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A vaccination and challenge model using calcein marked fish.
Phillip H Klesius1, Joyce J Evans, Craig A Shoemaker
1U.S. Department of Agriculture, Agricultural Research Service, Aquatic Animal Health Research Laboratory, Auburn, AL 36831-0952, USA. pklesius@ars.usda.gov
Fish & Shellfish Immunology
|July 16, 2005
Summary
Calcein marking is an effective, non-lethal method for identifying vaccinated tilapia in a challenge model. This technique helps differentiate vaccinated fish from controls, proving valuable for disease research in aquaculture.
Area of Science:
- Aquatic Animal Health
- Fish Vaccination
- Biomarking Techniques
Background:
- Aquaculture relies on effective disease prevention strategies.
- Accurate methods are needed to assess vaccine efficacy in fish.
- Streptococcus iniae is a significant pathogen in tilapia.
Purpose of the Study:
- To evaluate a vaccination and challenge cohabitation model for Nile tilapia (Oreochromis niloticus).
- To assess the utility of calcein marking for differentiating vaccinated fish.
- To determine the optimal conditions for calcein marking in tilapia.
Main Methods:
- Nile tilapia were non-invasively marked with calcein.
- Fish were sham-vaccinated or vaccinated against Streptococcus iniae.
- Marked and unmarked fish were cohabited and subsequently challenged with S. iniae.
- Cumulative mortality was monitored over 15 days.
Main Results:
- Calcein marking did not affect S. iniae susceptibility or the cohabitation model's validity.
- Cumulative mortality was significantly lower in vaccinated tilapia compared to sham-vaccinated controls.
- Optimal calcein marking was achieved at 500 mg L(-1) for 4 hours, with marks visible on skeletal structures under UV light.
Conclusions:
- Calcein is a valuable tool for non-lethal, mass marking of fish in cohabitation models.
- The vaccination and challenge cohabitation model effectively demonstrated vaccine efficacy.
- This model offers statistical advantages by using individual fish as experimental units.