Journal of General Virology, Vol 80, 1045-1053, Copyright © 1999 by Society for General Microbiology
Specificity of polyhedrin in the generation of baculovirus occlusion bodies
Z Hu, T Luijckx, LC van Dinten, MM van Oers, JP Hajos, FJ Bianchi, JW van Lent, D Zuidema and JM Vlak
Department of Virology, Wageningen Agricultural University, The Netherlands.
The role of polyhedrin in the occlusion of virions was studied by
substituting two heterologous polyhedrin-coding sequences, one from a
multiple-nucleocapsid (M) nucleopolyhedrovirus (NPV) of Spodoptera exigua
(Se) and one from a single-nucleocapsid (S) NPV of Buzura suppressaria
(BusuNPV), into the genome of Autographa californica (Ac) MNPV. Both
heterologous polyhedrin genes were highly expressed and polyhedra were
produced in the nuclei of cells infected with the respective recombinant
AcMNPVs. Polyhedra produced by the recombinant with BusuNPV polyhedrin
showed normal occlusion of multiple- nucleocapsid virions and were equally
as infectious to S. exigua larvae as were wild-type AcMNPV polyhedra. This
indicates that virion occlusion is not specific with respect to whether the
virions or polyhedrin are from an SNPV or MNPV. Polyhedra produced by the
recombinant containing the SeMNPV polyhedrin had an altered morphology,
being pyramidal rather than polyhedral in shape, and many fewer virions
were occluded. These occlusion bodies were less infectious to S. exigua
larvae than were those of wild-type AcMNPV. These results indicate that
virion occlusion is a finely controlled process that is to some extent
specific to the polyhedrin involved and may also require other viral or
host factors for optimal morphogenesis.
