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ABSTRACT: Previous studies have implicated reactive antibodies to the low molecular weight rhoptry-associated proteins (RAP-1, RAP-2/RSP-2 and RAP-3) in erythroid cell destruction during Plasmodium falciparum infection. In this pilot study, the frequency, specificity and functional capacity of naturally acquired anti-RAP-2/RSP-2 antibodies were investigated in the sera of anaemic and nonanaemic malaria-infected Cameroonian children. All sera recognized RAP-2/RSP-2 by FACS, irrespective of the clinical status of the subjects. However, the anaemic children showed higher levels of IgG antibodies than the nonanaemic group, while both groups showed similar levels of IgM antibodies. Only few individuals had detectable levels of RAP-2/RSP-2-specific IgG1 and IgG3 subclass antibodies, while no IgG2 and IgG4 subclass antibodies were detected in these subjects. By ELISA, the anaemic group tended to show higher levels of antibodies to RAP-2/RSP-2 regarding all antibody classes tested, except for IgG4 and IgE. Unexpectedly, sera from the nonanaemic group activated complement to a greater extent than those from the anaemic group. These results need to be confirmed in extended studies but indicate that the effector functions of the RAP-2/RSP-2-reactive antibodies may be more important than their amounts. Such antibodies could play a role in both immunity and pathogenesis during P. falciparum infection.
Parasite Immunology 02/2011; 33(2):104-15. · 2.60 Impact Factor
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ABSTRACT: Mycobacterium tuberculosis genotypes resistant to reactive nitrogen intermediates (RNI) predominate in certain urban communities, suggesting that this phenotype influences disease transmission.
To compare different M. tuberculosis genotypes for resistance to RNI generated in vitro.
We genotyped 420 M. tuberculosis isolates from a neighborhood in Sao Paulo, Brazil, and analyzed them for susceptibility to RNI generated in acidified sodium nitrite (ASN) solution.
Seventy-one (43%) of 167 recent-infection strains and 68 (43%) of 158 endogenous infection strains showed moderate- to high-level ASN resistance.
ASN resistance of M. tuberculosis is not necessarily a determining factor for enhanced transmission.
The international journal of tuberculosis and lung disease: the official journal of the International Union against Tuberculosis and Lung Disease 06/2009; 13(5):665-8. · 2.73 Impact Factor
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ABSTRACT: Malaria is undoubtedly the world's most devastating parasitic disease, affecting 300 to 500 million people every year. Some cases of Plasmodium falciparum infection progress to the deadly forms of the disease responsible for 1 to 3 million deaths annually. P. falciparum-infected erythrocytes adhere to host receptors in the deep microvasculature of several organs. The cytoadhesion of infected erythrocytes to placental syncytiotrophoblast receptors leads to pregnancy-associated malaria (PAM). This specific maternal-fetal syndrome causes maternal anemia, low birth weight and the death of 62,000 to 363,000 infants per year in sub-Saharan Africa, and thus has a poor outcome for both mother and fetus. However, PAM and non-PAM parasites have been shown to differ antigenically and genetically. After multiple pregnancies, women from different geographical areas develop adhesion-blocking antibodies that protect against placental parasitemia and clinical symptoms of PAM. The recent description of a new parasite ligand encoded by the var2CSA gene as the only gene up-regulated in PAM parasites renders the development of an anti-PAM vaccine more feasible. The search for a vaccine to prevent P. falciparum sequestration in the placenta by eliciting adhesion-blocking antibodies and a cellular immune response, and the development of new methods for evaluating such antibodies should be key priorities in mother-child health programs in areas of endemic malaria. This review summarizes the main molecular, immunological and physiopathological aspects of PAM, including findings related to new targets in the P. falciparum var gene family. Finally, we focus on a new methodology for mimicking cytoadhesion under blood flow conditions in human placental tissue.
Brazilian Journal of Medical and Biological Research 01/2007; 39(12):1525-36. · 1.13 Impact Factor
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ABSTRACT: In the present study, 470 children less than 72 months of age and presenting acute diarrhea were examined to identify associated enteropathogenic agents. Viruses were the pathogens most frequently found in stools of infants with diarrhea, including 111 cases of rotavirus (23.6% of the total diarrhea cases) and 30 cases of adenovirus (6.3%). The second group was diarrheogenic Escherichia coli (86 cases, 18.2%), followed by Salmonella sp (44 cases, 9.3%) and Shigella sp (24 cases, 5.1%). Using the PCR technique to differentiate the pathogenic categories of E. coli, it was possible to identify 29 cases (6.1%) of enteropathogenic E. coli (EPEC). Of these, 10 (2.1%) were typical EPEC and 19 (4.0%) atypical EPEC. In addition, there were 26 cases (5.5%) of enteroaggregative E. coli, 21 cases (4.4%) of enterotoxigenic E. coli, 7 cases (1.4%) of enteroinvasive E. coli (EIEC), and 3 cases (0.6%) of enterohemorrhagic E. coli. When comparing the frequencies of diarrheogenic E. coli, EPEC was the only category for which significant differences were found between diarrhea and control groups. A low frequency of EIEC was found, thus EIEC cannot be considered to be a potential etiology agent of diarrhea. Simultaneous infections with two pathogens were found in 39 diarrhea cases but not in controls, suggesting associations among potential enteropathogens in the etiology of diarrhea. The frequent association of diarrheogenic E. coli strains was significantly higher than the probability of their random association, suggesting the presence of facilitating factor(s).
Brazilian Journal of Medical and Biological Research 05/2006; 39(4):507-17. · 1.13 Impact Factor
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ABSTRACT: Tuberculosis (TB) status among county jail prisoners in the western sector of the city of São Paulo, Brazil.
To estimate the prevalence of TB disease and the rate of TB infection in prisoners.
An observational study was conducted in 2000-2001 among 1052 prisoners in nine São Paulo county jails. After the application of an interview and tuberculin skin testing (TST), the following laboratory investigations were carried out: sputum smear examination and culture, identification and drug sensitivity testing.
Of 1052 prisoners, 932 underwent TST (PPD RT23 - 2TU/0.1 ml) and 64.5% were reactors. The prevalence rate of prisoners with active TB per 100,000 prisoners was 2065, around 70 times higher than among the Brazilian population and 79 times higher than in the population of the city of São Paulo. Among the 21 Mycobacterium tuberculosis strains identified, 85.7% were sensitive and 9.5% were resistant to isoniazid (INH) and rifampicin (RMP); 4.8% of the total were resistant to INH, RMP and pyrazinamide.
TB prevalence and infection rates were much higher in prisoners than among the general population.
The international journal of tuberculosis and lung disease: the official journal of the International Union against Tuberculosis and Lung Disease 03/2006; 10(2):203-8. · 2.73 Impact Factor
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ABSTRACT: Cytoadhesion of parasitized red blood cells (PRBCs) to vascular endothelial cells (sequestration) and binding of unparasitized RBCs to PRBCs (rosetting) are virulence factors of Plasmodium falciparum, the species responsible for lethal human malaria. Variant antigens involved in both phenomena have been identified as products of the multicopy var gene family. In this review, progress in the understanding of molecular mechanisms of sequestration is summarized, in particular, concerning the structure of var gene products related to specificity of binding to endothelial receptors, and the origin of var gene diversity.
Research in Microbiology 03/2001; 152(2):141-7. · 2.76 Impact Factor
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ABSTRACT: The revaccination of schoolchildren can restore the residual allergy induced by vaccination in the first years of life but can not modify the allergy resulting from a natural infection. So revaccination in this population should indicate the group infected by the Koch bacilli. To assess the applicability of these assumptions in estimating the risk of tuberculosis infection in regions with high BCG coverage a study was undertaken on schoolchildren between 6 and 9 years of age who were attending the municipal schools in the east zone of S. Paulo City, in the course of the first semester of 1988. Of 11,455 who were vaccinated only 7,470 were tested with PPD, revaccinated and retested ten weeks later; 3,314 of these were vaccinated in the first trimester of life with a half dose and 4,156 received a full dose at later ages (75% during the first year, 20% during the second and 5% during the third). In comparing the results pre and post vaccination by correlation table, the calculation of infection was made according to the criteria of the original method and to the modifications made by the authors under separate cover for those vaccinated in the first trimester and those vaccinated later. The risk of infection was 0.35% and 0.37%, respectively, for the original model and 0.45% and 0.49% for the modified model. The referential was 0.55%. The difference between model and age or with the referential was not significant (p > 0.005). Data suggest that the method is applicable to estimate the risk of tuberculosis infection in schoolchildren vaccinated with a full dose of BCG during the first year of life.
Revista de Saúde Pública 04/1992; 26(2):96-107. · 1.33 Impact Factor
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ABSTRACT: The successful application of Bhattacharya's method (decomposition of frequency distribution into normal components by a graphic method) in the analysis of the results of tuberculin test performed on a population sensitized by "anonymous" strains of mycobacteria, suggested the possibility of its application to two samples of BCG vaccinated school-children, living in the city of S. Paulo (Brazil). One of the sample groups, vaccinated between the second and seventh years of life, was surveyed in 1982 and the other, vaccinated during the first year of life, was surveyed in 1988. In both populations it was possible to characterize the normal component corresponding to children infected by tuberculous bacilli and to quantify them. In the first one, the average size of the reactions was 17.40 mm, the standard deviation 3.72 mm and the proportion of infected children 7.71%, against 4.85% in the unvaccinated control group; otherwise, in the population surveyed in 1988, the average size was 17.00 mm, the standard deviation 4.67 mm and the proportion of infected children amounted to 4.14% against 4.48% in the control group. It is concluded that the method permits the estimation of the prevalence of tuberculosis infection among BCG-vaccinated school-children, provided that the vaccine has been given during the first year of life.
Revista de Saúde Pública 05/1991; 25(2):112-20. · 1.33 Impact Factor
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Revista de Saúde Pública 04/1977; 11(1):111-7. · 1.33 Impact Factor
