Humoral response to low molecular weight antigens of Mycobacterium tuberculosis by tuberculosis patients and contacts

Much effort has been devoted to the identification of immunologically important antigens of Mycobacterium tuberculosis and to the combination of target antigens to which antibodies from serum of tuberculous patients could react specifically. We searched for IgG antibodies specific for antigens of 45 to 6 kDa obtained after sonication of the well-characterized wild M. tuberculosis strain in order to detect differences in the antibody response to low molecular weight antigens from M. tuberculosis between patients with pulmonary tuberculosis and contacts. Specific IgG antibodies for these antigens were detected by Western blot analysis of 153 serum samples collected from 51 patients with confirmed pulmonary tuberculosis. Three samples were collected from each patient: before therapy, and after 2 and 6 months of treatment. We also analyzed 25 samples obtained from contacts, as well as 30 samples from healthy individuals with known tuberculin status, 50 samples from patients with other lung diseases and 200 samples from healthy blood donors. The positive predictive value for associated IgG reactivity against the 6-kDa and 16-kDa antigens, 6 and 38 kDa, and 16 and 38 kDa was 100 percent since simultaneous reactivity for these antigens was absent in healthy individuals and individuals with other lung diseases. This association was observed in 67 percent of the patients, but in only 8 percent of the contacts. The humoral response against antigens of 16 and 6 kDa seems to be important for the detection of latent tuberculosis since the associated reactivity to these antigens is mainly present in individuals with active disease.

Combined use of Western blot/ELISA to improve the serological diagnosis of human tuberculosis

Two recombinant antigens and a crude bacterial antigen of a wild M. tuberculosis strain were used to detect specific IgG antibodies in sera from 52 patients with pulmonary tuberculosis, confirmed by an acid-fast smear and serum culture of these patients and that of 25 contacts. The patients were not infected with HIV. We evaluated the sensitivity and specificity of ELISA, based on the recombinant TbF6® and TbF6/DPEP antigen and a search for reactivity patterns in the Western blot technique, using whole mycobacterium antigen. Serum samples from 22 healthy individuals and from 30 patients with lung diseases other than tuberculosis were used as controls. The best ELISA results were obtained with the TbF6/DPEP antigen combination, which gave 85 percent sensitivity and 91 percent specificity. ELISA sensitivity improved from 85 percent to 92 percent when the Western blot results were used. Western blot specificity was 100 percent when antibody reactivity with different antigenic bands was analyzed and associated. The association of TbF6/DPEP antigens used in ELISA with specific patterns of reactivity determined by Western blot can help make an identification when classic methods for the diagnosis of pulmonary tuberculosis are not sufficient.

Transmisión congénita del Trypanosoma cruzi en Brasil: estimativa de prevalencia baseada en resultados preliminares de la encuesta nacional serológica en niños menores de cinco años, así como otras fuentes / Congenital transmission of Trypanosoma cruzi in Brazil: estimation of prevalence based on preliminary data of national serological surveys in children under 5 years old and other sources

A prevalence estimation of congenital transmission in Brazil is performed, based on several sources of recent data. From a serological survey conducted now in Brazil, with children below 5 years old, preliminary data from the state of Minas Gerais only 19/9,556 children did have antibodies against Trypanosoma cruzi. All 19 mothers were infected, but only one child persisted with antibodies on a second blood collection, hence diagnosed as congenital. The other were just passive transference of maternal antibodies. From a recent publication, 278 children born from 145 infected mothers were studied. Two cases (0.7%) were congenital. In other source, from 1,348 blood donors, 35 were born in non endemic areas. When 10 of them were called, 8 were born from infected mothers and five may be congenital. Finally, no infection was detected in 93 children born from 78 infected mothers. The reasons for this low prevalence are discussed, are lower than in other countries of the South Cone, that harbor also T. cruzi 2, but are unrecognized up to now.

Malaria diagnosis: a review

Malaria is the most prevalent endemic disease in large parts of the world and is subject to control by health authorities. Today, the goal of malaria control is to prevent mortality and reduce morbidity and socioeconomic losses through the progressive improvement and strengthening of local and national capabilities. The World Health Organization considers early diagnosis as the first basic element of the strategy to control the disease. Traditionally, laboratory diagnosis has been made using the thick blood film, which continues to be the gold standard test. However, this test has disadvantages such as the manner in which the film is prepared, the level of training of the observer, the adequacy of maintenance of materials and equipment and its only fair sensitivity. Thus, many research laboratories have concentrated their efforts on the development of alternative methods for malaria diagnosis. These include methods for the detection of Plasmodia within erythrocytes (fluorescent microscopy, Quantitative Buffy Coat (QBC(), dark field microscopy, nucleic acid probes and immunofluorescence), methods for the detection of plasmodial antigens in body fluids (radioimmunoassay, enzyme immunoassay) and methods for the detection of anti-plasmodial antibodies in serum (indirect immunofluorescence, enzyme immunoassay, Western blotting). Here, we critically review the various methods for malaria diagnosis based on the world's literature and our experience with most of them, with emphasis on recent advances.

Anti-leishmania IgA immunoenzymatic assay in mucocutaneous leishmaniasis (preliminary report).

Os Autores descrevem a reacao de IgA ELISA na leishmaniose mucocutanea. Titulos acima do normal foram encontrados no primeiro e segundo anos de infeccao e em soros de micoses profundas acompanhados por envolvimento mucoso ou doenca disseminada

Spinal fluid immunoenzymatic assay (ELISA) for neurocysticercosis.

Investigou-se o comportamento de tres antigenos de Cysticercus cellulosae, o liquido vesicular, um extrato salino e um extrato alcalino, no teste imunoenzimatico (ELISA) para a cisticercose. Em seguida, para o diagnostico da neurocisticercose, comparou-se esse teste com os testes de imunofluorescencia, fixacao do complemento e hemaglutinacao, em amostras de liquido cefalorraqueano. Os resultados obtidos indicam o teste imunoenzimatico como satisfatorio para fins de rotina, em vista da sensibilidade, especificidade e facilidade de execucao