Vaccination of the grouper, epinephalus awoara, against vibriosis using the ultrasonic technique

Abstract

A novel ultrasonic technique was used to facilitate the vaccination of fish against Vibrio alginolyticus. To establish the safety parameters, we first tested the effects of ultrasound treatment on juvenile groupers, Epinephalus awoara. Results showed that, at an intensity of ≤ 400 mW/cm2, 10 min of ultrasound treatment were safe, whereas an ultrasound intensity of ≥ 600 mW/cm2 produced a certain degree of damage to the experimental groupers. The ultrasound frequency had little effect on the survival of the treated fish. Next we determined the protective effect of the ultrasound-facilitated vaccination. A low frequency ultrasound (35 kHz) with an intensity of 175 mW/cm2 was used for vaccinating fish against vibriosis. Different ultrasonic vaccination methods were examined; each contains a total of 2-min continuous or pulsed ultrasound combined with or without 2-min immersion in the presence of vibriosis vaccine. Of all the eight ultrasonic inoculating methods tested, 'pulsed ultrasound followed by immersion' and 'immersion, pulsed ultrasound and immersion again' provided the best protection from bacterial challenge. Compared to other traditional methods, the protective effect provided by ultrasonic vaccination is comparable to that by the intraperitoneal injection method, and the operation convenience is comparable to that by the immersion method. Thus, the ultrasound-facilitated vaccination provides an effective and practical approach for vaccinating fish on large scale. © 2002 Elsevier Science B.V. All rights reserved.