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Appl. Environ. Microbiol., 02 1997, 532-536, Vol 63, No. 2
CG Yu, MA Mullins, GW Warren, MG Koziel and JJ Estruch
The Vip3A protein is a member of a newly discovered class of vegetative
insecticidal proteins with activity against a broad spectrum of
lepidopteran insects. Histopathological observations indicate that Vip3A
ingestion by susceptible insects such as the black cutworm (Agrotis
ipsilon) and fall armyworm (Spodoptera frugiperda) causes gut paralysis at
concentrations as low as 4 ng/cm2 of diet and complete lysis of gut
epithelium cells resulting in larval death at concentrations above 40
ng/cm2. The European corn borer (Ostrinia nubilalis), a nonsusceptible
insect, does not develop any pathology upon ingesting Vip3A. While
proteolytic processing of the Vip3A protein by midgut fluids obtained from
susceptible and nonsusceptible insects is comparable, in vivo
immunolocalization studies show that Vip3a binding is restricted to gut
cells of susceptible insects. Therefore, the insect host range for Vip3A
seems to be determined by its ability to bind gut cells. These results
indicate that midgut epithelium cells of susceptible insects are the
primary target for the Vip3A insecticidal protein and that their subsequent
lysis is the primary mechanism of lethality. Disruption of gut cells
appears to be the strategy adopted by the most effective insecticidal
proteins.
Copyright © 1997, American Society for Microbiology
The Bacillus thuringiensis vegetative insecticidal protein Vip3A lyses midgut epithelium cells of susceptible insects
Seeds-Insect Control, CIBA Agricultural Biotechnology, Research Triangle Park, North Carolina 27709, USA.
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