Cryptococcus neoformans. I. Nonencapsulated mutants.

Seven nonencapsulated mutants of Cryptococcus neoformans were isolated from an encapsulated strain of human origin. Initially, the mutants were avirulent for mice. After several months of subculturing, six of the seven isolates reverted to the encapsulated state and possessed varying degrees of virulence. The results of these experiments suggest that a strong correlation exists between the presence of a capsule and the virulence of C. neoformans.