Performance of absolute CD4+ count in predicting co-infection with human T-lymphotropic virus type 1 in antiretroviral-naive HIV-infected patients.

Early identification of patients co-infected with HIV and human T-lymphotropic virus type 1 (HTLV-1) is essential to improve care, as CD4+ T-cell counts have been revealed to be an unreliable laboratory parameter to monitor HIV infection in co-infection. Unfortunately, HTLV-1 testing is not currently available in sub-Saharan Africa. We conducted this study to determine the performance of absolute CD4+ T-cell count estimation in guiding the clinical suspicion of co-infection. A cross-sectional survey was conducted in antiretroviral-naïve HIV (AN-HIV) patients attending an HIV outpatient clinic in Maputo city, Mozambique. Seven hundred and one AN-HIV patients were enrolled in the study. The prevalence of HTLV-1 co-infection was 4.5% (95% confidence interval [CI] 3.0-6.0%). Logistic regression analysis showed that CD4+ T-cell count was an independent predictor of co-infection (P value: 0.000). The performance of absolute CD4+ T-cell counts in predicting co-infection was higher in symptomatic HIV patients when compared with asymptomatic HIV patients. The best performance was achieved with the cut-off of CD4+ count of 500 cells/mm(3), which gave sensitivity, specificity, positive and negative predictive values of 54.2%, 87.2%, 24.0% and 96.2%, respectively. In conclusion, our data provide evidence that the absolute CD4+ T-cell count is of moderate accuracy in guiding the clinical suspicion of co-infection in AN-HIV and its implementation could improve the care provided to a significant number of HIV patients in Mozambique.

Human T-cell leukemia viruses: epidemiology, biology, and pathogenesis.

The human T-cell lymphotropic viruses type I and type II are closely related human retroviruses that have similar biological properties, genetic organization and tropism for T lymphocytes. Along with the simian T-cell lymphoma virus type I, they define the group of retroviruses known as the primate T-cell leukemia/lymphoma viruses. Initially identified in 1980, the human T-cell lymphotropic virus type I has been implicated as the etiologic agent of adult T-cell leukemia/lymphoma and of a degenerative neurologic disorder known as tropical spastic paraparesis or human T-cell lymphotropic virus type I-associated myelopathy. The intriguing link between human T-cell lymphotropic virus type, T-cell malignancy, and a totally unrelated and non-overlapping neurological disorder suggests divergent and unique pathogenetic mechanisms. This review will address the epidemiology, molecular biology, and pathogenesis of human T-cell leukemia viruses.

Chagas' disease: an algorithm for donor screening and positive donor counseling

Classical serological screening assays for Chagas' disease are time consuming and subjective. The objective of the present work is to evaluate the enzyme immuno-assay (ELISA) methodology and to propose an algorithm for blood banks to be applied to Chagas' disease. Seven thousand, nine hundred and ninety nine blood donor samples were screened by both reverse passive hemagglutination (RPHA) and indirect immunofluorescence assay (IFA). Samples reactive on RPHA and/or IFA were submitted to supplementary RPHA, IFA and complement fixation (CFA) tests. This strategy allowed us to create a panel of 60 samples to evaluate the ELISA methodology from 3 different manufacturers. The sensitivity of the screening by IFA and the 3 different ELISA's was 100%. The specificity was better on ELISA methodology. For Chagas disease, ELISA seems to be the best test for blood donor screening, because it showed high sensitivity and specificity, it is not subjective and can be automated. Therefore, it was possible to propose an algorithm to screen samples and confirm donor results at the blood bank.

Os testes sorológicos clássicos utilizados na triagem de doadores de sangue são trabalhosos e subjetivos. O objetivo do presente trabalho é o de avaliar a metodologia imuno-enzimática (ELISA) e propor um algorítmo para doença de Chagas em bancos de sangue. Foram estudados 7999 doadores de sangue e/ou componentes cujas amostras foram testadas com o objetivo de tria-las sorologicamente para doença de Chagas utilizando hemaglutinação passiva reversa (RPHA) e imunofluorescência indireta (IFA). As amostras reativas em pelo menos uma destas metodologias, foram retestadas com reativos diferentes por RPHA, IFA e fixação de complemento (CFA). Esta estratégia nos permitiu criar um painel de 60 amostras com as quais tornou-se possível a avaliação do método imunoenzimático (ELISA). A sensibilidade da triagem dos doadores pelos métodos ELISA e IFA foi de 100%. A especificidade foi melhor para a metodologia imunoenzimática. O teste ELISA parece ser o ideal para triagem em bancos de sangue pois é altamente sensível, específico, não é subjetivo e pode ser automatizado. Desta forma, torna-se possível a formulação de um algorítimo a ser utilizado na triagem sorológica e confirmação de resultados em doadores de bancos de sangue.

Chagas' disease: an algorithm for donor screening and positive donor counseling.

Classical serological screening assays for Chagas' disease are time consuming and subjective. The objective of the present work is to evaluate the enzyme immuno-assay (ELISA) methodology and to propose an algorithm for blood banks to be applied to Chagas' disease. Seven thousand, nine hundred and ninety nine blood donor samples were screened by both reverse passive hemagglutination (RPHA) and indirect immunofluorescence assay (IFA). Samples reactive on RPHA and/or IFA were submitted to supplementary RPHA, IFA and complement fixation (CFA) tests. This strategy allowed us to create a panel of 60 samples to evaluate the ELISA methodology from 3 different manufacturers. The sensitivity of the screening by IFA and the 3 different ELISA's was 100%. The specificity was better on ELISA methodology. For Chagas disease, ELISA seems to be the best test for blood donor screening, because it showed high sensitivity and specificity, it is not subjective and can be automated. Therefore, it was possible to propose an algorithm to screen samples and confirm donor results at the blood bank.

Risk factor analysis and serological diagnosis of HIV-1/HIV-2 infection in a Brazilian blood donor population: validation of the World Health Organization strategy for HIV testing.

OBJECTIVE: To determine the relative prevalence of HIV-1 and HIV-2 and to evaluate the World Health Organization testing strategy for HIV diagnosis in a low-risk population in Brazil. In addition, to assess risk factors for HIV infection. DESIGN: Sera obtained from 9885 consecutive blood donors were screened in parallel by two HIV enzyme-linked immunosorbent assays (ELISA) with different antigen composition and test principles (Ortho HIV-1 and Wellcozyme HIV-1/2). Samples reactive to either ELISA were submitted to a Western blot assay and to a rapid HIV-1/2 ELISA (Sero-Immuno Diagnostics). An ELISA test with specific HIV-1/HIV-2-derived synthetic peptide was used to discriminate between samples reactive on the Wellcozyme HIV-1/2 assay. Demographic and serological data were used to address risk factors for HIV infection. RESULTS: All the 28 Western blot-confirmed positive samples were reactive in both Ortho HIV-1 and Wellcozyme HIV-1/2 assays (sensitivity, 100%). The Wellcozyme HIV-1/2 specificity (99.9%) was higher than Ortho HIV-1 (99.5%). If sample reactivity to both tests was considered positive, the sensitivity and specificity of the screening would be 100%. However, further analysis with a third rapid HIV-1/2 ELISA reduced both the sensitivity and the specificity of the sequential testing strategy. Discrimination between HIV-1 and HIV-2 showed evidence for the presence of HIV-1 only. Finally, in the group aged 18-35 years, the presence of serological markers of hepatitis C virus and hepatitis B virus infections and the elevated levels of beta 2-microglobulin were variables associated with the identification of HIV-1-seropositive blood donors. CONCLUSION: In a low-risk population, application of two high quality ELISA tests with different antigens and test principles can replace the use of the Western blot. In addition to the cost being reduced by 10-16%, a rapid diagnosis and the absence of indeterminate Western blot results confer an advantage to this strategy.

Isolation of Mycobacterium avium complex from bone marrow aspirates of AIDS patients in Brazil.

Mycobacterium avium complex (MAC) infection has not been reported as a major opportunistic infection among patients with AIDS in Latin America or Africa. In this study, 125 AIDS patients who had persistent fever, anemia, and leukopenia were examined among 2628 AIDS patients admitted to Instituto de Infectologia Emilio Ribas between May 1990 and April 1992. From the bone marrow aspirates of the 125 patients, MAC was isolated from 23 (18.4%) and Mycobacterium tuberculosis was isolated from 9 (7.2%). Between 1985 and 1990, only 11 MAC isolations among 60,000 cultures obtained from human immunodeficiency virus-seronegative patients were documented in São Paulo. Hence, the minimal estimated rate of MAC infection in AIDS patients in this city was 23/2628, or 0.88%. These findings suggest that MAC infection is an important opportunistic infection, especially among a subset of patients with AIDS in Brazil who have clinical characteristics and risk activities similar to those associated with MAC infections in North America and Europe.

Specific binding of the human monocytic cell line U937 to the alternatively spliced connecting segment (IIICS) of fibronectin.

U937 cells attach to the RGDS-containing 80-kD fragment of fibronectin (Fn). The present report examined whether these cells recognize other domains of Fn. U937 cells attach to a 38-kD fragment derived from the A chain of Fn, which includes the Hep II domain and most of the alternatively spliced IIICS region. U937 did not bind to a 58-kD fragment derived from the B chain (which lacks IIICS) and has the Hep II site. They also did not bind to a 31-kD COOH-terminal fibrin-binding fragment or to a 29-kD fragment containing the Hep I domain. Cell adhesion to the 38-kD fragment was not inhibited by the 80-kD fragment, by GRGDSPC synthetic peptides, or by a mAb directed to the RGDS-containing domain of Fn. Attachment was completely inhibited by the 38-kD fragment and by the synthetic peptide CS-1, comprising the first 25 amino acid residues of IIICS. These results indicate that U937 cells interact with two sites of Fn, the RGDS-containing region, and the IIICS region.

Fibronectin receptors of mononuclear phagocytes: binding characteristics and biochemical isolation.

Fibronectin receptors on mononuclear phagocytes are involved in the localization of monocytes at inflammatory sites and in the subsequent expression of macrophage-like phenotypes. In this study, we have investigated the hypothesis that proteolytically derived fragments of fibronectin may interfere with binding of fibronectin to monocytes in the extracellular matrix. We report on the reactivity of U937 cells with an 80-kDa tryptic fragment of fibronectin which contains the cell-binding domain but lacks the gelatin/collagen-binding domain. U937 cells attached to surfaces coated with the 80-kDa fragment as well as with intact fibronectin. Preincubation of the cells with the 80-kDa fragment inhibited attachment to both surfaces while intact fibronectin had little or no inhibitory effect. The Ki for inhibition of attachment (0.5 microM) was consistent with the Kd for binding of the 3H-labeled 80-kDa fragment (0.34 microM) to U937 cells in suspension. There were 4-5 x 10(5) 80-kDa binding sites per cell. The relatively high affinity of the 80-kDa fragment for the monocyte surface permitted the isolation and characterization of fibronectin-binding proteins from U937 cells and peripheral blood monocytes by affinity chromatography. When octylglucoside lysates of lactoperoxidase iodinated cells were applied to 80-kDa-Sepharose columns, a polypeptide complex of 152/125 kDa was eluted with the synthetic peptide GRGDSPC, but not with GRGESP. This complex resolved into a single diffuse band of 144 kDa upon reduction. Binding of the protein complex to the affinity column required divalent cations. The complex bound to wheat germ agglutinin and could be specifically eluted by N-acetylglucosamine. Similar cell-surface proteins were isolated from peripheral blood monocytes.