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

Streptococcosis and Yersiniosis are important diseases for the rainbow trout (Oncorhynchus mykiss) in our country. The aim of this study was to compare the efficacy of divalent vaccine (Streptococcus iniae and Yersinia rockeri) in the immune responses contains, serum lysozyme rate, complement activation, bactericidal, respiratory burst (NBT), total protein, albumin, globulin and some hematological indices contains, RBC and WBC count, hematocrit and haemoglobin in rainbow trout. In this study three hundred rainbow trout fingerlings (25±2g) were randomly divided into four equal groups in triplicates. Treatments contains 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. 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 provided appropriate protection against disease and effectively induced the immune response against these two diseases which is comparable to either of the vaccines separately. Therefore, investigation of the efficiency of the bivalent vaccine at commercial level is highly warranted.