title: Expression of prtA from Photorhabdus luminescens in Bacillus thuringiensis enhances mortality in lepidopteran larvae by sub-cutaneous but not oral infection.
abstract: The prtA gene from Photorhabdus luminescens encodes the virulence factor Protease A. When P. luminescens is injected into the hemocoel of insects by entomopathogenic nematodes, PrtA is a key component of pathogenicity thought to help degrade the immune system. The prtA gene was cloned and introduced on a plasmid into Bacillus thuringiensis. PrtA was shown to be actively expressed in vitro by cleavage of a specific Dabcyl-Edans heptapeptide substrate. There was no difference in the speed or level of mortality when spores and δ-endotoxins crystals of the transformed strain were fed to larvae of Pieris brassicae, as compared to the wild-type strain. When vegetative cells were injected into the hemocoel of larvae of Galleriamellonella, however, there was a significant increase in the rate and level of mortality over the wild type. The yield of B. thuringiensis per cadaver was a hundred-fold greater in the PrtA-secreting strain. The increased pathogenicity from intrahemocoelic infection may have been due to a greater ability to overcome the immune response of G. mellonella while other factors such as resident gut bacteria may have negated this advantage after oral dosage.
authors.affiliation: Detection Department, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, UK. Electronic address: AHBishop@dstl.gov.uk.
authors.forename: A H
authors.initials: AH
authors.lastname: Bishop
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics*; D003001:Cloning, Molecular; D008666:Metalloendopeptidases / Q000235:genetics*; D009036:Moths; D030781:Organisms, Genetically Modified / Q000378:metabolism; D010572:Pest Control, Biological / Q000379:methods*; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D037521:Virulence Factors; D008666:Metalloendopeptidases; C079508:PrtA metalloprotease
keywords: Bacillus thuringiensis; Lepidoptera; Pathogenicity; Photorhabdus luminescens; prtA Expression