Innate immune responses of whiteleg shrimp (Penaeus vannamei) experimentally infected with acute hepatopancreas necrosis disease-causing Vibbrio parahaemolyticus

Abstract

The innate immune responses of the whiteleg shrimps (Penaeus vannamei) experimentally challenged with V. parahaemolyticus by immersion were investigated for a period of 120 h. The results showed that the lethal dose 50% (LD50) of shrimps (2 - 3 g) challenged with V. parahaemolyticus was 4.7 × 106 CFU/mL. No significant differences in immune parameters were observed between the control and challenged group right after challenge (0 hpi). However, the total haemocyte count, phenoloxidase activity and respiratory burst activity were decreased in the challenged shrimps after 24 and 48 hpi and significantly different from those in the control shrimps (P < 0,05). At 72, 96 and 120 hpi, there were no significant differences in the total haemocyte count, phenoloxidase activity and respiratory burst activity between two treatments. The observations of this study showed that the innate immune responses of the whiteleg shrimp were decreased due to the infection by V. parahaemolyticus.