Journal of Microbiology

Functional Characterization of Autographa californica Multiple Nucleopolyhedrovirus ORF43 and Phenotypic Changes of ORF43-Knockout Mutant: Xue Ying Tao , Jae Young Choi , Yong Wang , Jong Yul Roh , Joo Hyun Lee , Qin Liu , Jong Bin Park , Jae Su Kim , Woojin Kim , Yeon Ho Je; J. Microbiol. 2013;51(4):515-521. Published online August 30, 2013; DOI: https://doi.org/10.1007/s12275-013-3058-0

Abstract: ORF43 (ac43) of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is a highly conserved baculovirus gene of unknown function. To investigate the role of ac43 in the baculovirus lifecycle, we constructed an ac43-deleted mutant AcMNPV, Ac43KO. After transfection into Spodoptera frugiperda cells, Ac43KO produced polyhedra much larger in size than those of wild-type AcMNPV. Interestingly, some of the nucleocapsids were singly enveloped in the polyhedrin matrix while the nucleocapsids of AcMNPV are known to be multiply enveloped. Furthermore, Ac43KO led to a defect in the transcription and expression of polyhedrin, which resulted in reduced occlusion body production. However, Ac43KO did not affect production of budded virus as there was no remarkable difference in budded virus titer. These results suggest that ac43 plays an important role in the expression of polyhedrin, the morphogenesis of occlusion body, and the assembly of virions occluded in occlusion bodies.

Comparative Analysis of the Genomes of Bombyx mandarina and Bombyx mori Nucleopolyhedroviruses: Yi-Peng Xu , Zheng-Pei Ye , Chang-Ying Niu , Yan-Yuan Bao , Wen-Bing Wang , Wei-De Shen , Chuan-Xi Zhang; J. Microbiol. 2010;48(1):102-110. Published online March 11, 2010; DOI: https://doi.org/10.1007/s12275-009-0197-4

Abstract: The Bombyx mandarina nucleopolyhedrovirus (BomaNPV) S1 strain can infect the silkworm, Bombyx mori, but is significantly less virulent than B. mori nucleopolyhedrovirus (BmNPV) T3 strain. The complete nucleotide sequence of the S1 strain of BomaNPV was determined and compared with the BmNPV T3 strain. The circular, double stranded DNA genome of the S1 strain was 126,770 nucleotides long (GenBank accession no. FJ882854), with a G+C content of 40.23%. The genome contained 133 potential ORFs. Most of the putative proteins were more than 96% identical to homologs in the BmNPV T3 strain, except for bro-a, lef-12, bro-c, and bro-d. Compared with the BmNPV T3 strain, however, this genome did not encode the bro-b and bro-e genes. In addition, hr1 lacked two repeat units, while hr2L, hr2R, hr3, hr4L, hr4R, and hr5 were similar to the corresponding hrs in the T3 strain. The sequence strongly suggested that BomaNPV and BmNPV are variants with each other, and supported the idea that baculovirus strain heterogeneity may often be caused by variation in the hrs and bro genes.

Characterization of a Baculovirus Newly Isolated from the Tea Slug Moth, Iragoidae fasciata: Li-Rong Yang , Xiao Qiang , Bao-Qin Zhang , Mei-Jun Tang , Chuan-Xi Zhang; J. Microbiol. 2009;47(2):208-213. Published online May 2, 2009; DOI: https://doi.org/10.1007/s12275-008-0253-5

Abstract: The tea slug moth Iragoidae fasciata (Lepidoptera, Eucleidae) is one of the main insect pests that attack tea bushes. A new nucleopolyhedrovirus (NPV) called Iragoidae fasciata NPV (IrfaNPV) was recently isolated from diseased larvae. An 11,626 bp fragment of the viral genomic DNA containing the polyhedrin gene and other 12 genes was cloned and sequenced. Gene comparison and phylogenetic analysis showed that IrfaNPV is a member of the Group I NPVs. However, the genomic organization of IrfaNPV is highly distinct. In addition, electron microscopy analysis showed that IrfaNPV is a single nucleocapsid NPV (SNPV). An inoculation assay showed that IrfaNPV is semi-permissive in the Trichoplusia ni cell line Tn-5B1-4. Bioassays on lethal concentration (LC50) and lethal time (LT50) were conducted to test the susceptibility of I. fasciata larvae to the virus.

Propagation of Bombyx mori Nucleopolyhedrovirus in Nonpermissive Insect Cell Lines: Soo-Dong Woo , Jong Yul Roh , Jae Young Choi , Byung Rae Jin; J. Microbiol. 2007;45(2):133-138.; DOI: https://doi.org/2522 [pii]

Abstract: This study addresses the susceptibility of Spodoptera frugiperda (Sf9 and Sf21), Trichoplusia ni (Hi5), and S. exigua (Se301) cells to the Bombyx mori nucleopolyhedrovirus (BmNPV). Although these cells have classically been considered nonpermissive to BmNPV, the cytopathic effect, an increase in viral yield, and viral DNA synthesis by BmNPV were observed in Sf9, Sf21, and Hi5 cells, but not in Se301 cells. Very late gene expression by BmNPV in these cell lines was also detected via β-galactosidase expression under the control of the polyhedrin promoter. Sf9 cells were most susceptible to BmNPV in all respects, followed by Sf21 and Hi5 cells in decreasing order, while the Se301 cells evidenced no distinct viral replication. This particular difference in viral susceptibility in each of the cell lines can be utilized for our understanding of the mechanisms underlying the host specificity of NPVs.

Morphological, Phylogenetic and Biological Characteristics of Ectropis obliqua Single-Nucleocapsid Nucleopolyhedrovirus: Xiu-cui Ma , Hai-Jun Xu , Mei-Jun Tang , Qiang Xiao , Jian Hong , Chuan-Xi Zhang; J. Microbiol. 2006;44(1):77-82.; DOI: https://doi.org/2333 [pii]

Abstract: The tea looper caterpillar, Ectropis obliqua, is one of the major pests of tea bushes. E. obliqua single-nucleocapsid nucleopolyhedrovirus (EcobSNPV) has been used as a commercial pesticide for biocontrol of this insect. However only limited genetic analysis for this important virus has been done up to now. EcobSNPV was characterized in this study. Electron microscopy analysis of the occlusion body showed polyhedra of 0.7 to 1.7 μm in diameter containing a single nucleocapsid per envelope of the virion. A 15.5 kb genomic fragment containing EcoRI-L, EcoRI-N and HindIII-F fragments, was sequenced. Analysis of the sequence revealed that the fragment contained eleven potential open reading frames (ORFs): lef-1, egt, 38.7k, rr1, polyhedrin, orf1629, pk-1, hoar and homologues to Spodoptera exigua multicapsid NPV (SeMNPV) ORFs 15, 28, and 29. Gene arrangement and phylogeny analysis suggest that EcobSNPV is closely related to the previously described Group II NPV. Bioassays on lethal concentration (LC50 and LC90) and lethal time (LT50 and LT90) were conducted to test the susceptibility of E. obliqua larvae to the virus.

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