Expression and diversity of Echinococcus multilocularis AgB genes in secondarily infected mice: evaluating the influence of T-cell immune selection on antigenic variation.

Graichen, D A S; Gottstein, B; Matsumoto, J; Müller, N; Zanotto, P M A; Ayala, F J; Haag, K L

Graichen, D A S; Gottstein, B; Matsumoto, J; Müller, N; Zanotto, P M A; Ayala, F J; Haag, K L.

Afiliación

Graichen DA; Programa de Pós Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.

Gene ; 392(1-2): 98-105, 2007 May 01.

Article en En | MEDLINE | ID: mdl-17208391

RESUMEN

The T-cell-mediated immune response exhibits a crucial function in the control of the intrahepatic proliferation of Echinococcus multilocularis larvae in mice and humans, both being natural intermediate hosts of the parasite. Antigen B (AgB), a metabolized Echinococcus spp. lipoprotein, contributes to the modulation of the T-cell immune response, and distinct sites of the corresponding AgB1, AgB3 and AgB4 genes were shown to be under positive selection pressure. Since several AgB gene variants are present in a single Echinococcus metacestode, we used secondary E. multilocularis infections in BALB/c and in athymic nude mice (devoid of T-cell responses) to analyze the effect of the cellular immune response on the expression and diversity of EmAgB1-EmAgB4 genes. We demonstrated hereby that EmAgB transcripts were less abundant in nude mice during the early phase of infection (at one month post-infection), and that EmAgB2 is simultaneously down-regulated when compared to the other three genes. A negative relationship exists between the level of transcription and diversity of EmAgB genes. Moreover, no excess of non-synonymous substitutions was found among the distinct EmAgB alleles from a single host. Together, these results pointed to the effect of purifying selection, which seemed to eliminate the detrimental AgB variants generated during the development of the metacestode within the peritoneal cavity of its intermediate host.

Asunto(s)

Variación Antigénica/genética; Equinococosis/parasitología; Echinococcus multilocularis/genética; Epítopos de Linfocito T/genética; Expresión Génica; Proteínas del Helminto/genética; Lipoproteínas/genética; Animales; Variación Antigénica/inmunología; Equinococosis/inmunología; Equinococosis/transmisión; Femenino; Variación Genética; Inmunidad Celular; Ratones; Ratones Endogámicos BALB C; Ratones Desnudos; Modelos Biológicos; Mutación Puntual

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Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Variación Antigénica / Expresión Génica / Proteínas del Helminto / Epítopos de Linfocito T / Echinococcus multilocularis / Equinococosis / Lipoproteínas Límite: Animals Idioma: En Revista: Gene Año: 2007 Tipo del documento: Article País de afiliación: Brasil Pais de publicación: Países Bajos

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