Factors influencing the uptake of ¹⁴C‐labelled Vibrio anguillarum vaccine in direct immersion experiments with rainbow trout, Salmo gairdneri Richardson

The factors influencing the uptake of a 14 C‐labelled Vibrio anguillarum vaccine in direct immersion experiments with rainbow trout, Salmo gairdneri were studied. Immersion times of longer than 10 s did not increase vaccine uptake. A pre‐immersion dip in a hyperosmotic solution had no effect on uptake, even at lower vaccine bath concentrations. It appeared that the head end of the fish was implicated in uptake. Vaccine uptake decreased at lower temperatures, whereas the use of an adjuvanted vaccine and a soluble vaccine preparation led to increased uptake. Larger fish took up more vaccine.