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BMC Infect Dis ; 18(1): 153, 2018 04 02.
Artículo en Inglés | MEDLINE | ID: mdl-29609530


BACKGROUND: Characterization of the Mycobacterium leprae genome has made possible the development of Polymerase Chain Reaction (PCR) systems that can amplify different genomic regions. Increased reliability and technical efficiency of quantitative PCR (qPCR) makes it a promising tool for early diagnosis of leprosy. Index cases that are multibacillary spread the bacillus silently, even before they are clinically diagnosed. Early detection and treatment could prevent transmission in endemic areas. METHODS: In this study, the qPCR technique is used to detect DNA of M. leprae in samples of slit skin smears (SSS) of the ear lobe and blood of leprosy patients and their asymptomatic household contacts residing in Governador Valadares, MG, Brazil, a hyperendemic area for leprosy. A total of 164 subjects participated in the study: 43 index cases, 113 household contacts, and, as negative controls, 8 individuals who reported no contact with patients nor history of leprosy in the family. The qPCR was performed to amplify 16S rRNA fragments and was specifically designed for M. leprae. RESULTS: Of asymptomatic household contacts, 23.89% showed bacillary DNA by qPCR in samples of SSS and blood. Also, 48.84% of patients diagnosed with leprosy were positive for qPCR while the bacillary load was positive in only 30.23% of patients. It is important to note that most patients were already receiving treatment when the collection of biological material for qPCR was performed. The level of bacillary DNA from household contacts was similar to the DNA levels detected in the group of paucibacillary patients. CONCLUSION: Considering that household contacts comprise a recognizable group of individuals with a high risk of disease, as they live in close proximity to a source of infection, qPCR can be used to estimate the risk of progress towards leprosy among household contacts and as a routine screening method for a chemoprophylactic protocol.

Infecciones Asintomáticas/epidemiología , ADN Bacteriano/aislamiento & purificación , Composición Familiar , Lepra/epidemiología , Mycobacterium leprae/genética , Adulto , Brasil/epidemiología , Trazado de Contacto/métodos , Femenino , Humanos , Lepra/diagnóstico , Lepra/transmisión , Masculino , Mycobacterium leprae/aislamiento & purificación , Prevalencia , ARN Ribosómico 16S/análisis , Reacción en Cadena en Tiempo Real de la Polimerasa , Reproducibilidad de los Resultados
J Infect Dis ; 201(3): 464-72, 2010 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-20043751


During natural schistosome infection, the induction of T helper type 2 (Th2) responses has been ascribed to parasite eggs, because exposure of the host to this life-cycle stage elicits a polarized Th2 response to egg antigens. In the present study, we show that schistosome worms also elicit systemic, antigen-specific type 2 responses during prepatent infection, before egg deposition begins. CD4(+) T cells producing interleukin (IL)-4 were induced by both male and female worms during single-sex infections, demonstrating that this response is independent of exposure to eggs. The Th2 response was accompanied by production of immunoglobulin E and the sensitization of circulating basophils to produce additional IL-4 in response to schistosome antigens. Together, our data show that schistosome worms establish an immunologic milieu where CD4(+) T cells and basophils are both primed to produce IL-4 before eggs are laid, suggesting that worms play a role in establishment of the Th2 response that is critical for host survival and parasite transmission.

Genes MHC Clase II/genética , Schistosoma mansoni/fisiología , Esquistosomiasis mansoni/inmunología , Animales , Antígenos Helmínticos , Basófilos/fisiología , Linfocitos T CD4-Positivos/metabolismo , Femenino , Humanos , Inmunoglobulina E/sangre , Interleucina-4/genética , Interleucina-4/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Óvulo/inmunología
Res Microbiol ; 155(9): 731-40, 2004 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-15501650


Several studies indicate Actinobacillus (Haemophilus) actinomycetemcomitans and Fusobacterium nucleatum as etiologic agents of periodontal disease. Immunosuppressive factors produced by microorganisms probably contribute to the initiation and evolution of this disease. This study evaluated the antiproliferative activity of ammonium precipitate fractions of A. (H.) actinomycetemcomitans and F. nucleatum isolates from humans and marmosets both with and without periodontal disease. All A. (H.) actinomycetemcomitans and most F. nucleatum strains inhibited PBMC proliferation in a dose-dependent manner. The degree of cell proliferative inhibition of each bacterial species differed among the strains and was independent of host clinical status. The in vitro inhibition of stimulated lymphocyte proliferation induced by different A. (H.) actinomycetemcomitans and F. nucleatum isolates demonstrated the importance of this phenomenon in bacterial virulence, playing a possible suppressor role in host defense mechanisms in vivo. Moreover, our findings pointed out a marked difference between A. (H.) actinomycetemcomitans and F. nucleatum cytoplasmic extracts in their antiproliferative activity, regarding the antigen concentration required for maximum inhibition and their vulnerability to heating and proteolytic treatment.

Aggregatibacter actinomycetemcomitans/patogenicidad , Fusobacterium nucleatum/patogenicidad , Inmunosupresión , Leucocitos Mononucleares/inmunología , Activación de Linfocitos/inmunología , Enfermedades Periodontales/inmunología , Infecciones por Actinobacillus/inmunología , Infecciones por Actinobacillus/microbiología , Adulto , Animales , Callithrix , Células Cultivadas , Femenino , Infecciones por Fusobacterium/inmunología , Infecciones por Fusobacterium/microbiología , Humanos , Activación de Linfocitos/fisiología , Masculino , Enfermedades Periodontales/microbiología