Phenotypic Plasticity in the Productions of Virulence Factors Within and Among Serotypes in the Cryptococcus neoformans Species Complex

Abstract

The Cryptococcus neoformans species complex (CNSC) is a common opportunistic human fungal pathogen and the most frequent cause of fungal meningitis. There are three major serotypes in CNSC: A, D, and their hybrids AD, and they have different geographic distributions and medical signi cance.Melanin pigment and a polysaccharide capsule are the two major virulence factors in CNSC. However, the relationships between serotype and virulence factor production and how environmental factors might impact their relationships are not known. This study investigated the expressions of melanin and capsular polysaccharide in a genetically diverse group of CNSC strains and how their phenotypic expressions were in uenced by oxidative and nitrosative stress levels. We found signi cant differences in melanin and capsular polysaccharide productions among serotypes and across stress conditions. Under oxidative stress, the laboratory hybrids exhibited the highest phenotypic plasticity for melanin production while serotype A showed the highest for capsular polysaccharide production. In contrast, serotype D exhibited the highest phenotypic plasticity for capsular polysaccharide production and clinical serotype AD the highest phenotypic plasticity for melanin production under nitrosative stress. These results demonstrated that different serotypes have different environmental condition-speci c mechanisms to modulate the expression of virulence factors.

Metabolic Plasticity and Virulence-Associated Factors of Sporothrix brasiliensis Strains Related to Familiar Outbreaks of Cat-to-Human Transmitted Sporotrichosis

“…The present study also shows that S. brasiliensis has metabolic plasticity and may also suffer microevolution depending on the host. This plasticity to adapt to various stress conditions imposed during protracted infections on different patients was also observed previously for patients with cryptococcosis [46] and sporotrichosis [18].…”

Faster Cryptococcus Melanization Increases Virulence in Experimental and Human Cryptococcosis

“…Another limitation is that the virulence measurements were performed with pure cultures in controlled laboratory conditions, which are very different from the environment in a human host. Cryptococcal melanization, for instance, is affected by oxidative and nitrosative stresses [60] and multiple other environmental conditions [46]. Despite the caveats of a reductionist approach such as this, however, we observed correlations between faster colony pigmentation and secreted laccase activity with the outcomes of the interactions between clinical isolates and human patients, G. mellonella larvae and macrophages.…”