The Rana grylio virus (RGV) is a member of the genus Ranavirus. It belongs to the family Iridoviridae, and contains the gene 67R encoding dUTPase. In order to investigate the function of 67R in the replication and infection of RGV, we constructed Δ67R-RGV, a recombinant virus with deletion of 67R. First, we constructed the plasmid pGL3-67RL-p50-EGFP-67RR which carried an enhanced green fluorescence gene (EGFP) as a selectable marker. After homologous recombination between pGL3-67RL-p50-EG- FP-67RR and the RGV genome, Epithelioma papulosum cyprini (EPC) cells were infected with the resulting mixture. Through ten successive rounds of plaque isolation via EGFP selection, all plaques emitted green fluorescence, and finally Δ67R-RGV was generated. Total DNA of Δ67R-RGV infected cells was extracted for PCR analyses. Simulateously, mock infected and wild-type RGV (wt-RGV) infected cells were used as a comparison. Results showed that 67R could be detected in wt-RGV infected cells, but that only the EGFP gene was detected in Δ67R-RGV infected cells. Furthermore, one-step growth curves of wt-RGV and Δ67R-RGV were similar. Therefore, 67R and its encoding product dUTPase might not be essential for the growth of RGV. These results suggest that, homologous recombination and recombinant rana- virus could be used to study the gene function of viruses in aquatic animals.
Genes, Viral ; physiology ; Genome, Viral ; Polymerase Chain Reaction ; Pyrophosphatases ; genetics ; Ranavirus ; genetics ; Recombination, Genetic

One type of important plant disease resistance, gene-for-gene resistance, is resulted from the interactions between products of the pathogen avirulence (Avr) genes and their matching plant resistance (R) genes. Avr genes have been cloned from a variety of pathogens including fungi, bacteria, viruses and oomycetes. No significant homology is found between sequences of the most cloned Avr genes and those of known proteins or between those of themselves. However, significant homology has been found between sequences of the cloned R genes and those of known proteins or between those of themselves. R proteins consist of similar domains. It has been reported that hypersensitive cell death and resistance, which are induced by interactions between products of different Avr/R gene pairs consisting of similar R genes but different Avr genes, are distinct in development speed, strength, and organ and tissue specificity. Avr genes have dual functions: Pathogens containing Avr genes are avirulent to plants carrying the matching R genes, while they are virulent in race, strain, pathovar or species-specific way to plants without carrying the matching R genes.
Bacteria ; genetics ; pathogenicity ; Fungi ; genetics ; pathogenicity ; Gene Expression ; Genes, Bacterial ; physiology ; Genes, Fungal ; physiology ; Genes, Viral ; physiology ; Plant Diseases ; genetics ; microbiology ; virology ; Plant Viruses ; genetics ; pathogenicity ; Virulence

Latent Epstein-Barr virus (EBV) infection has a substantial role in causing many human disorders. The persistence of these viral genomes in all malignant cells, yet with the expression of limited latent genes, is consistent with the notion that EBV latent genes are important for malignant cell growth. While the EBV-encoded nuclear antigen-1 (EBNA-1) and latent membrane protein-2A (LMP-2A) are critical, the EBNA-leader proteins, EBNA-2, EBNA-3A, EBNA-3C and LMP-1, are individually essential for in vitro transformation of primary B cells to lymphoblastoid cell lines. EBV-encoded RNAs and EBNA-3Bs are dispensable. In this review, the roles of EBV latent genes are summarized.
Epstein-Barr Virus Infections/complications/virology ; Epstein-Barr Virus Nuclear Antigens/genetics/metabolism ; *Genes, Viral ; Herpesvirus 4, Human/*physiology ; Humans ; MicroRNAs/genetics ; Neoplasms/etiology ; Protein Binding ; RNA, Viral/genetics ; Viral Matrix Proteins/genetics/metabolism ; *Virus Latency

Ebola virus, the cause of severe and fatal hemorrahagic fever in humans, belongs to filovirus family. This study was designed to establish a cell-based screening and evaluation system in the pharmacological study of antivirus compounds. Three reporter systems were established with recombinant pseudoviral luciferase of HIV core (pNL4-3.Luc.R(-)E(-)) packed with filovirus glycoprotein (EBOV-Zaire GP/HIV-luc, EBOV-Sudan GP/HIV-luc and Marburg GP/HIV-luc), which are required for virus entry of cells. The level of filovirus entry was determined by the expression of luciferase reporter gene in the infected cells. For screening of filovirus entry inhibitors, the vesicular stomatitis G packed pseudovirions (VSVG/HIV-luc) was used to determine the compound specificity. The results of known filovirus entry inhibitors demonstrated successful establishment of the new model systems, which would be useful in high throughput screening of anti-filovirus drugs in the future.
Antiviral Agents ; pharmacology ; Drug Evaluation, Preclinical ; methods ; Ebolavirus ; drug effects ; physiology ; Genes, Reporter ; Glycoproteins ; genetics ; Hemorrhagic Fever, Ebola ; Humans ; Luciferases ; Viral Proteins ; genetics ; Virus Internalization ; drug effects

A human embryonic kidney cell line 293 is widely used for adenovirus production and propagation. With this cell line, however, replication-competent virus (RCV) is frequently generated, especially during large-scale production and successive propagation because 293 cells contain not only E1 gene but also non-E1 adenovirus gene. Homologous recombination between non-E1 region of 293 genomic DNA and its homologous region in the recombinant adenoviral vector generate RCV. To overcome this problem, we developed a new packaging cell line, Hela-E1, which contains minimum E1 region and from which non-E1 adenoviral region that is homologous with recombinant adenovirus vector was excluded. No RCV was detected during adenovirus propagation in Hela-E1 compared to in 293. In addition, adenovirus-p53 produced in HeLa-E1 was able to overexpress p53 protein when introduced into an ovarian cancer cell line, SKOV3. These results may have a significant impact on the development of packaging cell lines for replication-deficient adenovirus production.
Adenoviridae/*genetics/physiology ; Adenovirus E1 Proteins/*genetics/metabolism ; Cell Line ; Genes, Viral ; Genes, p53 ; *Genetic Vectors ; *Hela Cells ; Human ; Protein p53/genetics/metabolism ; Recombination, Genetic ; Support, Non-U.S. Gov't ; Tumor Cells, Cultured ; Virus Cultivation ; Virus Replication

BmNPV bacmid constructed recently and Red recombinant system were used to rapidly disrupted Bombyx monri nucleopolyhedrovirus (BmNPV) orf60 in Escherichia coli (E. coli) BW25113. BmNPV bacmid isolated from E. coli BmDH10Bac was electroporated into E. coli BW25113, which harbors plasmid pKD46 encoding lamda Red recombinase,to produce E. coli BW25113-Bac, which could be used for gene deletion of BmNPV. A linear fragment was amplified by PCR from plasmid pKD3 (containing a chloramphenicol acetyltransferase gene cat) using a pair of primers with length of 63bp,which had 45 bp homologous to the orf60 gene and 18bp homologous to cat sequences. The linear fragment was electroporated into E. coli BW25113-Bac and homologous recombination occurred between the linear fragment and orf60 with the help of lamda Red recombinase. Three specific primer pairs were used to confirm the replacement of orf60 by cat gene. Western blot analysis showed that orf60 was not expressed in BmN cells infected with knockout bacmid.
Animals ; Bacteriophage lambda ; enzymology ; genetics ; Bombyx ; virology ; Electroporation ; Escherichia coli ; genetics ; metabolism ; Gene Expression ; Gene Knockout Techniques ; Genes, Viral ; genetics ; Nucleopolyhedrovirus ; enzymology ; genetics ; Open Reading Frames ; genetics ; physiology ; Recombinases ; genetics ; metabolism ; Viral Proteins ; genetics ; metabolism

The inactivation of p53 and p105RB by viral proteins or by mutations plays a key role in the oncogenesis of cervical carcinoma. The E6 and E7 proteins of HPV type 16 can bind to p53 and p105RB tumor suppressor gene products, respectively. In the present study, we tested a simple in vivo model that could explain the interactions between HPV E6 oncoprotein and p53 tumor suppressor protein. Our results showed that the life span of normal cervical epithelial cells was increased up to 4.5 times when transfected with expression vector containing E6/E7 ORF of HPV type 16. However, these cells did not divide after second crisis. Therefore, we employed an established human epidermal keratinocytes, RHEK-1. When transfected with an expression vector containing E6 ORF of HPV type 16, RHEK-1 cells showed anchorage independent growth character. When RHEK-E6 cells were transfected with wild type p53 expression vector, the growth rate of the RHEK-E6 cells was diminished. After 48 hours of transfection, many cells showed apoptotic signal but no more apoptotic signal was observed thereafter. These results suggested that the overexpression of the wild type p53 could overcome the dysfunction of the p53 on the cell cycle regulation imposed by E6 protein although not being of physiological condition.
Animal ; Base Sequence ; Cells, Cultured ; Cervix Uteri/*cytology ; Female ; Genes, p53/*physiology ; Human ; Keratinocytes/*cytology ; Mice ; Molecular Sequence Data ; Oncogene Proteins, Viral/genetics/*physiology ; Papillomavirus, Human/*genetics ; Support, Non-U.S. Gov't ; Transfection

BACKGROUND/AIMS: Hepatitis B virus (HBV) is the etiological factor for hepatocellular carcinoma (HCC). Numerous evidence has indicated a link between chronic infection with HBV and the development of HCC. Among the four proteins encoded by HBV, Hepatitis B virus X gene(HBx), best characterized as a transcriptional transactivator, gained attention owing to its presumptive role in oncogenesis. Further, HBx has been shown to stimulate signal transduction pathways such as Ras-MAPK pathway, NF-kappaB, and Src kinase. The pleiotropic events caused by HBx may be the key to understanding the HBV-mediated oncogenicity. However, the specific roles of HBx in oncogenesis remain largely elusive. To explore the role of HBx in hepatocarcinogenesis, we examined the deregulation of host genes induced by HBx expression. METHODS: HBx was ectopically expressed in HepG2 cells using a recombinant adenovirus to transiently express HBx. Gene expression profiling of HBx was conducted on cDNA microarrays that contained 1,028 cDNAs. RESULTS: A number of oncogenes and genes that are involved in cell growth, DNA repair, cell cycle regulation, and cell motility were deregulated by HBx. CONCLUSIONS: Theses results suggest that HBx regulates transcription in a way that contributes to the proliferation of hepatocytes, a probable early event of HCC.
Carcinoma, Hepatocellular/*virology ; Cell Line, Tumor ; English Abstract ; *Gene Expression Profiling ; Gene Expression Regulation ; Genes, Viral/*physiology ; Genetic Vectors ; Hepatitis B Antigens/genetics ; Hepatitis B Virus/*genetics ; Human ; Liver Neoplasms/*virology ; Oligonucleotide Array Sequence Analysis ; Trans-Activators/*genetics/physiology

OBJECTIVETo evaluate the possibility of hepatitis B virus (HBV) as a vector in liver-targeting gene therapy.

METHODSA fragment containing the small envelope gene of HBV was replaced with the reporter gene green fluorescent protein (GFP) to construct the recombinant HBV vector, which was transfected into HepG2 cells with liposome. The expression of GFP was observed with fluorescence microscope. The HBV cccDNA was testified using semi-nest PCR. The viral particles of the recombinant HBV in culture medium were detected by PCR as well as Southern blot.

RESULTSThe HBV vector carrying the interesting gene of GFP could express the functional protein in the transfected hepatocytes. However, the recombinant HBV vector was replication-deficient, which could not be packed and replicated in the hepatocytes to secrete mature recombinant HBV particles carrying the interesting gene of GFP when transfected solely but could when cotransfected with the recombinant and helper construct which lacked part of 5'-proximal HBV RNA packaging signal epsilon.

CONCLUSIONIt is possible that HBV is reconstructed as a liver-targeting vector for gene therapy.

Cell Transformation, Viral ; Cells, Cultured ; Gene Transfer Techniques ; Genes, Reporter ; Genetic Therapy ; methods ; Genetic Vectors ; genetics ; physiology ; Hepatitis B virus ; genetics ; physiology ; Hepatocytes ; cytology ; virology ; Humans ; Liver ; cytology ; virology ; Recombinant Proteins ; genetics ; Transfection ; Virus Replication

OBJECTIVETo observe the effect of Chinese medicine therapy for strengthening-Pi and nourishing-Shen (SPNS) in preventing lamivudine induced YMDD mutation and its immunological mechanism.

METHODSOne hundred and sixty chronic hepatitis B (CHB) patients with positive HBeAg were equally assigned to two groups at random: the observation group and the control group. Patients in the observation group were treated with lamivudine combined with SPNS, and those in the control group were treated with lamivudine only, with the treatment lasting for 52 weeks in total. Changes in indexes, including liver function, HbeAg, HBV-DNA, YMDD variation, CD(4), CD(4)/CD(8) ratio, interferon-gamma (IFN-gamma), interleukin-4 (IL-4), blood routine, renal function, as well as any adverse reactions that occurred in patients, were observed at different time points.

RESULTSThe ALT, AST recovery rate and HBV-DNA negatively inversing rate at the 24th week, the 36th week and the 52nd week were all higher (P<0.05); meanwhile, the YMDD mutation rate at the 36th week and the 52nd week was lower (P<0.05) in the observation group than in the control group. The posttreatment levels of CD(4), CD(4)/CD(8) ratio, IFN-gamma, and IL-4 as well as the pre-post treatment difference of these indexes in the observation group were significantly different from those in the control group (P<0.05).

CONCLUSIONChinese medicine SPNS therapy can significantly reduce the YMDD variation of HBV, and the mechanism may be related to its regulation of the CD(4) level, CD(4)/CD(8) ratio and Th1/Th2 balance.

Adult ; Antiviral Agents ; adverse effects ; therapeutic use ; DNA, Viral ; genetics ; Drug Resistance, Viral ; drug effects ; genetics ; immunology ; Female ; Genes, Viral ; Hepatitis B virus ; genetics ; immunology ; Hepatitis B, Chronic ; drug therapy ; immunology ; prevention & control ; virology ; Humans ; Immune Evasion ; genetics ; Lamivudine ; adverse effects ; therapeutic use ; Male ; Medicine, Chinese Traditional ; methods ; Middle Aged ; Mutation ; physiology ; Palliative Care ; methods ; Secondary Prevention ; Young Adult