Experimental infection of kuruma prawn (Penaeus japonicus) with Vibrio penaeicida

Abstract

To estimate the portal of entry of Vibrio penaeicida in kuruma prawn (Penaeus japonicus), immersion and oral infection experiments were conducted with pre-treated and intact prawns. In immersion challenge, V. penaeicida produced 30% mortality in the shell-removed group at both 10⁸ and 10⁷ CFU/ml doses while in the eye-cut group, mortalities were 44% and 13% at 10⁸ and 10⁷ CFU/ml, respectively. In the intact group, 10% mortality was observed at 10⁸ CFU/ml and no mortality at 10⁷ CFU/ml after two weeks. The pathogen produced high mortalities in the orally incubated group, the median lethal dose (LD₅₀) being 10³-10⁴ CFU/animal. In the groups given V. penaeicida-inoculated kuruma prawn meat and V. penaeicida-contaminated commercial pellets, mortalities within 60 days were 10% and 20%, respectively. These results suggest that the main portal of entry of V. penaeicida is the gastro-intestinal tract although the cuticle (epidermis) or wounds can also be portals.