for the 3 replicate groups of prawns (102.00, 102.50 and
102.30 LD50 ml-1) was 102.27±0.25 LD50 ml-1. A reduced
LD50 compared to PID50 for prawns injected with the
WSSV-Viet strain was indicative of its lower relative
virulence predicted from bioassays in penaeid shrimp.