and priming of HIV-1 cross-reactive T-cell responses over time. However, we cannot exclude the possibility that HIV-2 replication is controlled by other host factors and that HIV-2-specific T-cell responses are better maintained in the context of slow viral divergence and a less damaged immune system. Understanding the nature of immune control of HIV-2 infection could be crucial for HIV vaccine design.

Plasma HIV RNA Decline and Emergence of Drug Resistance Mutations among Patients with Multiple Virologic Failures Receiving Resistance Testing-Guided HAART

Early recognition of virologic failure in patients with extensive drug resistance receiving salvage-HAART is essential to avoid exposure to subinhibitory regimens. We studied plasma viral load (PVL) decline and rates of drug-resistance mutation (DRM) accumulation in such patients. A prospective, 48 week study of 38 heavily pretreated patients receiving genotypic resistance testing (GRT)-guided HAART was conducted. The rate of PVL decline was studied by weekly PVL determinations. To assess DRM accumulation, serial GRTs were performed in all nonresponders (never reaching PVL <50 or two PVLs >50 copies/ml after suppression). Over 48 weeks, 10 patients (26%) were nonresponders. Receiving less then two fully active drugs and having an elevated number of PI and NRTI mutations at baseline were strongly associated with virologic failure. There was no evidence of a difference in the change from baseline PVL to week 1 and 2 between responders and nonresponders. By contrast, PVL reductions from week 2 to week 3 and thereafter were significantly greater for responders (p < 0.01). Among nonresponders, the incidence rates per patient-month (95% CI) of emergent DRM were 0.67 (0.13-1.20), 0.40 (0.00-0.74), and 0.37 (0.00-0.75) at weeks 4, 8, and 24, respectively. Having limited baseline resistance, receiving at least two fully active drugs, and showing constant PVL reductions from week 2 to week 3 and thereafter were predictive of virologic response. In contrast, early changes in PVL levels were not. Virologic failure was associated with detection of emergent DRMs. Virologic rebound in patients on salvage-HAART should be addressed aggressively.

Cinacalcet in HIV haemodialysis patients.

Sir, Cinacalcet HCL (MIMPARA®), a positive allosteric modulator of the calcium-sensing receptor (CaR) on the surface of the parathyroid glands, reduces serum parathyroid hormone (PTH) levels in more than 80% of haemodialysis (HD) patients [1]. The efficacy and safety of cinacalcet has been demonstrated in several studies [1,2], but its use in HIV patients on chronic dialysis is not described. We report two HD patients with HIV infection treated simultaneously with anti-retroviral therapy and cinacalcet. A 24-year-old black woman was admitted in July 2002 for end-stage renal disease (ESRD) of unknown origin that required chronic HD. Simultaneously, HIV-1 infection was diagnosed. A tritherapy with efavirenz 600 mg, lamivudine 25 mg and didanosine 100 mg per day was initiated in January 2004, resulting in sustained undetectable HIV plasma viral load and stable T4 levels (>550/mm3). Cinacalcet was started in May 2007 at 30 mg/day and progressively increased to 90 mg without any efficacy (intact parathyroid hormone (iPTH) > 1000 pg/ml). In December 2007, cinacalcet was stopped and a parathyroidectomy was performed. Histological examination revealed a bilateral parathyroid adenoma. Efavirenz residual serum concentration after surgery and cinacalcet withdrawal was 1.5 μg/ml (normal range: 1.1–4 μg/ml). A 45-year-old Caucasian man was treated by chronic HD for ESRD of unknown aetiology since July 2003. HIV-1 and hepatitis B virus (HBV) co-infection was discovered at the time of dialysis initiation. A combination of efavirenz 600 mg, lamivudine 50 mg, didanosine 125 mg per day and tenofovir 245 mg per week resulted in undetectable HBV and HIV plasma viral load with sustained stable T4 levels (>600/mm3). Because of high serum iPTH (>1000 pg/ml), cinacalcet was initiated in May 2007 at 30 mg per day and further increased to 120 mg in November 2007 without efficacy. Efavirenz mean residual serum concentration on three consecutive measurements under cinacalcet therapy (120 mg) was 1.3 ± 0.5 (SD) μg/ml. The two patients received concomitant treatment with sevelamer, calcium carbonate and vitamin D3 during cinacalcet therapy. In both the cases, tolerance of cinacalcet and anti-retroviral treatment was good. Monthly monitoring of pancreatic and liver enzymes and serum calcium levels was not modified. Analysis of the literature shows that more than 80% of HD patients on cinacalcet therapy achieve an ≥30% reduction in iPTH level from the baseline over 6 months [1]. In our cases, whereas cinacalcet was administered for more than 6 months, no effect on iPTH was observed despite increased cinacalcet dosage. Little is known about the pathophysiology of resistance to cinacalcet. A role for non-compliance to the drug was excluded in both the cases. Defective sensitivity of the parathyroid cell to the calcimimetic drug has been proposed. Additionally, a relative resistance to cinacalcet was demonstrated in the case of severe decreased expression of CaR in parathyroid glands [3]. In our cases, resistance to cinacalcet was likely the result of drug interaction. Cinacalcet is metabolized through cytochrome P450 (CYP) isoenzymes 3A4, 2D6 and 1A2. In vitro studies have demonstrated that cinacalcet is a potent inhibitor of CYP2D6. Additionally, data suggest that during concomitant treatment with cinacalcet, dose adjustment may be necessary for CYP3A4 and CYP1A2 inductors or inhibitors [4]. As the metabolism of lamivudine, didanosine and tenofovir do not involve CYP450, the culprit drug seems to be efavirenz. Efavirenz is metabolized via CYP450, particularly by 3A4 and 2B6 isoenzymes. Although efavirenz is an in vitro inhibitor for 2C9, 2C19, 3A4, 2D6 and 1A2 isoenzymes, it has been demonstrated in humans that efavirenz can be inductor for CYP450 enzymes and can also induce its own metabolism by this mechanism [5,6]. This enzymatic induction, especially for CYP3A4 isoenzyme, is probably responsible for most drug interactions with efavirenz. Despite the absence of a known pharmakokinetics interaction between cinacalcet and efavirenz, enzymatic induction of CYP3A4 metabolism by efavirenz is probably responsible for therapeutic failure of cinacalcet in the present cases. Unfortunately, this hypothesis could not be verified, as the measurement of the serum cinacalcet level is not currently available. However, a role for decreased numbers of CaR or defective sensitivity of parathyroid cells cannot be excluded. In summary, cinacalcet in HD patients with chronic HIV infection treated by efavirenz seems inappropriate. Nephrologists need to be aware of this rare potential interaction. Surgical parathyroidectomy should be recommended. Conflict of interest statement. None declared. The results presented in this paper have not been published previously in whole or part, except in abstract format.