排序方式: 共有5条查询结果,搜索用时 0 毫秒
1
1.
José L. Tapia Benjamin Nogueda Torres Govinda S. Visvesvara 《The Journal of eukaryotic microbiology》2013,60(5):448-454
Although Balamuthia mandrillaris was identified more than two decades ago as an agent of fatal granulomatous encephalitis in humans and other animals, little is known about its ecological niche, biological behavior in the environment, food preferences and predators, if any. When infecting humans or other animals, Balamuthia feeds on tissues; and in vitro culture, it feeds on mammalian cells (monkey kidney cells, human lung fibroblasts, and human microvascular endothelial cells). According to recent reports, it is believed that Balamuthia feeds on small amebae, for example, Acanthamoeba that are present in its ecological niche. To test this hypothesis, we associated Balamuthia on a one‐on‐one basis with selected protozoa and algae. We videotaped the behavior of Balamuthia in the presence of a potential prey, its ability to hunt and attack its food, and the time required to eat and cause damage to the target cell by direct contact. We found that B. mandrillaris ingested trophozoites of Naegleria fowleri, Naegleria gruberi, Acanthamoeba spp., Trypanosoma cruzi epimastigotes, Toxoplasma gondii tachyzoites, and Giardia. However, it did not feed on Acanthamoeba cysts or algae. Balamuthia caused cytolysis of T. cruzi epimastigotes and T. gondii tachyzoites by direct contact. Balamuthia trophozoites and cysts were, however, eaten by Paramecium sp. 相似文献
2.
A method is described for obtaining maximum yield of Toxoplasma tachyzoites from the peritoneal cavity of infected mice. Mice injected with 102 parasites contain more Toxoplasma in this site at the time of death than mice injected with larger numbers. The host does not mount a detectable humoral response to the parasite. 相似文献
3.
B L Munday 《International journal for parasitology》1978,8(4):285-288
Three calves dosed per os with 0.75 × 106, 0.75 × 106 and 1.5 × 106Toxoplasma oocysts developed high titres of Toxoplasma antibodies as measured by the indirect fluorescent antibody test and the dye test. Toxoplasma gondii was reisolated from 2 of these animals. Two calves given 1 × 103 tissue cysts and 2 × 106 tachyzoites intramuscularly did not develop such high fitres, but T. gondii was reisolated from the calf injected with tachyzoites.Of 4 pregnant cows given 7 × 104, 7 × 104 and 1.6 × 105 oocysts and 1.5 × 102 tissue cysts only 2 developed significant levels of Toxoplasma antibodies. There was no evidence of Toxoplasma infection in the calves born by these cows.It was concluded that cattle do not readily acquire persistent T. gondii infections, and this may be due, in part at least, to early elimination of Toxoplasma from their tissues. 相似文献
4.
Botelho AS Teixeira L Correia-da-Costa JM Faustino AM Castro AG Vilanova M 《Experimental parasitology》2007,115(1):68-75
C57BL/10ScCr mice, lack Toll-like receptor 4 and a functional Interleukin-12 receptor. Taking this into account, susceptibility of these mice to Neospora caninum infection was assessed comparatively to that of immunocompetent C57BL/10ScSn mice. C57BL/10ScCr mice inoculated intraperitoneally with 5x10(5)N. caninum tachyzoites showed a high susceptibility to this parasite. All infected C57BL/10ScCr mice were dead by day 8 post-infection whereas all control C57BL/10ScSn mice survived this parasitic challenge. Immunohistochemical analysis of infected C57BL/10ScCr mice showed N. caninum tachyzoites spread in the pancreas, liver, lung, intestine, heart and brain whereas no parasites were detected in similarly infected C57BL/10ScSn controls. The higher susceptibility of C57BL/10ScCr mice to neosporosis correlates with reduced interferon-gamma mRNA expression and increased IL-4 mRNA expression, comparatively to C57BL/10ScSn controls, detected in the spleen after the parasitic challenge. C57BL/10ScCr mice could thus be used as a new experimental model where to study immunobiological mechanisms associated with host susceptibility to neosporosis. 相似文献
5.
SYNOPSIS. Toxoplasma gondii, passed from mouse to mouse in the tachyzoite stage for 30–35 generations, developed cysts, which, when fed to cats, failed to produce oocysts. Besnoitia jellisoni, passed similarly for 20 generations, lost the capacity to form cysts. These phenomena are explained by a loss of genomes or gene products during the rapid passage selecting for tachyzoites. 相似文献
1