Mosquitocidal activity of the CryIC delta-endotoxin from Bacillus thuringiensis subsp. aizawai

• Published in: Applied and Environmental Microbiology Vol. 62; no. 2; pp. 680 - 684
• Main Authors: Smith, G.P. (MRC Centre, Cambridge, UK.), Merrick, J.D, Bone, E.J, Ellar, D.J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.02.1996
• Subjects: Aedes - drug effects; AEDES AEGYPTI; Animals; Anopheles - drug effects; ANOPHELES GAMBIAE; BACILLUS THURINGIENSIS; Bacillus thuringiensis - genetics; Bacillus thuringiensis aizawai; Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - pharmacology; Bacterial Toxins; Bacteriology; Biochemistry; Biological and medical sciences; Biological control; Cell Line; Control; Culex - drug effects; CULEX QUINQUEFASCIATUS; Culicidae; Culicidae - drug effects; CULTIVO DE CELULAS; CULTURE DE CELLULE; Diptera; ENDOTOXINAS; ENDOTOXINE; Endotoxins - genetics; Endotoxins - pharmacology; Escherichia coli - genetics; EXPRESION GENICA; EXPRESSION DES GENES; Fundamental and applied biological sciences. Psychology; Hemolysin Proteins; INSECTICIDAS; INSECTICIDE; INTESTIN; INTESTINOS; LARVAS; LARVE; Microbiology; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Pest Control, Biological; Pesticides; Phytopathology. Animal pests. Plant and forest protection; Proteins; PROTEOLISIS; PROTEOLYSE; Protozoa. Invertebrates; Recombinant Proteins - genetics; Recombinant Proteins - pharmacology; Spodoptera - drug effects; Spodoptera frugiperda; Spodoptera littoralis; TOXICIDAD; TOXICITE; TOXINAS; TOXINE; TRANSFERENCIA DE GENES; TRANSFERT DE GENE; Entomopathogen; Toxicity; Insecta; Biological control; Bacillaceae; Endotoxin; In vitro; Biological activity; Culex quinquefasciatus; Toxin; In vivo; Cell line; Bacillales; Anopheles gambiae; Larva; Arthropoda; Culicidae; Bacteria; Aedes aegypti; Recombinant protein; Parasporal body; Invertebrata; Diptera; Microbial insecticide
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/aem.62.2.680-684.1996

The cloned 135-kDa CryIC delta-endotoxin from Bacillus thuringiensis is a lepidopteran-active toxin, displaying high activity in vivo against Spodoptera littoralis and Spodoptera frugiperda larvae and in vitro against the S. frugiperda Sf9 cell line. Here, we report that the CryIC delta-endotoxin cloned from B. thuringiensis subsp. aizawai HD-229 and expressed in an acrystalliferous B. thuringiensis strain is also toxic to Aedes aegypti, Anopheles gambiae, and Culex quinquefasciatus mosquito larvae. Furthermore, when solubilized and proteolytically activated by insect gut extracts, CryIC is cytotoxic to cell lines derived from the first two of these dipteran insects. This activity was not observed for two other lepidopteran-active delta-endotoxins, CryIA(a) and CryIA(c). However, in contrast to the case with a lepidopteran and dipteran delta-endotoxin cloned from B. thuringiensis subsp. aizawai IC1 (M. Z. Haider, B. H. Knowles, and D. J. Ellar, Eur. J. Biochem. 156:531-540, 1986), no differences in the in vitro specificity or processing of CryIC were found when it was activated by lepidopteran or dipteran gut extract. The recombinant CryIC delta-endotoxin expressed in Escherichia coli was also toxic to A. aegypti larvae. By contrast, a second cryIC gene cloned from B. thuringiensis subsp. aizawai 7.29 (V. Sanchis, D. Lereclus, G. Menou, J. Chaufaux, S. Guo, and M. M. Lecadet, Mol. Microbiol. 3:229-238, 1989) was nontoxic. DNA sequencing showed that the two genes were identical. However, CryIC from B. thuringiensis subsp. aizawai 7.29 had been cloned with a truncated C terminus, and when it was compared with the full-length CryIC delta-endotoxin, it was found to be insoluble under alkaline reducing conditions. These results show that CryIC from B. thuringiensis subsp. aizawai is a dually active delta-endotoxin