TABLE 1.

Definitions

ExpressionDefinition
AdaptationChange in an organism resulting from selection pressure.
Amoeba-resistant microorganismsaMicroorganisms that have evolved to resist destruction by free-living amoebae, being neither internalized nor killed while within the amoeba.
Amoeba-resistant bacteriaa (ARB)Bacteria that have evolved to resist destruction by free-living amoebae.
CharacterPhenotypic traits possessed by an organism.
CribaLiterally, bed for a newborn baby. Here, it refers to free-living amoebae that act as a reservoir of new ARB and as a potent evolutionary incubator for adaptation to life in human macrophages.
CommensalismSymbiosis in which one organism benefits from the association, with other being neither harmed nor benefited.
EndosymbiontSymbiont that lives within another organism.
EndosymbioticNonlytic behavior of an endosymbiont, although this might occur during only a short part of the life history.
LyticAbility to lyse the host cell, i.e., to rupture the host cell wall.
MutualismSymbiosis in which both organisms benefit from the association.
ParasiteAn organism that benefits from the association with another organism while being harmful to the host.
ParasitismSymbiosis in which one organism benefits from the association while the other is harmed.
SymbiontAn organism that lives in close contact with another living organism throughout a significant portion of its life history (167).
Symbiosis“A phenomenon in which dissimilar organisms live together,” i.e. association of two organisms throughout a significant portion of their life history (167).
Symbiosis islandBy analogy to “pathogenicity island,” a cluster of genes that confer symbiotic traits and may be transferred horizontally.
Trojan horseLiterally, a strategy used to invade the town of Troy. Here, it refers to the protozoal “horse” that may bring a hidden amoeba-resistant microorganism within the human “Troy,” protecting it from the first line human defenses.
VirulenceDegree of pathogenicity.
Virulence traitCharacter that confers pathogenicity to an otherwise less pathogenic or nonpathogenic strain or organism.
  • a New expression first defined in the present paper.