Submitted to: European Association of Fish Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: 5/19/2005
Publication Date: 9/11/2005
Citation: Klesius, P.H., Evans, J.J., Shoemaker, C.A., Pasnik, D.J. 2005. Streptococcus iniae extracellular-product vaccine: evaluation in vaccination and challenge model using calcein marked tilapia, oreochromis niloticus. European Association of Fish Pathologists. 12th EAFP International Conference on Diseases of Fish and Shellfish 11th – 16th September 2005 Copenhagen, Denmark. pg 100.
Technical Abstract: A Streptococcus iniae extracellular-product vaccine was evaluated in vaccination and challenge model using fluorescent chromophore calcein to non-invasively mark tilapia. The calcein marked, sham-vaccinated (CMSV) tilapia were cohabited with non-marked S. iniae vaccinated (NMV) tilapia in single aquarium. The cohabitants were challenged with virulent S. iniae after 30 days and the cumulative mortality was measured over a 15 day period. Dead fish (CMSV and NMV) were examined for calcein fluorescent staining of their calcified skeletal structures of the head and fins using a portable handheld UV lamp set at 365 nm wavelength. The efficacy results showed that the cumulative mortality of CMSV was significantly greater than those of NMV. No significant differences in cumulative mortality were noted between the CMSV and NMV fish or individual aquaria. The calcein concentration and immersion exposure time to produce detectable fluorescent markings was 500 mgL-1 for 4 hours. Calcein marking did not influence the vaccination and challenge results. In summary, the vaccination and challenge cohabitation model offers statistical advantages of using individual fish as the experimental unit kept in the same experimental tank. Furthermore, calcein is a valuable tool for non-invasive, non-lethal, non-stressful, mass marking of fish to establish the efficacies of fish vaccines in a cohabitation model.