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Effects of Ergosan on the expression of cytokine genes in the liver of juvenile rainbow trout (Oncorhynchus mykiss) exposed to enteric red mouth vaccine

Gioacchini, Giorgia, Smith, Patrick, Carnevali, Oliana
Veterinary immunology and immunopathology 2008 v.123 no.3-4 pp. 215-222
Oncorhynchus mykiss, vaccination, cytokines, gene expression, juveniles, immunomodulators, liver, stress tolerance, immune response, blood plasma, alginates, algae and seaweeds, plant extracts, interleukins, tumor necrosis factor-alpha, heat shock proteins, immunity, vaccines
The effects of administration of the immunomodulator Ergosan, an algal extract containing alginic acid, in juvenile rainbow trout (Oncorhynchus mykiss) exposed to AquaVac[trade mark sign] vaccination, were tested. Juveniles treated with Ergosan, 95 days after the beginning of first solid feeding and control fish fed solely on commercial diet, were vaccinated by immersion in AquaVac[trade mark sign] solution. The time-course of the effects of vaccination on liver immunorelated gene modulation and on the tolerance to stress manipulation connected with the vaccination was investigated. Liver and plasma sampling was performed at the following times: T =pre-vaccination, T0=5min, T1=2h, T2=8h, T3=24h, T4=48h and T5=72h post-vaccination. Interleukin-1β (IL-1β), interleukin-8 (IL-8), tumor necrosis factor α 2 (TNF alpha 2) and heat shock protein 70 (Hsp70) gene expression in trout liver was monitored by real-time PCR using Acidic Ribosomal Phosphoprotein P0 (ARP) as internal standard. The evaluation of the plasma cortisol levels was performed by EIA. In AquaVac[trade mark sign]-vaccinated fish, both the gene expression of Hsp70 and the plasma cortisol levels during the time-course were significantly (P <0.05) lower in Ergosan-treated fish with respect to control, indicating the positive role of Ergosan on handling stress tolerance. This study also demonstrated the stimulatory properties of Ergosan on cytokine genes expression involved in innate immune response: liver IL-1β, IL-8 and TNF alpha 2 gene expression was significantly (P <0.05) higher in trout fed on Ergosan compared to control, indicating a positive role of this feed additive in improving the immune responsiveness to AquaVac[trade mark sign] vaccine.