Deep-sea hydrothermal vents are considered as some of the most adverse environments in the world, yet the animals dwelling around the vent sites exhibit high productivity and therefore must cope with unusual levels of heavy metals, pH, temperature, CO2 and sulfide, in addition to environmental microbes. In an attempt to understand the physiological reactions of animals normally set to endure extreme conditions we investigated molecular indicators of acclimation processes during which the mussel Bathymodiolus azoricus was maintained over long periods of time under without methane and/or sulfide supplementation, vent mussels seem to endure well aquarium conditions. The presence and induction of a Rel Homology Domain containing gene was investigated along with the induction of the antibacterial gene mytilin following experimental infections carried out with the marine bacteria Vibrio parahaemolyticus. It was then concluded that vent mussels are capable of performing typical immune gene transcription activity as their shallow water congeners. The mussel's viability was determined during stimulations achieved with the hyperbaric chamber IPOCAMP, by comparing the expression levels of, among other genes, the metal-responsive Metallothionein (MT) gene at 170 bars. laboratory conditions. Even in the absence of the characteristic high hydrostatic pressure found at deep-sea vent sites and Our results suggest that Bathymodiolus azoricus maybe used in experimental studies as an indicator species, for assessing immunity, toxicity or metal stress and the effect of hydrostatic pressure.