The intracellular life ofChlamydia psittaci: how do the bacteria interact with the host cell?

Throughout the life of any organism interactions with the surrounding environment are always taking place, a process that leads to evolution. Chlamydia psittaci is an obligate intracellular parasite, but it must also be capable of extracellular survival in order to search for new host cells. Therefore, these peculiar prokaryotes have evolved two different particles and a unique developmental cycle that, together with a series of not yet fully understood interactions with their host cells, allow them to fulfil the requirements for their permanence in nature. These interactions are the subject of this paper. Particular attention is paid to the attachment and internalization of the bacteria, the chlamydial vacuole, and the avoidance of lysosomal degradation.