Acanthamoeba spp. as a universal host for pathogenic microorganisms: One bridge from environment to host virulence.
Free-living amoebas (FLA) are ubiquitous environmental protists that have enormously contributed to the microbiological contamination of water sources. FLAs have displayed resistance to environmental adversities and germicides and have played important roles in the population control of microbial communities due to its predatory behavior and microbicidal activity. However, some organisms have developed resistance to the intracellular milieu of amoebas, as in the case of Acanthamoebas, which in turn, have been functioning as excellent reservoirs for amoeba-resistant microorganisms (ARMs), such as bacteria, viruses and fungi. Little is known about these relationships and interaction mechanisms, but it is speculated that the FLAs need a very broad repertoire or universal class of receptors to bind and recognize these diverse species of microorganisms. By harboring these organisms as a "Trojan Horse", the Achantamoeba has been working as an excellent vector for pathogens. Moreover, studies have demonstrated that the interaction of pathogens with Acanthamoeba results in environmental selective pressure responsible for induction and maintenance of virulence factors and increase in microbial pathogenicity. This phenomenon is correlated to the observation of higher gene number and DNA content of ARMs, when compared to their relatives which are adapted to other hosts, due to allopatric or sympatric gene transfer and acquisition, contradicting the overall genome reduction theory for intracellularly adapted pathogens. Thus, adaptation to FLAs indirectly provided a "learning" environment for pathogens to resist later to macrophages; besides the evolutionary distance, these phagocytes share similar predatory mechanisms, such as phagocytosis and phagolysossomal degradation. In this mini-review, we cover the most important aspects of Acanthamoeba biology and their interactions with endemically important human pathogens.
Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Brazil. Electronic address: allanguimaraes@id.uff.br.
Allan J
AJ
Guimaraes
Departamento de Microbiologia e Parasitologia, Instituto Biomédico, Universidade Federal Fluminense, Brazil.
Kamilla Xavier
KX
Gomes
Departamento de Virologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Brazil.
Juliana Reis
JR
Cortines
Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Brazil. Electronic address: peralta@micro.ufrj.br.
José Mauro
JM
Peralta
Departamento de Patologia, Faculdade de Medicina, Universidade Federal Fluminense, Brazil.
Regina H Saramago
RH
Peralta
D000048:Acanthamoeba / Q000382:microbiology*; D000818:Animals; D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification*; D004783:Environmental Microbiology; D005658:Fungi / Q000254:growth & development / Q000302:isolation & purification*; D006801:Humans; D056265:Microbial Interactions; D014774:Virulence; D014780:Viruses / Q000302:isolation & purification*
Acanthamoeba castellanii; Environment; Host; Pathogens; Virulence