Gene targeting in the silkworm by use of a baculovirus

The Bombyx mori fibroin light (L)-chain gene was cloned and the green fluor escent protein (GFP) gene inserted into exon 7. The chimeric L-chain-GFP ge ne was used to replace the polyhedrin gene of Autographa californica nucleo polyhedrovirus (AcNPV). This recombinant virus was used to target the L-cha in-GFP gene to the L-chain region of the silkworm genome, female moths were infected with the recombinant virus and then mated with normal male moths. Genomic DNA from their progenies was screened for the desired targeting ev ent. This analysis showed that the chimeric gene had integrated into the L- chain gene on the genome by homologous recombination and was stably transmi tted through generations. The chimeric gene was expressed in the posterior silk gland, and the gene product was spun into the cocoon layer.