TABLE 1.
Definitions
| Expression | Definition |
|---|---|
| Adaptation | Change in an organism resulting from selection pressure. |
| Amoeba-resistant microorganismsa | Microorganisms 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. |
| Character | Phenotypic traits possessed by an organism. |
| Criba | Literally, 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. |
| Commensalism | Symbiosis in which one organism benefits from the association, with other being neither harmed nor benefited. |
| Endosymbiont | Symbiont that lives within another organism. |
| Endosymbiotic | Nonlytic behavior of an endosymbiont, although this might occur during only a short part of the life history. |
| Lytic | Ability to lyse the host cell, i.e., to rupture the host cell wall. |
| Mutualism | Symbiosis in which both organisms benefit from the association. |
| Parasite | An organism that benefits from the association with another organism while being harmful to the host. |
| Parasitism | Symbiosis in which one organism benefits from the association while the other is harmed. |
| Symbiont | An 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 island | By analogy to “pathogenicity island,” a cluster of genes that confer symbiotic traits and may be transferred horizontally. |
| Trojan horse | Literally, 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. |
| Virulence | Degree of pathogenicity. |
| Virulence trait | Character that confers pathogenicity to an otherwise less pathogenic or nonpathogenic strain or organism. |
a
New expression first defined in the present paper.