Functional studies of per os infectivity factor 3 of Helicoverpa armigera nucleopolyhedrovirus.
PIF3 is one of the six conserved per os infectivity factors (PIFs) of baculoviruses. In this study, PIF3 of Helicoverpa armigera nucleopolyhedrovirus (HearNPV) was analysed by infectivity bioassays using a series of recombinant viruses harbouring various PIF3 truncation/substitution mutants. The results demonstrated that the N-terminal region (L26-Y45) and C-terminal region (T160-Q199) are essential for HearNPV oral infectivity. In the C-terminal T160-Q199 region, there are three conserved cysteines (C162, C164 and C185). Our results showed that substitutions of C162 or C164, predicted to be involved in disulfide-bond formation, led to a severe decrease in HearNPV per os infectivity. Mutation of C185, predicted not to be involved in disulfide-bond formation, did not affect the per os infectivity. The data suggest that disulfide bonds are important for PIF3 conformation and function. Immunofluorescence assays showed that none of the mutations affected the subcellular localization of PIF3 to the nuclear ring zone region of infected cells. Western blot results showed that all mutants except C162G and C185G failed to incorporate PIF3 into occlusion-derived viruses, which resulted in impaired oral infectivity of the latter. The data provide insights for future study of PIF3 function.
State Key Laboratory of Virology and Joint Laboratory of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.|Division of Clinical Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
Jingjiao
J
Song
State Key Laboratory of Virology and Joint Laboratory of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Manli
M
Wang
State Key Laboratory of Virology and Joint Laboratory of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Huachao
H
Huang
State Key Laboratory of Virology and Joint Laboratory of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Xin
X
Luo
State Key Laboratory of Virology and Joint Laboratory of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Fei
F
Deng
State Key Laboratory of Virology and Joint Laboratory of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Hualin
H
Wang
State Key Laboratory of Virology and Joint Laboratory of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Zhihong
Z
Hu
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D007915:Lepidoptera / Q000821:virology; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D017924:Nucleopolyhedroviruses / Q000235:genetics / Q000472:pathogenicity*; D017386:Sequence Homology, Amino Acid; D016019:Survival Analysis; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
D050505:Mutant Proteins; D014764:Viral Proteins; D037521:Virulence Factors