In Experiment 1, shrimp were divided into three groups, and each group with two subgroups. There were 20 shrimp in triplicate in each subgroup. The three groups were treated by feeding rVP28-bs-, B. subtilis- and p85 buffer-coated food pellets, respectively, for 20 days. At the end of oral delivery, part of shrimp were anaesthetised by placing on ice and pierced to collect haemolymph using a wide-bore (19G) needle. The haemolymph was collected in a Petri-dish containing 5 ml ice-cold marine anticoagulant (0.45 M Nacl, 0.1 M glucose, 30 mM trisodium citrate, 26 mM citric acid, 10 mM EDTA; pH 4.6) over ice for the subsequent immune-related gene expression and phagocytosis assays. On the 7th day after 20-Day feeding, the remaining shrimp were challenged with WSSV or pBS buffer. Before the beginning of the experiments, in vivo titration of WSSV was conducted as previously described. In order to mimic the natural route of infection and the initial situation in a pond, shrimp were challenged via immersion. Dead shrimp were tested for the presence of WSSV bu PCR. Mortality was recorded for 25 days post-challenge.