Identification and characterization of HIV positive Ethiopian elite controllers in both Africa and Israel.

OBJECTIVES: HIV elite controllers (ECs) are a unique subgroup of HIV-positive patients who are long-term virologically suppressed in the absence of antiretroviral treatment (ART). The prevalence of this subgroup is estimated to be < 1%. Various cohorts of ECs have been described in developed countries, most of which have been demographically heterogeneous. The aim of this study was to identify ECs in two large African cohorts and to estimate their prevalence in a relatively genetically homogenous population. METHODS: We screened two cohorts of HIV-positive Ethiopian patients. The first cohort resided in Mekelle, Ethiopia. The second was comprised of HIV-positive Ethiopian immigrants in Israel. In the Mekelle cohort, ART-naïve subjects with stable CD4 counts were prospectively screened using two measurements of viral load 6 months apart. Subjects were defined as ECs when both measurements were undetectable. In the Israeli cohort, subjects with consistently undetectable viral loads (mean of 17 viral load measurements/patient) and stable CD4 count > 500 cells/µL were defined as ECs. RESULTS: In the Mekelle cohort, 16 of 9515 patients (0.16%) fitted the definition of EC, whereas seven of 1160 (0.6%) in the Israeli cohort were identified as ECs (P = 0.011). CONCLUSIONS: This is the first large-scale screening for HIV-positive ECs to be performed in entirely African cohorts. The overall prevalence of ECs is within the range of that previously described in developing countries. The significant difference in prevalence between the two cohorts of similar genetic background is probably a consequence of selection bias but warrants further investigation into possible environmental factors which may underlie the EC state.

Temporal trends in the incidence of HIV infection in antenatal clinic attendees in Addis Ababa, Ethiopia, 1995-2003.

BACKGROUND: The HIV incidence data are relevant in depicting the current dynamics and trend of the epidemic. Using a new laboratory method for HIV-1 incidence, we aimed at estimating a 10-year trend in HIV-1 incidence in Addis Ababa, Ethiopia. METHODS: We determined the temporal trends in HIV incidence based on a total of 7744 serum specimens from pregnant women who attended antenatal clinics in Addis Ababa between 1995 and 2003. HIV incidence was determined by IgG-capture HIV-1 BED incidence enzyme immunoassay following a validation using a well-characterized panel of serial serum specimens from subtype C-infected seroconverters. FINDINGS: Of the 1350 HIV+ specimens tested as part of the annual sentinel survey between 1995 and 2003, a total of 1332 (98.7%) were tested by BED HIV-1 incidence assay. The incidence rate of HIV-1 infection declined significantly from 7.7% (95% CI, 3.9-11.5%) in 1995 to 2.0% (95% CI, 0.7-3.3%) in 2003. Although there was a trend, amongst the age group of 15-29 years, in age-specific decline in incidence, it was not statistically significant. No change in HIV incidence rate was observed for the group aged above 30 years. INTERPRETATION: A corresponding decline in the incidence of HIV infection was observed with the decline in the prevalence of HIV infection between 1995 and 2003 in Addis Ababa City. Whether the declines were because of changes in sexual behaviours or other reasons needs to be explored. The BED HIV-1 incidence assay provides a valuable tool in obtaining information on recent HIV-1 infection.

Determinants of CD4 counts among HIV-negative Ethiopians: role of body mass index, gender, cigarette smoking, khat (Catha Edulis) chewing, and possibly altitude?

To study the determinants of CD4% and CD4 counts among HIV-negative Ethiopians, and to identify factors susceptible to explain the low CD4 counts observed among Ethiopian subjects. Cohort studies among factory workers in Akaki and Wonji, Ethiopia. Clinical and laboratory examinations, including determination of HIV serological status and T-cell subsets, were performed during follow-up visits every six months. In addition, micronutrients (retinol, carotenoids, tocopherol, transferrin receptor, and selenium) plasma concentrations were determined in a subset of 38 HIV-positive and 121 HIV-negative participants. HIV-negative participants with at least one CD4 count measurement were 157 females in Akaki, 203 males in Akaki, and 712 males in Wonji. CD4 counts were independently and positively associated with body mass index (through an increase in lymphocyte counts), female gender (through an increase in CD4%), cigarette smoking (through an increase in CD4%), khat chewing (through an increase in both lymphocyte counts and CD4%), and Akaki study site (through a large increase in lymphocyte counts compensating a decrease in CD4%). Intestinal parasitic infections were not associated with CD4% or CD4 counts. Retinol, carotenoids, and alpha-tocopherol plasma concentrations decreased with HIV infection and advancing immunosuppression, but were not associated with CD4 counts among HIV-negative subjects. Low body mass index among Ethiopians may have contributed to their overall low CD4 counts. Other factors remain to be elucidated.

Drug susceptibility of Mycobacterium tuberculosis in HIV-infected and -uninfected Ethiopians and its impact on outcome after 24 months of follow-up.

From a prospective cohort study on tuberculosis/human immunodeficiency virus (TB/HIV) interaction in Addis Ababa, Ethiopia, drug susceptibility results were available for 94 TB patients (46% HIV-infected). Resistance to one or more drug(s) was detected in 21 (22.3%) and multidrug resistance in five (5.3%) patients. Occurrence of resistance was not related to HIV status or outcome after 24 months of follow-up. However, among HIV-infected TB patients who died during follow-up, survival time in those with a resistant Mycobacterium tuberculosis strain was significantly shorter compared to those with a sensitive strain (6 vs. 13 months). Early detection of drug resistance and timely treatment change can therefore have a positive impact on survival in HIV-infected TB patients.

Risk factors associated with failure of syndromic treatment of sexually transmitted diseases among women seeking primary care in Addis Ababa.

OBJECTIVE: To determine risk factors associated with the failure of syndromic management of sexually transmitted diseases (STDs) among women seeking treatment in primary healthcare centre in Addis Ababa, Ethiopia. METHODS: Women with symptomatic STDs seeking care in a health centre were prospectively enrolled. A total of 259 women were interviewed and underwent clinical examination; 106 were enrolled and received syndromic STD treatment and 91% returned for follow up. Logistic regression analysis was used to identify risk factors associated with treatment failure. RESULTS: Of the 106 women enrolled and presenting with symptomatic STDs 67% were HIV seropositive. Syndromic STD treatment did not result in clinical improvement in 30% of the women. Having genital ulcer disease, genital ulcer disease with genital discharge, genital warts, bacterial vaginosis and plasma HIV-1 load >10,000 copies RNA/ml or being HIV seropositive were all significantly associated with treatment failure. In multivariate analysis, however, only genital ulcer disease was significantly associated with treatment failure. CONCLUSION: In our setting, the association between HIV and genital ulcer disease caused by herpes may, therefore, be the reason for the failure of treatment.

Performance of routine syphilis serology in the Ethiopian cohort on HIV/AIDS.

OBJECTIVES: To assess the performance of routine syphilis screening during 5 year follow up of Ethiopian factory workers, participating in a cohort study on HIV/AIDS. METHODS: Syphilis serology test results of factory workers, who each donated at least six blood samples were evaluated. Screening in 1997-8 had been performed by the Treponema pallidum particle agglutination (TPPA) assay and in 1999-2001 by the rapid plasma reagin (RPR) test. TPPA had been followed by RPR or RPR by TPPA, in case of a positive screening result. Samples of study subjects showing inconsistent sequential TPPA and/or RPR results were retested independently by three laboratory technicians. RESULTS: A total of 540 cohort participants (8.3% HIV positive at enrollment) donated 4,376 blood samples (mean 8.3 per subject). From 93 of the 176 participants with at least one positive TPPA result during follow up, 152 samples were retested by RPR and/or TPPA. Based on the revised syphilis test results, the 540 cohort participants were classified as having no (70.5%), past (20.6%), prevalent (6.9%), or incident (2.0%) syphilis. The RPR screening test was difficult to interpret and yielded 8.2% biological false positive (BFP) RPR results, or 3.2% if weak positive results were excluded. There was no correlation between HIV infection and BFP RPR reactions. Sample mix-ups were detected in 1.2%. CONCLUSION: Evaluation of routine syphilis screening as performed in a long term cohort study on HIV/AIDS in Ethiopia showed difficulties encountered in syphilis screening programmes such as a high percentage of BFP RPR, inconsistencies in interpretation of the RPR test, and sample mix ups. The findings stress the need to develop a syphilis screening assay that is easy to perform and interpret and to implement quality assurance programmes.

Role of incidental and/or cured intestinal parasitic infections on profile of CD4+ and CD8+ T cell subsets and activation status in HIV-1 infected and uninfected adult Ethiopians.

Intestinal parasitic infections have been suggested to cause persistent immune activation leading to an unbalanced immune state. Such a state has been proposed to be a major factor in the pathogenesis of AIDS in an African context. The present study investigated the effect of incidental parasitic infection and treatment on the profile of T cell differentiation and activation markers on CD4+ and CD8+ T cells from HIV-1 infected and uninfected adult Ethiopians. Cryopreserved PBMCs from 64 subjects (41 HIV-negative and 23 HIV-positive) with follow-up visits at 6-monthly intervals were used to compare the effect of incidental intestinal parasites and their treatment upon T cell subset profiles and activation status. The samples were stained with antibodies to various T cell differentiation and activation markers allowing naive, memory, effector, memory/effector, activated and resting CD4+ and CD8+ T cell subsets to be quantified by triple-colour FACScan. Incidental intestinal parasitic infections resulted in a significant increase in memory CD4+ T cell numbers both in HIV-negative and HIV-positive subjects (P < 0.05). There was also a significant increase in the percentage of CD8+ HLA-DR+ T cells (P < 0.05) in HIV-positive subjects co-infected with parasites. In HIV-negative subjects, a significant decline in activated cells and a significant increase in resting CD8+ T cells (P < 0.05) was observed after treatment for parasites. These data suggest that intestinal parasitic infections could result in the alteration of T cell subset counts and also in the up-regulation of T cell activation markers in peripheral blood. Treatment of parasitic infections showed a tendency to reduce the activation suggesting that, together with other community based intervention strategies, such treatment could be used to down-regulate immune activation and hence protect the host from being easily attacked by HIV.

Low CD4+ T-cell count and high HIV viral load precede the development of tuberculosis disease in a cohort of HIV-positive ethiopians.

SETTING: Prospective cohort study, Ethiopia. OBJECTIVE: To study changes in biological markers of HIV infection progression before and after development of TB disease. DESIGN: A longitudinal study of 804 adult factory workers (95 HIV-positive, 709 HIV-negative), who were followed every 6 months for a median of 3.8 years. RESULTS: Overall, the incidence rate of TB was 10/ 222 = 45.1 (95%CI 24.3-83.9) per 1000 person-years of observation (PYO) among HIV-1-positive participants, compared to 14/2,054 = 6.8 (95%CI 4.0-11.5) per 1,000 PYO among HIV-1-negative participants (incidence rate ratio 6.62, 95%CI 2.94-14.9). Among the 10 HIV-positive participants who subsequently developed TB disease, the CD4 count was low (median 201/microl, range 45-419), and viral load high (median 4.97 log copies/ml, range 3.70-5.58), at the routine follow-up visit prior to TB diagnosis. Following TB treatment, plasma viral load remained persistently elevated despite clinical resolution of TB disease, and seven of the 10 patients died within a median time of 8 months. CONCLUSION: In this cohort, HIV-infected Ethiopians who developed TB disease already had low CD4 counts and high viral load prior to the diagnosis of TB. Viral load did not decrease following TB treatment, leading to a poor overall prognosis in these patients.

Low CD4+ T-cell count and high HIV viral load precede the development of tuberculosis disease in a cohort of HIV-positive Ethiopians.

SETTING: Prospective cohort study, Ethiopia. OBJECTIVE: To study changes in biological markers of HIV infection progression before and after development of TB disease. DESIGN: A longitudinal study of 804 adult factory workers (95 HIV-positive, 709 HIV-negative), who were followed every 6 months for a median of 3.8 years. RESULTS: Overall, the incidence rate of TB was 10/222 = 45.1 (95%CI 24.3-83.9) per 1000 person-years of observation (PYO) among HIV-1-positive participants, compared to 14/2054 = 6.8 (95%CI 4.0-11.5) per 1000 PYO among HIV-1-negative participants (incidence rate ratio 6.62, 95%CI 2.94-14.9). Among the 10 HIV-positive participants who subsequently developed TB disease, the CD4 count was low (median 201/microliter, range 45-419), and viral load high (median 4.97 log copies/ml, range 3.70-5.58), at the routine follow-up visit prior to TB diagnosis. Following TB treatment, plasma viral load remained persistently elevated despite clinical resolution of TB disease, and seven of the 10 patients died within a median time of 8 months. CONCLUSION: In this cohort, HIV-infected Ethiopians who developed TB disease already had low CD4 counts and high viral load prior to the diagnosis of TB. Viral load did not decrease following TB treatment, leading to a poor overall prognosis in these patients.

Alteration of Fas and Fas ligand expression during human visceral leishmaniasis.

Several studies in murine systems have suggested a role of apoptosis in the pathogenesis of leishmaniasis. However, the role of apoptosis in visceral leishmaniasis in man has not been explored. In this study, we show that patients with visceral leishmaniasis demonstrate significant dysregulation of Fas and Fas ligand. Levels of soluble Fas (sFas) and soluble Fas ligand (sFasL) were elevated in plasma of patients with active visceral leishmaniasis (VL) and individuals co-infected with VL-HIV-1 compared to healthy controls. The levels of sFas and sFasL were normalized 6 months after successful treatment. In VL patients, the expression of membrane bound Fas, and to a lower extent FasL, were up-regulated on Leishmania donovani-infected spleen cells, the site of parasite multiplication. Expression of Fas and FasL on peripheral blood mononuclear cells was within normal range, probably reflecting that the blood is not a normal site of L. donovani infection. Furthermore, this is suggested by the finding that in vitro infection of macrophages with L. donovani up-regulated Fas expression on the surface of infected cells and enhanced the levels of sFasL in supernatants from infected cultures. How this dysregulation may affect the pathogenesis of human visceral leishmaniasis is discussed.

Distribution of lymphocyte subsets in healthy human immunodeficiency virus-negative adult Ethiopians from two geographic locales.

Immunological values for 562 factory workers from Wonji, Ethiopia, a sugar estate 114 km southeast of the capital city, Addis Ababa, Ethiopia, were compared to values for 218 subjects from Akaki, Ethiopia, a suburb of Addis Ababa, for whom partial data were previously published. The following markers were measured: lymphocytes, T cells, B cells, NK cells, CD4(+) T cells, and CD8(+) T cells. A more in depth comparison was also made between Akaki and Wonji subjects. For this purpose, various differentiation and activation marker (CD45RA, CD27, HLA-DR, and CD38) expressions on CD4(+) and CD8(+) T cells were studied in 60 male, human immunodeficiency virus-negative subjects (30 from each site). Data were also compared with Dutch blood donor control values. The results confirmed that Ethiopians have significantly decreased CD4(+) T-cell counts and highly activated immune status, independent of the geographic locale studied. They also showed that male subjects from Akaki have significantly higher CD8(+) T-cell counts, resulting in a proportional increase in each of the CD8(+) T-cell compartments studied: naïve (CD45RA(+)CD27(+)), memory (CD45RA(-)CD27(+)), cytotoxic effector (CD45RA(+)CD27(-)), memory/effector (CD45RA(-)CD27(-)), activated (HLA-DR(+)CD38(+)), and resting (HLA-DR(-)CD38(-)). No expansion of a specific functional subset was observed. Endemic infection or higher immune activation is thus not a likely cause of the higher CD8 counts in the Akaki subjects. The data confirm and extend earlier observations and suggest that, although most lymphocyte subsets are comparable between the two geographical locales, there are also differences. Thus, care should be taken in extrapolating immunological reference values from one population group to another.

Helminths, human immunodeficiency virus and tuberculosis.

Helminth infections affect over a quarter of the world's population, especially in the developing countries. These long-lasting parasitic infections cause widespread immune activation and dysregulation, a dominant Th2 cytokine immune profile and an immune hyporesponsiveness state. Considering these profound immune changes and the similar geographic distributions of helminthic infections, HIV and tuberculosis (TB), we suggest that helminthic infections play a major role in the pathogenesis of AIDS and TB. They apparently make the host more susceptible to infection by HIV and Mycobacterium tuberculosis, and impair his/her ability to generate protective immunity against both infections. The implication of these ideas is that without eradication of helminth infections and/or modulation of the immune changes that they cause, HIV and TB vaccines may fail to confer protection against their respective infections in helminth-endemic areas.

Induction and abrogation of LACK reactive cells in the evolution of human leishmaniasis.

Peripheral blood mononuclear cells (PBMC) from cutaneous leishmaniasis patients with ongoing Leishmania aethiopica infection and individuals cured/under treatment from L. infantum or L. donovani infection were stimulated in vitro with LACK, the Leishmania homologue of receptors for activated C kinase. The LACK protein is conserved in related leishmanial species and is expressed both in the promastigote and amastigote stages of Leishmania. Our results show that LACK induced marked NK and some CD8+ cell proliferation in PBMC from cutaneous leishmaniasis patients with active disease. These responses were coupled with high levels of IFN-gamma and IL-10 production. At the concentration tested, the proliferative responses to freeze-thawed Leishmania antigen (Ft-Leish) were higher, while the levels of IFN-gamma were consistently lower than that of LACK. Although cells from individuals cured of leishmaniasis could respond to whole Leishmania lysate by proliferation and IFN-gamma production, there was no evident response to LACK. Ethiopian controls tested at the same time also showed LACK induced proliferation with IFN-gamma and IL-10 responses. Thus LACK reactivity in terms of proliferation and cytokine induction were present in cells from some healthy donors and most of the patients with active lesions, while this response was absent in individuals cured of L. infantum or L. donovani leishmaniasis. Since cure from leishmaniasis often results in life-long protection, and active but not cured patients showed in vitro responses to LACK stimulation, questions arose as to how this highly immunodominant molecule functions during human leishmanisasis. Some possible mechanisms are discussed.

Field trial of the RTM dipstick method for the rapid diagnosis of malaria based on the detection of Plasmodium falciparum HRP-2 antigen in whole blood.

The performance of the Quorum RapidTest Malaria (RTM) dipstick method that detects Plasmodium falciparum histidine-rich protein-2 (PfHRP-2) antigen in whole blood was evaluated in a malaria endemic area. Results were compared with conventional Giemsa-stained blood films. Of 306 people tested 37.9% (116/306) were found to be parasitaemic; of these 66.4% (77/116) were P. vivax and 32.8% (38/116) were P. falciparum infections. There was only one (0.9%) mixed P. falciparum plus P. vivax infection. The RTM test was positive in 35/36 patients with P. falciparum identified on blood smear examination, resulting in a sensitivity of 97.2% [95% confidence interval (CI): 91.6-102.8%]. Specificity was 96.3% (95% CI: 93.9-98.6%). The RTM test had a positive predictive value of 77.8% (95% CI: 65.7-89.9%) and a negative predictive value of 99.6% (95% CI: 98.4-100.8%). Of the 10 false positives, seven reported recent malaria episode and treatment, indicating persistence of antigenaemia. If these were assumed truly infected, the positive predictive value is increased to 93.3% (95% CI: 85.8-100.8%). The RTM test was positive in all seven P. falciparum infections with gametocytes and one mixed infection, but was negative in all falciparum gametocytes and relapsing fever cases. All but one P. vivax infection gave negative result on the RTM test. The RTM test missed one patient with parasitaemia. The test is highly sensitive and specific requiring no instrument or trained personnel. It appears to be a very useful tool for rapid diagnosis of malaria, especially in the rural health institutions with limited diagnostic facilities.

Effect of deworming on human T cell responses to mycobacterial antigens in helminth-exposed individuals before and after bacille Calmette-Guérin (BCG) vaccination.

The protective efficacy of BCG vaccination against pulmonary tuberculosis (TB) is highly variable in different populations. The reason remains to be elucidated. This study aims to investigate the possible effect of intestinal helminths on the immune response to PPD in naturally immunized or BCG-vaccinated humans. The study population was assessed for helminthic infection and those found to be positive were randomly assigned to either an albendazole treatment group or a control group who received a placebo. The immune response to PPD was compared between the two groups. In addition, subjects who were tuberculin skin test-negative in both groups were BCG vaccinated and later on tested for PPD-specific responses. Albendazole induced elimination/or reduction in intestinal worms resulting in a significant improvement in T cell proliferation and in interferon-gamma production by peripheral blood mononuclear cells (PBMC) stimulated with PPD. Moreover, BCG vaccination significantly improved PPD-specific immune responses in the treated group but not in the placebo group. The differences in the in vivo skin test responses were not significant. The data show that cellular immune responses to PPD are reduced in persons with concurrent helminthic infections, perhaps reflecting a lowered resistance to mycobacterial infections. This could explain, at least in part, the reduced efficacy of BCG against TB in helminth-endemic areas of the world.

Emerging Leishmania/HIV co-infection in Africa.

The HIV/AIDS pandemic is spreading at an alarmingly high rate in Africa. Leishmaniasis is also highly prevalent in the continent. Despite the emergence of Leishmania/HIV co-infection in Africa, the numbers reported are disproportionately low. Moreover, the number of cases of co-infection is expected to rise in Africa owing to the simultaneous spread of the two infectious diseases and their increasingly overlapping geographical distribution.

HIV-1 alters T helper cytokines, interleukin-12 and interleukin-18 responses to the protozoan parasite Leishmania donovani.

OBJECTIVE: To investigate the in vitro and in vivo effect of HIV-1 on lymphoproliferative and T helper (Th) cytokine responses in leishmaniasis. METHODS: Th1 [interleukin (IL)-2 and interferon (IFN)-gamma] and Th2 (IL-4 and IL-10) as well as IFN-gamma-inducing cytokines (IL-12 and IL-18) were measured in antigen and mitogen-stimulated culture supernatants of peripheral blood mononuclear cells (PBMC) of healthy donors, HIV-infected and visceral leishmaniasis (VL) patients with or without HIV co-infection. RESULTS: Proliferative responses to phytohaemagglutinin (PHA) were significantly lower in PBMC from VL and asymptomatic HIV-infected persons compared with responses in healthy individuals. VL-HIV co-infected patients showed the lowest responses. Although there was no significant difference in the Leishmania-induced proliferative responses among the healthy group and those infected with HIV only, VL patients (with or without HIV) exhibited very low proliferation. When cultured with PHA or Leishmania, PBMC from healthy donors produced high levels of a Th1 cytokine (IFN-gamma) and low levels of Th2 cytokines (IL-4 and IL-10). In addition, co-culturing PBMC from healthy donors with a killed HIV preparation abrogated the production of IFN-gamma induced by Leishmania and augmented IL-4 and IL-10 production. Cells from HIV-infected patients produced low levels of IFN-gamma, but high levels of IL-10. The addition of anti-IL-10 did not increase Leishmania-induced proliferative responses or IFN-gamma production. Both IL-12 and/or IL-18 responses were lower in VL patients, HIV-infected, or VL-HIV co-infected patients as compared with those of healthy donors. CONCLUSION: The data suggest that the inhibitory effect of HIV and VL on proliferation and IFN-gamma production is not due to IL-10 alone, but that the defect induced by HIV and VL probably operates at the level of regulation of IFN-gamma-inducing factors, such as IL-12 and IL-18.

HIV viral load and response to antileishmanial chemotherapy in co-infected patients.

OBJECTIVE: To investigate whether clearance of Leishmania parasites from tissue aspirate smears in patients with HIV and visceral leishmaniasis (VL) co-infection treated with pentavalent antimonials is influenced by initial HIV viral load and to assess the effect of active VL on HIV viral load and replication in vivo. METHODS: Leishmania parasites were identified in Giemsa-stained smears prepared from tissue aspirates. Parasite index was determined by quantifying Leishmania donovani bodies in smears. HIV-1 RNA was quantitated by using the nucleic acid sequence-based amplification technique with a limit of detection of 500 copies/ml. All patients were treated with pentavalent antimonials at 20 mg pentavalent antimony (Sb(V))/kg daily for a total of 28 days. None of the patients received specific anti-retroviral therapy. RESULTS: Seventeen patients (73.9%) showed good initial response to anti-leishmanial treatment and the remaining six (26.1%) had very poor response. Among the good responders, 11 (64.7%) had no demonstrable Leishmania donovani bodies in post-therapy tissue aspirate smear preparations, and in the remaining six (35.3%) their parasite loads were reduced to very low levels. Patients with poor response had persistently high parasite index despite completion of anti-leishmanial chemotherapy. Poor responders had pre-treatment median HIV viral load that was >160-fold higher than responders to anti-leishmanial chemotherapy; [410000 copies/ml (quartile range, 33000-530000) and 2500 copies/ml (quartile range 500-297500), respectively]. Furthermore, compared with pre-treatment viral concentrations, patients with good response showed marked reduction in post-treatment viral load. In contrast, post-treatment HIV viral concentrations were markedly increased among patients with poor response to anti-leishmanial therapy. CONCLUSIONS: The results suggest that pre-treatment HIV viral load influences response to anti-leishmanial chemotherapy and active VL is associated with increased viral replication in vivo, supporting the notion that dual infection plays an important role in the pathogenesis and disease progression of either infection.

Role of Leishmania donovani and its lipophosphoglycan in CD4+ T-cell activation-induced human immunodeficiency virus replication.

Chronic immune activation by coinfecting pathogens has been suggested as a cofactor in human immunodeficiency virus (HIV) disease progression, particularly in the setting of developing countries. Here, we used in vivo-infected mononuclear cells to examine the role of the protozoan parasite Leishmania donovani and its major membrane constituent, lipophosphoglycan (LPG), in mediating CD4+ T-lymphocyte activation-induced HIV replication and CD4+ T-cell death. We found that Leishmania antigens upregulated HIV replication in CD8-depleted peripheral blood mononuclear cells from asymptomatic HIV-infected donors compared to unstimulated cells. L. donovani-induced viral replication was associated with cellular proliferation, increased expression of the cellular immune activation markers CD25 and HLA-DR within the CD4+ subpopulation, and enhanced secretion of tumor necrosis factor alpha (TNF-alpha), interleukin 2 (IL-2), and IL-6. LPG induced TNF-alpha secretion in the absence of increased expression of cellular activation markers. Moreover, in a few cases we observed that L. donovani induced HIV replication without significant cellular activation but with cytokine secretion. The rate of apoptosis was accelerated in these latently infected CD4+ T cells primed with Leishmania antigens compared to controls, and TNF-alpha production appeared to be the central event necessary for this effect. Furthermore, we demonstrate that thalidomide inhibited Leishmania-induced virus replication coupled with abrogated Leishmania-induced TNF-alpha secretion but not IL-2 or IL-6 production. Furthermore, thalidomide did not affect Leishmania-induced apoptosis. The results suggest that Leishmania and its product, LPG, up-regulate HIV replication in latently infected cells through distinct antigen-specific and non-antigen-specific cellular immune activation mechanisms and that TNF-alpha secretion is pivotal in this process. The immunomodulatory role of thalidomide raises interest as a potential adjuvant to reduce HIV disease progression in Leishmania-HIV coinfected individuals.