RESUMO
Leishmania (L.) amazonensis [L. (L.) amazonensis] is widely distributed in Brazil and its symptomatic infections usually lead to few localized lesions and sometimes to diffuse cutaneous form, with nodules throughout the body, anergy to parasite antigens and poor therapeutic response. The variability of these manifestations draws attention to the need for studies on the pathophysiology of infection by this species. In this study, we analysed the course and immunological aspects of L. (L.) amazonensis infection in BALB/c and C57BL/6 strains, both susceptible, but displaying different clinical courses, and athymic BALB/c nude, to illustrate the role of T cell dependent responses. We analysed footpad thickness and parasite burden by in vivo imaging. Furthermore, we evaluated the cellular profile and cytokine production in lymph nodes and the inflammatory infiltrates of lesions. Nude mice showed delayed lesion development and less inflammatory cells in lesions, but higher parasite burden than BALB/c and C57BL/6. BALB/c and C57BL/6 mice had similar parasite burdens, lesion sizes and infiltrates until 6 weeks after infection, and after that C57BL/6 mice controlled the infection. Small differences in parasite numbers were observed in C57BL/6 macrophages in vitro, indicating that in vivo milieu accounts for most differences in infection. We believe our results shed light on the role of host immune system in the course of L. (L.) amazonensis infection by comparing three mouse strains that differ in parasitaemia and inflammatory cells.
Assuntos
Interações Hospedeiro-Parasita/imunologia , Leishmaniose Cutânea/imunologia , Animais , Citocinas/imunologia , Leishmania/imunologia , Linfonodos/citologia , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Nus , Carga Parasitária , Especificidade da EspécieRESUMO
It is hypothesized the existence of marker antigens capable to define early (acute phase) or late (convalescent phase) infection course with Anaplasma marginale. Five parasitologically free hybrid calves were splenectomized and experimentally infected with a Zulia isolate of Anaplasma marginale. Sera samples were collected before inoculation and during the overall period of the infection. The course of infection was followed through Giemsa stained blood smears and by packed cell volume (PCV). The period of infection was divided into the prepatent phase in which no apparent infection was evident, an acute phase in which a rapid increase of the parasitemia and the hematocrit reduction were conspicuous and a convalescent phase subjectively considered as a marked decrease in parasitemia, after treatment of the infected animals with Oxytetracycline. Western blot assays and immunoplot analyses were performed. The frequency analysis of the detected antigens showed that some of them reacted with normal or prepatent sera, being non-specific cross reaction. Band 63 (p65 kDa) was specific in the acute phase. Bands 188; 68 (p70 kDa) and 58 (p60 kDa) were recognized mainly in the late or convalescent phases. These results also showed that band 18 (p19 or MSP5) was a marker for specific infection with Anaplasma.
Se hipotetiza que existen antígenos marcadores capaces de definir el curso de la infección con Anaplasma marginale, tanto durante la fase temprana (aguda) como la tardía de recuperación (convalecencia) de la infección. Cinco becerros, mestizos, parasitológicamente negativos a A. marginale, fueron esplenectomizados y experimentalmente infectados con un aislado Zulia de A. marginale. Las muestras de suero fueron colectadas antes de la inoculación y durante todo el periodo de la infección. El curso de la infección fue monitoreado a través de la determinación del hematocrito y de la parasitemia usando frotis sanguíneos teñidos con colorante de Giemsa. El periodo de la infección fue dividido en: fase prepatente, en la que la infección no era evidente, fase aguda en la que un rápido incremento de la parasitemia y reducción del hematocrito son conspicuas y la fase convaleciente, después del tratamiento del animal con oxitetraciclina y en la que se evidencia un claro descenso de la parasitemia. Los sueros colectados fueron usados para los ensayos de Inmunotransferencia y el análisis de las frecuencias de reconocimiento por inmunoplot. El reconocimiento de cada molécula mostró que hay antigenos que reaccionaron con sueros normales o prepatente, es decir, los antigenos de reacción cruzada no específica. Los antigenos marcadores específicos son la banda 63 (proteína p65 kDa) para la fase aguda y las bandas 188; 68 (p70 kDa) y 58 (p60 kDa) para la fase convaleciente. Los resultados obtenidos demuestran también que la banda 18 (p19 kDa o MSP5) es un marcador especifico de infección con Anaplasma.