EXPRESSION OF GRASS CARP GROWTH-HORMONE BY BACULOVIRUS IN SILKWORM LARVAE

A total of five recombinant Bombyx mori nuclear polyhedrosis viruses ( BMNPV) carrying the grass carp (Ctenopharyngodon idellus) growth hormo ne (GH) cDNA were constructed in this study. Two of them were able to express the hormone up to a level of 12 mu g/ml medium when cultured B . mori cells were infected for 4 days. Inoculation of the Viruses into silkworm (B. mori) host significantly increased the level of GH achie vable. The amount of hormone produced per larva was estimated to be ar ound I mg. The recombinant grass carp GH had immunological and biologi cal activities similar to the native hormone. The N-terminal sequence of the recombinant hormone was the same as the native one, indicating that the fish signal peptide was correctly processed by the insect cel ls. Silkworm powder prepared from larvae infected with the recombinant virus was used as food supplement for fish. Compared with the control , this dietary supplement was effective ih increasing the growth rate of juvenile carp. (C) 1998 Elsevier Science B.V. All rights reserved.