Lysozyme level during acute infection of bacterium Aeromonas salmonicida subsp Salmonicida in halibut and atlantic salmon

Abstract

Lysozme, a humoral defence protein, played an important bactericidal activity in Atlantic salmon and halibut. Turbidometric and bactericidal killing assays were used to determine the lysozyme level and serum killing activity respectively. A challenged experiment in native halibut (Hippoglossus hippoglossus) with different doses (103 ,105 , 109 ) of Aeromonas salmonidae (MT423) has been proved that there is no significant relationship between the lysozyme level and bactericidal killing activity (p>0.005). Lysozyme level in halibut serum was significantly higher than that of Atlantic salmon serum. Lysozyme activity of serum collected from fish during the summer was found to be significantly higher, ranging from 650 to 850 µg. Halibut serum showed varying level of killing activity (KI) during summer (0.266-0.873) and winter (0.255-1.344) whereas Atlantic salmon had very poor killing activity (0.414 -6.867). There was no correlation between the lysozyme activity of the serum and bactericidal activity in the serum of A. salmonicida infected halibut.