Short-term hyperthermic treatment of Penaeus monodon increases expression of heat shock protein 70 (HSP70) and reduces replication of gill associated virus (GAV)

Disease is the result of interactions amongst pathogens, the environment and host organisms. To investigate the effect of stress on Penaeus monodon, juvenile shrimp were given short term exposure to hypoxic, hyperthermic and osmotic stress twice over a 1-week period and estimates of total haemocyte count (THC), heat shock protein (HSP) 70 expression and load of gill associated virus (GAV) were determined at different time points. While no significant differences were observed in survival and THC between stressed and control shrimp (P > 0.05), HSP 70 expression and GAV load changed significantly (P < 0.05). HSP 70 expression was higher in the hyperthermic treatment than in other treatments (P < 0.05). GAV load increased throughout the 21-day experiment for all groups and treatments except for hyperthermic stress. These findings suggest that a beneficial reduction in the rate of GAV replication, which cannot simply be attributed to holding the animals at a non-permissive temperature for GAV, results from short-term hyperthermic treatment.