Comparative evaluation of administration methods for a vaccine protecting rainbow trout against Yersinia ruckeri O1 biotype 2 infections

Jiwan Kumar Chettri, Sidhartha Deshmukh, Lars Holten-Andersen, Rzgar M Jafaar, Inger Dalsgaard, Kurt Buchmann

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39 Citationer (Scopus)

Abstract

Numerous outbreaks of enteric red mouth disease (ERM) caused by Yersinia ruckeri O1 biotype 2 in rainbow trout farms are currently being recorded despite established vaccination procedures against this disease. This could indicate that the currently used application of single immersion vaccination (using a commercial vaccine AquaVac® RELERA™) does not provide full protection. We elucidated by a controlled duplicated experiment if different vaccine administration methods can improve level and extent of protection. Rainbow trout, Oncorhynchus mykiss were vaccinated by: (1) a single immersion in bacterin diluted 1:10 for 30 s (only primary vaccination); (2) two times 30 s immersion (primary immersion vaccination followed by booster immersion vaccination 1 month later); (3) a single i.p. injection (only primary vaccination); (4) immersion vaccination followed by injection booster 1 month later; (5) a single 1 h bath in bacterin diluted 1:2000; and (6) immersion (30 s, 1:10) plus booster (1 h in diluted 1:2000 vaccine) 5 months later). Injection challenge experiments were performed 3, 5 and 7 months post primary vaccination with 8.5 × 106 CFU/fish, 10.6 × 106 CFU/fish and 1 × 108 CFU/fish, respectively. In the first challenge trial, control fish exhibited a mortality of 76%, one time immersion vaccination had a mortality of 37%, two times immersion vaccinated fish had a 4% mortality, the one-time injection vaccinated group showed a mortality of 2% and the immersion plus injection boostered fish showed no mortality at all. When rainbow trout were challenged 5 months post primary vaccination, 26% mortality occurred in control fish, 21% in one time immersion group, 12% in two times immersion group, 5% in the one-time injection vaccinated group whereas immersion plus injection boostered fish again showed no mortality at all. When challenged 7 months post vaccination, one-time immersion vaccinated were not protected at all compared to the control group whereas injection vaccinated fish showed lower mortality (17%) compared to booster immersed fish (32% mortality) which was still better than un-vaccinated controls (44% mortality). It was noteworthy that a diluted bacterin (1:2000 for 1 h after 5 months post primary vaccination) booster showed the same effect as a booster with 1:10 bacterin dilution for 30 s applied 1 month after primary vaccination. Antibody levels showing significant elevations 28 days post challenge in vaccinated fish point to this immune parameter as a protective element. The superior and extended protection offered by booster vaccination or simply injection is noteworthy and may be applied in future vaccination strategies at farm level.
OriginalsprogEngelsk
TidsskriftVeterinary Immunology and Immunopathology
Vol/bind154
Udgave nummer1-2
Sider (fra-til)42-47
Antal sider6
ISSN0165-2427
DOI
StatusUdgivet - 2013

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