Analyses of Hemolymph Immunoparameters in Kuruma Shrimp Infected with Penaeid Rod-shaped DNA Virus.

Abstract

The present study was conducted to examine the changes provoked by penaeid acute viremia (PAV) in hemolymph immunoparameters of peptidoglycan (PG)-fed kuruma shrimp Penaeus japonicus. The shrimps were fed a commercial diet containing PG for 14 days prior to the challenge with PRDV, causative agent of PAV, by the water-borne method. A control group fed PG-free diet was also challenged. Hemolymph obtained from infected and control shrimps was analyzed for total hemocyte count, plasma protein concentration, plasma Mg concentration, phenoloxidase activities in the hemocyte lysate and cell protein concentration. The total hemocyte count declined over 5 days after challenge in both groups. The total hemocyte count values of the PG-fed group were higher than those of the control group at every sampling point, but no significant differences were observed. A significant increase in plasma Mg concentration was found toward 3rd day of post-challenge for the control group (p<0.05). The control group had significantly increased values in plasma protein concentration in 1st and 3rd days of post-challenge, but these changes were mitigated in PG-fed group. The survival rates after 10 days of the challenge were 70% and 35% for the PG-fed group and control group, respectively. These results indicate that PG can mitigate physiological changes during PRDV infection.