Study of the type 4B protein secretion system (Dot/Icm) and the effector protein SdhA in Piscirickettsia Salmonis

• Main Author: Cortés Sobarzo, Marcos Andrés
• Format: Thesis
• Language: English
• Published: 2017
• Subjects: 570 Biowissenschaften; Biologie; ddc:570; Atlantic salmon
• Online Access: https://epub.uni-regensburg.de/36466/; https://epub.uni-regensburg.de/36466/2/PhD%20Thesis%20MCortesconfirmas.pdf

Chilean Salmon Farming is an important industry nowadays in Chile with significanteconomics entry to the country. The troubles with the handling and maintenance of this industry to avoid product losses is a key factor of concern right now. Piscirickettsiosis disease has been a problem that persist over the time in this industry and several attempts had been made to try to solve the mortalities induced by this fish pathogen. According to Aquaculture and Fishery report from Sernapesca, the amount of harvest Chilean Atlantic salmon was around 152.806 tons in 2014 and represent around USD$ 1,292 million. During the year 2014, the main cause of mortalities is Piscirickettsiosis, affecting all three salmonid species farmed in Chile, reaching 74% in Atlantic salmon, 73% in rainbow trout and 36% in coho salmon. The lack of effective treatments to control Piscirickettsiosis has emphasized the need to develop techniques for diseases prevention. Management of the disease is based on several husbandry practices including the application of immunostimulants of unproven efficacy and the control of vertical transmission by an expensive selection procedure during reproduction. Piscirickettsia salmonis is the causative agent for Piscirickettsiosis diseases that affects the three salmonid species farming in Chile. Currently, our knowledge about this pathogen is limited to a few articles that described the induction of apoptosis in phagocytic host cells, the presence of the type 4B secretion system at transcript level, the possible evasion of the phagocytic pathway after internalization in the host cell, the increased gene expression levels of two virulence factors with a key role in the intracellular survival (ClpB and BipA), and recently the enclosed genome for the LF-89 strain. The results found in this work, could provide a real evidence how the bacteria can establish the infection inside the host cell, using the Type 4B Secretion System to translocate effector proteins that subvert the vesicle trafficking to its own benefits. ...