Abstract: Using fluorescent differential display (FDD) technique, the differential expression of genes related to BmNPV resistance in highly resistant strain NB, highly susceptible strain 306 and near isogenic line 306NNZZ of the silkworm, Bombyx mori L. was analyzed. Based on the differential display bands, a 702 bp fragment named C18₇₀₂ was cloned and confirmed by Northern blot hybridizations. The sequence was then electrically extended based on homology comparison with NCBI ESTs, and further confirmed by RT-PCR using specific primers. A novel gene was characterized and revealed to encode a putative BmS3A protein. The gene had 97.7% homology to Spodoptera frugiperda S3A, 94% homology to Heliothis virescens S3A and 75.3% homology to Drosophila melanogaster S3A, and was named B. mori s3a(Bms3a).   It had higher expression in the highly resistant strain and near isogenic line than in the highly susceptible silkworm strain, and it also had higher expression in BmNPV treated strains than untreated strains. The results suggested that Bms3a is involved in silkworm BmNPV resistance.

Key words: Bombyx mori, BmNPV, gene;s3a, resistance, fluorescent differential display