title: Virulence of an exotoxin A-deficient strain of Pseudomonas aeruginosa toward the silkworm, Bombyx mori.
abstract: We studied the contribution of exotoxin A to the virulence of Pseudomonas aeruginosa against the silkworm, Bombyx mori. First, an exotoxin A-deficient mutant strain (PAO1toxA) was created, and its virulence compared with that of the parental PAO1 strain. In a short-term mortality assay, the mutant harboring pBBR1MCS2 did not kill B. mori until 120 h after inoculation and complementation of the corresponding gene in trans restored the strain's virulence. Next, to ascertain whether or not it lost all virulence, PAO1toxA (pBBR1MCS2, pGFP) was used in a long-term mortality assay. B. mori inoculated with the mutant strain did not die until early in the 5th instar (240 h after inoculation). However, 50% of the inoculated B. mori died late in the 5th instar or in the early pupal stage (408 h after inoculation). All had died by the pupal stage (600 h after inoculation). The mutant strain was isolated from dead larvae and cocoons. The bacterial population of PAO1toxA in hemolymph reached 4.77 × 10(7) cfu/ml. These results indicated that exotoxin A acts as a virulence factor in B. mori and that other virulence factor(s) are involved during the late stages of infection.
authors.affiliation: Laboratory of Insect Pathology and Microbial Control, Institute of Biological Control, Graduate School, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Yuuka
authors.initials: Y
authors.lastname: Chieda
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Iiyama
authors.forename: Jae Man
authors.initials: JM
authors.lastname: Lee
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kusakabe
authors.forename: Chisa
authors.initials: C
authors.lastname: Yasunaga-Aoki
authors.forename: Susumu
authors.initials: S
authors.lastname: Shimizu
mesh_terms: D036002:ADP Ribose Transferases / Q000172:deficiency* / Q000378:metabolism*; D000818:Animals; D058491:Bacterial Load; D001427:Bacterial Toxins / Q000378:metabolism*; D012831:Bombyx / Q000382:microbiology* / Q000502:physiology; D005098:Exotoxins / Q000172:deficiency* / Q000378:metabolism*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D006458:Hemolymph / Q000382:microbiology; D007814:Larva / Q000382:microbiology / Q000502:physiology; D011550:Pseudomonas aeruginosa / Q000254:growth & development / Q000472:pathogenicity*; D016019:Survival Analysis; D014774:Virulence; D037521:Virulence Factors / Q000172:deficiency* / Q000378:metabolism*; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D001427:Bacterial Toxins; D005098:Exotoxins; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A