Effects of mutations in the autographa californica multiple nucleopolyhedrovirus E25 on its trafficking to nucleus and budded virus production / 病毒学报

This study was performed to investigate the effects of different regions of the Autographa califor nica multiple nucleopolyhedrovirus envelope protein E25 on its trafficking into nucleus and nuclear localization in host cells and on virus replication. Fourteen recombinant bacmids, each containing an e25 mutant with substitution or insertion of egfp, in the absence or presence of the native e25, were constructed and used to transfect Sf9 cells. The E25-EGFP fusion proteins and native E25 expressed in the cells transfect ed with individual recombinant bacmid were traced by autofluorescence from EGFP or by immuno-fluorescence assays. Confocal microscopy revealed that the E25-EGFP fusion protein with the N-domain (2-45aa) of E25 substituted by EGFP only distributed in the cytoplasm in transfected cells; and the fusion protein with EGFP inserted at the laa/2aa site of E25 completely remained outside of the nucleus and resided along the nuclear membrane. The E25-EGFPs with 46-118aa of E25 substituted by EGFP or with EGFP inserted at the 118aa/119aa site were present outside, across from the nuclear membrane or in nuclear plasm in dot-like shapes. The fusion proteins with the C-domain substituted by EGFP or with EGFP inserted at the site of 45/46aa or at the C-terminal formed a condensed ring or spread throughout the nucleus, in a similar manner to the E25 distributed in the cells transfected by the e25-knockout repair bacmid. These results prove that the N-terminal domain is critical for nuclear transportation of E25 and possibly to its position on the cytoplasm membrane as well; and the sequence downstream of the N-terminal domain also affects trafficking and nuclear localization of the protein. In cells transfected with bacmids containing both the native e25 and individual e25-egfp mutants, the E25-EGFP fusion proteins co-localized with E25 individually, showing similar patterns of subcellular localization as E25 mutants in the absence of native E25 in most cases, suggesting that the E25 likely exists and functions as dimmers or polymers. Production of infectious BV was dramatically reduced and even completely eliminated in most cases, either in the absence or presence of the native e25.

Functional analysis of the late expression factor genes of plutella xylostella granulovirus / 病毒学报

Plutella xylostella granulovirus (PlxyGV) contains homologs of 15 Autographa californica MNPV (AcMNPV) late expression factor (lef) genes. The prospective products of 14 PlxyGV lef genes (ie-0 is not included) share 13%-53% amino acid similarity with their corresponding homologs of AcMNPV, among which LEF-9, LEF-8 and P47, three subunits of the virus-encoded RNA polymerase, share 49%, 53% and 46% sequence identity, respectively. In this study, an established transient expression system was used to test the ability of the PlxyGV LEFs to activate an AcMNPV vp39 promoter-driven reporter gene in SF9 cells. It was shown that PlxyGV le f-2 replaced the corresponding AcMNPV gene and exhibited partial activity in the context of the remaining set of AcMNPV le fs. PlxyGV LEF-2 was found to contain additional 100aa and 70aa at the C-terminus in comparison with the LEF-2 of other GVs and lepidopteran NPVs respectively.

Cloning and functional research of Arp2/3-P40/ARPC1 subunit of Sf9 cells / 病毒学报

The baculovirus-induced actin polymerization is mainly associated with the virus nucleocapsid protein P78/83, which is homologous with WASP proteins that can activate Arp2/3 complex and induce the actin polymerization. In order to explore the role of Arp2/3 complex in the baculovirus replication, the P40 subunit of Arp2/3 complex from Sf9 (Spodoptera frugiperda 9) cell line was cloned and characterized. Immunofluorescent microscopy assay indicated that P40 was recruited to the inner-side of nuclear membrane during virus infection, which was in accordance with nuclear F-actin distribution in virus-infected cells as documented in our previous research, suggesting P40 could be used to track Arp2/3 complex subcellular distribution changes during virus infection. In addition, co-immunoprecipitation assay demonstrated that P40 interacted with P78/83 only in virus-infected cells, suggesting that actin polymerization induced by P78/83-Arp2/3 complex during baculovirus infection was regulated by some unidentified virus factors.

Plutella xylostella granulovirus PP31 interacts with two host proteins / 病毒学报

Protein-protein interactions between viruses and hosts are common during viral infection and replication. In this study, a cDNA library from larvae of Plutella xylostella was constructed and used for screening of genes encoding proteins interacting with Plutella xylostella granulovirus (PlxyGV) proteins. Two cDNA clones containing genes encoding proteins interacting with PlxyGV PP31 were identified by yeast two-hybrid assays. Sequence analysis showed that the genes encoded homologues of receptor for activated protein C kinase (RACK) and methionine aminopeptidase 2 (MetAP2), respectively. The P. xylostella rack gene and the PlxyGV pp31 was expressed in an E. coli strain to produce proteins fused with a 6-His or a GST tag. It was shown that the rack was expressed as a 38kD peptide as prospected. The 38kD His-tagged peptide was co-purified with GST-PP31 by GST-bind resin in GST-pulldown assays, confirming interaction between the PlxyGV PP31 and the RACK protein of P. xylostella.

Therapeutic effects of FOLFOX6 versus TLF regimen as the first line chemotherapy for advanced gastric cancer / 南方医科大学学报

<p><b>OBJECTIVE</b>To compare the efficacy, time to disease progression (TTP), overall survival (OS) and toxicity of FOLFOX6 and TLF regimens for advanced gastric cancer.</p><p><b>METHODS</b>The clinical data of 81 chemotherapy-naive patients with advanced gastric cancer were analyzed. Of the 81 patients, 41 were treated with FOLFOX6 regimen and 40 with TLF regimen. The patients in FOLFOX6 group received intravenous infusion of L-OHP(100 mg/m2) at day 1, bolus injection of 5-FU (400 mg/m2) at day 1, and continuous intravenous infusion of 5-FU (1200 mg/m2/d) for 22 h at days 1-2, each treatment cycle lasting 14 days. The patients in TCF group received TAX (90 mg/m2) at day 1, bolus injection of 5-FU (400 mg/m2) at days 1-2, and continuous intravenous infusion of 5-FU (400 mg/m2/d) for 22 h at days 1-2, and each treatment cycle also lasted 14 days.</p><p><b>RESULTS</b>The objective response rates were 48.8% in FOLFOX6 group and 50.0% in TLF group (P=0.962). The median TTP in the two groups was 6.30 months and 6.50 months (P=0.958), with median survival time of 9.80 months and 10.70 months (P=0.578), respectively. The most frequent adverse events were nausea, vomiting and hematologic toxicities. The incidences of grade III-IV leucopenia and neutropenia were lower in FOLFOX6 group than in TLF group, but the difference was not statistically significant (12.2% vs 30.0%, P=0.112; 14.6% vs 32.5%, P=0.126). Three patients in FOLFOX6 group developed intestinal obstruction during the chemotherapy.</p><p><b>CONCLUSION</b>Both FOLFOX6 and TLF regimens are effective in treating advanced gastric cancer and the toxicities can be tolerated.</p>