Characterization of Spodoptera exigua multicapsid nucleopolyhedrovirus ORF17/18, a homologue of Xestia c-nigrum granulovirus ORF129.
Spodoptera exigua multicapsid nucleopolyhedrovirus (SeMNPV) contains a number of genes with a homologue found so far only in a distantly related baculovirus. One of these, SeMNPV ORF17/18 (Se17/18) shares 55% amino acid similarity to ORF129 of Xestia c-nigrum granulovirus (XcGV). Se17/18 was transcribed in cultured S. exigua 301 cells, as a polyadenylated transcript of 1.1 kb. 5'-RACE analysis demonstrated that Se17/18 transcripts started at 134, 131 and 126 nt upstream of the putative translational start codon. These sites overlap with a baculovirus consensus early promoter motif. Se17/18 transcripts were detected by Northern blot analysis and RT-PCR with increasing abundance from 8 h to 24 h post infection (p.i.) and still present until 72 h p.i. A C-terminal GFP-fusion protein of Se17/18 was primarily localized in the cytoplasm of Se301 and Sf21 cells. A chicken polyclonal antiserum was raised that reacted specifically to Se17/18 protein produced in E. coli. However, no immunoreactive protein was detected in SeMNPV-infected Se301 cells and S. exigua larvae, neither in concentrated BV and ODV preparations. These observations and the inability to detect a C-terminal GFP-fusion protein of Se17/18 in Se301 cells using a GFP antibody suggest that Se17/18 protein is present, if at all, in spurious amounts. Based on the low homology of the Se17/18 protein to (methyl) transferases its possible involvement in transcription regulation is discussed.
IJkel
Wilfred F J
WFJ
Laboratory of Virology, Wageningen University, Binnenhaven 11, 6709 PD Wageningen, The Netherlands1.
Roode
Els C
EC
Laboratory of Virology, Wageningen University, Binnenhaven 11, 6709 PD Wageningen, The Netherlands1.
Goldbach
Rob W
RW
Laboratory of Virology, Wageningen University, Binnenhaven 11, 6709 PD Wageningen, The Netherlands1.
Vlak
Just M
JM
Laboratory of Virology, Wageningen University, Binnenhaven 11, 6709 PD Wageningen, The Netherlands1.
Zuidema
Douwe
D
Laboratory of Virology, Wageningen University, Binnenhaven 11, 6709 PD Wageningen, The Netherlands1.
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern / Q000379:methods; D036022:Capsid Proteins / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D002460:Cell Line; D002874:Chromosome Mapping; D004279:DNA, Viral; D005814:Genes, Viral; D025722:Granulovirus / Q000235:genetics; D008969:Molecular Sequence Data; D017924:Nucleopolyhedroviruses / Q000235:genetics*; D016366:Open Reading Frames; D012333:RNA, Messenger / Q000032:analysis; D012367:RNA, Viral / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D018411:Spodoptera / Q000821:virology*; D014158:Transcription, Genetic
D036022:Capsid Proteins; D004279:DNA, Viral; D012333:RNA, Messenger; D012367:RNA, Viral