PRODUCTION OF POLYHEDRA OF THE AUTOGRAPHA-CALIFORNICA NUCLEAR POLYHEDROSIS-VIRUS USING THE SF21 AND TN5B1-4 CELL-LINES AND COMPARISON WITH HOST-DERIVED POLYHEDRA BY BIOASSAY

Both wild-type and recombinant baculoviruses are becoming more attract ive for the control of insect pests. Thus, there is an increased incen tive to address and resolve logistical problems associated with large- scale production of these viruses. In this study, we have compared the potential of two insect cell Lines, Tn5B1-4 and Sf21, for the product ion of polyhedra and compared the efficacy of both cell culture-derive d and host-derived viruses by bioassay, The efficacy of both wild-type AcMNPV and AcAaIT, a recombinant baculovirus expressing an insect-spe cific scorpion toxin, were compared. Yields of polyhedra from Tn5B1-4 were sixfold higher than those from the cell line Sf21. Morphological analysis of polyhedra derived from cell culture showed greater variabi lity in size relative to host-derived polyhedra. The maximum size of c ell culture-derived polyhedra was over 1.5 times larger than that of i nsect-derived polyhedra, The efficacy of AcMNPV and AcAaIT derived fro m cell culture, or from amplification in larvae of Trichoplusia ni or Heliothis virescens, was compared by bioassay in H. virescens. There w as a significant difference between the slopes for lethal time data fo r host-derived and cell culture-derived wild-type virus. Mortality occ urred at a faster rate following infection with host-derived virus. No significant difference was seen for the recombinant virus AcAaIT. Let hal doses of cell- and host-derived polyhedra were not significantly d ifferent. The reasons for and implications of this for pest control ar e discussed. The data suggest that polyhedra production in larvae may be preferable to production in cell culture for the wild-type virus, b ut that this does not hold for recombinant viruses with enhanced speed of kill. (C) 1995 Academic Press, Inc.