The effect of bivalent vaccine, streptococcus / yersinios on some of the blood and Immunologic factors in rainbow trout, Oncorhynchus mykiss

Abstract

Introduction: Streptococcosis and Yersiniosis are important diseases for the aquaculture
industry especially in rainbow trout (Oncorhynchus mykiss) in our country. The aim of this
study was to investigate the effects of a bivalent vaccine (Streptococcus iniae and Yersinia
rockeri) on the immune responses including serum lysozyme, complement activation,
bactericidal, respiratory burst (NBT), total protein, albumin, globulin and some
hematological indices in rainbow trout.
Materials & Methods: In this study three hundred rainbow trout fingerlings (25±2g) were
randomly divided into four equal groups, each in triplicates. The groups were as follow:
Streptococcosis vaccine, Yersiniosis vaccine, bivalent vaccine and control group. Fish in
vaccinated treatment intraperitonealy injected with 100 microliter vaccine on the first day.
The control group was injected with sterile PBS, identical to vaccinated group. Blood
samples were collected from vaccinated and non-vaccinated groups at days 0, 30, and 60 of
study.
Result: The results demonstrated that lysozyme rate in bivalent vaccine were significantly
higher at day 60 post-immunization compared to the control group (p<0.05). A significant
increase was observed in the complement activation in bivalent vaccine at day 30 and 60
post-vaccination compared to the other groups (p<0.05). Also this results demonstrated that
number of WBC in vaccinated groups were higher than control treatment. Generally, it can
be concluded that the administration of bivalent Streptococosis/Yersiniosis vaccine to the
rainbow salmon provided appropriate protection against disease and effectively induced the
immune response against these two diseases which is comparable to either of the vaccines
separately.
Conclusion: Investigation of the efficiency of the bivalent vaccine at commercial level is
highly warranted.