Use of silkworm larvae to study pathogenic bacterial toxins.
Injection of stationary phase culture-supernatants of Staphylococcus aureus and Pseudomonas aeruginosa into the hemolymph of silkworm larvae caused their death, whereas a culture-supernatant of a non-pathogenic strain of Escherichia coli did not. A culture-supernatant of a mutant of agr, a global virulence regulator of S. aureus that is required for exotoxin production, was much less toxic to silkworm larvae. A culture-supernatant of a disruption mutant of the S. aureus beta-toxin gene did not kill larvae, whereas one of a deletion mutant of alpha-toxin, gamma-toxin, or aureolysin killed larvae, indicating that the beta-toxin gene is required for staphylococcal supernatant-mediated killing of silkworm larvae. The 50% lethal doses (LD50) of staphylococcal alpha-toxin and beta-toxin, Pseudomonas exotoxin A and diphtheria toxin were 12 microg/g, 9 microg/g, 0.14 microg/g and 1.1 microg/g, respectively. As the purified toxins killed the larvae, silkworm larvae could be used as a model to study the actions of pathogenic bacterial toxins in animal bodies.
Hossain
Muktadir S
MS
Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 3-1, 7-chome, Hongo, Bunkyo-ku, Tokyo 113-0033. sekimizu@mol.f.u-tokyo.ac.jp
Hamamoto
Hiroshi
H
Matsumoto
Yasuhiko
Y
Razanajatovo
Iony M
IM
Larranaga
Jorge
J
Kaito
Chikara
C
Kasuga
Hiroshi
H
Sekimizu
Kazuhisa
K
D000818:Animals; D001427:Bacterial Toxins / Q000633:toxicity*; D012831:Bombyx / Q000187:drug effects*; D004195:Disease Models, Animal; D007814:Larva / Q000187:drug effects; D007928:Lethal Dose 50; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000472:pathogenicity; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000472:pathogenicity
D001427:Bacterial Toxins