Arch Virol (1998) 143: 743–767
Identiﬁcation and characterization of the Spodoptera littoralis
nucleopolyhedrovirus type B lef-3 gene
J.-L. C. Wolff
, L. M. Herzog, L. Sun, and D. B. Levin
Department of Biology, University of Victoria, Victoria, Canada
Accepted November 11, 1997
Summary. We have identiﬁed a gene from the Spodoptera littoralis nucleopoly-
hedrovirus type B (SpliNPV-B) with several characteristics that suggest that it is
homologous to the lef-3 genes of the Autographa californica and Orgyia pseu-
dotsugata NPVs (AcMNPV and OpMNPV, respectively). The SpliNPV-B lef-3
gene was mapped between 43.6 and 45.5 map units of the SpliNPV-B genome.
Northern blot analysis showed that SpliNPV-B lef-3 was expressed as a 1.6 Kb
transcript at 5 h post infection (p.i.), reached high levels at 24 h p.i., and remained
highly expressed at 56 h p.i. Transcription of SpliNPV-B lef-3 initiated at two
distinct sites downstream from a TATA-box motif and terminated 25 nucleotides
downstream from the translation stop site of the putative LEF-3 polypeptide. The
-boundaries of lef-3 promoter elements were investigated by transient expres-
sion assays, which revealed that the major components of the lef-3 promoter are
within a 183 base pair region upstream of the distal transcription initiation site.
Transfection of SpliNPV-B infected Sf9 cells with anti-sense oligonucleotides
designed to inhibit LEF-3 expression resulted in substantial reduction of viral
DNA replication, suggesting that the role of SpliNPV-B lef-3 may be similar to
that of AcMNPV and OpMNPV lef-3 genes, which are essential for viral DNA
Baculoviridae is a large family of double-stranded, circular DNA viruses that
infect invertebrates [5, 39]. The Spodoptera littoralis nucleopolyhedrovirus
(SpliNPV-B) infects the Egyptian cotton worm, Spodoptera littoralis, an insect
pest of economic importance in the Mediterranean region, Africa, and Asia .
SpliNPV-B variants have been isolated from diseased S. littoralis larvae collected
in Israel, Egypt, and Morocco, and also from diseased S. litura larvae collected
Present address: Instituto Butantan, Centro de Biotecnologia, Sao Paulo, Brazil.