scholarly journals Comparison of Genetic Variability at Multiple Loci across the Genomes of the Major Subtypes of Kaposi’s Sarcoma-Associated Herpesvirus Reveals Evidence for Recombination and for Two Distinct Types of Open Reading Frame K15 Alleles at the Right-Hand End

1999 ◽  
Vol 73 (8) ◽  
pp. 6646-6660 ◽  
Author(s):  
Lynn J. Poole ◽  
Jian-Chao Zong ◽  
Dolores M. Ciufo ◽  
Donald J. Alcendor ◽  
Jennifer S. Cannon ◽  
...  
Keyword(s):  
Amino Acid ◽  
Kaposi's Sarcoma ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
Amino Acid Identity ◽  
Open Reading Frame ◽  
Subtype C ◽  
Reading Frame ◽  
Right Hand ◽  
Amino Acid Variability

ABSTRACT Kaposi’s sarcoma (KS)-associated herpesvirus or human herpesvirus 8 (HHV8) DNA is found consistently in nearly all classical, endemic, transplant, and AIDS-associated KS lesions, as well as in several AIDS-associated lymphomas. We have previously sequenced the genes for the highly variable open reading frame K1 (ORF-K1) protein from more than 60 different HHV8 samples and demonstrated that they display up to 30% amino acid variability and cluster into four very distinct evolutionary subgroups (the A, B, C, and D subtypes) that correlate with the major migrationary diasporas of modern humans. Here we have extended this type of analysis to six other loci across the HHV8 genome to further evaluate overall genotype patterns and the potential for chimeric genomes. Comparison of the relatively conserved ORF26, T0.7/K12, and ORF75 gene regions at map positions 0.35, 0.85, and 0.96 revealed typical ORF-K1-linked subtype patterns, except that between 20 and 30% of the genomes analyzed proved to be either intertypic or intratypic mosaics. In addition, a 2,500-bp region found at the extreme right-hand side of the unique segment in 45 HHV8 genomes proved to be highly diverged from the 3,500-bp sequence found at this position in the other 18 HHV8 genomes examined. Furthermore, these previously uncharacterized “orphan” region sequences proved to encompass multiexon latent-state mRNAs encoding two highly diverged alleles of the novel ORF-K15 protein. The predominant (P) and minor (M) forms of HHV8 ORF-K15 are structurally related integral membrane proteins that have only 33% overall amino acid identity to one another but retain conserved likely tyrosine kinase signaling motifs and may be distant evolutionary relatives of the LMP2 latency protein of Epstein-Barr virus. The M allele of ORF-K15 is also physically linked to a distinctive M subtype of the adjacent ORF75 gene locus, and in some cases, this linkage extends as far back as the T0.7 locus also. Overall, the results suggest that an original recombination event with a related primate virus from an unknown source introduced exogenous right-hand side ORF-K15(M) sequences into an ancient M form of HHV8, followed by eventual acquisition into the subtype C lineage of the modern P-form of the HHV8 genome and subsequent additional, more recent transfers by homologous recombination events into several subtype A and B lineages as well.

scholarly journals Identification of Kaposin (Open Reading Frame K12) as a Human Herpesvirus 8 (Kaposi’s Sarcoma-Associated Herpesvirus) Transforming Gene

1998 ◽  
Vol 72 (6) ◽  
pp. 4980-4988 ◽  
Author(s):  
Sumitra Muralidhar ◽  
Anne M. Pumfery ◽  
Morad Hassani ◽  
M. Reza Sadaie ◽  
Norio Azumi ◽  
...  
Keyword(s):  
Cell Lines ◽  
Kaposi's Sarcoma ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
Body Cavity ◽  
Open Reading Frame ◽  
Human Herpesvirus 8 ◽  
Reading Frame ◽  
Herpesvirus 8 ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT The recently identified human herpesvirus 8 (HHV-8, or Kaposi’s sarcoma-associated herpesvirus) has been implicated in the etiology of both Kaposi’s sarcoma (KS) and primary effusion (body cavity-based) lymphoma (PEL) (Y. Chang et al., Science 266:1865–1869, 1994; P. S. Moore et al., J. Virol. 70:549–558, 1996). An important feature of the association of HHV-8 with these malignancies is the expression of an abundant, latency-associated 0.7-kb transcript, T0.7 (W. Zhong et al., Proc. Natl. Acad. Sci. USA 93:6641–6646, 1996). T0.7 is found in all stages in nearly all KS tumors of different epidemiologic origin, including AIDS-associated, African endemic, and classical KS (K. A. Staskus et al., J. Virol. 71:715–719, 1997), as well as in a body cavity-based lymphoma-derived cell line, BCBL-1, that is latently infected with HHV-8 (R. Renne et al., Nat. Med. 2:342–346, 1996). T0.7 encodes a unique HHV-8 open reading frame, K12, also known as kaposin. In this study, we report that the kaposin gene induced tumorigenic transformation. Constructs with kaposin expressed either from its endogenous promoter or from a heterologous promoter induced focal transformation upon transfection into Rat-3 cells. All transformed Rat-3 cell lines containing kaposin sequences produced high-grade, highly vascular, undifferentiated sarcomas upon subcutaneous injection of athymic nu/nu mice. Tumor-derived cell lines expressed kaposin mRNA, suggesting a role in the maintenance of the transformed phenotype. Furthermore, kaposin protein was detected in transformed and tumor-derived cells by immunofluorescence and localized to the cytoplasm. More importantly, expression of kaposin protein was also detected in the PEL cell lines BCBL-1 and KS-1. These findings demonstrate the oncogenic potential of kaposin and suggest its possible role in the development of KS and other HHV-8-associated malignancies.

scholarly journals Transcription Pattern of Human Herpesvirus 8 Open Reading Frame K3 in Primary Effusion Lymphoma and Kaposi's Sarcoma

2001 ◽  
Vol 75 (22) ◽  
pp. 11261-11261
Author(s):  
Paola Rimessi ◽  
Angela Bonaccorsi ◽  
Michael Stürzl ◽  
Marina Fabris ◽  
Egidio Brocca-Cofano ◽  
...  
Keyword(s):  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
Open Reading Frame ◽  
Human Herpesvirus 8 ◽  
Reading Frame ◽  
Herpesvirus 8 ◽  
Transcription Pattern

scholarly journals Kaposi's Sarcoma-Associated Herpesvirus (Human Herpesvirus 8) Open Reading Frame 4 Protein (Kaposica) Is a Functional Homolog of Complement Control Proteins

2003 ◽  
Vol 77 (6) ◽  
pp. 3878-3881 ◽  
Author(s):  
Jayati Mullick ◽  
John Bernet ◽  
Akhilesh K. Singh ◽  
John D. Lambris ◽  
Arvind Sahu
Keyword(s):  
Kaposi's Sarcoma ◽  
Expression System ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
Open Reading Frame ◽  
Reading Frame ◽  
Complement Control Proteins ◽  
Functional Homolog ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT The genome analysis of Kaposi's sarcoma-associated herpesvirus (KSHV) has revealed the presence of an open reading frame (ORF 4) with sequence homology to complement control proteins. To assign a function to this protein, we have now expressed this ORF using the Pichia expression system and shown that the purified protein inhibited human complement-mediated lysis of erythrocytes, blocked cell surface deposition of C3b (the proteolytically activated form of C3), and served as a cofactor for factor I-mediated inactivation of complement proteins C3b and C4b (the subunits of C3 convertases). Thus, our data indicate that this KSHV inhibitor of complement activation (kaposica) provides a mechanism by which KSHV can subvert complement attack by the host.

scholarly journals Transcription Pattern of Human Herpesvirus 8 Open Reading Frame K3 in Primary Effusion Lymphoma and Kaposi's Sarcoma

2001 ◽  
Vol 75 (15) ◽  
pp. 7161-7174 ◽  
Author(s):  
Paola Rimessi ◽  
Angela Bonaccorsi ◽  
Michael Stürzl ◽  
Marina Fabris ◽  
Egidio Brocca-Cofano ◽  
...  
Keyword(s):  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
Open Reading Frame ◽  
Human Herpesvirus 8 ◽  
Reading Frame ◽  
Herpesvirus 8 ◽  
Rna Molecules ◽  
Spindle Cells

ABSTRACT Human herpesvirus 8 (HHV-8) is found in immunoblastic B cells of patients with multicentric Castleman's disease (MCD) and, predominantly in a latent form, in primary effusion lymphoma (PEL) cells and Kaposi's sarcoma (KS) spindle cells. Recent studies have shown that upon reactivation, HHV-8 expresses factors that downregulate major histocompatibility class I proteins and coactivation molecules and that may enable productively infected cells to escape cytotoxic T lymphocytes and natural killer cell responses. One of these viral factors is encoded by open reading frame (ORF) K3. Here we show that in PEL cells, ORF K3 is expressed through viral transcripts that are induced very early upon virus reactivation, including bicistronic RNA molecules containing coding sequences from viral ORFs K3 and 70. Specifically, we found that a bicistronic transcript was expressed in the absence of de novo protein synthesis, thereby identifying a novel HHV-8 immediate-early gene product. Several features of the RNA molecules encoding the K3 product, including multiple transcriptional start sites, multiple donor splicing sites, and potential alternative ATG usage, suggest that there exists a finely tuned modulation of ORF K3 expression. By contrast, ORF K3 transcripts are not detected in the majority of cells present in KS lesions that are latently infected by the virus, suggesting that there are other, as-yet-unknown mechanisms of immune evasion for infected KS spindle cells. Nevertheless, because HHV-8 viremia precedes the development of KS lesions and is associated with the recrudescence of MCD symptoms, the prompt expression of ORF K3 in productively infected circulating cells may be important for virus pathogenesis. Thus, molecules targeting host or viral factors that activate ORF K3 expression or inactivate the biological functions of the K3 product should be exploited for the prevention or treatment of HHV-8-associated diseases in at-risk individuals.

scholarly journals Structure of the Open Reading Frame 49 Protein Encoded by Kaposi's Sarcoma-Associated Herpesvirus

2016 ◽  
Vol 91 (2) ◽  
Author(s):  
Kelly Hew ◽  
Saranya Veerappan ◽  
Daniel Sim ◽  
Tobias Cornvik ◽  
Pär Nordlund ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Life Cycle ◽  
Dna Binding ◽  
Protein Interaction ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Open Reading Frame ◽  
Reading Frame ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Herpesviruses alternate between the latent and the lytic life cycle. Switching into the lytic life cycle is important for herpesviral replication and disease pathogenesis. Activation of a transcription factor replication and transcription activator (RTA) has been demonstrated to govern this switch in Kaposi's sarcoma-associated herpesvirus (KSHV). The protein encoded by open reading frame 49 from KSHV (ORF49KSHV) has been shown to upregulate lytic replication in KSHV by enhancing the activities of the RTA. We have solved the crystal structure of the ORF49KSHV protein to a resolution of 2.4 Å. The ORF49KSHV protein has a novel fold consisting of 12 alpha-helices bundled into two pseudodomains. Most notably are distinct charged patches on the protein surface, which are possible protein-protein interaction sites. Homologs of the ORF49KSHV protein in the gammaherpesvirus subfamily have low sequence similarities. Conserved residues are mainly located in the hydrophobic regions, suggesting that they are more likely to play important structural roles than functional ones. Based on the identification and position of three sulfates binding to the positive areas, we performed some initial protein-DNA binding studies by analyzing the thermal stabilization of the protein in the presence of DNA. The ORF49KSHV protein is stabilized in a dose-responsive manner by double-stranded oligonucleotides, suggesting actual DNA interaction and binding. Biolayer interferometry studies also demonstrated that the ORF49KSHV protein binds these oligonucleotides. IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) is a tumorigenic gammaherpesvirus that causes multiple cancers and lymphoproliferative diseases. The virus exists mainly in the quiescent latent life cycle, but when it is reactivated into the lytic life cycle, new viruses are produced and disease symptoms usually manifest. Several KSHV proteins play important roles in this reactivation, but their exact roles are still largely unknown. In this study, we report the crystal structure of the open reading frame 49 protein encoded by KSHV (ORF49KSHV). Possible regions for protein interaction that could harbor functional importance were found on the surface of the ORF49KSHV protein. This led to the discovery of novel DNA binding properties of the ORF49KSHV protein. Evolutionary conserved structural elements with the functional homologs of ORF49KSHV were also established with the structure.

scholarly journals Kaposi's Sarcoma-Associated Herpesvirus Open Reading Frame 57 Encodes a Posttranscriptional Regulator with Multiple Distinct Activities

2000 ◽  
Vol 74 (8) ◽  
pp. 3586-3597 ◽  
Author(s):  
Jessica R. Kirshner ◽  
David M. Lukac ◽  
Jean Chang ◽  
Don Ganem
Keyword(s):  
Posttranscriptional Regulation ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Open Reading Frame ◽  
Luciferase Reporter ◽  
Reading Frame ◽  
Infected Cells ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus ◽  
Coding Potential

ABSTRACT Open reading frame (ORF) 57 of Kaposi's sarcoma-associated herpesvirus (KSHV) encodes a homolog of known posttranscriptional regulators that are essential for replication in other herpesviruses. Here, we examined the expression of this gene and the function(s) of its product. KSHV ORF 57 is expressed very early in infection from a 1.6-kb spliced RNA bearing several in-frame initiation codons. Its product is a nuclear protein that, in transient assays, has little effect on the expression of luciferase reporter genes driven by a variety of KSHV and heterologous promoters. However, ORF 57 protein enhances the accumulation of several viral transcripts, in a manner suggesting posttranscriptional regulation. These transcripts include not only known cytoplasmic mRNAs (e.g., ORF 59) but also a nuclear RNA (nut-1) that lacks coding potential. Finally, ORF 57 protein can also modulate the effects of the ORF 50 gene product, a classical transactivator known to be required for lytic induction. The expression from some (e.g., nut-1) but not all (e.g., tk) ORF 50-responsive promoters can be synergistically enhanced by coexpression of ORF 50 and ORF 57. This effect is not due to upregulation of ORF 50 expression but rather to a posttranslational enhancement of the transcriptional activity of ORF 50. These data indicate that ORF 57 is a powerful pleiotropic effector that can act on several posttranscriptional levels to modulate the expression of viral genes in infected cells.

scholarly journals Identification and functional characterization of a spliced rhesus rhadinovirus gene with homology to the K15 gene of Kaposi's sarcoma-associated herpesvirus

2009 ◽  
Vol 90 (5) ◽  
pp. 1190-1201 ◽  
Author(s):  
Linding Wang ◽  
Marcel Pietrek ◽  
Melanie M. Brinkmann ◽  
Anika Hävemeier ◽  
Irina Fischer ◽  
...  
Keyword(s):  
Kaposi's Sarcoma ◽  
Functional Characterization ◽  
Ectopic Expression ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
Reading Frame ◽  
Protein Isoform ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
The Right ◽  
Kaposi’S Sarcoma Associated Herpesvirus

Rhesus monkey rhadinovirus (RRV) is a gamma-2 herpesvirus related to the human Kaposi's sarcoma-associated herpesvirus (KSHV or human herpesvirus 8). This study identified an alternatively spliced gene at the right side of the RRV genome (strain 17577) between open reading frame 75 and the terminal repeat region. Of its eight exons, the first seven encoded up to 12 transmembrane domains, whilst the eighth exon encoded a predicted C-terminal cytoplasmic domain. Structurally and positionally, this RRV gene therefore resembles the K15 gene of KSHV; it was provisionally named RK15 to avoid confusion with other RRV17577 genes. In ectopic expression studies, the 55 kDa RK15 protein isoform activated the JNK and NF-κB pathways, like the 45 kDa KSHV K15-encoded protein isoform. In contrast to K15, which activates angiogenic and inflammatory cytokines such as interleukin (IL)-8, IL-6 and CCL20, the range of cellular transcripts activated by the RRV K15 homologue was much more restricted, but included IL-6, IL-8 and FGF21. These data suggest functional differences between terminal membrane proteins at the right end of the genomes of Old World primate gamma-2 herpesviruses.

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