Inhibition of Marek's Disease Virus DNA Transfection by a Sequence Containing an Alphaherpesvirus Origin of Replication and Flanking Transcriptional Regulatory Elements

Morgan, Robin; Cantello, John L.; Claessens, Johnny A. J.; Sondermeyer, P.

doi:10.2307/1591297

“…This could affect the binding of the UL9 Protein (originbinding protein) to this region thus reducing the replicative fitness of these attenuated strains. Compounding this is the fact that sequences encompassing the origin of replication (Ori) form a palindrome resembling microRNAs and this may be significant in light of research demonstrating plasmids containing the Ori sequences can reduce virus titers in transient assays [45]. Moreover, Niikura et al [46] have identified a cellular protein termed growth related translationally controlled tumor protein or (TCTP) that binds RLORF12 using a two hybrid approach.…”

Section: Discussionmentioning

confidence: 99%

Polymorphisms in the repeat long regions of oncogenic and attenuated pathotypes of Marek’s disease virus 1

Spatz

¹

,

Silva

²

2006

View full text Add to dashboard Cite

The nucleotide sequences of the terminal repeat long (TR(L)) and internal repeat long regions (IR(L)) in the genomes of 13 strains of Marek's disease virus type 1 (MDV-1) were determined and represent the largest collection of sequencing data from a contiguous region (12.8 kb) in the serotype 1 genomes. The collection of strains used in this study has been well characterized with respect to their virulence and contains members of each pathotype (4 attenuated, 1 mildly virulent, 3 virulent, 2 very virulent and 3 very virulent plus). It has previously been reported that two loci (meq and RLORF4) in the RL regions are likely to encode virulence factors based on comparative genomic studies involving vaccine and virulent strains. Additional studies using knockout mutants have provided stronger evidence that indeed RLORF4 and meq or the overlapping genes 23 kD and RLORF6 are involved in virulence. In this report, we provide evidence that additional open reading frames (ORFs) in the RL regions differ significantly between the extremes of the pathotypes (attenuated vs. nonattenuated). A deletion of 10 base pairs has been identified in RLORF12 from two attenuated strains CVI988 BP-5, p48 and RM-1, p40; and the lower virulence strain JM/102W. A deletion of 40 bp was also identified in RLORF4 of the attenuated strain R2/23, passage 106. A 177 bp insertion within the meq loci has been identified in most of the attenuated strains examined. Interestingly, R2/23 did not contain this insertion but instead truncated proteins are predicted for the three overlapping ORFs (meq, 23 kD and RLORF6) due to a frameshift mutation. Single nucleotide polymorphisms (SNPs), which loosely partition between attenuated and nonattenuated strains, have been identified in the ORFs encoding RLORF12, RLORF8, meq, 23 kD, RLORF6, RLORF4, RLORF3 and ICP0 and three previously unidentified short ORFs: MHLS, MLHG and MPSG. Although no single nucleotide polymorphism in the RL regions could predict virulence, their overall contribution to virulence can now be examined in defined mutants containing additional insertions or deletions in ORFs, suspected of encoding virulence factors, identified by this research.

show abstract

“…Because an ori sequence is found in the bidirectional promoter of pp38 and the 1.8 kb family RNA gene (BamHI-H), it is likely that in the late T9 cells MDV is unable to replicate. [56][57][58] Indeed, immunodiffusion performed with blood samples from chickens inoculated with late T9 cells did not reveal antibody against MDV (data not shown), confirming the fact that late T9 cells did not produce infectious viruses and were no longer capable of inducing Marek's disease.…”

Section: Discussionmentioning

confidence: 67%

Alterations of the MDV oncogenic regions in an MDV transformed lymphoblastoid cell line

Rouzic

¹

,

Thoraval²,

Afanassieff³

et al. 2002

Molecular Pathology

View full text Add to dashboard Cite

Aims: Lymphoblastoid cell lines derived from Marek's disease virus (MDV) induced tumours have served as models of MDV latency and transformation. They are stable and can be cultured with no detectable MDV genomic alterations upon repeated passaging. An MDV transformed lymphoblastoid T cell line (T9 cell line) has been reported to contain a disrupted MDV BamHI-H fragment and a Rous associated virus insertional activation of the c-myb protooncogene. In an attempt to define the respective participation of c-myb and MDV in the transformed phenotype of T9 cells, an analysis of MDV oncogenic sequences (BamHI-H, BamHI-A, and EcoQ fragments) was performed in these cells. Methods: Using two different passages of the T9 cell line (late and early passages), the organisation of the MDV oncogenic regions and their expression in these cells were analysed. In vivo assessment of the oncogenicity of the virus contained within these cells was assessed by injecting them into 1 day old chickens. Results: In T9 cells maintained in culture for up to six months (late T9), the MDV ICP4 gene was disrupted, whereas the meq gene was actively transcribed. The alterations of the MDV genome in these cells correlated with the inability of the virus to induce the classic signs of Marek's disease in 1 day old chickens. However, early T9 cells submitted to a limited number of passages induced classic MDV pathogenicity, as efficiently as the MDV control cell line (T5), and did not show gross structural changes in the oncogenic MDV sequences. Conclusions: Although the expression pattern of the MDV oncogenes in early T9 cells was identical to the one reported for other MDV transformed cells, longterm culture of an MDV transformed cell line containing a RAV insertional activation of the c-myb protooncogene led to the disruption of the MDV BamHI-H and BamHI-A oncogenic regions. In the late T9 cells MEQ was the only detected MDV oncoprotein. These results suggest that in the late T9 cells the truncated MYB protein compensates for the loss of MDV oncoproteins and reinforce the possibility that MEQ and MYB cooperate in the maintenance of the transformed state and the tumorigenic potential of these cells.

show abstract

“…Because an ori sequence is found in the bidirectional promoter of pp38 and the 1.8 kb family RNA gene (BamHI-H), it is likely that in the late T9 cells MDV is unable to replicate. [56][57][58] Indeed, immunodiffusion performed with blood samples from chickens inoculated with late T9 cells did not reveal antibody against MDV (data not shown), confirming the fact that late T9 cells did not produce infectious viruses and were no longer capable of inducing Marek's disease.…”

Section: Discussionmentioning

confidence: 78%

Correction

2002

Molecular Pathology

0

View full text Add to dashboard Cite

Aims: Lymphoblastoid cell lines derived from Marek's disease virus (MDV) induced tumours have served as models of MDV latency and transformation. They are stable and can be cultured with no detectable MDV genomic alterations upon repeated passaging. An MDV transformed lymphoblastoid T cell line (T9 cell line) has been reported to contain a disrupted MDV BamHI-H fragment and a Rous associated virus insertional activation of the c-myb protooncogene. In an attempt to define the respective participation of c-myb and MDV in the transformed phenotype of T9 cells, an analysis of MDV oncogenic sequences (BamHI-H, BamHI-A, and EcoQ fragments) was performed in these cells. Methods: Using two different passages of the T9 cell line (late and early passages), the organisation of the MDV oncogenic regions and their expression in these cells were analysed. In vivo assessment of the oncogenicity of the virus contained within these cells was assessed by injecting them into 1 day old chickens. Results: In T9 cells maintained in culture for up to six months (late T9), the MDV ICP4 gene was disrupted, whereas the meq gene was actively transcribed. The alterations of the MDV genome in these cells correlated with the inability of the virus to induce the classic signs of Marek's disease in 1 day old chickens. However, early T9 cells submitted to a limited number of passages induced classic MDV pathogenicity, as efficiently as the MDV control cell line (T5), and did not show gross structural changes in the oncogenic MDV sequences. Conclusions: Although the expression pattern of the MDV oncogenes in early T9 cells was identical to the one reported for other MDV transformed cells, longterm culture of an MDV transformed cell line containing a RAV insertional activation of the c-myb protooncogene led to the disruption of the MDV BamHI-H and BamHI-A oncogenic regions. In the late T9 cells MEQ was the only detected MDV oncoprotein. These results suggest that in the late T9 cells the truncated MYB protein compensates for the loss of MDV oncoproteins and reinforce the possibility that MEQ and MYB cooperate in the maintenance of the transformed state and the tumorigenic potential of these cells.

show abstract

Inhibition of Marek's Disease Virus DNA Transfection by a Sequence Containing an Alphaherpesvirus Origin of Replication and Flanking Transcriptional Regulatory Elements

Cited by 6 publications

References 35 publications

Polymorphisms in the repeat long regions of oncogenic and attenuated pathotypes of Marek’s disease virus 1

Polymorphisms in the repeat long regions of oncogenic and attenuated pathotypes of Marek’s disease virus 1

Alterations of the MDV oncogenic regions in an MDV transformed lymphoblastoid cell line

Correction

Contact Info

Product

Resources

About