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I'm still trying to understand how all this works so..

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my question is what is going on with the HIV that hides in the reservoirs that can't be reached by HAART? Assuming someone is undetectable due to HAART therapy the virus is successfully supressed in the blood but not in the reservoirs like the gut. What is HIV up to when it is in those areas? Is it still doing its thing with replicating on cd4 cells that are there? Do we know yet?

I'm just trying to understand as much as I can about the virus.

my understanding is that the anti retro go thru out the body in the blood stream and then into the nucleus of every cell and throw a wrench into the replicating of the virus, but 98% of virus is in gut and  is not in blood only 2% in blood, in the gut there is constant work to figure out what is good stuff and bad, good is vit. min. aminos, etc, sometimes a bug gets in, i think that the gut is like a wound or womb in the sence that it was absorb nutrients and kind of be semi permiable so that is a very very stressful situation, in otherwords to open itself up to absorbing molecules and sorting which are good, takes alot of energy and repair, imagine if you had to rub your oranges into your skin, to digest them, it would be tramatic for the skin, so the gut cells have to be replaced every three days, well, why isnt haart effective in the gut, there are some breakthrus in finding out why, mostly it is in the inflamation process of this healing and rejuvinating and recreating the cells every 3 days that takes place, the inflamation, and oxidation of this area is great compared to a bone, which just kind of sits there, so in an area of body which is contantly being re created rebuilt, there is more inflamtion, more chances for such things

do a google scholar search on "hiv gut inflammation"

another thing i just thought of is the acid, the tremendous acidic-stress that the cells in the stomach and intestine have to endure to survive and that is also why they have to be replaced and possibly why meds allow the resevour to exist there, imagine all the repair so that give hiv chance to replicate, perhaps that is why the one science paper suggested hiv perople take anti inflamitory meds

gut is continueous bombarded by dietary antigens
meaning food this is from one of these papers below

should we all be on....
Thalidomide treatment reduces the alteration of paracellular barrier function in mice ileum during … - group of 4 »
E Mazzon, S Cuzzocrea - Shock, 2006 -
... the epithelium is in constant interplay with luminal bacteria, dietary antigens,
and with ... R, Zeitz M, Pauli G, Schulzke JD: Supernatants of HIV-infected immune ...
Cited by 1 - Related Articles - Web Search - BL Direct

Role of regulatory T cells in human diseases - group of 3 »
TA Chatila - The Journal of Allergy and Clinical Immunology, 2005 - Elsevier
... results suggested that mucosal induction of tolerance against dietary antigens is
associated ... 117 In HIV infection CD4 + CD25 + Treg cells inversely correlate ...
Cited by 14 - Related Articles - Web Search

HIV-1 in semen: an isolated virus reservoir - group of 5 »
RA Byrn, D Zhang, R Eyre, K McGowan, AA Kiessling - J Virol, 1996 -
... semen HIV-1 does not arise from the same reservoir of infection ... We determined
HIV-1 protease-gene sequences of infectious virus recovered ... Gut 1995; 37: 449–54 ..

Macrophage HIV-1 infection and the gastrointestinal tract reservoir - group of 8 »
PD Smith, G Meng, JF Salazar-Gonzalez, GM Shaw - 219 - Soc Leukocyte Biology
... macrophages a prominent role as a HIV-1 reservoir. ... In vertical transmission,
HIV-1 is inoculated into the ... or infant likely enters the gut-associated lymphoid ...

HIV-1 Protease Inhibitors and the MDR1 Multidrug Transporter - group of 3 »
CGL Lee, MM Gottesman - 1998 - Am Soc Clin Investig
... of potential Pgp substrates in the gut and brain ... 1997) Recovery of replication-competent
HIV despite prolonged ... et al (1997) Identification of a reservoir for HIV ...
Cited by 33 - Related Articles - Web Search - BL Direct

The mucosal immune system and HIV-1 infection - group of 5 »
R Veazey, A Lackner - AIDS Rev, 2003 -
... and may be the major viral reservoir, even in ... In considering the gut-associated lymphoid
tis- sues, it ... Lackner: The Mucosal Immune System and HIV-1 Infection ...
Cited by 21 - Related Articles - View as HTML - Web Search

Alterations in intestinal permeability - group of 4 »
MC Arrieta, L Bistritz, JB Meddings - Gut, 2006 - Br Soc Gastroenterology
... of autoimmune disease we now have evidence for a dietary antigen and an ... absorptive
capacity, intestinal permeability and jejunal histology in HIV and their ...
Related Articles - Web Search

Importance of gastrointestinal ingestion and macromolecular antigens in the vein for oral tolerance … - group of 4 »
A Wakabayashi, Y Kumagai, E Watari, M Shimizu, M … - Immunology, 2006 - Blackwell Synergy
... Although the gastrointestinal tract is incessantly exposed to dietary antigens and
commensal micro ... Transepithelial transport of HIV-1 by intestinal M cells: a ...
Related Articles - Web Search

Probiotics in humans–evidence based review - group of 2 »
K Harish, T Varghese - Calicut Medical Journal, 2006 -
... of intestinal barrier function • Controlled transfer of dietary antigens • Stimulation
of ... might be effective in some subjects with HIV-related chronic ...
Related Articles - View as HTML - Web Search

mmune privilege: a recurrent theme in immunoregulation? - group of 2 »
AL Mellor, DH Munn - Immunological Reviews, 2006 - Blackwell Synergy
... gut: the establishment and maintenance of nonresponsiveness to dietary antigens
and commensal ... Persidsky Y, Poluektova L. Immune privilege and HIV-1 persistence ...
Related Articles - Web Search

Elemental and Semi-Elemental Formulas: Are They Superior to Polymeric Formulas?
... chemically syn- thesized amino acids that are entirely antigen free thus limiting
the patient’s exposure to dietary antigens that may ... HIV Related Disease ...
Related Articles - View as HTML - Web Search - BL Direct

Immunologic Research - group of 10 »
F Inside - Immunologic Research, 2005 -
... CTL in the Gastrointestinal Mucosa Models of rotavirus and HIV infection have given
the greatest insight into the importance of gas- trointestinal CTL responses ..

Multiple measures of HIV burden in blood and tissue are correlated with each other but not with clinical parameters in aviremic subjects.

AIDS. 17(1):53-63, January 3, 2003.
Anton, Peter A a; Mitsuyasu, Ronald T a; Deeks, Steven G b; Scadden, David T c; Wagner, Bridget d; Huang, Christine e; Macken, Catherine f; Richman, Douglas D g; Christopherson, Cindy h; Borellini, Flavia j; Lazar, Richard j; Hege, Kristen M j

Objectives: To determine the levels of residual HIV DNA and RNA in blood and gut reservoirs in aviremic patients, assess correlations among compartmental measurements of HIV burden, and evaluate association with clinical parameters.

Design: Cross-sectional analysis of baseline data only, on 40 patients enrolled in phase II study evaluating efficacy of autologous gene-modified CD4+ and CD8+ T cells. All patients were on stable antiretroviral regimen with undetectable plasma HIV RNA (< 50 copies/ml).

Methods: Measurements repeatedly performed over 8-12 weeks pre-intervention: blood HIV DNA, analysis of rectal mucosa-associated lymphoid tissue for both HIV RNA and HIV DNA, and quantitative co-culture of HIV from CD8-depleted peripheral blood mononuclear cells (PBMC).

Results: Quantifiable levels of HIV detected in compartments despite undetectable levels of plasma HIV RNA: HIV co-culture of PBMC (88%), blood HIV DNA (95%), rectal biopsy HIV DNA (95%), rectal biopsy HIV RNA (65%). A significant correlation existed among various measures of HIV burden (HIV co-culture, blood HIV DNA, rectal biopsy HIV RNA and DNA) but not between assays and clinical parameters [duration of highly active antiretroviral therapy (HAART), type of HAART]. All assays had comparable or less variability than in plasma viral load assays; HIV co-culture had the highest coefficient of variability whereas the blood HIV DNA assay had the lowest and was considered the most reliable assay.

Conclusions: The data support safety, feasibility and high compliance of quantifying reservoirs of residual HIV in treated subjects with undetectable plasma HIV RNA. Lack of correlation between levels of HIV in residual reservoirs and duration of HAART suggests treatment-mediated viral suppression alone does not lead to reproducible decay in HIV reservoirs.

Using highly active antiretroviral therapy (HAART), it is now possible to reduce plasma HIV-1 RNA to undetectable levels [1]. In addition to the pronounced effect on HIV-1 viremia, clinical trials have now shown that combination antiretroviral therapy (ART) delays disease progression and prolongs life [2,3]. Although healthy, asymptomatic patients with normal levels of CD4+ T cells often have low levels of plasma viral RNA, active viral replication and T-cell turnover is still present in lymph nodes [4,5]. Recent studies have demonstrated that viable, replication-competent virus persists for at least 2 years in the face of HAART, despite complete suppression of HIV-1 RNA in blood and in some cases, lymphoid tissue [6-8]. Assays to detect HIV-1 RNA and DNA levels in lymphoid tissue have recently been described and these assays can now be used to follow the status of HIV infection in these tissues [9-12]. What has not been clarified is the degree to which quantified levels of virus in compartments correlate with and possibly predict clinical status and whether these measures may function as surrogate markers in clinical trials and/or care.

As the gut is the largest lymphoid organ in the body and a known reservoir for HIV, it is reasonable to investigate this compartment as a readily accessible source of lymphoid tissue in subjects with undetectable plasma viral load. The interest in quantifying viral burden of gastrointestinal-associated lymphoid tissue (GALT) HIV RNA and HIV DNA is compounded by the enhanced vulnerability to HIV infection of lymphocytes at this site compared to circulating peripheral blood mononuclear cells (PBMC) [13,14] based on activation state, memory phenotypes, expression of HIV coreceptors, and increased levels of soluble inflammatory mediators (e.g. tissue chemokines) [15].

We have recently completed a phase II study to evaluate the efficacy of autologous CD4-zeta gene-modified CD4+ and CD8+ T cells in HIV-infected subjects with undetectable plasma HIV RNA (< 50 copies/ml) and CD4+ cell counts > 200 × 106 cells/l on HAART for > 6 months [16]. Such subjects have been estimated to have a total body load of latently infected CD4+ T cells with replication-competent HIV of < 107 cells [11]. The virologic endpoints of the trial focused on quantitation of reservoirs of HIV-infected cells in blood and lymphoid (mucosal) tissues before and after cell infusions and is reported elsewhere [16]. Assays at baseline and throughout the trial included measurement of HIV DNA in blood, analysis of rectal mucosa-associated lymphoid tissue for changes in viral burden (both HIV RNA and HIV DNA), and quantitative co-culture of HIV from CD8-depleted PBMCs using an enhanced limiting dilution co-culture assay [6].

We now report the results from baseline, steady-state, quantitative measurements of HIV burden using five assays in blood and gut compartments. Our primary objective in this analysis was to assess the relationship between viral burden in a variety of long-lived cellular reservoirs, and to describe the relationship between virus burden and clinical status (years of HIV infection, duration of antiviral therapy and CD4+ cell count). Our secondary objective was to determine the feasibility of using novel assays for measuring outcome in patients without detectable plasma viremia.

Discussion TOP

Antiretroviral therapy prevents de novo infection and inhibits viral replication but does not eradicate long-lived cellular reservoirs of virus. Immune based therapies that are cytolytic and have the potential to eradicate virus from latent cellular reservoirs may be necessary for viral eradication. Reports have suggested that replication competent HIV can be isolated from the vast majority of patients with prolonged plasma virus suppression, confirming that residual HIV reservoirs remain [11,19,20]. Assessments of these reservoirs with reliable and reproducible methods with minimal variability are critical in providing measurable endpoints for adjunctive therapies aimed at further reducing total body viral burden.

In this assessment of steady-state measurements of viral reservoirs, the vast majority of subjects had quantifiable levels of HIV measured using the HIV co-culture (88%), blood HIV DNA (95%), and rectal biopsy HIV DNA (95%) assays. Furthermore, most patients (65%) had detectable levels of HIV RNA in rectal biopsies despite having undetectable levels of HIV RNA in plasma. The procedure for obtaining rectal biopsies is relatively painless, fast, has few complications and allows for frequent sampling [21]. An important observation in this trial is the high degree of adherence to the invasive procedures performed (100% of 80 baseline and 97.5% of the entire study's 200 scheduled flexible sigmoidoscopies).

Eradication efforts need to address these mucosal tissue sites directly as such tissues may continue to foster low-level replication due to, among other factors, the inherent difference in susceptibility to infection of GALT T cells compared with PBMC [13,14], the increased activation status of the resident lymphocytes and the presumed, although not documented, lower concentrations of antiviral drugs in tissue than in plasma. This latter point is suggested by reports of isolated cases of slightly different HIV resistance panels in gut- and blood-derived virus, despite the majority of isolates having concordant profiles [15]. Regardless of the pathogenic variables, the demonstration of persistent viral detection in the mucosal compartment of aviremic subjects coupled with the documentation by co-culture that the presence of PBMC-associated viral DNA sequences was significantly correlated with replicating virus, suggests that at least a fraction of the mucosal viral RNA and DNA reflects replication-competent HIV. To confirm the presence of replication-competent HIV in GALT in aviremic patients, mucosal HIV co-culture assays would be necessary. However, such assays are not available and would be technically challenging due to the large numbers of lymphocytes required.

However, one can use the acquired information to make rough estimates of the percentage of HIV DNA in PBMCs that reflects replication-competent versus non-replicative DNA by comparing the number of copies of HIV DNA detected in PBMC with the number of infectious units (cells) determined by the limiting dilution co-culture assay. With the assumption that 1 μg DNA reflects 150 000 cells, comparison of the number of PBMC with HIV DNA with the number of PBMCs with infectious virus demonstrates a two to three orders of magnitude greater number of HIV DNA-containing cells than infectious virus-containing cells. This suggests that in PBMC, ∼ 99.9% of detectable HIV DNA is of non-replicative potential (under the stimulating co-culture assay). Nevertheless, it also demonstrates that infectious potential remains. In viewing the gut environment, it is plausible to imagine low-level replication and maintenance of infection given the proximity to highly vulnerable cellular targets. Even without having tissue co-culture data to support this, the blood analysis suggests that there may be sufficient infectious potential of residual HIV in the gut to implicate GALT as an important reservoir of latent infection.

There was a significant correlation between the various measures of HIV burden (HIV co-culture, blood HIV DNA, rectal biopsy HIV RNA and DNA) suggesting that these are interrelated measures of total body HIV burden. However, there was no significant correlation between HIV reservoir assays and clinical parameters including duration of HIV infection, ART or HAART usage or number of CD4+ T lymphocytes. A curious exception to this was the isolated inverse correlation between HIV tissue RNA level and years of HIV infection although the relevance of this is unclear given the multiple statistical analyses performed. Given the small sample size in this study no attempt was made to make statistical adjustments for the variation in the number of data-points available for each assay or the multiple univariate correlations performed. However, given the multiple associations across all reservoir assays and the relative lack of association between reservoir assays and clinical parameters, it is unlikely that these observations are due to chance alone.

There was no significant correlation between tissue HIV RNA and years of any ART exposure. The lack of correlation between levels of HIV in residual blood and tissue reservoirs and patient clinical characteristics supports previous published data focused on quantitative HIV co-culture data only in a smaller cohort of patients [7]. Our analysis extends this previous observation to include measures of both blood and gut mucosal reservoirs and suggests that HAART therapy alone does not lead to a reproducible decay in HIV reservoirs; other factors such as host immune response, viral fitness, size of reservoirs, tissue penetration etc. are likely to be important co-factors that need to be addressed in future efforts to reduce viral reservoirs [19,22-24].

Under optimal treatment conditions, approximately 90% of the HIV-infected population undergoing therapy with HAART can be rendered aviremic, at least for a period of time [1]. Given that such therapy is now generally accepted to be incapable of eradicating HIV infection, new surrogate endpoints are needed to evaluate the next generation of HIV therapeutics designed to eliminate these residual reservoirs of virus. The assays employed here were evaluated with this in mind. A reliability analysis was carried out for each of the assays (HIV co-culture, blood HIV DNA, rectal biopsy HIV DNA, rectal biopsy HIV RNA) based on two or more baseline values to determine whether such assays are reliable with low variability and, therefore, potentially suitable for use as surrogate efficacy endpoints in trials in patients with undetectable plasma viremia. This analysis was based on the assumption that the multiple values taken over an 8-12 week period in this well-characterized population prior to initiation of a clinical trial represented steady-state levels of viral burden. All assays studied had comparable or less variability than that seen in currently used plasma viral load assays. HIV co-culture had the highest coefficient of variability whereas the blood HIV DNA assay had the lowest coefficient of variation and was considered to be the most reliable assay. The variability in the HIV co-culture assay was similar to that of current plasma viral load assays in clinical use.

The inherent virologic failure rate in subjects who initially achieve an undetectable plasma viral load on HAART and are maintained on optimal regimens is estimated at 4% over 16 weeks. This failure rate may be higher in those with prior history of suboptimal regimens, those with higher pre-treatment viral loads, or longer time to initial viral suppression [25]. Patients successfully treated with HAART may have transient 'blips' in viral load (defined as transient increase in plasma HIV RNA to > 50 copies/ml at isolated time-points). During the pre-treatment period for this clinical trial, eight subjects experienced viral load 'blips'. Such subjects might reflect a different immunologic and virologic cohort. However, when a subset analysis was performed on these two virologic cohorts (persistently undetectable and transient viral blips), no new correlations between clinical parameters and viral reservoirs emerged. Similarly, when we retrospectively assessed the ART history of the subjects prior to the study's 6 month pre-screening period as to whether it was 'optimal' or 'sub-optimal' and then evaluated if either sub-group's clinical parameters correlated with their viral reservoirs, no new patterns emerged. Interpretations of these results are stronger in that there were 20 subjects in each group and suggest that the extent of antiviral coverage does not reflect differently in viral reservoirs. In addition, there was no evidence of increased viral burden in blood and gut compartments in those with periodic plasma viral blips. Taken together, whether the antiviral regimen was fully suppressive or of optimal design did not yield any clinically relevant correlates with viral activity and reservoir reserve.

Plasma viral load may not provide information regarding tissue HIV reservoirs nor residual viral activity in patients responding well to HAART. Thus, there is a need for additional efficacy endpoints for trials assessing the impact of antiviral regimens in subjects with undetectable viremia on HAART. As plasma viral load proved to be an important surrogate of clinical activity of antiviral regimens in those with detectable plasma viral burden, once levels fall below detection in plasma, sampling from those tissue sites shown to have persistent viral presence will need to be assessed. Monitoring of rectosigmoid tissue viral burden may prove to be a useful biologic surrogate endpoint with low assay and intra-subject variability and excellent patient compliance [12] for use in future intervention trials in aviremic subjects. The procedure is minimally invasive and may identify changing viral and immune parameters that may be unappreciated when sampling blood alone, as exemplified at the conclusion of this clinical trial in which reductions in gut HIV DNA, but not blood HIV-DNA were demonstrated following infusion of gene-modified HIV targeted T cells (results reports elsewhere) [16]. Blood HIV DNA measurements may also be a useful parameter to follow and demonstrated the greatest sensitivity and reliability in this study but again, may not accurately reflect the tissue dynamics during treatment [16]. Although scientifically interesting and the only assay to directly measure the replication capacity of residual HIV, quantitative HIV co-culture assays are laborious and expensive and, therefore, not feasible for large clinical studies.

The data presented here support the feasibility of the described assays in quantifying HIV in various compartments and demonstrate their inter-relatedness in subjects with undetectable plasma HIV. The rectal biopsy HIV RNA assay had the lowest sensitivity, HIV co-culture assay the highest variability and blood HIV DNA the lowest variability. While the assays did correlate with each other, the degree of viral burden in these different compartments did not correlate with clinical parameters. Therapeutic strategies aimed at eradicating HIV in both early-stage disease and in those with undetectable plasma viral load will need to be active in mucosal lymphoid tissue where the majority of HIV replication is taking place. These assays can be used to follow the status of HIV infection in different tissues but shed no illumination on distinguishing clinical factors contributing to the size of the residual viral reservoir in fully suppressed patients. The size of these reservoirs is not clearly correlated with historical clinical descriptors. Whether they emerge as predictors of future clinical course remains to be seen.


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