HIV-1–specific CD8+ T cells can mature to memory in patients receiving ART. Part 3
Based on the various viral infections, there is a clear relationship between antigen load and the distribution of CD8+ T cells across the various subsets. In the case of FLU and EBV, where the antigen burden is expected to be low, antigen-specific T cells were found to distribute primarily into the memory subsets. In contrast, for CMV where the antigen burden is expected to be higher, the antigen-specific T cells distributed primarily into the terminally differentiated effector subset. For the HIV-1–infected patients with PVLs >1000 copies/mL (n=8), the majority (mean, 76%) of HIV-1–specific tetramer-positive cells were of a phenotype that is associated with acute expansions.
In support of the results reported here, an “early” T cell phenotype in HIV-1 infection has been reported by others. Appay et al. and Kostense et al. have both described the persistence of CD27 expression on HIV-1–specific T cells. The work of Champagne et al. showed that HIV-1–specific T cells were predominantly CD45RA−CCR7−, whereas CMV-specific T cells were predominantly CD45RA+CCR7−. In the same study, in vitro patterns of differentiation indicated that CD45RA+CCR7− was the most advanced differentiation stage, which provided additional evidence that, for most HIV-1–infected patients, the HIV-1–specific CD8+ T cells accumulate in a preterminally differentiated state. Down-regulation of key signaling molecules, such as CD3ζ in addition to CD28, also is a feature of this early phenotype.
The basis for the failure of CD8+ T cells to mature to terminally differentiated effectors in patients with detectable PVLs is not known. Mueller et al. have recently suggested that the lack of maturation may be the consequence of an increased susceptibility to CD95/Fas-induced apoptosis. Others have postulated that the lack of maturation may be caused by the lack of HIV-1–specific CD4+ T cells, which is characteristic of the majority of chronic HIV-1–infected patients. Although there is little direct evidence for this idea, enhancement of HIV-1–specific CD8 function in vitro with interleukin-2 does suggest that CD4-mediated help could play a role. Alternatively, the lack of terminal differentiation may reflect ongoing antigenic stimulation. The initial acute response to HIV-1 does not appear to differ significantly from that of EBV or CMV, but, as HIV-1 infection evolves, the cells do not mature as they do in EBV and CMV infection, which could be a result of the relatively high levels of antigen that prevent the cells from maturing. Interestingly, 2 individuals without previous ART with detectable PVLs but with a low vRNA set point (253 and 859 copies/mL) were found to have a significant proportion of HIV-1–specific CD8+ T cells that were CD45RA−27−, which suggests that control of HIV-1 infection while not receiving ART may be associated with a more mature effector phenotype (data not shown)
HIV-1–specific CD8+ T cells can mature to memory in patients receiving ART. Part 2
Patients 4480, SP1549, 4496, and 4170 were included in this statistical analysis as we did have reliable data regarding time since the last positive PVL test for these patients. A significant correlation was observed between the length of time since the last positive Ultrasensitive test and egress of cells from the acute subset. The percentage of memory versus time (r=0.54) was not significant, which could reflect the fact that some of these patients had a substantial proportion of cells in the intermediate stage. No correlation was found between either PVLs or CD4+ T cell counts at the start of ART and the maturation of cells (data not shown). These results suggest that, if there were a high degree of control for a sustained period, HIV-1–specific CD8+ T cells would mature to memory cells.
Longitudinal analyses of subset distributions in patients receiving ART confirm that antigen load determines the maturation stateWe measured longitudinally the subset distribution for 4 patients, 3 before and after the initiation of ART and the 1 patient while receiving ART and then after discontinuing ART. For the 3 patients initiating therapy, a proportion of the HIV-1–specific T cells matured to memory as the PVL declined. For the 2 patients receiving ART for >1 month, this proportion increased as a function of the time that the virus is controlled. For the 1 patient discontinuing ART, the cells shifted toward the acute-phase phenotype as the PVL increased.
The models of viral infection used in this study were chosen because they reflect a variety of outcomes and therefore allow us to explore the relationship between antigen burden and T cell maturation. FLU was chosen as an example of an acute/resolved infection, in which there should be no antigen load. EBV and CMV are both herpesviruses, but they differ fundamentally in their strategies for maintaining virus reservoirs, which would lead to differences in antigen load. EBV is a γ-herpesvirus that is able to drive clonal expansion of latently infected B cells and consequently maintain a latent pool with minimal viral replication. CMV is a β-herpesvirus that persistently replicates. Therefore, the relative antigen load is likely to be lower for EBV than for CMV. Additional indirect support for these differences in antigen load derives from the differences in the levels of antigen-specific CD8+ T cells that were, on average, higher for CMV (mean, 1.9%; range, 0.4%–5% of CD8+ cells) than for EBV (mean, 0.52%; range, 0.2%–1.7% of CD8+ cells). In addition, we studied a panel of HIV-1–infected patients representing a range of control over the virus.
HIV-1–specific CD8+ T cells can mature to memory in patients receiving ART
We extended the analysis to 11 patients receiving ART with a good clinical response, as noted by a reduction of viral replication to undetectable levels and an increase in absolute CD4+ T cell counts. PVLs, as measured by the Ultrasensitive assay, were <50 HIV RNA copies/mL for all 11 patients at the time of the phenotype assay. The minimum length of time that a patient had been receiving ART at the time of the T cell phenotype assay was 1 month, although most patients had been receiving ART for >1 year
The tetramer-positive cells for these donors were virtually all CD27+; therefore, only the CD45RA and CD28 analysis is shown. For 6 of the 11 patients (patients 4480, SP1549, 1602,1549, 1596, and 4496), the acute-phase phenotype predominated. However, 1 of these patients (patient 1602) showed a relatively reduced percentage of cells found in the acute subset, which was accompanied by an increase in the percentage of cells in the intermediate subset. For 5 of the 11 patients (patients 4170, 1551, 6455, 1604, and 1552), >40% of the tetramer-positive cells were memory. Three of these 5 patients (patients 1551, 6455, and 1604) had subset distributions that were similar to that found on average for EBV in healthy volunteers. One patient, patient 1552, had a subset distribution that was similar to that found on average for FLU, with 75% of the tetramer-positive cells having matured to memory.
Monthly Amplicor and Ultrasensitive PVL measurements were available over a 3–4-year period for 6 of these 11 patients (patients 1602, 1549, 1596, 1551, 1604, and 1552). The lower limits of quantification for these tests are 400 HIV RNA copies/mL and 50 HIV RNA copies/mL, respectively.
These 6 patients divided evenly as to whether they were primarily of an acute or memory phenotype. Two of the 3 patients with responses of a primarily acute phenotype (patients 1549 and 1596) had frequent positive Ultrasensitive test results throughout the 3–4–year period and positive Ultrasensitive tests within 2–7 months of the phenotypic analysis. The third patient with a primarily acute phenotype, patient 1602, had 1 positive Ultrasensitive test 15 months before phenotypic analysis. For the 3 patients with shifts toward memory, the last positive Ultrasensitive test was 21–30 months before phenotypic analysis. Therefore, those individuals with either multiple-positive Ultrasensitive tests and/or a positive test relatively close to the time of the subset analysis were the individuals with responses primarily of the acute expansion phenotype.
Results
Subset distributions differ in CMV, EBV, FLU, and HIV-1–specific CD8+ T cellsModels of virus infection were used to confirm that combined staining for these markers distinguishes the effector, memory, and recently activated subsets and that the maturation state can provide a measure of the degree of control over the virus. We evaluated the distribution of antigen-specific T cells across the various maturation states in the context of several common viral infections. FLU represents a resolved infection in which virus is no longer present. EBV and CMV represent persistent, well-controlled infections. In the case of EBV, antigen burden is expected to be moderate because the virus can propagate without the need to replicate. In contrast, CMV represents a persistent infection with ongoing replication in the host. In addition, we also studied a series of HIV-1–infected patients who were chosen to reflect a spectrum of viral control.
These phenotypes and functional assignments are based on the collective experimental data found elsewhere. Combined CD45RA and CD27 staining distinguishes terminally differentiated and intermediate effector cells from acute, intermediate memory, and memory T cells. For cells that are CD27+, CD45RA, and CD28 staining is then used to distinguish the acute, intermediate memory, and memory subsets. In nonhuman primate immunization studies, we have observed that tetramer-positive T cells sometimes pass through the RA+27+28− stage before regaining CD28 expression (data not shown), and this is the basis for describing the RA+27+28− cells as an intermediate stage of maturation toward the memory subset.
Subset distributions for CMV-, EBV-, and FLU-specific responses from healthy donors and for HIV-1–specific responses in patients with PVLs >1000 copies/mL were determined by staining PBMC with the various combinations of tetramer and cell surface markers.
The distribution for the different virus-specific T cells was remarkably similar among different donors. For FLU and EBV, the tetramer-positive cells were >85% CD27+, which made determination of the subset distribution on the basis of the combined stains straightforward. The results from 7 donors indicate that FLU-specific CD8+ T cells have matured primarily to memory. On average, 79% of the FLU tetramer-positive cells were found to be memory, 59% of these were RA−27+28+, and 20% had reverted to CD45RA expression and were RA+27+28+. Compared with that of FLU, EBV-specific T cells had a more heterogenous subset distribution. For 10 donors, the tetramer-positive cells were primarily memory (on average 55%), with the rest being distributed between the acute stage and a stage that is apparently an intermediate between the acute and memory stages of maturation. In the case of CMV, where the cells are mixed for CD27 expression, the subset distribution is determined by accounting for the CD27− cells in the CD45RA and CD28 subsets (see Subjects, Materials, and Methods). CMV-specific T cells had the most heterogenous distribution of the 3 viruses, but terminally differentiated effectors predominated (CD45RA+CD27−CD28−). In contrast to well controlled infections, in which the majority of T cells have matured past the acute stage, HIV-1–specific T cells from donors with PVLs >1000 copies/mL are of a phenotype that is associated with acute-phase expansions. For 8 donors, 60%–90% (mean, 76%) of the tetramer-positive cells remained in the RA−27+28− subset.
Subjects, Materials, and Methods
Donors Frozen peripheral blood mononuclear cells (PBMC) from healthy donors were screened for tetramer-positive responses to HLA*A0201 complexed with an Epstein-Barr virus (EBV) epitope, a cytomegalovirus (CMV) epitope, or an influenza A (FLU) epitope. HIV-1–infected subjects in this study were recruited from the AIDS clinic at the University of Alabama at Birmingham, as well as from the State University of New York at Stony Brook
Isolation of PBMC PBMC were isolated from fresh heparinized blood by use of ficoll-hypaque density gradient centrifugation or by use of Accuspin tubes (Sigma) and usually were frozen in 90% fetal calf serum (FCS) and 10% dimethyl sulfoxide for later analysis
TetramersHLA-A2 tetramers were synthesized as described elsewhere, using the following epitopes: from the EBV lytic cycle protein, BMLF1, GLCTLVAML; CMV matrix phosphoprotein, pp65, NLVPMVATV; FLU matrix, M1, GILGFVFTL; HIV gag SLYNTVATL; and HIV pol ILKEPVHGV. HLA-A3 tetramers containing the HIV gag epitope RLRPGGKKKHIV and HLA-B8 tetramers containing the HIV nef epitope FLKEKGGL were sythesized as described elsewhere.
Tetramer staining and phenotypingTetramer (0.5–1 μg) was added to 1–2×106 PBMC in PBS containing 1% FCS and 0.1% sodium azide (fluorescence-activated cell sorter [FACS] buffer). Cells were incubated in the dark for 20 min at room temperature. Antibodies were added to a final concentration, as suggested by the manufacturer (see below), and cells were incubated in the dark at 4°C for 20 min. Antibody clones were as follows: CD45RA-FITC clone HI100, CD28-APC clone CD28.2, CD27-APC Clone MT21 (Pharmingen), and CD8-PerCP Clone SK1 (Becton Dickinson). Cells were washed with cold FACS buffer and were resuspended in 400–500 μL of FACS buffer containing 1% formaldehyde. Cells were acquired on a FACS Calibur (Becton Dickinson) instrument within 24 h of staining and were analyzed by use of Cellquest software (Becton Dickinson). For analysis of tetramer-positive cells, the lymphocyte gate, R1, was taken from forward and side scatter plots. R1-gated cells were plotted for CD8 expression versus side scatter, and the R2 gate was drawn around the CD8+ cells. R1- and R2-gated cells were plotted for tetramer staining versus side scatter, and the R3 gate was drawn around the tetramer-positive cells. Tetramer-positive cells were plotted for CD27 versus CD45RA expression or for CD28 versus CD45RA expression. Quadrants for determining negative and positive populations were taken from CD8-gated cells plotted for expression of the relevant markers. Reproducibility of the 2 stains was determined from multiple independent stainings of cells from a healthy donor with a CMV-specific tetramer and the cocktails used in this study. Assays performed on repeated identical samples demonstrated that the range in staining for any combination of 2 antibodies, whether it represented 80% or 10% of the tetramer-positive cells, was about ±3%. Full phenotyping when cells are mixed for CD27 expression uses the fact that, for CD8+ cells, the CD27− cells are all contained within the CD28− cells (data not shown), the full subset distribution is determined by subtracting the CD45RA+CD27− cells from the CD45RA+CD28− cells and the CD45RA−CD27− cells from the CD45RA−CD28− cells.
Measurement of PVL and absolute CD4+ T cell counts T lymphocyte subgroups were quantified by means of flow cytometry. Plasma was processed, stored at −70°C, and subsequently assayed for HIV RNA (Amplicor and UltraSensitive assays; Roche)
Antigen Burden Is a Major Determinant of Human Immunodeficiency Virus–Specific CD8+ T Cell Maturation State. Part 2
An obvious potential correlate is an enhanced HIV-1–specific immune response in terms of magnitude. However, it has been difficult to correlate the magnitude of the T cell response with effective control of infection in untreated HIV-1–infected individuals. Although some studies have reported an inverse correlation between PVL and levels of HIV-1–specific T cell responses, other studies have not confirmed these relationships. The results, when taken together, suggest that the magnitude of the T cell response may not necessarily correlate with clinical outcome, which, in turn, has led to an interest in identifying qualitative aspects of the immune response that might correlate with effective control of the virus
Recent advances in the detection of antigen-specific T cell responses have allowed the dissection of the T cell response during the course of a variety of viral infections. In both rapidly resolved and persistent but well controlled viral infections, T cells appear to pass through a series of maturation steps as the virus is brought under control. As the cells pass through these maturation stages, they exhibit distinct cell surface phenotypes. In particular, cell surface molecules, such as CD45RA/RO, CD28, and CD27, which play a role in modulating the signaling threshold of the cell, are differentially expressed throughout these different stages of T cell maturation. The acute and highly activated CD8+ T cells found in the initial phase of infection are CD45RA−, CD45RO+, CD27+, and CD28−. A proportion of these acute and highly activated CD8+ T cells can go on to lose CD27 expression as they gain full lytic potential and mature into terminally differentiated CD8+ T cells. It is now clear from T cell activation studies, as well as studies using tetrameric forms of major histocompatibility complex (MHC) class I molecules, that these terminally differentiated CD8+ T cells usually revert from CD45RO to CD45RA expression. Therefore, terminally differentiated effector T cells are characterized by a CD45RA+, CD45RO−, CD27−, and CD28− phenotype. As the infection resolves, the memory CD8+ T cells that ultimately emerge are CD27+, CD28+, and, often, CD45RO+, although these cells also can revert from CD45RO to CD45RA expression. Memory cells then are characterized by a CD45RA− and CD45RO+ or a CD45RA+, CD45RO−, and CD27+CD28+ phenotype. Therefore, combined staining for specific combinations of these markers can distinguish effector, memory, and recently activated CD8+ T cell maturation subsets
We hypothesized that, in persistent viral infections, these T cell maturation subsets will represent a dynamic system with the antigen-specific CD8+ T cells moving among the acute, effector, and memory subsets in response to changes in PVL. Thus, if there has been a recent burst of viral replication, the cells would distribute primarily between the acute and effector subsets, and, if a significant period of time has passed since a burst of viral replication, the cells would be found primarily in the memory subset. If this were the case, then staining for these markers could be used in combination with tetramer staining as an indication of the degree of control over virus infection
Antigen Burden Is a Major Determinant of Human Immunodeficiency Virus–Specific CD8+ T Cell Maturation State
The majority of untreated human immunodeficiency virus (HIV) type 1–infected individuals ultimately develop uncontrolled viremia and progressive disease. Cytotoxic T lymphocytes (CTLs) are known to play an important role in controlling HIV-1 replication, which has led to an increasing interest in augmenting conventional antiretroviral therapy with therapeutic vaccination. The successful development of a therapeutic vaccine will rely on the ability to correlate an aspect of the immune response with clinical outcome. In this study, the CD8+ T cell maturation status of antigen-specific cells in models of well and poorly controlled virus infections were compared, to show that a memory phenotype predominates when antigen loads are absent or low. In HIV-1 infection, the emergence of memory CD8+ T cells was found to occur only in individuals with highly suppressed viral replication for an extended duration. Such assessments of the immune response may provide a refined measure of virus control
Several lines of evidence indicate that human immunodeficiency virus (HIV) type 1–specific cytotoxic T lymphocytes (CTLs) play an important role in containing initial HIV-1 infection and maintaining long-term control of viral replication. Their appearance in blood coincides with the initial decrease in plasma virus load (PVL) during acute HIV-1 infection and potent CTL responses have been associated with delayed progression to AIDS. The appearance of CTL escape mutants and their positive association with disease progression suggest that there is selective pressure placed on the virus by this arm of the immune system. Finally, HIV-1–specific CTL responses also have been demonstrated in several cohorts of individuals who were heavily exposed to HIV-1 yet remained clinically uninfected, which suggests that CTL responses also may play a role in protection against chronic HIV-1 infection.
Despite the marked antiviral effect of HIV-1–specific CTLs, most untreated individuals eventually develop uncontrolled viremia and progressive disease. Although longer term control of viremia can be achieved with antiretroviral therapy (ART), ART, as currently given, may be associated with side effects and does not eradicate the virus, which thereby necessitates lifelong therapy. The difficulties associated with ART, as well as the data suggesting that cell-mediated immune (CMI) responses are important in the control of initial HIV-1 infection, have lead to an increasing interest in augmenting conventional ART with therapeutic vaccination. An important component in the development of such a vaccine will be the ability to correlate a facet of the antigen specific T cell response with clinical outcome after vaccination.
The Extraordinary Hope of Antiretroviral Therapy in South Africa. Part 3
The increased CD4+ cell count in patients with active TB was relatively greater than that in patients with KS, possibly because patients with TB have a larger, more dynamic population of highly productive CD4+ cells. For both cohorts, the increase in CD4+ cell counts was greatest during the first 7 days of treatment, a finding consistent with those from studies of HIV therapy in the developed world. These findings, together with other studies, strongly suggest that treatment of HIV-1 subtype C results in significant virologic and immunologic benefit, even in the setting of active OIs and low CD4+ cell counts. The long-term effects of ART in the resource-limited setting will need to confirmed by continued follow-up of the patients in the Cassol et al. study and by other ongoing studies. Further research is needed on predictors and effective strategies to manage immune reconstitution syndrome in patients with OIs, particularly TB, who have begun receiving ART.
There are hosts of unanswered questions regarding HIV therapy in the developing world that must be addressed by research. How will response to ART in resource-limited settings be affected by differences in human genetics, culture, diet, and comorbidities? Will the extraordinary successes of treatment and outstanding suppression of viral load by triple combination ART with an NNRTI be durable over 1, 2, 5, or even 10 years? In a setting in which access is highly challenging and patients may be starting and stopping treatment, will NNRTI resistance develop quickly, and will NNRTI-resistant virus be transmitted, leading to primary resistant HIV infection? What are the best and least expensive second-line regimens? Will patients, once they achieve dramatic improvement of their health, continue to be committed to treatment? Other, larger issues regarding broad-scale implementation of ART must be addressed, including the tremendous needs in health-care infrastructure, education and training of health care professionals in the areas of HIV and AIDS, low-cost monitoring of therapy, the introduction of new technologies, and secondary prevention to reduce new infections. The study by Cassol et al., along with many others that have appeared within the past 12 months, clearly demonstrates that triple combination ART is extraordinarily effective and practical in resource-limited settings, even in patients with low CD4+ cell counts and active OIs. Broad-scale implementation of this life-saving treatment must be widely supported not just by medical communities but also by governments, industry, and philanthropic groups worldwide. As treatment is implemented, an aggressive research agenda must be pursued in parallel, to determine how best to deliver ART, sustain it, and prevent new HIV infections worldwide, as well as improve the lives of those already infected.
The Extraordinary Hope of Antiretroviral Therapy in South Africa. Part 2
Coinfection with M. tuberculosis and HHV-8 are common in the developing world—in sub-Saharan Africa, in particular—and manifestations of these coinfections (tuberculosis [TB] and Kaposi sarcoma [KS], respectively) could complicate application of ART in these areas of the world. HIV-infected patients in the developing world tend to present with HIV very late during the course of the disease, usually with active OIs. TB is, by far, the most common OI. TB leads to significant nutritional wasting and will cause both specific and nonspecific activation in the immune system, which might lead to an increase in viral load and further impair both HIV suppression and immunologic recovery. Some clinicians have wondered whether patients with active TB or KS would be “just too sick” to benefit from triple combination ART or whether combination therapies for both HIV and these OIs would be too complex and impossible to manage effectively. Effective therapy for either TB or KS in the setting of triple combination ART may involve taking anywhere from 5 to 10 medications at any one time. The study by Cassol et al. demonstrates that patients with either of these active OIs respond well to triple combination ART utilizing a nonnucleoside reverse-transcriptase inhibitor (NNRTI)-based regimen.
Although the study by Cassol et al. is small, it is well done, and the results provide important insight into the short-term antiviral effects of ART in a resource-limited setting. After 90 days of therapy, almost 94% of patients with active TB had undetectable viral loads (<40 copies/mL). Eighty percent of patients with KS had undetectable viral loads by 90 days. Patients with TB had slightly greater decreases in viral load, but this is probably because the baseline viral load in patients with TB was higher than that in patients with KS. The phase I decay of virus, which occurs within the first 7 days, was rapid and comparable to the decay observed in studies in the developed world. The phase II decay was slower and more gradual, consistent with that found in previous studies of HIV treatment. Despite the generalized immune activation that can occur with TB, which almost certainly has some impact on HIV replication, triple combination ART in this setting was enormously effective. It is important to note that, in the Cassol et al. study, patients with active TB were treated with 600 mg of efavirenz. Recent studies from Thailand have indicated that responses among patients in that country who were treated with rifampicin and 600 mg of efavirenz may be adequate. These findings suggest that the pharmacokinetic interaction between efavirenz and rifampicin observed in populations in developed countries does not significantly impact the antiviral response of efavirenz-based therapy in resource-limited settings.
The Extraordinary Hope of Antiretroviral Therapy in South Africa
The article “Therapeutic response of HIV-1 subtype C in African patients coinfected with either Mycobacterium tuberculosis or human herpesvirus-8” in this issue of the Journal of Infectious Diseases demonstrates that outstanding virologic and immunologic responses to triple combination antiretroviral therapy (ART) occur in South African patients. These observations provide important insight into the feasibility of treating HIV-infected persons in resource-limited settings.
HIV and AIDS treatment in North America and Europe was revolutionized by the use of triple combination ART, which resulted in dramatic decreases in morbidity and mortality. As the potency, adverse effects, and ease of ART administration continue to improve, HIV is becoming more and more manageable within the developed world. The hallmark of triple combination ART has been profound suppression of viral load to undetectable levels (<400 copies/mL) with increases in CD4+ cell counts. Moreover, ART has uniformly translated to improved health for HIV-infected persons by decreasing the risk of AIDS-related complications and death, as well as by decreasing the overall cost of medical care. Unfortunately, the benefits of ART have been slow to arrive in the developing world, particularly in sub-Saharan Africa, which bears a disproportionate burden of the HIV/AIDS epidemic. As ART has percolated slowly into the developing world, 2 myths have been propagated. The first myth is that the benefits of ART observed in developed areas of the world cannot be replicated in resource-poor settings. This myth gave rise to many arguments that have been made to discourage the introduction of this extraordinary, life-saving therapy in the areas of the world that need it the most. The past 12 months have provided an array of studies, including the study by Cassol et al. in this issue of the Journal, that have shattered this myth. The Cassol et al. study and studies conducted in Cameroon, southern India, and southern Africa have demonstrated dramatically the positive impact of triple combination ART in the developing world. HIV-1 subtype C appears to respond no differently to ART than does subtype B. Adherence in resource-poor settings (when access is guaranteed) is excellent —often better than in North American or European patients. These studies have also shown that the active ingredients in the most commonly used generic ARTs are comparable to “brand name” ART medications.
The second myth is that patients in the developing world will be too ill with farprogressed opportunistic infections (OIs) to benefit from ART. The study by Cassol et al. in this issue of the Journal addresses the use of ART for the treatment of HIV in persons who have clinical manifestations of coinfection with Mycobacterium tuberculosis or human herpesvirus-8 (HHV-8).