Molecular and phylogenetic characterization of Spodoptera litura granulovirus

Baculovirus, Spodoptera litura granulovirus (SlGV) was isolated from the infected S. litura larvae, and was characterized. The granule of SlGV was ovoidal shape with an approximate size of 240∼340 nm× 140∼180 nm. Each granule contained one single rod-shape virion with a mean size of 180∼200 nm×20∼40 nm. Restriction endonuclease fragment analysis estimated that the total genome size of SlGV is about 115 kb. Necleotide sequence analysis of the granulin gene showed that the gene encodes 249 amino acids with a predicted molecular mass of 29 kDa. When the phylogenic relationship was analyzed using the nucleotide sequence of the granulin gene, SlGV was most closely related to Trichoplusia ni granulovirus (TnGV) and Xestia c-nigrum granulovirus (XcGV) which belong to Type I granulovirus.     

Isolation of a strain of Bacillus thuringiensis ssp. kurstaki HD-1 encoding δ-endotoxin Cry1E

A strain of Bacillus thuringiensis, STB-1, toxic against Spodoptera exigua , was isolated. Bacillus thuringiensis STB-1 produced bipyramidal inclusions and reacted with the H antiserum of B. thuringiensis ssp. kurstaki . The plasmid and protein profiles of B. thuringiensis STB-1 were compared with those of its reference strains, ssp. kurstaki and ssp. kenyae . To verifiy the gene type of B. thuringiensis STB-1, PCR analysis was performedwith Spodoptera -specific cry gene primers. The result showed that B. thuringiensis STB-1, unlike its reference strains, had cry1Aa , cry1Ab , cry1Ac and cry1E , suggesting that B. thuringiensis STB-1 was a unique strain with respect to gene type. In addition, B. thuringiensis STB-1 showed a high level of toxicity against both S. exigua and Bombyx mori , whereas B. thuringiensis ssp. kurstaki HD-1 or ssp. kenyae showed a high level of toxicity against only Bombyx mori or S. exigua , respectively.