1
|
Yao L, Zhou Y, Sui Z, Zhang Y, Liu Y, Xie H, Gao H, Fan H, Zhang Y, Liu M, Li S, Tang H. HBV-encoded miR-2 functions as an oncogene by downregulating TRIM35 but upregulating RAN in liver cancer cells. EBioMedicine 2019; 48:117-129. [PMID: 31530503 PMCID: PMC6838411 DOI: 10.1016/j.ebiom.2019.09.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 08/24/2019] [Accepted: 09/06/2019] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Hepatitis B virus (HBV) infection has been well established as a high-risk factor for the carcinogenesis of hepatocellular carcinoma (HCC). Cellular microRNA (miRNA) is involved in tumorigenesis by accelerating the malignant phenotype in HCC. However, whether HBV can encode miRNAs that contribute to HCC is not entirely clear. METHODS In this study, an miRNA encoded by HBV (HBV-miR-2) was identified by Solexa sequencing in HBV-positive HCC specimens and further verified in serum samples from HCC patients with HBV infection and in HBV-positive HCC cell lines. To evaluate the roles of HBV-miR-2 in liver cancer cells, we determined cell viability and migration/invasion ability by gain-of-function experiment in HBV(-) liver cancer cells (HepG2 and Huh7) and loss-of-function experiments in Huh7 cells stably expressing HBV-miR-2 (Huh7/HBV-miR-2 cells) and HepG2.2.15 cells. Furthermore, to elucidate the mechanism by which HBV-miR-2 work on cell malignancy, we identified and studied the effect of two target genes (TRIM35 and RAN) of HBV-miR-2 in liver cancer cells. FINDINGS We revealed that HBV-miR-2 promoted HCC cell growth ability by suppressing apoptosis and promoting migration and invasion by enhancing the epithelial-mesenchymal transition (EMT), functioning as an oncogene in the development of HBV-related HCC. Furthermore, we demonstrated that HBV-miR-2 suppresses the expression of TRIM35 but enhances RAN expression by targeting their 3'-untranslated regions (3'UTR) and that the ectopic expression of TRIM35 or knockdown of RAN counteracted the malignant phenotypes induced by HBV-miR-2. INTERPRETATION Our findings indicate that an HBV-encoded miRNA, HBV-miR-2, promotes oncogenic activity by downregulating TRIM35 expression and upregulating RAN expression in liver cancer cells, likely providing insight into tumorigenesis in HBV-related liver cancer. FUND: This work was supported in part by the National Natural Science Foundation of China (No: 81830094; 91629302; 31270818) and the Natural Science Foundation of Tianjin (No: 12JCZDJC25100).
Collapse
Affiliation(s)
- Lili Yao
- Tianjin Life Science Research Center, Tianjin Laboratory of Inflammation Biology, Collaborative Innovation Center of Tianjin for Medical Epigenetics, Department of Pathogen Biology, Basic Medical School, Tianjin Medical University, Tianjin 300070, China
| | - Yadi Zhou
- Tianjin Life Science Research Center, Tianjin Laboratory of Inflammation Biology, Collaborative Innovation Center of Tianjin for Medical Epigenetics, Department of Pathogen Biology, Basic Medical School, Tianjin Medical University, Tianjin 300070, China
| | - Zhenhua Sui
- Tianjin Life Science Research Center, Tianjin Laboratory of Inflammation Biology, Collaborative Innovation Center of Tianjin for Medical Epigenetics, Department of Pathogen Biology, Basic Medical School, Tianjin Medical University, Tianjin 300070, China
| | - Yanling Zhang
- Tianjin Life Science Research Center, Tianjin Laboratory of Inflammation Biology, Collaborative Innovation Center of Tianjin for Medical Epigenetics, Department of Pathogen Biology, Basic Medical School, Tianjin Medical University, Tianjin 300070, China
| | - Yankun Liu
- The Cancer Institute, Tangshan People's Hospital, Tangshan 063001, China
| | - Hong Xie
- Tianjin Life Science Research Center, Tianjin Laboratory of Inflammation Biology, Collaborative Innovation Center of Tianjin for Medical Epigenetics, Department of Pathogen Biology, Basic Medical School, Tianjin Medical University, Tianjin 300070, China.
| | - Huijie Gao
- Tianjin Life Science Research Center, Tianjin Laboratory of Inflammation Biology, Collaborative Innovation Center of Tianjin for Medical Epigenetics, Department of Pathogen Biology, Basic Medical School, Tianjin Medical University, Tianjin 300070, China
| | - Hongxia Fan
- Tianjin Life Science Research Center, Tianjin Laboratory of Inflammation Biology, Collaborative Innovation Center of Tianjin for Medical Epigenetics, Department of Pathogen Biology, Basic Medical School, Tianjin Medical University, Tianjin 300070, China
| | - Yi Zhang
- Tianjin Life Science Research Center, Tianjin Laboratory of Inflammation Biology, Collaborative Innovation Center of Tianjin for Medical Epigenetics, Department of Pathogen Biology, Basic Medical School, Tianjin Medical University, Tianjin 300070, China
| | - Min Liu
- Tianjin Life Science Research Center, Tianjin Laboratory of Inflammation Biology, Collaborative Innovation Center of Tianjin for Medical Epigenetics, Department of Pathogen Biology, Basic Medical School, Tianjin Medical University, Tianjin 300070, China
| | - Shengping Li
- State Key Laboratory of Oncology in Southern China, Department of Hepatobiliary Oncology, Cancer Center, Sun Yat-sen University, Guangzhou 510060, China.
| | - Hua Tang
- Tianjin Life Science Research Center, Tianjin Laboratory of Inflammation Biology, Collaborative Innovation Center of Tianjin for Medical Epigenetics, Department of Pathogen Biology, Basic Medical School, Tianjin Medical University, Tianjin 300070, China.
| |
Collapse
|
2
|
Spatz SJ, Smith LP, Baigent SJ, Petherbridge L, Nair V. Genotypic characterization of two bacterial artificial chromosome clones derived from a single DNA source of the very virulent gallid herpesvirus-2 strain C12/130. J Gen Virol 2011; 92:1500-1507. [PMID: 21450941 DOI: 10.1099/vir.0.027706-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The identification of specific genetic changes associated with differences in the pathogenicity of Marek's disease virus strains (GaHV-2) has been a formidable task due to the large number of mutations in mixed-genotype populations within DNA preparations. Very virulent UK isolate C12/130 induces extensive lymphoid atrophy, neurological manifestations and early mortality in young birds. We have recently reported the construction of several independent full-length bacterial artificial chromosome (BAC) clones of C12/130 capable of generating fully infectious viruses with significant differences in their pathogenicity profiles. Two of these clones (vC12/130-10 and vC12/130-15), which showed differences in virulence relative to each other and to the parental strain, had similar replication kinetics both in vitro and in vivo in spite of the fact that vC12/130-15 was attenuated. To investigate the possible reasons for this, the nucleotide sequences of both clones were determined. Sequence analysis of the two genomes identified mutations within eight genes. A single 494 bp insertion was identified within the genome of the virulent vC12/130-10 clone. Seven non-synonymous substitutions distinguished virulent vC12/130-10 from that of attenuated vC12/130-15. By sequencing regions of parental DNA that differed between the two BAC clones, we confirmed that C12/130 does contain these mutations in varying proportions. Since the individual reconstituted BAC clones were functionally attenuated in vivo and derived from a single DNA source of phenotypically very virulent C12/130, this suggests that the C12/130 virus population exists as a collection of mixed genotypes.
Collapse
Affiliation(s)
- Stephen J Spatz
- Southeast Poultry Research Laboratory, Agricultural Research Service, United States Department of Agriculture, Athens, GA 30605, USA
| | | | - Susan J Baigent
- Institute for Animal Health, Compton, Berkshire RG20 7NN, UK
| | | | - Venugopal Nair
- Institute for Animal Health, Compton, Berkshire RG20 7NN, UK
| |
Collapse
|
3
|
Spatz SJ, Rue C, Schumacher D, Osterrieder N. Clustering of mutations within the inverted repeat regions of a serially passaged attenuated gallid herpesvirus type 2 strain. Virus Genes 2008; 37:69-80. [PMID: 18516669 DOI: 10.1007/s11262-008-0242-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 05/05/2008] [Indexed: 11/25/2022]
Abstract
Marek's disease (MD) is the leading cause of losses in chicken production in the world. Over the past 40 years significant progress has been made in the control of MD through the use of vaccines which reduce or delay tumor formation in vaccinated flocks. However, these vaccines fail to induce an immune response that protects against infection and virus shedding. Little is known about the genetic changes that lead to attenuation and are necessary for the generation of vaccine strains. Previous research has demonstrated that serial passage of virulent strains in cell culture results in the generation of attenuated progeny. Obtaining detailed knowledge of the changes which are needed for attenuation will be important for advancing our understanding of MD biology and should facilitate the development of more potent vaccines. We have determined the complete nucleotide sequence of a bacterial artificial chromosome (BAC) construct representing the 80th passage of a very virulent plus (vv+) MD virus strain termed 584A. Pathotyping studies have indicated that this strain (584Ap80) is indeed attenuated. Bioinformatic analysis of the sequencing data has identified numerous gross genetic changes clustering in the inverted repeat regions of the genome, as well as subtle changes (single nucleotide polymorphisms or SNPs) scattered throughout the genome. Relative to the parental strain (584Ap9), insertional mutations were identified in the MD-specific genes encoding RLORF1, RLORF3, RLORF6, 23 kDa, RLORF7 (Meq), vIL8, vLip, RSORF1, and five uncharacterized novel genes. Deletions were found in four locations within the 584Ap80 genome. A large deletion (297nt) was found in the diploid genes 85.6/98.6 and a 321 nt deletion within the intergenic region between the U(L)3 and U(L)3.5 genes is predicted to create a fusion polypeptide. A single nucleotide deletion was identified within the origin of replication. Both insertions and deletions were found in the dipoid genes MDV3.4/78.3 encoding the virulence factor RLORF4. The sequencing of the attenuated strain 584Ap80 and comparison to that of the virulent parent 584A passage 9 (584Ap9) has provided a wealth of information regarding genetic changes which have occurred during the attenuation process.
Collapse
Affiliation(s)
- Stephen J Spatz
- Southeast Poultry Research Laboratory, United States Department of Agriculture, Agricultural Research Service, 934 College Station Rd, Athens, GA 30605, USA.
| | | | | | | |
Collapse
|
4
|
Venugopal K, Payne LN. Molecular pathogenesis of Marek's disease—recent developments. Avian Pathol 2007; 24:597-609. [DOI: 10.1080/03079459508419100] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
5
|
Osterrieder N, Kamil JP, Schumacher D, Tischer BK, Trapp S. Marek's disease virus: from miasma to model. Nat Rev Microbiol 2006; 4:283-94. [PMID: 16541136 DOI: 10.1038/nrmicro1382] [Citation(s) in RCA: 297] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Marek's disease virus (MDV) is an oncogenic herpesvirus that causes various clinical syndromes in its natural host, the chicken. MDV has long been of interest as a model organism, particularly with respect to the pathogenesis and immune control of virus-induced lymphoma in an easily accessible small-animal system. Recent advances in MDV genetics and the determination of the chicken genome sequence, aided by functional genomics, have begun to dramatically increase our understanding not only of lytic MDV replication, but also of the factors and mechanisms leading to latency and tumour formation. This new information is helping to elucidate cellular signalling pathways that have undergone convergent evolution and are perturbed by different viruses, and emphasizes the value of MDV as a comparative biomedical model. Furthermore, the door is now open for rational and efficient engineering of new vaccines against one of the most important and widespread infectious diseases in chickens.
Collapse
Affiliation(s)
- Nikolaus Osterrieder
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
| | | | | | | | | |
Collapse
|
6
|
|
7
|
Parcells MS, Dienglewicz RL, Anderson AS, Morgan RW. Recombinant Marek's disease virus (MDV)-derived lymphoblastoid cell lines: regulation of a marker gene within the context of the MDV genome. J Virol 1999; 73:1362-73. [PMID: 9882341 PMCID: PMC103960 DOI: 10.1128/jvi.73.2.1362-1373.1999] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Marek's disease is a herpesvirus (Marek's disease virus [MDV])-induced pathology of chickens characterized by paralysis and the rapid appearance of T-cell lymphomas. Lymphoblastoid cell lines (LBCLs) derived from MDV-induced tumors have served as models of MDV latency and transformation. We have recently reported the construction of mutant MDVs having a deletion (M. S. Parcells et al., J. Virol. 69:7888-7898, 1995) and an insertion (A. S. Anderson et al., J. Virol. 72:2548-2553, 1998) within the unique short region of the virus genome. These mutant MDVs retained oncogenicity, and LBCLs have been established from the mutant-induced tumors. We report the characterization of these cell lines with respect to (i) virus structure within and reactivated from the cell lines, (ii) surface antigen expression, (iii) kinetics of MDV and marker gene induction, (iv) localization and colocalization of induced MDV antigens and beta-galactosidase (beta-Gal), and (v) methylation status of the region of lacZ insertion in recombinant- and non-recombinant-derived cell lines. Our results indicate that (i) recombinant-derived cell lines contain no parental virus, (ii) the established cell lines are predominantly CD4(+) CD8(-), (iii) the percentage of Lac-expressing cells is low (1 to 3%) but increases dramatically upon 5'-iododeoxyuridine (IUdR) treatment, (iv) lacZ expression is induced with the same kinetics as several MDV lytic-phase genes (pp38, US1, gB, gI, and US10), and (v) the regulation of lacZ expression is not mediated by methylation. Furthermore, the MDV-encoded oncoprotein, Meq, could be detected in cells expressing beta-Gal and various lytic antigens but did not appear to be induced by IUdR treatment. Our results indicate that regulation of the lacZ marker gene can serve as sensitive measure of virus lytic-phase induction and the reactivation from latency.
Collapse
Affiliation(s)
- M S Parcells
- Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas 72701, USA.
| | | | | | | |
Collapse
|
8
|
Abujoub AA, Coussens PM. Evidence that Marek's disease virus exists in a latent state in a sustainable fibroblast cell line. Virology 1997; 229:309-21. [PMID: 9126245 DOI: 10.1006/viro.1997.8444] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Previously, we reported the development of two fibroblastic cell lines (MDV OU2.1 and OU2.2) infected with Marek's disease virus (MDV). The two cell lines, in nonconfluent continuous cultures, displayed characteristics consistent with MDV existing in a latent state. However, presence of distinct plaques in confluent cell monolayers and the ability to transfer cytolytic infection to susceptible birds and primary chick embryo fibroblasts, suggest that, if latent, the virus is easily reactivated from MDV OU2 cell lines. In this report, we present evidence which supports the hypothesis that MDV genomes in MDV OU2 cells are latent. PCR analyses and in vivo experiments demonstrate that CHCC-OU2 cells stabilize MDV so that serial in vitro passage does not attenuate the virus. Following two years of active culture, MDV genomes in MDV OU2 cells are still oncogenic, similar to that seen in MDV-lymphoblastoid cell lines. Expansion of the 132-bp repeat within MDV BamHI fragments H and D, typical of highly passaged serotype 1 MDV, has not been observed beyond two copies in MDV OU2 cells. Indirect immunofluorescence assays clearly demonstrate that MDV OU2 cells do not express glycoproteins B and I when subconfluent. However, upon reaching confluence these proteins are expressed in readily detectable amounts. Using RT-PCR we demonstrate that glycoproteins E and D are highly expressed in confluent MDV OU2 cells but absent from subconfluent cells, and MDV latency-associated transcripts (LATs), which are antisense to ICP4 transcripts and have been associated with latent MDV infection, are expressed in subconfluent MDV OU2 cells. Coincident with an increase in ICP4 expression, MDV LAT expression is down regulated when MDV OU2 cells become confluent.
Collapse
Affiliation(s)
- A A Abujoub
- Department of Microbiology, Michigan State University, East Lansing 48824, USA
| | | |
Collapse
|
9
|
Hong Y, Frame M, Coussens PM. A 14-kDa immediate-early phosphoprotein is specifically expressed in cells infected with oncogenic Marek's disease virus strains and their attenuated derivatives. Virology 1995; 206:695-700. [PMID: 7831828 DOI: 10.1016/s0042-6822(95)80091-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Previously, we reported two cDNAs derived from the Marek's disease virus (MDV) long internal repeat region. A 14-kDa polypeptide (p14) encoded by two small open reading frames (ORFs) from at least two distinct cDNAs is expressed in cells lytically infected with both oncogenic and attenuated MDV as well as in cells latently infected and transformed by MDV. In this study, we demonstrate that p14 is serotype 1 specific and highly phosphorylated. Given the degree of phosphorylation and lack of homology to known proteins, we propose the name pp14 for the polypeptide encoded by ORF1a and ORF1b. Further analysis reveals that pp14 is predominantly found in cytoplasmic fractions of MDV-infected cells and can be detected in the cytoplasm of MDV-infected cells by immunofluorescence with polyclonal antisera prepared against pp14-glutathione S-transferase fusion protein.
Collapse
Affiliation(s)
- Y Hong
- Department of Animal Science, Michigan State University, East Lansing 48824
| | | | | |
Collapse
|
10
|
Cantello JL, Anderson AS, Morgan RW. Identification of latency-associated transcripts that map antisense to the ICP4 homolog gene of Marek's disease virus. J Virol 1994; 68:6280-90. [PMID: 8083968 PMCID: PMC237048 DOI: 10.1128/jvi.68.10.6280-6290.1994] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Two small RNAs (0.9 and 0.75 kb), named Marek's disease virus (MDV) small RNAs (MSRs) and a 10-kb RNA, all of which map antisense to the MDV ICP4 homolog gene, have been readily detected in MDCC-MSB1 MDV-transformed T-lymphoblastoid cells. These RNAs were not detectable in reticuloendotheliosis virus-transformed T cells. When MDV was reactivated by treatment of lymphoblastoid cells with 25 micrograms of iododeoxyuridine per ml, the relative levels of the transcripts decreased. These RNAs were not detected by Northern (RNA) hybridization in productively infected chicken embryo fibroblasts 48 h postinfection; however, they were apparent 140 h postinfection. By using Northern hybridization, RNase protection assays, and primer extension analysis, the MSRs were determined to map antisense to the predicted translational start site of the ICP4 homolog gene. The conclusion most consistent with the data is that the two MSRs are overlapping, spliced RNAs. Both small RNAs contain a latency promoter binding factor consensus recognition sequence located toward their 5' ends as well as two potential ICP4 recognition consensus sequences, one in each orientation. The region contains a number of small open reading frames on each side and within the MSRs. Although the exact endpoints are unknown, the large 10-kb species spans the entire ICP4 homolog region. We believe that this group of RNAs, which map antisense to the ICP4 homolog gene, are latency-associated transcripts of MDV.
Collapse
MESH Headings
- Animals
- Base Sequence
- Blotting, Northern
- Cell Line, Transformed
- Cell Transformation, Viral
- Cells, Cultured
- Chick Embryo
- Cloning, Molecular
- DNA Primers
- Fibroblasts
- Genes, Viral
- Herpesvirus 2, Gallid/genetics
- Immediate-Early Proteins/genetics
- Molecular Sequence Data
- Plasmids
- Polymerase Chain Reaction
- RNA, Antisense/metabolism
- RNA, Viral/biosynthesis
- Restriction Mapping
- Sequence Homology, Nucleic Acid
- T-Lymphocytes
- Transcription, Genetic
Collapse
Affiliation(s)
- J L Cantello
- Delaware Agricultural Experiment Station, Department of Animal Science and Agricultural Biochemistry, College of Agricultural Sciences, University of Delaware, Newark 19717-1303
| | | | | |
Collapse
|
11
|
Hong Y, Coussens PM. Identification of an immediate-early gene in the Marek's disease virus long internal repeat region which encodes a unique 14-kilodalton polypeptide. J Virol 1994; 68:3593-603. [PMID: 8189498 PMCID: PMC236863 DOI: 10.1128/jvi.68.6.3593-3603.1994] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Marek's disease virus (MDV) is an oncogenic avian herpesvirus whose genomic structure is similar to those of herpes simplex virus and varicella-zoster virus. Repeat regions of the MDV genome have been intensively investigated because of a potential relationship to MDV oncogenicity and abundant expression of immediate-early transcripts. In this study, a 1.6-kb immediate-early transcript was localized to the BamHI-I2 region by Northern (RNA) hybridization analysis. With cDNA cloning and sequencing, two cDNAs of 1.4 kb (C1) and 1.35 kb (C2) were identified. Both cDNAs are derived from spliced mRNAs spanning the BamHI-H and -I2 fragments. C1 and C2 use the same splice acceptors and 3' ends, but they differ at their 5' ends and utilize different splice donors. The upstream promoter-enhancer region of C1 cDNA has been defined as a bidirectional regulatory region shared by the MDV pp38 gene. Sequencing analysis shows two small open reading frames (ORFs) within each cDNA (ORF1a and ORF2 in C1, ORF1b and ORF2 in C2). Potential ORFs of the sequence have no significant homology with any known protein in the Swiss-Protein data base. DNA fragments encoding ORF1a and ORF1b were cloned into pGEX-3X vectors to produce glutathione S-transferase fusion proteins and induce antisera. In Western blot (immunoblot) analysis of MDV-infected-cell lysates, a 14-kDa polypeptide was identified by antisera against both ORF1a and ORF1b. This 14-kDa protein is expressed in cells which are lytically infected with MDV strains GA, Md11 passage 14 (oncogenic), and Md11 passage 83 (attenuated), as well as in the latently MDV-infected and transformed MSB-1 cell line.
Collapse
Affiliation(s)
- Y Hong
- Department of Animal Science, Michigan State University, East Lansing 48824
| | | |
Collapse
|
12
|
Makimura K, Peng FY, Tsuji M, Hasegawa S, Kawai Y, Nonoyama M, Tanaka A. Mapping of Marek's disease virus genome: identification of junction sequences between unique and inverted repeat regions. Virus Genes 1994; 8:15-24. [PMID: 8209419 DOI: 10.1007/bf01703598] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Polymerase chain reaction (PCR) to amplify MDV DNA and subsequent sequencing identified the junction of TRL/UL, UL/IRL, IRS/US, and US/TRS. The TRL/UL junction is located 192 bp downstream of the last EcoRI site in the TRL region, while the UL/IRL junction is located 192 bp upstream of the first EcoRI restriction enzyme site in the IRL region. The IRS/US junction is located 950 bp downstream of the second EcoRI site in the IRS region, while the US/TRS junction is located 950 bp upstream of the first EcoRI restriction enzyme site in the TRS region. BamHI restriction enzyme mapping of one of the PCR products identified two novel DNA subfragments, BamHI-U2 and -P4, upstream of the US/TRS junction of the MDV genome. Sequencing of the BamHI-D fragment revealed a novel open reading frame (ORF) encoding a 155 amino acid protein. The TRL/UL junction is located in this ORF. The N-terminal 65 amino acids of this protein is homologous to the N-terminal region of the previously reported pp38, which is located in the UL/IRL region. Computer-assisted analysis indicated that both are transmembrane proteins and that they share an antigenic domain.
Collapse
Affiliation(s)
- K Makimura
- Department of Virology, Tampa Bay Research Institute, St. Petersburg, FL 33716
| | | | | | | | | | | | | |
Collapse
|
13
|
Ross N, Binns MM, Sanderson M, Schat KA. Alterations in DNA sequence and RNA transcription of the Bam HI-H fragment accompany attenuation of oncogenic Marek's disease herpesvirus. Virus Genes 1993; 7:33-51. [PMID: 8385839 DOI: 10.1007/bf01702347] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The nucleotide sequences of the BamHI-H fragment of the HPRS16 strain of Marek's disease virus (MDV) and of its attenuated derivative HPRS16/att have been determined. The results show that in addition to the tandem expansion of a 132 bp sequence from two copies in HPRS16 virus to eight copies in HPRS16/att, nucleotide substitutions, deletions, and insertions were also noted. Several potential open reading frames (ORFs) were identified. One of these (ORF 13) encoded a deduced protein, mol wt 32 kD, which is likely to be the serotype-1 specific phosphoprotein expressed in tumours (1) and mapped to an EcoRI fragment within BamHI-H (2). Our results suggest that this ORF is unlikely to be the B antigen (3). ORF 4, which had some similarity to CD4 and immunoglobulin M heavy chain, was encoded by a transcript that originated within the first copy of the 132 bp repeat. ORF 21, which mapped entirely within UL, encoded a deduced protein at least 322 amino acids long that had some similarity to varicella zoster virus (VZV) alpha trans-inducing protein. None of these ORFs was altered significantly by attenuation, except ORF 4 and another small ORF (ORF 3), 5' of the 132 bp repeats, which would probably fail to be transcribed because of truncation of an RNA transcript.
Collapse
Affiliation(s)
- N Ross
- AFRC Institute for Animal Health, Compton Laboratory, Berkshire, UK
| | | | | | | |
Collapse
|
14
|
Delecluse HJ, Hammerschmidt W. Status of Marek's disease virus in established lymphoma cell lines: herpesvirus integration is common. J Virol 1993; 67:82-92. [PMID: 8380099 PMCID: PMC237340 DOI: 10.1128/jvi.67.1.82-92.1993] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Six cell lines derived from Marek's disease lymphomas of chickens and turkeys were investigated for the status of Marek's disease virus (MDV) DNA. In the transformed T- and B-cell lines, viral DNA could be detected by conventional Southern blot hybridization, by Gardella gel electrophoresis, and by in situ hybridization of metaphase and interphase chromosomes. Integration of viral DNA into the host cell chromosome was observed in all cell lines. Two to 12 integration sites of viral DNA could be detected in metaphase chromosome spreads. The integration sites were characteristic for the individual cell lines and were preferentially located at the telomers of large- and mid-sized chromosomes or on minichromosomes. In four of six cell lines, a minor population of latently infected cells supported the lytic cycle of MDV, giving rise to linear virion DNAs. In one of these cell lines, a third species of MDV DNA could be detected with properties reminiscent of covalently closed circular DNA. The finding that MDV integrates regularly into the genomes of latently infected cells is crucial to understanding the molecular biology of herpesvirus-induced tumors in the natural host.
Collapse
Affiliation(s)
- H J Delecluse
- Institut für Klinische Molekularbiologie und Tumorgenetik, GSF-Forschungszentrum für Umwelt und Gesundheit, GmbH, Munich, Germany
| | | |
Collapse
|
15
|
Pratt WD, Morgan RW, Schat KA. Characterization of reticuloendotheliosis virus-transformed avian T-lymphoblastoid cell lines infected with Marek's disease virus. J Virol 1992; 66:7239-44. [PMID: 1279200 PMCID: PMC240427 DOI: 10.1128/jvi.66.12.7239-7244.1992] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The expression of Marek's disease virus (MDV) transcripts and protein products was investigated in reticuloendotheliosis virus-transformed avian T-lymphoblastoid cell line RECC-CU91, which was superinfected with MDV. The presence of MDV in the superinfected cell line, renamed RECC-CU210, was demonstrated by Southern hybridization with 32P-labeled BamHI-H and -B fragments of the BamHI MDV DNA library. Examination of RECC-CU210 for the expression of MDV-specific RNA transcripts encoded by the internal repeat long (IRL), internal repeat short (IRS), and unique short (US) regions of the MDV genome revealed two small transcripts of 0.6 and 0.7 kb. These transcripts were mapped to the IRL and IRS regions, respectively. In contrast, RECC-CU211, which was developed through transfection of CU210 with the BamHI-A fragment of MDV, expressed an additional nine transcripts from the IRL, IRS, and US regions. CU211 but not CU210 also expressed a complex of polypeptides of 40, 38, and 24 kDa, identified by monoclonal antibodies as MDV-specific phosphoproteins. The 38-kDa phosphoprotein is likely to be pp38, an early viral protein that maps within the IRL region of the MDV genome. These findings suggest that genes located within the transfected BamHI-A fragment transactivated a number of genes located in the IRL region of the MDV genome.
Collapse
MESH Headings
- Animals
- Birds
- Blotting, Northern
- Blotting, Southern
- Cell Line
- Cell Line, Transformed
- Cell Transformation, Viral
- DNA/genetics
- DNA/isolation & purification
- DNA, Viral/genetics
- DNA, Viral/isolation & purification
- Electrophoresis, Polyacrylamide Gel
- Genome, Viral
- Herpesvirus 2, Gallid/genetics
- RNA/genetics
- RNA/isolation & purification
- RNA, Viral/genetics
- RNA, Viral/isolation & purification
- Restriction Mapping
- Reticuloendotheliosis virus/genetics
- T-Lymphocytes
- Transcription, Genetic
- Viral Proteins/analysis
- Viral Proteins/biosynthesis
Collapse
Affiliation(s)
- W D Pratt
- Department of Avian and Aquatic Animal Medicine, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853-6401
| | | | | |
Collapse
|
16
|
Peng F, Bradley G, Tanaka A, Lancz G, Nonoyama M. Isolation and characterization of cDNAs from BamHI-H gene family RNAs associated with the tumorigenicity of Marek's disease virus. J Virol 1992; 66:7389-96. [PMID: 1279201 PMCID: PMC240445 DOI: 10.1128/jvi.66.12.7389-7396.1992] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
It has been reported that loss of the tumorigenic potential of attenuated Marek's disease virus (MDV) is strongly associated with amplification of the 132-bp repeat sequences found within the BamHI-D and BamHI-H fragments contained within the long terminal repeat and the long internal repeat, respectively. The expansion of this region results in loss of transcripts that are 3.8, 3.0, and 1.8 kbp long that are produced by tumorigenic strains of MDV. This evidence suggests that production of one or more of these three RNAs is strongly associated with the tumorigenic potential of the virus. In this study, we have cloned and sequenced 1.69-, 1.5-, 1.9-, and 2.2-kbp cDNAs from the BamHI-H gene family RNAs associated with tumorigenicity. The 1.69- and 2.2-kbp cDNAs are derived from nonspliced transcripts, whereas the 1.5- and 1.9-kbp cDNAs are from single spliced mRNAs spanning the BamHI-H and BamHI-I2 fragments of MDV DNA. Sequence analysis has shown two potential open reading frames in each of the cDNAs. The putative 63-amino-acid protein encoded by the first open reading frame in the 1.69-kbp cDNA and a putative 75-amino-acid protein encoded by the first open reading frame in the 1.5-kbp cDNA showed limited homology with the mouse T-cell lymphoma oncogene and the fes/fps family of kinase-related transforming proteins.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Northern
- Cells, Cultured
- Chick Embryo
- DNA, Viral/genetics
- DNA, Viral/isolation & purification
- Deoxyribonuclease BamHI
- Fusion Proteins, gag-onc/genetics
- Genes, Viral
- Genome, Viral
- Herpesvirus 2, Gallid/genetics
- Herpesvirus 2, Gallid/pathogenicity
- Molecular Sequence Data
- Multigene Family
- Oligodeoxyribonucleotides
- Oncogene Proteins, Viral/genetics
- Oncogenes
- Open Reading Frames
- Poly A/genetics
- Poly A/isolation & purification
- Polymerase Chain Reaction
- Protein-Tyrosine Kinases/genetics
- Proto-Oncogene Proteins/genetics
- Proto-Oncogenes
- RNA/genetics
- RNA/isolation & purification
- RNA, Messenger
- Restriction Mapping
- Sequence Homology, Amino Acid
Collapse
Affiliation(s)
- F Peng
- Laboratory of Virology, Tampa Bay Research Institute, St. Petersburg, Florida 33716
| | | | | | | | | |
Collapse
|
17
|
Chen XB, Sondermeijer PJ, Velicer LF. Identification of a unique Marek's disease virus gene which encodes a 38-kilodalton phosphoprotein and is expressed in both lytically infected cells and latently infected lymphoblastoid tumor cells. J Virol 1992; 66:85-94. [PMID: 1309266 PMCID: PMC238263 DOI: 10.1128/jvi.66.1.85-94.1992] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The identification of unique Marek's disease (MD) virus (MDV) antigens expressed not only in lytically infected cells but also in latently infected MD lymphoblastoid tumor cell lines is important in understanding the molecular mechanisms of latency and transformation by MDV, an oncogenic lymphotropic herpesvirus of chickens. Through cDNA and nucleotide sequence analysis, an open reading frame (designated the pp38 ORF) which encodes a predicted polypeptide of 290 amino acids was identified in BamHI-H. Demonstration that the pp38 ORF spans the junction of the MDV long unique and long internal repeat regions (MDV has an alphaherpesvirus genome structure) precludes the presence of the gene encoding the B-antigen complex (gp100, gp60, and gp49) in the same region of BamHI-H, where it was originally thought to exist. Duplication of the complete pp38 ORF was not observed in BamHI-D, but part of it (encoding 45 amino acids) was found in the long terminal repeat region of the fragment. By use of trpE-pp38 fusion proteins, antisera against pp38 were prepared. By immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a predominant virus-specific 38,000-dalton polypeptide (designated pp38) and a minor 24,000-dalton polypeptide (designated p24) were found. No precursor-product relationship was found between pp38 and p24 by pulse-chase analysis, and only pp38 was detected by Western blot (immunoblot) analysis with antiserum to pp38. pp38 was found to be phosphorylated and present in oncogenic serotype 1-but not nononcogenic serotype 3-infected cells. Expression of the gene encoding pp38 was relatively insensitive to phosphonoacetic acid inhibition, suggesting that pp38 may belong to one of the early classes of herpesvirus proteins. pp38 was also detected in the latently infected MSB-1 lymphoblastoid tumor cell line. The detection of antibody against pp38 in immune chicken sera indicates that pp38 is an immunogen in birds with MD. Most of the properties described here for a protein detected by methods based on finding the ORF first are identical to those of a 38-kDa phosphoprotein reported by others, suggesting that they are the same. Collectively, the data reported here provide (i) more definitive information on the complete ORF of another MDV gene and the protein that it encodes, (ii) clarification of the gene content within a specific region of the MDV genome, and (iii) the molecular means to conduct further studies to determine whether pp38 plays a role in MDV latency and transformation.
Collapse
MESH Headings
- Amino Acid Sequence
- Antibodies, Viral/immunology
- Antigens, Viral/genetics
- Antigens, Viral/immunology
- Antigens, Viral/metabolism
- Base Sequence
- Blotting, Northern
- Cells, Cultured
- DNA, Viral/analysis
- DNA, Viral/metabolism
- Electrophoresis, Polyacrylamide Gel
- Gene Expression
- Genes, Viral
- Herpesvirus 2, Gallid/genetics
- Herpesvirus 2, Gallid/physiology
- Molecular Sequence Data
- Open Reading Frames
- Phosphoproteins/genetics
- Phosphoproteins/immunology
- Phosphoproteins/metabolism
- Recombinant Fusion Proteins/immunology
- Recombinant Fusion Proteins/metabolism
- Restriction Mapping
- Transcription, Genetic
- Tumor Cells, Cultured
- Viral Proteins/genetics
- Viral Proteins/immunology
- Viral Proteins/metabolism
- Virus Replication
Collapse
Affiliation(s)
- X B Chen
- Department of Microbiology and Public Health, Michigan State University, East Lansing 48824-1101
| | | | | |
Collapse
|
18
|
Coussens PM, Tieber VL, Mehigh CS, Marcus M. Identification of a novel transcription factor, ACF, in cultured avian fibroblast cells that interacts with a Marek's disease virus late gene promoter. Virology 1991; 185:80-9. [PMID: 1656607 DOI: 10.1016/0042-6822(91)90756-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Interactions between factors in duck and chick embryo fibroblast (DEF and CEF, respectively) nuclear extracts and the Marek's disease virus (MDV) gp57-65 gene promoter were investigated. Results of in vitro transcription and gel mobility-shift assays indicated that multiple cellular factors interact with 5'-flanking sequences of the MDV gp57-65 gene. One sequence-specific DNA binding activity (termed ACF for avian cell factor(s)) was identified by interaction of DEF and CEF nuclear extract proteins with a particular site (nucleotides -193 to -177) in the MDV gp57-65 gene promoter. Binding of ACF to its apparent recognition sequence, contained within the 17-bp oligonucleotide 5'-CTAGTTTACTTGTTTGT-3' (ACF-12), was highly sequence-specific. Radiolabeled ACF-12 oligonucleotide bound significant ACF protein in the presence of a 400-fold molar excess of unlabeled nonspecific competitor DNA. A similar amount of specific competitor completely abolished ACF binding to probe DNA. Deletion of the ACF binding site from MDV gp57-65 gene promoters linked to a chloramphenicol acetyltransferase (CAT) reporter gene reduced expression of CAT activity by twofold relative to that seen with a gp57-65 promoter-CAT construct containing an intact ACF binding site. Transfection inhibition assays using double-stranded ACF binding site competitors reduced steady-state levels of gp57-65 mRNA in MDV infected cells by over twofold relative to those in control infected cells. Introduction of a similar amount of nonspecific double-stranded oligonucleotide had no adverse effect on gp57-65 mRNA levels. These data suggest that ACF is important for efficient expression of gp57-65.
Collapse
Affiliation(s)
- P M Coussens
- Department of Animal Science, Michigan State University, East Lansing 48824
| | | | | | | |
Collapse
|
19
|
Levy H, Maray T, Davidson I, Malkinson M, Becker Y. Identification of viral proteins encoded by two DNA fragments of herpesvirus of turkeys (HVT). Virus Genes 1991; 5:227-33. [PMID: 1722930 DOI: 10.1007/bf00568972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Herpesvirus of turkeys (HVT) vaccine is used worldwide to immunize chickens against Marek's disease (MD). Polyclonal antiserum directed against one virus cross-reacts with proteins of the other, while only 5% homology at the DNA level was demonstrated between the two viruses. A partial library of HVT DNA fragments ranging from 1.5 to 13.5 kbp in size was constructed in pBR 322. Under stringent conditions of hybridization (low salt concentration, 10% dextran sulfate at 68 degrees C), two of the cloned HVT DNA fragments (13.5 and 11.0 kbp) hybridized to three MDV DNA fragments: BamHI-C, D, and G. The 13.5 kbp fragment detected two transcripts of 1.8 and 3.0 kb in RNA extracted from HVT-infected chicken embryo fibroblasts, while the 11.0 kbp fragment detected three transcripts of 1.6, 2.0, and 3.0 kb in the extracted RNA. Using hybrid selection, specific RNA was isolated by hybridization with the two cloned HVT DNA fragments and then was translated in vitro using rabbit reticulocyte lysate, and the resulting proteins were analyzed by NaDodSO4-PAGE. The RNA selected by the two HVT DNA fragments coded for a 30 kD protein and for several smaller proteins 10-20 kD in size, while the RNA selected by the 11.0 kb HVT DNA fragment was translated into a 40 kD protein. Immunoprecipitation of these in vitro synthesized proteins with hyperimmune anti-HVT chicken serum showed that they were of viral origin.
Collapse
Affiliation(s)
- H Levy
- Department of Molecular Virology, Faculty of Medicine, Hebrew University, Jerusalem, Israel
| | | | | | | | | |
Collapse
|
20
|
Schat KA. Importance of cell-mediated immunity in Marek's disease and other viral tumor diseases. Poult Sci 1991; 70:1165-75. [PMID: 1649464 DOI: 10.3382/ps.0701165] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Cell-mediated immune (CMI) responses to viral tumor diseases are often used as examples of the importance of antiviral and antitumor immunity in chickens. Especially, reticuloendotheliosis virus (REV) and Marek's disease herpesvirus (MDV) are used as models to study the development of cytotoxic T-lymphocytes against viral and tumor antigens and activation of natural killer (NK) cells. Major histocompatibility complex Class I-restricted, antiviral cytotoxic T-lymphocytes expressing CD4-/CD8+ markers are induced after infection with REV. Thus far, this is the only example of Class I-restricted cytotoxic T-lymphocytes in chickens. Antiviral cytotoxic T-lymphocytes may be induced by infection with MDV or by vaccination, but conclusive evidence has not yet been provided. Antitumor responses have not been demonstrated against REV-induced tumors. Although Marek's disease is often used as an example for the importance of antitumor immunity, there is a lack of convincing data demonstrating antitumor immunity mediated by cytotoxic T-lymphocytes. Activation of NK cells by MDV infection or vaccination is probably an important part of CMI responses against Marek's disease viral antigens but not against tumor antigens.
Collapse
Affiliation(s)
- K A Schat
- Department of Avian and Aquatic Animal Medicine, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853
| |
Collapse
|
21
|
Sugaya K, Bradley G, Nonoyama M, Tanaka A. Latent transcripts of Marek's disease virus are clustered in the short and long repeat regions. J Virol 1990; 64:5773-82. [PMID: 1700823 PMCID: PMC248728 DOI: 10.1128/jvi.64.12.5773-5782.1990] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Marek's disease herpesvirus (MDV) induces tumors in chickens, and lymphoblastoid cells derived from such tumors contain the viral genome in a latent state and do not produce infectious virus. Poly(A)+ RNAs extracted from MDV-induced kidney lymphoma cells and from MKT-1 cells, a nonproducing lymphoblastoid cell line derived from a tumor induced by MDV, were electrophoretically separated under denaturing conditions, transferred to a solid substrate, and hybridized with labeled DNA probes representing approximately 95% of the virus genome. These analyses revealed 29 viral RNA transcripts in the kidney lymphoma and 32 viral RNAs in MKT-1 cells. In both instances, the transcripts hybridized to a restricted region comprising approximately 20% of the MDV genome located in the repeats flanking the long and short unique sequences and in the adjacent unique sequences. The sizes of the transcripts derived from kidney lymphoma and MKT-1 cells and the distributions of the homologous regions in the viral genome were very similar. The most abundant transcripts were homologous to the BamHI I2 fragment. The results suggest that expression of the MDV genome in MKT-1 cells closely reflects the expression of the MDV genome in tumors. The gene expression over extended regions of the genome is in concordance with that observed in latent gammaherpesviruses rather than that observed in latent alphaherpesviruses.
Collapse
Affiliation(s)
- K Sugaya
- Laboratory of Virology, Tampa Bay Research Institute, St. Petersburg, Florida 33716
| | | | | | | |
Collapse
|
22
|
Schat KA, Buckmaster A, Ross LJ. Partial transcription map of Marek's disease herpesvirus in lytically infected cells and lymphoblastoid cell lines. Int J Cancer 1989; 44:101-9. [PMID: 2545632 DOI: 10.1002/ijc.2910440119] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Marek's disease herpesvirus (MDV) can cause either a productive-restrictive or lytic infection, a latent infection or can transform thymus-derived lymphocytes. RNA was extracted from infected chicken embryo fibroblasts (CEF) or from lymphoblastoid tumour cell lines. Some of the infected CEF were treated with 200 micrograms/ml cycloheximide to identify immediate early (IE) transcripts, and others with 1 microM 1-(2-fluoro-2-deoxy-B-D-arabinofuranosyl)-5-methyluracil (FMAU), an inhibitor of herpesvirus DNA synthesis to identify early transcripts. An extensive Northern blot analysis was carried out using DNA probes spanning almost the complete MDV genome. In the lytically infected CEF at least 66 discrete transcripts were detected, ranging in size from 9.1 kb to 0.6 kb. Eleven IE transcripts were identified, of which 8 were mapped in the genome segment consisting of the IRL, IRS, US and TRS. Six transcripts were identified as early genes. In the MD lymphoblastoid cell lines MDCC-HPI, a non-producer cell line, and MDCC-CU41, a non-expression cell line, 4 and 7 transcripts were detected, respectively. These RNAs were transcribed from IE genes located mainly in the repeat sequences flanking UL and US and in US. Treatment of the lymphoblastoid cell lines with 20 micrograms/ml 5-iodo-2-deoxyuridine resulted in the additional transcription of 1 RNA species in HPI and 9 in CU41. Most of the transcripts present in lytically infected cells were also detected in MDCC-CU36, a cell line with a high percentage of antigen-positive cells (expression cell line).
Collapse
Affiliation(s)
- K A Schat
- AFRC Institute for Animal Health, Houghton Laboratory, Huntingdon, Cambs, UK
| | | | | |
Collapse
|