RESUMEN
A comparative morphometric study was performed to identify host-induced morphological alterations in Schistosoma mansoni adult worms. A wild parasite population was obtained from a naturally infected rodent (Nectomys squamipes) and then recovered from laboratory infected C3H/He mice. Furthermore, allopatric worm populations maintained for long-term under laboratory conditions in Swiss Webster mice were passed on to N. squamipes. Suckers and genital system (testicular lobes, uterine egg, and egg spine) were analyzed by a digital system for image analysis. Confocal laser scanning microscopy (CLSM) showed details of the genital system (testicular lobes, vitelline glands, and ovary) and the tegument just below the ventral sucker. Significant morphological changes (p < 0.05) were detected in male worms in all experimental conditions, with no significant variability as assessed by CLSM. Significant changes (p < 0.05) were evident in females from the wild population related to their ovaries and vitelline glands, whereas allopatric females presented differences only in this last character. We conclude that S. mansoni worms present the phenotypic plasticity induced by modifications in the parasite's microenvironment, mainly during the first passage under laboratory conditions.
Asunto(s)
Schistosoma mansoni/ultraestructura , Animales , Femenino , Interacciones Huésped-Parásitos , Masculino , Ratones , Ratones Endogámicos C3H/parasitología , Microscopía Confocal , Ovario/ultraestructura , Fenotipo , Roedores/parasitología , Testículo/ultraestructuraRESUMEN
Experiments were carried out to analyze the biological characteristics of two sympatric isolates of Schistosoma mansoni derived from humans and murines in a low endemic transmission area (Sumidouro county, state of Rio de Janeiro, Brazil). Sympatric reared-laboratory Biomphalaria glabrata and C3H/He mice were used as experimental hosts. Parameters assessed comprised: precercarial period, infectivity and mortality (snails), prepatent period, infectivity (percentage of cercariae maturation into adult worm) and intestinal egg count (mice). The murine isolate showed a shorter precercarial period and higher infectivity than human isolate (p<0.05). This biological heterogenicity did not correspond to the vertebrate data because any biological parameter presented significant difference (p>0.05). These data suggest that both isolates are local sub-populations, providing support for the hypotheses that in a same biotope mixed populations or sub-populations circulate among their main host (human beings) and/or rodent as an anfixenous infection.
Asunto(s)
Biomphalaria/parasitología , Interacciones Huésped-Parásitos/fisiología , Ratones Endogámicos C3H/parasitología , Schistosoma mansoni/crecimiento & desarrollo , Animales , Brasil , Humanos , Ratones , Recuento de Huevos de Parásitos , Schistosoma mansoni/patogenicidad , Especificidad de la EspecieRESUMEN
Histopathologic and morphometric (area, perimeter, major and minor diameters) analysis of hepatic granulomas isolated from twelve naturally infected Nectomys squamipes were compared to four experimentally infected ones and six C3H/He mice. Liver paraffin sections were stained for cells and extracellular matrix. Both groups of N. squamipes presented peculiar granulomas consisting predominantly of large macrophages, full of schistosome pigment, characterizing an exudative-macrophage granuloma type, smaller than the equivalent granuloma type in mouse. Naturally infected animals exhibited granulomas in different stages of development, including large number of involutional types. Morphometric analysis showed that all measurements were smaller in naturally infected animals than in other groups. The results demonstrated that both N. squamipes groups reproduced, with small variations, the hepatic granuloma aspects already described in cricetidium (Calomys callosus), showing a genetic tendency to set up strong macrophage responses and small granulomas. Unexpectedly, natural infection did not engender distinguished histopathological characteristics distinct from those derived from experimental single infection, showing changes predominantly secondary to the duration of infection. It appears that the variability of the inocula (and the number of infections?) interfere more with the quantity than with the quality of the pathological changes, denoting some morpho-functional determinism in the response to schistosomal infection dependent on the animal species.
Asunto(s)
Parasitosis Hepáticas/veterinaria , Ratones Endogámicos C3H/parasitología , Muridae/parasitología , Enfermedades de los Roedores/patología , Esquistosomiasis mansoni/veterinaria , Animales , Heces/parasitología , Granuloma/parasitología , Granuloma/patología , Granuloma/veterinaria , Hígado/parasitología , Hígado/patología , Parasitosis Hepáticas/parasitología , Parasitosis Hepáticas/patología , Macrófagos , Ratones , Recuento de Huevos de Parásitos , Enfermedades de los Roedores/parasitología , Esquistosomiasis mansoni/parasitología , Esquistosomiasis mansoni/patologíaRESUMEN
We report the first systematic epidemiological research carried out in Argentina on the skunk Conepatus chinga. Forty-nine animals were captured in the settlements of Amamá, Trinidad, and nearby forested areas located in the Department of Moreno, Province of Santiago del Estero, between April 1985 and May 1989. Isolation of parasites was done through xenodiagnosis, and their identification as Trypanosoma cruzi was achieved by biological and biochemical criteria. The isolate was highly virulent and pathogenic in inoculated C3H mice. Prevalence was 4.1% (2 of 49). Two facts account for a possible domestic source of infection: both infected skunks were captured near Trinidad, in an area that had never been treated with insecticides, and electrophoretic isoenzyme patterns of the parasites isolated from the skunks were identical to those found in humans. Because extensive deforestation probably would increase the distribution area of C. chinga, further investigation should be performed to evaluate the epidemiological role of this wild mammal.
Asunto(s)
Mephitidae/parasitología , Trypanosoma cruzi/patogenicidad , Animales , Argentina , Enfermedad de Chagas/epidemiología , Reservorios de Enfermedades , Ratones , Ratones Endogámicos C3H/parasitología , Trypanosoma cruzi/aislamiento & purificaciónRESUMEN
Culture forms of thirteen Trypanosoma cruzi strains from 4 zymodemes and 9 schizodemes were inoculated and kept by successive passages in C3H mice. The strains were initially from the following zymodemes: 3 from A, 3 from B, 4 from C and 2 from D and 1 from AB mixed zymodemes. After approximately 18 months maintenance the parasites were isolated by hemoculture and again typed according to their isoenzyme and kinetoplast DNA patterns. The zymodeme A strains kept their initial patterns; from the 3 zymodeme B strains, two kept the initial patterns and one changed to zymodeme A; from the 4 zymodeme C, two kept the initial pattern and two changed to zymodeme B; from the 2 zymodeme D strains, one kept the initial pattern and one changed to zymodeme A. The strain from AB mixed zymodeme was reduced to zymodeme. A. The zymodeme changes were accompanied by schizodeme changes. Although not simultaneously, in one T. cruzi strain the parasitemia change was followed by zymodeme and schizodeme changes. The results showed that prolonged maintenance of T. cruzi in mice by successive passages alters the isoenzyme and k-DNA patterns of some strains and that these alterations tend to move towards zymodeme A, suggesting a selective effect of mice over these T. cruzi populations.
Asunto(s)
ADN Circular , Isoenzimas/análisis , Trypanosoma cruzi/clasificación , Animales , Gránulos Citoplasmáticos/metabolismo , ADN de Cinetoplasto , Ratones , Ratones Endogámicos C3H/parasitología , Especificidad de la Especie , Trypanosoma cruzi/enzimología , Trypanosoma cruzi/aislamiento & purificaciónRESUMEN
Some strains of mice are known to be relatively resistant to hepatic or intestinal amebic infections. In order to know if the intestinal resistance is expressed few hours after infection, we inoculated axenic amebae in three inbred strains of mice either by direct intracecal injection or by infection of a washed-closed cecal loop. We found that amebae do not survive in conventional animals but they colonize longer in animals with the cecal loop. However, the survival was low after 24 hours postinfection. Balb/c mice were more susceptible and CBA mice more resistant. Our results suggest that genetic resistance to intestinal amebiasis is expressed in mice in the early phases of infection.
Asunto(s)
Disentería Amebiana/genética , Ratones Endogámicos BALB C/parasitología , Ratones Endogámicos C3H/parasitología , Ratones Endogámicos CBA/parasitología , Animales , Ciego/parasitología , Supervivencia Celular , Entamoeba histolytica/crecimiento & desarrollo , Femenino , Interacciones Huésped-Parásitos/genética , Inmunidad Innata/genética , Ratones , Ratones Endogámicos BALB C/genética , Ratones Endogámicos C3H/genética , Ratones Endogámicos CBA/genéticaRESUMEN
Dez clones isolados das cepas Y, CL e MR foram caracterizados segundo infectividade das culturas, curvas de parasitemia, polimorfismo e mortalidade em camundongos C3H isogênicos. Entra os clones das cepas Y e CL foram encontradas diferenças intragrupos bastante significativas. Os clones da cepa MR apresentaram maior homogeneidade. Estes resultados indicam que as cepas do T. cruzi podem apresentar diferentes graus de heterogeneidade. Também sugerem que as condiçöes utilizadas para a manutençäo de cepas de T. cruzi podem resultar em vantagens seletivas para algumas subpopulaçöes, podendo uma cepa ser o resultado da interaçäo destas subpopulaçöes (clones) selecionadas após alguns anos de manutençäo em laboratório
Asunto(s)
Ratones , Animales , Masculino , Vectores Genéticos , Ratones Endogámicos C3H/parasitología , Trypanosoma cruzi/genéticaRESUMEN
Ten clones of Trypanosoma cruzi isolated from Y, CL and MR strains were studied. The infectivity of culture forms, parasitemia pattern, polymorphism and mortality were studied in C3H inbred mice. Significant intra-group differences among Y and CL clones were found. MR clones showed higher homogeneity. These data indicate that T. cruzi strains can show different degrees of heterogeneity. It is suggested that conditions used to maintain T. cruzi strains may result in a selective advantage for some subpopulations (clones) after many years of laboratory maintenance.