Increased release of glucuronoxylomannan antigen and induced phenotypic changes in Trichosporon asahii by repeated passage in mice
Increased release of glucuronoxylomannan antigen and induced phenotypic changes in Trichosporon asahii by repeated passage in mice
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DOI：
10.1099/0022-1317-51-5-423
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发表时间：
2002-05-01
影响因子：
3
通讯作者：
Nasu, M
中科院分区：
文献类型：
--
作者：
Karashima, R;Yamakami, Y;Nasu, M
已知临床上重要的真菌如白色念珠菌和新型隐球菌在体内反复传代或传代后会发生表型变化。然而，没有报道描述这种现象在丝孢酵母属物种。本研究调查了在小鼠体内传代的环境菌株的阿萨希丝孢酵母菌改变其表型;使用了三个环境菌株和14个临床菌株（来自深部感染）。观察各菌株的殖民地形状和细胞类型，测定葡萄糖醛酸甘露聚糖（GXM）抗原滴度和（1->3）-β-D-葡聚糖浓度。在小鼠中环境分离株三次传代后，还检查了这些特征的变化。环境分离株和临床分离株的菌落形态和细胞类型明显不同。此外，临床分离株释放的GXM抗原水平显著高于环境分离株（滴度：log（2）9.4 SD 0.7 vs log（2）5.4 SD 1.4）。在菌落形态、细胞类型和GXM释放方面，传代分离株的表型与原始环境分离株显着不同（滴度：log（2）10.0 SD 0.7 vs log（2）5.4 SD 1.4）。这些结果表明，表型的变化，在T asahii发生作为在体内传代的结果。这个过程可能会使一部分真菌种群逃脱宿主免疫系统的根除，因为GXM抗原被认为可以保护真菌免受体内多形核白细胞和单核细胞的吞噬作用。
Clinically important fungi such as Candida albicans and Cryptococcus neoformans are known to undergo phenotypic changes after repeated subculture or passages in vivo. However, there are no reports describing this phenomenon in Trichosporon species. This study investigated whether in-vivo passages of environmental isolates of Trichosporon asahii in mice changes their phenotype; three environmental isolates and 14 clinical isolates (from deep-seated infections) were used. The shape of the colony and cell type were observed, and the titre of glucuronoxylomannan (GXM) antigen and concentration of (1-->3)-beta-D-glucan were measured for each isolate. Changes in these features were also examined after three passages of the environmental isolates in mice. The shape of colonies and cell types were clearly different in environmental and clinical isolates. Furthermore, the clinical isolates released significantly higher levels of GXM antigen than environmental isolates (titre: log(2) 9.4 SD 0.7 versus log(2) 5.4 SD 1.4). The phenotype of passaged isolates was significantly different from the original environmental isolates with respect to the morphology of colonies and cell type and GXM release (titre: log(2) 10.0 SD 0.7 versus log(2) 5.4 SD 1.4). These results suggest that the phenotypic changes in T asahii occur as a result of in-vivo passages. This process may allow a proportion of the fungal population to escape eradication by the host immune system, as GXM antigen is considered to protect the fungi against phagocytosis by polymorphonuclear leucocytes and monocytes in vivo.