In vivo biological activity of recombinant goldfish gonadotropins produced by baculovirus in silkworm larvae

Recombinant gonadotropins (GTHs), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) of goldfish Carassius auratus were produced by baculovirus in silkworm Bombyx mori larvae. The induction of gonadal maturation is an important aspect of fish aquaculture and the possible biotechnological production of recombinant hormones was examined. cDNAs encoding goldfish GTH subunits (FSHβ, LHβ and common α) were introduced into the baculovirus, which was infected into silkworm larvae after propagation of the recombinant virus in B. mori culture cells. Hemolymph of silkworm larvae containing recombinant FSH (rFSH) or LH (rLH) was collected, and biological activities of recombinant hormones were analyzed in vivo using goldfish and the bitterling Rhodeus ocellatus ocellatus. Injection of hemolymph containing rFSH or rLH induced milt production in male goldfish. Plasma testosterone levels were increased by rLH in male goldfish and plasma estradiol levels were increased by rFSH in female goldfish. rLH induced ovulation in female bitterling, but rFSH showed weak potency. In conclusion, biologically active goldfish recombinant GTHs were able to be produced in a baculovirus-silkworm larvae system and it is suggested that recombinant fish GTHs produced by this system could be applied for the induction of gonadal development in aquaculture fishes.