Current HIV Research - Volume 5, Issue 3, 2007

The oral cavity of human immunodeficiency virus type I (HIV-1) infected individuals is subjected to a series of opportunistic infections which are usually considered as a prognostic marker for the severity of infection as well as an indicator of immunodeficiency. The highly active antiretroviral therapy (HAART) has significantly lessened the severity of HIV-associated oral infections although this therapeutic regimen is considered to be responsible for some of the oral lesions such as oral warts and salivary gland disorders. In addition, the beneficial effects of HAART on HIV associated oral lesions are stratified with age, with the adult population showing improvements whereas the oral lesions among children remain unchanged with this therapy. The presence of HIV-1 in the saliva, and infectivity of oral epithelial cells suggest that the oral cavity is a site of HIV pathogenesis and potential reservoir for the disease in the setting of virally suppressive HAART. Overall HIV associated oral lesions are usually due to fungal, bacterial, and viral infections as well as some of unknown etiology. This review describes the current status of HIV associated oral lesions by comparing historically available pre- HAART data. Future directions envisioned by the National Institutes of Health as well as novel avenues to be explored are also presented.

Productive infection with HIV-1 is mediated by fusion of the HIV-1 envelope with the cell membrane and subsequent entry of the virion core into the cytoplasm. The core is then rearranged to form the reverse transcription complex which is responsible for conversion of the genomic RNA to its double-stranded DNA copy. Various genetic, biochemical and microscopy studies have shed light on the role of viral proteins in the core in this process; Gag cleavage products, in particular, are crucial. It is also at this point that core is potentially exposed to the action of restriction factors such as TRIM5α and APOBEC3G, highlighting the vulnerability of this stage of the retrovirus life-cycle to the cell's defenses. Rearrangement of the core may be an active process involving host-cell activities, although this is not clear, but may also be partly passive due to the instability of the structure. What regulates this process is unknown. Several host-cell kinase activities are important for replication and have been shown to be incorporated in the virion. We speculate that these kinases may regulate core rearrangement or the interaction of the reverse transcription complex/pre-integration complex with the cytoplasm. Recent real-time microscopy experiments with fluorescent-labeled probes suggest a model in which the virion utilizes the cytoskeleton for transport whilst in the cytoplasm. After entering the cell, the virion interacts initially with actin filaments which assist binding to microtubles enabling transport to the nuclear periphery. An actin-transport process may then facilitate the remaining short journey to the nuclear membrane.

HIV-1 infection with concurrent methamphetamine (MA) abuse results in exacerbated neurodegenerative changes and rapid progression of a form of sub-cortical dementia termed HIV-1 associated dementia (HAD). A notable feature of HAD is the involvement of the dopaminergic system manifested as parkinsonian like movement abnormalities. The HIV-1 transactivator of transcription (Tat) protein is very often used in experimental studies trying to understand neurotoxic consequences of HIV-1 infection, since the pathophysiological changes induced by Tat mirrors, in part, the means by which HIV-1 infection of the nervous system results in neuronal damage. Understanding the interaction of Tat and MA in the basal ganglia and the resultant injury to the dopaminergic system in rodent models as well as cell culture will shed light on the dopaminergic pathology occurring in HIV-1 infected-MA abusers. The aim of this review is to update the reader on the current knowledge of MA and HIV-1 neurotoxicity, specifically Tat, and discuss the progress in understanding how MA synergizes with the HIV-1 transactivator protein Tat to damage the basal ganglia.

A role for the actin cytoskeleton in retrovirus assembly has long been speculated. However, specific mechanisms by which actin facilitates the assembly process remain elusive. We previously demonstrated differential effects of experimentally modified actin dynamics on virion production of equine infectious anemia virus (EIAV), a lentivirus related to HIV-1, suggesting an involvement of actin dynamics in retrovirus production. In the current study, we used bimolecular fluorescence complementation (BiFC) to reveal intimate (<15nm) and specific associations between EIAV Gag and actin, but not tubulin. Specific interaction between Gag and filamentous actin was also demonstrated by co-immunoprecipitation experiments combined with the actin severing protein gelsolin to solubilize F-actin. Deletion of capsid (CA) or nucleocapsid (NC) genes reduced Gag association with F-actin by 40% and 95%, respectively. Interestingly, GCN4, a leucine zipper motif, could substitute for the NC domain in mediating F-actin association. Furthermore, deficiency of the ΔNC Gag in F-actin interaction was restored upon co-expression of Gag constructs containing both CA and NC or the GCN4, suggesting a requirement for Gag polyprotein multimerization prior to F-actin association. The observed Gag-F-actin association appeared to correlate with viral budding, as enhanced budding of the ΔNC mutant was evident upon restoration of F-actin association. Intracellular association of Gag complexes with F-actin was also detected by immunoscanning electron microscopy of Triton-extracted EIAV-infected cells. Together, these data suggest that Gag multimers induced by CA and NC domains interact with F-actin and that this association is important for efficient virion production.

HIV-1 infection is associated with dysregulation of cytokine production by peripheral blood (PB) monocytes and dendritic cells (DC), but controversial results have been reported. We aimed to analyze the effect of antiretroviral therapy (ART) on the in vitro production of inflammatory cytokines by PB-stimulated monocytes and DC of myeloid origin -CD33high+ myeloid DC (mDC) and CD33+/CD14-/dim+/CD16high+ DC- from HIV-1+ patients and its relationship with CD4+ T-cell recovery and co-infection with hepatitis C virus (HCV). In vitro cytokine production was analyzed at the single cell level in 32 HIV-1+ patients, grouped according to the number of CD4+ T-cells/μl in PB (<200 CD4 versus >200 CD4). Patients were tested prior to therapy and at weeks +2, +4, +8, +12 and +52 after ART. Prior to ART, production of IL-6, TNF-α and IL-12 by mDC and of IL-8 and IL-12 by CD16+ DC was significantly increased among >200 CD4 patients. After one year of ART, increased production of IL-8 by monocytes, of TNF-α by mDC and of IL-1β, IL-6 and TNF-α by CD16+ DC was specifically observed among <200 CD4 HIV-1+ individuals showing a high recovery of PB CD4+ T-cell counts. In turn, we found that the significantly reduced percentage of IL-1β, IL-6, IL-8 and TNF-α-producing monocytes and of IL-6 and IL-8-producing mDC and CD16+ DC, as well as the significantly diminished mean amount of IL-6 produced per monocyte, mDC and CD16+ DC and of IL-12 produced per CD16+ DC observed at week +52 for the >200 CD4 patients, were related to the presence of coinfection with HCV. In summary, HIV-1+ individuals show abnormal production of inflammatory cytokines by PB-stimulated monocytes and DC of myeloid origin even after one year of ART, such abnormalities being associated with the degree of recovery of PB CD4+ T-cell counts in more immunocompromised patients and HCV co-infection in more immunocompetent HIV-1+ individuals.

Structured treatment interruptions may have beneficial effects on metabolic parameters, while data on anthropometric parameters and on the quality of life are scanty. This study was designed to evaluate the effects of structured treatment interruptions on plasma cholesterol, triglycerides, anthropometric, immunologic, virologic changes and quality of life. A total of 112 HIV-infected patients under HAART with undetectable viremia for longer than 6 months were randomized to undergo 6 cycles of 1-month off and 1-month on therapy or to continue HAART. Patients treated with structured treatment interruptions (STI group) were evaluated monthly, patients in the control group (CTRL group) were evaluated every two months. Anthropometric and quality of life data were collected every four months. The study was designed as a two-arm, prospective, multicentred, controlled trial. Results on the primary endpoints showed a significant decrease in the cholesterol levels in the STI group compared to the CTRL group (total cholesterol median AUC [IQR] was 193.5 mg/dL/month [173.4-209.4], and 210.8 mg/dL/month [194-242.4], respectively, p=0.0009). Although the triglyceride levels were lower in the STI group, the results did not reach statistical significance (triglyceride median AUC [IQR] was 166.8 mg/dL/month [IQR: 112.5-234.9] in the CTRL group, and 169 [IR: 124.7-256.7] in the STI group; p=0.37). As for the secondary endpoints no major differences among groups were noted. Cyclic structured treatment interruptions may have a favorable, although limited, impact on plasma total cholesterol levels in HIVinfected subjects. No modifications of anthropometric and quality of life values were noted.

Central Nervous System (CNS) diseases that occur in HIV-positive patients are mainly due to HIV itself or to opportunistic microorganisms. Polyomavirus JCV, BKV and SV40 have been associated with encephalopathies in both HIV-positive and HIV-negative patients. To investigate the presence of Polyomavirus DNA sequences in patients affected by CNS disorders, 82 CSF samples from 70 HIV-positive and 12 HIV-negative patients were analyzed by PCR. A double HIV and SV40 infection was found in one patient suffering with AIDS dementia complex. SV40 DNA sequence analysis showed the homology with wild type SV40 strain. SV40 should be considered as a potential causal agent of CNS disorders in AIDS patients.

Rifampicin (RIF) decreases serum concentrations of several antiretroviral drugs. We carried out a prospective, comparative study to define efavirenz (EFV) pharmacokinetics in 16 cases and 13 controls. Cases were HIV and tuberculosis (TB) co-infected adults assuming RIF 600 mg once daily and EFV 800 mg once daily. Patients on EFV at standard 600 mg dose without RIF were taken as controls. EFV levels in plasma were assayed by high-performance liquid chromatography (HLPC) predose (Ctrough) and at 1, 2, 3, 4, 5, 6, 8, 10, 11, 12, 13, 14, 16, 18, 22 and 24 hours post-dose, and pharmacokinetic parameters were determined by non-compartmental methods. Among cases, 81% were males, mean age was 37 years, 50% were Caucasians, mean weight was 64 kg, mean CD4 cell counts and log HIV RNA copies were 160/μl and 5.2 /μl, respectively. Cases had a significantly higher Cl/F/kg if compared with controls (0.269 ± 0.12 versus 0.167 + 0.05 L/h/kg, p<0.01). Otherwise, dose-dependent pharmacokinetic parameters of EFV were similar between cases and controls. Interindividual variability was consistently higher among TB cases compared to controls for all considered parameters. All cases completed combined treatment and no increased EFV toxicity was observed. These results suggest that a dose of 800 mg of EFV in association with rifampicin may be appropriate for patients of weight > 60 kg in Europe. Therapeutic drug monitoring may be beneficial for patients on combination therapy with RIF.

Background: Cryptococcosis is an opportunistic infection with morbidity and mortality in HIV-infected patients. Impact of antiretroviral therapy (ART) on the relapse of cryptococcosis and survival of HIV-infected patients with cryptococcosis has not been well established. Methods: A retrospective cohort study of HIV-infected patients with cryptococcosis during 1997-2005 was conducted. Relapse and survival rates with corresponding risk factors were determined. Results: There were 149 patients with a mean age of 33.5±7.4 years and 57% were male. Median CD4 cell count was 22 cells/mm3. After exclusion of patients who died or were lost to follow-up during the first two weeks, 127 patients were eligible for the analysis of the effect of ART on relapse and survival rates. Of 127 patients, 52 received ART. The demographic data between the two groups were similar. Median time of ART initiation after cryptococcal diagnosis was 2.6 months. The most frequent ART used was NNRTI-based regimen (88.4%). Median CD4 change at six months of ART was 97 cells/mm3 and 87.9% achieved undetectable HIV-RNA. The cumulative 75% survival (free) from relapse duration was 10.4 months in no-ART group and 41.9 months in ART group (P<0.01). The 75% survival from cryptococcal-related mortality in no-ART group was 6.4 months whereas >54 months for ART group (P<0.01). In Cox proportional hazards model, ART was the only factor that associated with lower relapse and mortality rate (P<0.01). Conclusions: ART significantly reduced relapse and mortality rate from cryptococcosis in HIV-infected patients. ART is strongly recommended in this population and should not be delayed.

In the HIV infection, the short time-scale between the HIV-induced cardiovascular events and the onset of antiretroviral therapy elicits a thrombophilic co-factor that worsens the induced atherosclerosis. We compared the factor VIII plasma activity, previously implicated in arterial and venous thrombosis, with a surrogate marker of atherosclerosis, the carotid intima-media thickness, and with the usual atherosclerosis risk factors in 154 HIV infected outpatients. The FVIII plasma activity is significantly associated with the carotid intima-media thickness and, strongly, with blood glucose and triglycerides levels. A raised FVIII plasma activity is an important feature of the metabolic syndrome and a putative co-factor of HAART induced cardiovascular events. Thus the prevention of the HAARTinduced cardio-vascular events should probably not be exclusively focused on atherosclerosis but likewise on the thrombus formation process.