CONICET | Buscador de Institutos y Recursos Humanos

The mosquito Aedes aegypti, vector of the dengue and yellow fiber viruses, is found in nearly 100 countries worldwide. Current program strategies for the control of dengue and yellow fever have a small impact on the mosquito and are in critical need for a comprehensive, aggressive revamping. The World Health Organization makes special emphasis in the integrated epidemiological and entomological surveillance of the mosquitos populations. Bacillus thuringiensis comprises a group of aerobic, spore-forming bacteria that produce a toxic crystalline inclusion, delta-endotoxin, or Cry protein, lethal to various insect orders. Although insecticidal proteins from B. thuringiensis have been used as spray against A. aegypti for the past 20 years, a significant number of disease carrying mosquitos are not affected by the available Cry proteins. Therefore, it is necessary to search for proteins with wider and/or specific toxic spectrum. Additionally, it is important to provide alternatives for coping with the problem of insect resistance that has already appeared against some of the formulates. Recently, we have isolated a new mosquitocidal B. thuringiensis strain (FCC 41) native to Argentina. This isolate was partially charaterized as showing higher mosquitocidal effect than the strain B. thuringiensis israelensis (HD 567). Described in a previous work, the polypeptide pattern of purified parasporal bodies analyzed by SDS-PAGE, showed two major polypeptides of about Mr 70 - 80 kDa, and the cry gene sequence named cry24Ca was isolated. In the present work, a method was used based on PCR-RFLP and Denaturing Gradient Gel Electrophoresis (DGGE) profiling and sequencing of the highly variable cry gene to characterize gene contents from B. thuringiensis strains. By these methods we found three partial aminoacid sequences that showed identities of about 96 - 98% with the Cry24Ca protein previously described.