DNA fragments of Bombyx mori nuclear polyhedrosis virus containing the promoters active in prokaryotes.

Using a promoter probe plasmid in E. coli called pHE5, eight different HindIII and one SalI DNA fragments of Bombyx mori nuclear polyhedrosis virus, directing the expression of the tetracycline resistance gene, have been cloned and isolated. The tetracycline resistance levels of the strains containing the recombinant plasmids were measured. Among them, the highest level of the resistance to tetracycline was 30 micrograms/ml. Part of the nucleotide sequence of a DNA fragment was determined. A sequence similar to the E. coli promoter was found.