The effects of anti-Streptococcosis vaccine by bath method on the levels of cortisol and lactate dehydrogenase (LDH) and the expression of immune-related genes in Asian seabass (Lates calcarifer)

Abstract

Introduction: The aim of this study was to investigate the effects of immersion vaccine
(Garovak) against streptococcosis and lactococcosis in different weights on the growth,
feeding and survival rates of Asian seabass (Lates calcarifer).
Materials and Methods: Fish with an average weight of 5 gr were studied in 300-liter round
polyethylene tanks in 2 treatments and 3 repetitions, including the vaccinated treatments at a
weight of 5 grams (ST) and the control group without vaccination. Feeding was done twice a
day until satiety for 8 weeks.
Results: The results related to the bacterial challenge showed that the death rate in the
vaccinated treatment was significantly lower than the control group (P<0.05). According to
the general results of this study, the administration of Garovak immersion vaccine has been
able to improve the survival rate after bacterial challenge in Asian seabass weighing 5 grams.
In the statistical analysis of the results of the present study using SPSS software tests, the
expression of genes related to immunity using Real-time (RT)-PCR, which has a significant
difference in the gene expression of treatment samples was observed with control samples.
Also, the average levels of cortisol and lactate dehydrogenase (LDH) enzymes in the tested
treatments were 107 ng/g and 1279 u/kg, which had no significant difference with the control
group. Also, in the statistical analysis, no significant difference was observed between gene
expression data (Lysozymes, TNF, MHCI, and IGF-I). But in 1L-IB and MHCII, was seen
significant difference between treatments and controls. However, the average gene expression
(Lysozymes, 1L-IB, TNF, MHCI, MHCII and IGF-I) in the vaccinated treatment was higher
than the average values of the control treatment.
Conclusion: The results obtained in the current study showed that the vaccine had a better
effect on the health of Asian sea bass weighing 5 gr. According to the general results of this
study, the vaccine has been able to have a positive effect on fish health indicators, but on
cortisol and lactate dehydrogenase enzymes (LDH) and also gene expression (Lysozymes,
TNF, MHCI, and IGF-I) had no significant effect. The results obtained in the current study
showed that the vaccine had a better effect on the health of Asian sea bass weighing 5 grams.
But it had no significant effect on the levels of cortisol and lactate dehydrogenase (LDH).
While it had a significant effect on MHC1 and interleukin 1B gene expression.