Department of Microbiology, University of Szeged, Szeged, Hungary.
PLoS One. 2013 Jul 9;8(7):e68704. doi: 10.1371/journal.pone.0068704. Print 2013.
The C. parapsilosis sensu lato group involves three closely related species, C. parapsilosis sensu stricto, C. orthopsilosis and C. metapsilosis. Although their overall clinical importance is dramatically increasing, there are few studies regarding the virulence properties of the species of the psilosis complex. In this study, we tested 63 C. parapsilosis sensu stricto, 12 C. metapsilosis and 18 C. orthopsilosis isolates for the ability to produce extracellular proteases, secrete lipases and form pseudohyphae. Significant differences were noted between species, with the C. metapsilosis strains failing to secrete lipase or to produce pseudohyphae. Nine different clinical isolates each of C. parapsilosis sensu stricto, C. orthopsilosis and C. metapsilosis were co-cultured with immortalized murine or primary human macrophages. C. parapsilosis sensu stricto isolates showed a significantly higher resistance to killing by primary human macrophages compared to C. orthopsilosis and C. metapsilosis isolates. In contrast, the killing of isolates by J774.2 mouse macrophages did not differ significantly between species. However, C. parapsilosis sensu stricto isolates induced the most damage to murine and human macrophages, and C. metapsilosis strains were the least toxic. Furthermore, strains that produced lipase or pseudohyphae were most resistant to macrophage-mediated killing and produced the most cellular damage. Finally, we used 9 isolates of each of the C. parapsilosis sensus lato species to examine their impact on the survival of Galleriamellonella larvae. The mortality rate of G. mellonella larvae infected with C. metapsilosis isolates was significantly lower than those infected with C. parapsilosis sensu stricto or C. orthopsilosis strains. Taken together, our findings demonstrate that C. metapsilosis is indeed the least virulent member of the psilosis group, and also highlight the importance of pseudohyphae and secreted lipases during fungal-host interactions.
近平滑假丝酵母包括三个密切相关的种，即近平滑假丝酵母、中间假丝酵母和异滑假丝酵母。尽管它们的总体临床重要性显著增加，但关于假丝酵母复合体物种的毒力特性的研究很少。在这项研究中，我们测试了 63 株近平滑假丝酵母、12 株异滑假丝酵母和 18 株中间假丝酵母产生细胞外蛋白酶、分泌脂肪酶和形成假菌丝的能力。种间存在显著差异，其中异滑假丝酵母株既不能分泌脂肪酶也不能形成假菌丝。9 株不同的近平滑假丝酵母、中间假丝酵母和异滑假丝酵母的临床分离株分别与永生化的小鼠或原代人巨噬细胞共培养。与中间假丝酵母和异滑假丝酵母分离株相比，近平滑假丝酵母分离株对原代人巨噬细胞杀伤的抵抗力明显更高。相比之下，不同物种之间 J774.2 小鼠巨噬细胞对分离株的杀伤没有显著差异。然而，近平滑假丝酵母分离株对小鼠和人巨噬细胞的损伤最大，异滑假丝酵母株的毒性最小。此外，产生脂肪酶或假菌丝的菌株对巨噬细胞介导的杀伤最具抵抗力，并产生最多的细胞损伤。最后，我们使用每个近平滑假丝酵母种的 9 个分离株来检测它们对 G. mellonella 幼虫存活的影响。感染中间假丝酵母分离株的 G. mellonella 幼虫的死亡率明显低于感染近平滑假丝酵母或中间假丝酵母菌株的幼虫。总的来说，我们的研究结果表明，异滑假丝酵母确实是假丝酵母组中毒力最低的成员，并且还强调了假菌丝和分泌脂肪酶在真菌-宿主相互作用中的重要性。
