Brass C, Volkmann C M, Philpott D E, Klein H P, Halde C J, Stevens D A
Sabouraudia. 1982 Jun;20(2):145-58.
A spontaneous mutation occurred in cultures of a virulent strain of Blastomyces dermatitidis during serial passage at 35-37 degrees C. The mutant strain was shown to be 10,000-fold less virulent for mice than the parent strain, and this was independent of the challenge dose, the age of the challenged host, and the route of challenge (although attenuation was greater for pulmonary than for peritoneal challenge). The mutant grows as well as the parent in fungal media or in the presence of murine substrates. Studies of the chronology of pulmonary infection indicate the mutation affects an early event (first week after challenge) in establishment of infection and interaction with host defenses. Scanning electron microscopy showed that the mutant lacks deep irregular surface ridges and grooves present in the parent. It had increased resistance to crystal violet in vitro, increased susceptibility to bile, and could hydrolyze esculin. The latter findings are of interest because they place the mutant in an intermediate position with respect to these properties between the virulent parent and a previously studied avirulent strain. Lipid analyses indicated a marked increase in fatty acids in the mutant. Studies of four B. dermatitidis strains have also associated increasing palmitic acid and phospholipid content with increasing virulence.
在皮炎芽生菌强毒株于35 - 37摄氏度连续传代培养过程中发生了自发突变。结果显示，突变株对小鼠的毒力比亲代菌株低10000倍，且这种情况与攻击剂量、受攻击宿主的年龄以及攻击途径无关（尽管肺部攻击时的减毒程度比腹腔攻击时更大）。突变株在真菌培养基或存在鼠源底物的情况下生长情况与亲代相同。对肺部感染时间进程的研究表明，该突变影响感染建立和与宿主防御相互作用过程中的早期事件（攻击后第一周）。扫描电子显微镜显示，突变株缺乏亲代菌株所具有的深层不规则表面嵴和沟。它在体外对结晶紫的抗性增强，对胆汁的敏感性增加，并且能够水解七叶苷。后一发现很有意思，因为就这些特性而言，该突变株处于强毒亲代菌株和之前研究过的无毒菌株之间的中间位置。脂质分析表明，突变株中脂肪酸显著增加。对四株皮炎芽生菌的研究还表明，棕榈酸和磷脂含量增加与毒力增强相关。
