Long-time Immune Response of Rainbow Trout (Oncorhynchus mykiss) to a Local Yersiniosis Vaccine (Antiyersin) Under Farm Conditions

Document Type : Original Articles

Authors

1 Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.

2 Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran. & Department of Fish Health Group, Center of Sustainable Aquatic Ecosystem, Harry Butler Institute, Murdoch University, Murdoch, Australia.

3 Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.

10.32598/ijvm.20.3.1005714

Abstract

Background: Yersiniosis caused by Yersinia ruckeri is an economically important disease in aquaculture, especially rainbow trout farms. Developing an effective vaccination to combat this disease is an important strategy for improving fish production. 
Objectives: This study aimed to determine long-term immune response of rainbow trout to Antiyersin vaccine under field conditions.
Methods: Two vaccination routs, immersion (1:9 V/V) and intraperitoneal injection (0.2 ml/fish) were used. Antibody titer was recorded by enzyme-linked immunosorbent assay (ELISA) and agglutination plus immunocompetent cell population.
Results: No significant difference in heterophil value was observed between single immersion vaccination (SIV) and immersion vaccination plus booster (IVB) two months post-vaccination and between IBV and intraperitoneal vaccination (IPV) three and four months post-vaccination. Generally, the highest lymphocyte value was recorded in IPV, followed by IVB and SIV, respectively. Also, in general, there were no significant differences in monocyte value among the treatments during the study. IPV and IVB demonstrated significantly higher antibody titers than SIV, as measured by agglutination assay at all studied time points. The antibody titers by ELISA in all vaccinated groups were significantly higher than those in control fish. No significant difference was observed between IVB and IPV two months post-study, but both groups exhibited significantly higher levels than SIV. 
Conclusion: These data are useful for developing national policies to improve disease management in trout aquaculture. The results of the present study showed that the IVB route can be recommended for practical aquaculture because of its effective immune response and its ease of use.

Keywords

Iranian Journal of Veterinary Medicine
Volume 20, Issue 3
May and June 2026
Pages 487-496

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