Virulence Factors IN Fungi OF Systemic Mycoses

Abstract

Pathogenic fungi that cause systemic mycoses retain several factors which allow their growth in adverse conditions provided by the host, leading to the establishment of the parasitic relationship and contributing to disease development. These factors are known as virulence factors which favor the infection process and the pathogenesis of the mycoses. The present study evaluates the virulence factors of pathogenic fungi such as Blastomyces dermatitidis, Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum and Paracoccidioides brasiliensis in terms of thermotolerance, dimorphism, capsule or cell wall components as well as enzyme production. Virulence factors favor fungal adhesion, colonization, dissemination and the ability to survive in hostile environments and elude the immune response mechanisms of the host. Both the virulence factors presented by different fungi and the defense mechanisms provided by the host require action and interaction of complex processes whose knowledge allows a better understanding of the pathogenesis of systemic mycoses.

Paracoccidioides brasiliensis: phylogenetic and ecological aspects

“…Taking into account that P. brasilensis might have been associated with animal hosts for a long time, what kinds of genetic changes could have been occurring? Some physiological and morphological changes which are supposed to facilitate the pathogenic lifestyle and are commonly referred to as virulence factors, have been traditionally observed in pathogenic fungi [14]. Some cell-wall compounds such as a-(1,3)-glucan, adhesion molecules, and enzymes (proteinases, lipases, phospholipases), considered important for fungal nutrition and invasion of animal tissues, have been observed in P. brasiliensis and in other pathogenic dimorphic fungi [15][16][17][18][19][20].…”

“…Both thermo-tolerance and dimorphism have also been considered important virulence factors, since the body temperature of most vertebrate hosts is relatively high [14]. In fact, certain hypotheses generated on the origin of endothermy in animals consider it a protective factor against infectious diseases, in particular fungal diseases.…”

Decreased expression of 14-3-3 inParacoccidioides brasiliensisconfirms its involvement in fungal pathogenesis

“…5,6 The development and the course of the microbial infection can be considered a multifactorial process that results from the interaction between the virulence factors of pathogen, leading to the pathogen's establishment in the host and causing disease, and the host's ability to prevent and resist microbial colonization or invasion. [7][8][9][10] The pathogen uses a large repertoire of surface molecules, specifically adhesins, that can bind to the extracellular matrix (ECM) of various cell types in the host, inducing endocytosis in normally non-phagocytic cells (epithelial and endothelial cells) during the invasion process. 11,12 This interaction with the ECM has been correlated with the processes of adhesion and invasion.…”

Perfil epidemiológico das ceratomicoses atendidas no HC-UNICAMP

“…O aumento na incidência de casos deve-se, provavelmente, ao uso irrestrito de antibióticos de amplo espectro, que propiciam um ambiente de baixa competitividade, favorecendo o crescimento do fungo (2) . Outros fatores a serem considerados são o uso abusivo de cor ticoides tópicos, olho seco, lentes de contato, cirurgias oculares prévias, uso de medicações ou doenças imunossupressoras e doenças que alterem a flora ocular (3)(4)(5)(6)(7) . Embora com características clínicas particulares, as infecções fún gicas geralmente confundem-se com as bacterianas, tornando a pesquisa etiológica laboratorial mandatória.…”