Rhodes J C, Polacheck I, Kwon-Chung K J
Infect Immun. 1982 Jun;36(3):1175-84. doi: 10.1128/iai.36.3.1175-1184.1982.
A naturally occurring Mel- variant of Cryptococcus neoformans was isolated from the wild type. The effect of phenoloxidase activity on virulence was analyzed on genetically constructed Mel+ and Mel- isolates. The traits Mel+ and virulence in mice, as measured by cumulative mortality and replication potential in brain tissue, cosegregated among the progeny of a Mel+ X Mel- cross. Revertants (MelR) isolated during the course of the cumulative mortality experiment were used to compare virulence in isogenic sets of Mel- and MelR. In two separate sets of such isolates, Mel+ phenotype and virulence coreverted. Measurement of substrate uptake and phenoloxidase activity showed that loss of detectable phenoloxidase was the basis for the Mel- phenotype and that enzyme activity reappeared in the MelR isolates. An intermediate phenotype, Melbg, was also described. Cosegregation and coreversion of the melanin phenotype and virulence suggest that phenoloxidase is a virulence factor in C. neoformans.
从新型隐球菌的野生型中分离出一种自然发生的Mel-变体。在基因构建的Mel+和Mel-分离株上分析了酚氧化酶活性对毒力的影响。通过累积死亡率和脑组织中的复制潜力来衡量，Mel+性状和小鼠毒力在Mel+×Mel-杂交后代中共同分离。在累积死亡率实验过程中分离出的回复体（MelR）用于比较同基因的Mel-和MelR组中的毒力。在两组这样的分离株中，Mel+表型和毒力共同回复。底物摄取和酚氧化酶活性的测量表明，可检测到的酚氧化酶的丧失是Mel-表型的基础，并且酶活性在MelR分离株中重新出现。还描述了一种中间表型Melbg。黑色素表型和毒力的共同分离和共同回复表明酚氧化酶是新型隐球菌中的一种毒力因子。
