Cold Shock Proteins are known as DNA/RNA binding proteins, that play an important role in the regulation of the bacterial virulence and physiology process. In Aeromonas salmonicida , three cold shock proteins CspA , CspB , and CspD are found. Among these three cold shock proteins, CspB and CspD are DNA binding proteins and CspA is RNA binding protein. In this study, we evaluated the role of
the RNA binding protein (CspA) on A. salmonicida growth, survival at low temperatures, physiology, and virulence in lumpfish (Cyclopterus
lumpus ). A. salmonicida
ΔcspA mutant was constructed using suicide vector technology.
A. salmonicida ΔcspA showed no differences in LPS, vapA modification after heat-shock, growth at 15ºC and 28ºC. However, a reduction in survival at 4ºC and 0ºC was observed in contrast to the wild type . Additionally, a delay mortality was noticed after injecting A. salmonicida ΔcspA in lumpfish in contrast to the wild type. To get an in-depth insight into the function of ΔcspA, mutant additional genome-wide transcriptome analysis was carried out. A. salmonicida ΔcspA showed 632 differential expressed genes (Log2 fold- change 1; FDRpv
0.05), including 413 upregulated genes, and 219 downregulated genes . In conclusion, we noticed that CspA plays a role in A. salmonicida survival at cold temperatures and influence virulence in lumpfish.