Expression and applications of recombinant crustacean hyperglycemic hormone from eyestalks of white shrimp (Litopenaeus vannamei) against bacterial infection

Crustacean hyperglycemic hormone (CHH) has many functions to regulate carbohydrate metabolism, ecdysis and reproduction including ion transport in crustaceans. The cDNA encoding CHH peptides containing 369 bp open reading frame encoding 122 amino acids was cloned from eyestalk of white shrimp (Litopenaeus vannamei) and was produced by a bacterial expression system. The biological activity of recombinant L. vannamei crustacean hyperglycemic hormone (rLV-CHH) was tested. The hemolymph glucose level of shrimp increased two-fold at 1h after the rLV-CHH injection and then returned to normal after 3h. In addition to the effect of rLV-CHH administration (25 μg/shrimp) on immunological responses of white shrimp against pathogenic bacteria, Vibrio harveyi was studied. Results showed that the blood parameters of shrimp injected with rLV-CHH; the THC, PO activity, serum protein level and clearance ability to V. harveyi, were also higher than those of Neg-protein and PBS-injected shrimp. The survival of shrimp injected with rLV-CHH was significantly higher (66.0%) than shrimp that injected with Neg-protein (33.3%) and PBS (28.9%) after 14 days. It is possible that the administration of rLV-CHH in L. vannamei exhibited a higher immune response related to resistance against V. harveyi infection.