Cytolytic differences among lepidopteran cell lines exposed to toxins of Bacillus thuringiensis subsp. kurstaki (HD-263) and aizawai (HD-112): effect of aminosugars and N-glycosylation

Abstract

Comparison of lytic-dose response behavior of seven lepidopteran cell lines to the activated delta-endotoxin polypeptides of Bacillus thuringiensis subspecies kurstaki (HD-263) and aizawai (HD-112) indicated distinct differences among the lines. The lines derived from Spodoptera species S. exigua (URC-SE-1A) and S. littoralis (UIV-SL-575) were more susceptible to lysis by aizawai toxin (Bta) than kurstaki toxin (Btk) as were cells from the Lymantria dispar line (IPLB-LD652Y). However, the concentrations of Bta required for lysis of 50% of URC-SE-1A and IPLB-LD652Y cells (LC50) were 0.2 to 0.8 micrograms/ml compared to 5 to 9 micrograms/ml for UIV-SL-575 cells. In comparison, Btk LC50 concentrations for the three lines were similar (14 to 19 micrograms/ml). Cells from S. frugiperda (IPLB-SF-21AE) and Trichoplusia ni (TN368) were similar in their response to Bta (LC50 = 2.5 to 3.7 micrograms/ml) and Btk (LC50 = 1.0 to 2.8 micrograms/ml) whereas the lines derived from Heliothis spp. were the least susceptible to both toxins. The LC50 concentrations for Bta with the H. zea line (IPLB-HA-1075) and H. virescens line (BCIRL-HV-AM1) were > 50 micrograms/ml and for Btk were > 50 micrograms/ml and 42 to 50 micrograms/ml, respectively, yet for both lines Btk was the more cytolytic. Cytolysis of TN368 cells could be inhibited to varying extents by preincubation of the toxins with the aminosugars of galactose, mannose, and glucose and their N-acetyl derivatives. The unsubstituted hexoses were not inhibitory.(ABSTRACT TRUNCATED AT 250 WORDS)