Thermal Stress Triggers Broad Pocillopora damicornis Transcriptomic Remodeling, while Vibrio coralliilyticus Infection Induces a More Targeted Immuno-Suppression Response

To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by the Public Library of Science and is in the public domain. The published article can be found at: http://www.plosone.org/.Global change and its associated temperature increase has directly or indirectly changed the distributions of hosts and\ud pathogens, and has affected host immunity, pathogen virulence and growth rates. This has resulted in increased disease in\ud natural plant and animal populations worldwide, including scleractinian corals. While the effects of temperature increase on\ud immunity and pathogen virulence have been clearly identified, their interaction, synergy and relative weight during\ud pathogenesis remain poorly documented. We investigated these phenomena in the interaction between the coral\ud Pocillopora damicornis and the bacterium Vibrio coralliilyticus, for which the infection process is temperature-dependent. We\ud developed an experimental model that enabled unraveling the effects of thermal stress, and virulence vs. non-virulence of\ud the bacterium. The physiological impacts of various treatments were quantified at the transcriptome level using a\ud combination of RNA sequencing and targeted approaches. The results showed that thermal stress triggered a general\ud weakening of the coral, making it more prone to infection, non-virulent bacterium induced an ‘efficient’ immune response,\ud whereas virulent bacterium caused immuno-suppression in its host