A NOVEL CLASS OF MOSQUITOCIDAL DELTA-ENDOTOXIN, CRY19B, ENCODED BY A BACILLUS-THURINGIENSIS SEROVAR HIGO GENE

Partially digested HincII fragments of DNA from a mosquitocidal strain of Bacillus thuringiensis serovar higo were cloned into pBluescript I I SK(+) and propagated in Escherichia coli. Recombinant cells were scr eened immunologically for the production of parasporal inclusion antig ens. One E. coli clone harboring a recombinant plasmid exhibited larvi cidal activity to Culex pipiens molestus, bur not to Anopheles stephen si. Hybridization experiments revealed that the gene of the toxin prot ein is located on a 110 kb plasmid of B. thuringiensis serovar higo. S equence analysis detected an open reading frame of 2046 nucleotides en coding a polypeptide of 682 amino acid residues with a predicted molec ular weight of 78,467. The gene encoded five block regions commonly co nserved in the insecticidal protein genes of B. thuringiensis. Amino a cid sequence of the 78 kDa protein shared 49% identity and 56% similar ity with that of the Cry19A protein from B. thuringiensis serovar jega thesan. A new class of delta-endotoxin protein, designated Cry19B, was established on the basis of this protein.