Open reading frame Bm21 of Bombyx mori nucleopolyhedrovirus is not essential for virus replication in vitro, but its deletion extends the median survival time of infected larvae.
In this report, the open reading frame 21 (Bm21) of Bombyx mori nucleopolyhedrovirus (BmNPV), one of the unique genes of group I NPVs, was characterized. Bm21 is predicted to encode a protein of 55.8 kDa and was found to contain imperfectly conserved leucine-rich repeats. 3' Rapid amplification of cDNA ends (3'RACE) showed that the transcript of Bm21 was first detected from 6 h post-infection and that it also encompassed the complete Bm20. 5'RACE revealed three transcription initiation sites, one of which mapped to the baculovirus early transcription motifs CGTGC and CAGT. Transient-expression and superinfection assays indicated that BM21 localized in the nucleus of infected BmN cells. To study the function of BM21, a Bm21-null virus was constructed using bacmid technology. Viral one-step growth curve analyses showed that the Bm21-null virus had similar budded virus production kinetics to those of the parental virus. Bioassay analyses showed that the median lethal concentration (LC(50)) of the Bm21-null virus was similar to that of the control virus; however, the median survival time (ST(50)) of the knockout virus was significantly longer than the control virus. These results indicate that BM21 is not essential for virus replication in vitro, but that deletion of the gene delays the killing of the infected larvae.
Huang
Jinshan
J
Graduate School of the Chinese Academy of Sciences, Beijing 100039, PR China.|State Key Laboratory of Virology and Joint Lab of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Hao
Bifang
B
College of Animal Science and Technology, Northwest Agricultural and Forestry University, Yangling 712100, PR China.|State Key Laboratory of Virology and Joint Lab of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Deng
Fei
F
State Key Laboratory of Virology and Joint Lab of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Sun
Xiulian
X
State Key Laboratory of Virology and Joint Lab of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Wang
Hualin
H
State Key Laboratory of Virology and Joint Lab of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
Hu
Zhihong
Z
State Key Laboratory of Virology and Joint Lab of Invertebrate Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China.
D000595:Amino Acid Sequence; D000818:Animals; D012831:Bombyx / Q000821:virology*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D007814:Larva / Q000821:virology; D008969:Molecular Sequence Data; D009154:Mutation; D017924:Nucleopolyhedroviruses / Q000145:classification / Q000472:pathogenicity / Q000502:physiology*; D016366:Open Reading Frames / Q000235:genetics; D015996:Survival Rate; D024363:Transcription Initiation Site / Q000502:physiology; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism; D014774:Virulence; D014779:Virus Replication
D014764:Viral Proteins