Deletion of a Helicoverpa armigera nucleopolyhedrovirus gene encoding a virion structural protein (ORF107) increases the budded virion titre and reduces in vivo infectivity.
The open reading frame Ha107 of Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearNPV) encodes a putative protein of 51 kDa with homologues in a few group II NPVs and a granulovirus. Ha107 was transcribed as polyadenylated transcripts in infected HzAM1 insect cells. The transcripts were initiated at two distinct locations, one upstream of Ha106 (superoxide dismutase gene, sod) and the second upstream of Ha107. By Western blot analysis, two forms of the HA107 protein were detected in infected cells, a major polypeptide of 48 kDa and a minor one of 51 kDa. Western blot and immunoelectron microscopy analyses further showed that the HA107 protein was associated with the nucleocapsids of both budded virions (BVs) and occlusion-derived virions. A Ha107 knockout virus expressing enhanced green fluorescent protein and polyhedrin was constructed using bacmid technology. A one-step virus growth curve indicated that the BV titre of the knockout virus was significantly higher than that of the parental virus and a Ha107 repair virus. Bioassays indicated that the knockout virus was able to infect third-instar H. armigera larvae; however, its median lethal dose (LD50) was significantly higher than those of the parental virus and Ha107 repair virus. These data indicate that Ha107 encodes a non-essential structural protein of HearNPV virions and that deletion of this gene increases the BV titre and LD50 of the occluded virus.
Pan
Xiaoyu
X
Graduate School of the Chinese Academy of Sciences, Beijing 100039, PR China.|State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Long
Gang
G
Laboratory of Virology, Wageningen University, 6709 PD Wageningen, The Netherlands.|State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Wang
RanRan
R
Graduate School of the Chinese Academy of Sciences, Beijing 100039, PR China.|State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Hou
Songwang
S
State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Wang
Huiyuan
H
Graduate School of the Chinese Academy of Sciences, Beijing 100039, PR China.|State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Zheng
Yueting
Y
State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Sun
Xiulian
X
State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Westenberg
Marcel
M
Laboratory of Virology, Wageningen University, 6709 PD Wageningen, The Netherlands.
Deng
Fei
F
State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Wang
Hualin
H
State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Vlak
Just M
JM
Laboratory of Virology, Wageningen University, 6709 PD Wageningen, The Netherlands.
Hu
Zhihong
Z
State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D017353:Gene Deletion; D005814:Genes, Viral / Q000235:genetics; D007814:Larva / Q000821:virology; D007915:Lepidoptera / Q000821:virology; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D008970:Molecular Weight; D019251:Nucleocapsid / Q000737:chemistry; D017924:Nucleopolyhedroviruses / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity*; D016415:Sequence Alignment; D015678:Viral Structural Proteins / Q000737:chemistry / Q000502:physiology*; D014771:Virion / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity*; D014774:Virulence
D015678:Viral Structural Proteins