The present research has investigated the effect of Lactobacillus farraginis (LF) and Enterococcus durans (ED), isolated from kefir, as probiotic on innate immune parameters and expression of IL-1β and TNF-1α lysozyme genes in the intestine, as well as resistance to the Lactococcosis in rainbow trout. Four hundred and eighty juveniles (41.9 ± 2.4 g) were divided into eight groups with three replications, including the control, LF1 and LF2 supplemented with 10 7 and 10 8 Cfu/g feed of each strain, Bactocell equivalent to 10 10 , ED1 and ED2 with 10 7 and 10 8 Cfu/g feed of each strain, combination supplements LF1+ED1 and LF2+ED2 with 5 × 10 6 and 5 × 10 7 Cfu/g feed of each strain. Compared to control, a significant increase (p < 0.05) was observed in in serum lysozyme, ACH50, C3 and C4, total antibody, bactericidal activities and blood phagocytosis in LF2, Bactocell, LF2+ED2, and ED2 treatments. Besides, lysozyme gene expression in the intestinal tissue of fish treated with LF2, ED2, and Bactocell significantly increased (p < 0.05). A significant increase in TNF-1α gene expression was also observed in all treatments except LF1 and ED1 (p < 0.05). Moreover, a significant increase in the level of IL-1β gene expression was observed in all groups, except for ED1 and LF1+ED1, in comparison to the control treatment. After challenge with Lactococcus garvieae, the lowest mortality percentages were recorded for LF2, Bactocell, LF2+ED2, and ED2 treatment compared to the control. The results suggest beneficial effects of kefir derived LAB strains on immune responses, immune-related genes expression, and disease resistance in rainbow trout.

Since infectious pancreatic necrosis virus (IPNV) is the most predominant strain causing fatal viral disease in Iranian fish farms, an inactivated vaccine for this fatal pathogen was developed. Additionally, the effect of the above-mentioned vaccine was investigated against IPNV using Montanide 1312 VG adjuvant. Two hundred and forty healthy fish with an average weight of 3.00 ± 0.45 g were vaccinated using immersion method with ethylene amine-inactivated IPN vaccine in combination with Montanide IMS 1312 VG for 5 min at 11 ± 1°C. The control group was vaccinated with sterile phosphate-buffered saline. Correspondence: M Akhlaghi, Department of Veterinary, Shiraz university, Shiraz, Iran (e-mail: akhlaghi@shirazu.ac.ir). The immersed vaccine with Montanide IMS 1312 VG adjuvant increased the expression of immune system genes such as IgM, MX, and CD8 within 30 days of vaccination period. The expression of IgM, Mx (P<0.05) and CD8 (P>0.05) genes was higher for the vaccine containing 10g of Montanide than that of 50g of Montanide. In fish vaccinated with the adjuvant, the relative percent survival was notably higher than of fish vaccinated without the adjuvant and the control group. Results showed that the ethylene amine-inactivated IPNV vaccine by the immersion method with Montanide IMS 1312 VG significantly has a strong protective immunity against IPNV in rainbow trout.