Potential of Cry4-like1 and Cry4-like2 proteins produced by Bacillus wiedmannii biovar thuringiensis for the control of mosquito vectors

GIL MF; BATTAGLIA ME; BERÓN CM

College Park, MD

Congreso; 2023 International Congress on Invertebrate Pathology and Microbial Control & 55th Annual Meeting of the Society for Invertebrate Pathology; 2023

Society for Invertebrate Pathology

Vector-borne diseases are transmitted by the bite of infected arthropod species, among them mosquitoes are capable of vectoring several important etiological agents in public and veterinary health, such as bacteria, viruses and parasites. In the Americas, Aedes aegypti is the main vector of dengue, Zika, chikungunya, yellow fever, and lymphatic filariasis; while in Europe, Asia and Oceania, Ae. albopictus also presents vectorial competence for at least 26 arboviruses as well as some filarial nematode worms. On the other hand, Culex quinquefasciatus is a competent vector of filarial, West Nile Virus, St. Louis encephalitis and Venezuelan equine encephalitis. Biological control of these mosquito populations is carried out mainly through the application of formulations based on Bacillus thuringiensis subesp. israelensis. In this work, we analyze the insecticidal activity of a native strain against C. quinquefasciatus, Ae. aegypti and Ae. albopictus larvae. Bacillus wiedmannii biovar thuringiensis strain FCC41 (formerly known as Bacillus thuringiensis strain FCC41) was isolated in Argentina from soil samples. Whole genome sequencing revealed that the strain harbors 6 cry protein genes including cry24Ca, two cry4-like, two cry52-like, and a cry41-like parasporin gene. The phylogenetic analysis of the whole-genome sequence places this strain into the Bacillus wiedmannii cluster but due to the phenotypical characteristics, it was renamed as B. wiedmannii biovar thuringiensis strain FCC41, being the first reported B. wiedmannii specialized mosquitocidal pathogen strain that has Cry proteins with insecticidal activity. The cry4-like genes (cry4-like1 and cry4-like2) were cloned in pSTAB vector and expressed in the acrystalliferous strain 4Q7; cells with parasporal inclusions were observed at sporulated phase in optic an electronic microscope. Proteins Cry4-like exhibited high toxicity against C. quinquefasciatus larvae, confirming that these toxins present mosquitocidal activity and could be used in an integrated vector management approach.