Axenic culture establishment and characterization of Brazilian Acanthamoeba isolates: genotyping, phylogenetic inferences and pathogenic potential

Abstract

Free-living amoebae of the genus Acanthamoeba are worldwide distributed, being frequently isolated from the environment. The organisms grow and multiply as phagotrophic trophozoites, and encyst when the conditions become adverse. Cysts resist desiccation, a variety of chemical and physical agents, remaining viable and infective for several years. Acanthamoeba spp. are known to cause severe opportunistic diseases (granulomatous encephalitis, disseminated cutaneous infections) as well as keratitis, which affects healthy individuals, particularly contact lens wearers. The list of clinical and environmental Acanthamoeba isolates is increasing, thus bringing to light the importance in correctly identifying species/genotypes and to evaluate their pathogenic potential. Acanthamoeba remain poorly investigated in Brazil and almost nothing is known about the genetic diversity and the pathogenic potential of species prevalent in our Country. An ongoing screening of Brazilian soil and water samples resulted in the establishment of 30 new Acanthamoeba cultures. This project deals with the molecular characterization and the evaluation of the pathogenic potential of these new Acanthamoeba isolates. Through SSU rRNA gene sequencing and phylogenetic analyses, we propose: to determine the genotypes of the Brazilian environmental isolates; to examine the genetic polymorphism of environmental and clinical (keratitis) Brazilian isolates; infer the phylogenetic relationships between the Brazilian and other Acanthamoeba isolates. Features associated to pathogenicity (temperature tolerance, osmotolerance, secretion of proteolytic enzymes) will also be investigated. (AU)