Dawit Wolday

Immune Responses to the Mycobacterium tuberculosis-Specific Antigen ESAT-6 Signal Subclinical Infection among Contacts of Tuberculosis Patients

ABSTRACT Diagnosis of latent Mycobacterium tuberculosis infection is considered essential for tuberculosis control but is hampered by the lack of specific reagents. We report that strong recognition of tuberculosis complex-specific antigen ESAT-6 by healthy household contacts of tuberculosis patients correlates with the subsequent development of active tuberculosis during a 2-year follow-up period.

Treatment of intestinal worms is associated with decreased HIV plasma viral load

Background: We have previously suggested that helminthic infections make the host more susceptible to HIV infection and enhance its progression due to the chronic immune activation they cause. Objective: To study the effect of antihelminthic treatment on HIV plasma viral load (VL) in HIV‐ and helminth‐infected individuals living in Ethiopia. Methods: Fifty‐six clinically asymptomatic HIV‐1‐infected individuals, 31 (55%) of whom were also infected with helminths, were studied. All participants received antihelminthic treatment at baseline and at 3 and 6 months. Worm egg excretion, HIV plasma VL, and T‐cell subsets were determined at baseline and 6 months after treatment. Results: The mean age, number of CD4 T cells, and gender distribution were similar in the helminth‐infected and ‐noninfected groups. At baseline, HIV plasma VL was strongly correlated to the number of eggs excreted (p < .001) and was higher in individuals infected with more than one helminth (5.28 ± 0.35 versus 4.30 ± 1.13 log10 RNA copies/mL, respectively; p = .16). After treatment of helminths, the 6‐month change in HIV plasma VL was significantly different between the successfully treated group and the persistently helminth‐positive group (p = .04) Conclusions: Helminth “load” is correlated to HIV plasma VL, and successful deworming is associated with a significant decrease in HIV plasma VL. The results of the current study, if confirmed in a larger study, may have important implications for slowing disease progression and reducing risks of transmission.

Helminths, Human Immunodeficiency Virus and Tuberculosis

Helminth infections affect over a quarter of the worlds 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.Helminth infections affect over a quarter of the worlds 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.

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

ABSTRACT 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: naı̈ve (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.

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.

Sensitivity of Plasmodium falciparum in vivo to chloroquine and pyrimethamine-sulfadoxine in Rwandan patients in a refugee camp in Zaire

Resistance of Plasmodium falciparum to available antimalarial drugs is now thought to be spreading progressively throughout sub-Sahara Africa. In this study we measured the susceptibility of P. falciparum to chloroquine and pyrimethamine-sulfadoxine in vivo in Rwandan patients living in Kibumba refugee camp in Goma, Zaire. Of the 39 cases treated with chloroquine, only 8 (20.5%) showed sensitive or RI (delayed) response and 31 (79.5%) demonstrated resistance at RI (30.8%), RII (33.3%( and RIII (15.4%) levels. Of the 38 individuals receiving pyrimethamine-sulfadoxine, 13 (34.2%) showed sensitive or RI (delayed) responses, and 25 (65.%) showed resistance at RI (26.3%), RII (36.8%) and RIII (2.6%) levels. Both chloroquine and pyrimethamine-sulfadoxine reduced parasite counts by at least 75% in the majority of the patients within 2 d of treatment. A greater proportion of children with malnutrition showed a higher mean geometric parasite density and slower parasite clearance in vivo than those without malnutrition. Moreover, the frequency and degree of resistance were more pronounced in children with malnutrition. Moreover, the frequency and degree of resistance were more pronounced in children with malnutrition. The results suggest the existence of resistance to chloroquine and pyrimethamine-sulfadoxine. However, the drugs are still effective in significantly reducing parasitaemia and they can still be used as drugs of first and second choice in the region, even in the face of some degree of resistance.

Neurological evaluation of untreated human immunodeficiency virus infected adults in Ethiopia

Human immunodeficiency virus (HIV) has been implicated in neurological complications in developed countries. Developing countries have different viral clades and potentially different genetic and social risks for these complications. Baseline neurological performance measures associated with HIV infection have rarely been available from developing countries. The authors carried our a cross-sectional neurological evaluation of a cohort of community-dwelling treatment-naïve HIV-infected patients and similar control subjects from the same communities in Ethiopia. Blinded evaluation using standardized structured questionnaires and a neurological examination was performed by neurologists and treating physicians trained by an HIV neurology specialist. Quantitative performance measures for cognitive and motor function were employed. Data were analyzed with descriptive statistical methods, standard contingency table methods, and nonparametric methods. HIV-positive and control groups were similar by age, gender, and job site. Participants included 73 HIV-positive and 87 HIV-negative controls. Fingertapping speed in the dominant hand was more poorly performed in HIV positives than negatives (P = .01) and was significantly associated with HIV viral load levels (P = .03). Other quantitative neuropsychiatric tests including timed gait, grooved peg-board, task learning, and animal naming did not show significant differences between the two groups. The overall prevalence of central nervous system (CNS) and/or peripheral nervous system (PNS) disease did not significantly differ in the two populations. HIV patients had slowed fingertapping speed correlating with viral load. Other measures of CNS and/or peripheral nervous performance did not differ from controls. The unanticipated minor evidence of HIV-associated neurocognitive and peripheral nerve deficits in this untreated HIV-positive population invite further investigation.

Absence of APOL1 Risk Variants Protects against HIV-Associated Nephropathy in the Ethiopian Population

Background: Susceptibility to end-stage kidney disease (ESKD) among HIV-infected Americans of African ancestral heritage has been attributed to APOL1 genetic variation. We determined the frequency of the APOL1 G1 and G2 risk variants together with the prevalence of HIV-associated nephropathy (HIVAN) among individuals of Ethiopian ancestry to determine whether the kidney disease genetic risk is PanAfrican or restricted to West Africa, and can explain the previously reported low risk of HIVAN among Ethiopians. Methods: We studied a cohort of 338 HIV-infected individuals of Ethiopian ancestry treated in one Israeli and one Ethiopian center. We sought clinical evidence for HIVAN (serum creatinine >1.4 mg/dl or proteinuria >30 mg/dl in a spot urine sample). Genetic analyses included the genotyping of the APOL1 G1 and G2 variants, and a panel of 33 genomic ancestry-informative markers. Statistical analysis compared clinical and genetic indices for HIV-infected individuals of Ethiopian ancestry and overall Ethiopians to those reported for HIV-infected African-Americans, overall African-Americans, West Africans and non-Africans. Findings: Three (0.8%) of 338 HIV-infected patients of Ethiopian ancestry showed clinical criteria compatible with renal impairment. Two of these 3 patients also have severe poorly controlled diabetes mellitus. The third nondiabetic patient underwent renal biopsy which ruled out HIVAN. This absence of clinically apparent HIVAN was significantly different from that reported for African-Americans. The APOL1 G1 and G2 risk variants were found, respectively, in 0 and 2 (heterozygote state) of the 338 HIV-infected individuals. Global ancestry and the frequencies of the APOL1 G1 and G2 variants are not statistically different from their frequencies in the general Ethiopian population, but are significantly and dramatically lower than those observed among HIV-infected African-Americans, African-Americans and West Africans. Interpretation: The coinciding absence of HIVAN and the APOL1 risk variants among HIV-infected individuals of Ethiopian ancestry support a Western rather than Pan-African ancestry risk for ESKD, and can readily explain the lack of HIVAN among individuals of Ethiopian ancestry.

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

ObjectiveTo investigate the in vitro and in vivo effect of HIV-1 on lymphoproliferative and T helper (Th) cytokine responses in leishmaniasis. MethodsTh1 [interleukin (IL)-2 and interferon (IFN)-γ] and Th2 (IL-4 and IL-10) as well as IFN-γ-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. ResultsProliferative 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-γ) 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-γ induced by Leishmania and augmented IL-4 and IL-10 production. Cells from HIV-infected patients produced low levels of IFN-γ, but high levels of IL-10. The addition of anti-IL-10 did not increase Leishmania-induced proliferative responses or IFN-γ 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. ConclusionThe data suggest that the inhibitory effect of HIV and VL on proliferation and IFN-γ 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-γ-inducing factors, such as IL-12 and IL-18.

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