Abstract: Using the nucleotide sequence of the VEF (viral enhancing factor) gene of Trichoplusia ni granulosis virus for reference, we designed a primer for PCR and amplified a specific fragment by PCR reaction. A recombinant plasmid pUC19-SF was constructed by cloning the PCR product which was treated with EcoRⅠ, BamHⅠ into pUC19. The PCR product was proven to be a fragment of the gene encoding the synergistic factor of Pseudaletia unipuncta granulosis virus (PuGV-Ps) by DNA sequencing. After labeling this fragment as a probe, the gene encoding of the synergistic factor was located in many restrictive fragments of PuGV-Ps genome by Southern blot hybridization.

Key words: Pseudaletia unipuncta granulosis virus, synergistic factor, genetic location, Southern blot hybridization