Human gammaherpesvirus 8 | |
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Kaposi's sarcoma | |
Virus classification ![]() | |
(unranked): | Virus |
Realm: | Duplodnaviria |
Kingdom: | Heunggongvirae |
Phylum: | Peploviricota |
Class: | Herviviricetes |
Order: | Herpesvirales |
Family: | Orthoherpesviridae |
Genus: | Rhadinovirus |
Species: | Human gammaherpesvirus 8 |
Kaposi's sarcoma-associated herpesvirus (KSHV) is the ninth known human herpesvirus; its formal name according to the International Committee on Taxonomy of Viruses (ICTV) is Human gammaherpesvirus 8, or HHV-8 in short. [1] Like other herpesviruses, its informal names are used interchangeably with its formal ICTV name. This virus causes Kaposi's sarcoma, a cancer commonly occurring in AIDS patients, [2] as well as primary effusion lymphoma, [3] HHV-8-associated multicentric Castleman's disease and KSHV inflammatory cytokine syndrome. [4] It is one of seven currently known human cancer viruses, or oncoviruses. [2] Even after many years since the discovery of KSHV/HHV8, there is no known cure for KSHV associated tumorigenesis.
In 1872, Moritz Kaposi described a blood vessel tumor [5] (originally called "idiopathic multiple pigmented sarcoma of the skin") that has since been eponymously named Kaposi's sarcoma (KS). KS was at first thought to be an uncommon tumor of Jewish and Mediterranean populations until it was later determined to be extremely common throughout sub-Saharan African populations. This led to the first suggestions in the 1950s that this tumor might be caused by a virus. With the onset of the AIDS epidemic in the early 1980s, there was a sudden resurgence of KS affecting AIDS patients, with up to 50% of reported AIDS patients having this tumor—an extraordinary rate of cancer predisposition. [6]
Careful analysis of epidemiologic data by Valerie Beral, Thomas Peterman and Harold Jaffe, [7] led these investigators to propose that KS is caused by an unknown sexually transmitted virus that rarely causes tumors unless the host becomes immunosuppressed, as in AIDS.[ citation needed ]
As early as 1984, scientists reported seeing herpesvirus-like structures in KS tumors examined under electron microscopy. Scientists had been searching for the agent causing KS, and over 20 agents were proposed as the possible cause, including cytomegalovirus and HIV itself. The pathogen was ultimately identified in 1994 by Yuan Chang and Patrick S. Moore, a wife and husband team at Columbia University, through the isolation of DNA fragments from a herpesvirus found in a KS tumor in an AIDS patient. [8] [9] [10] Chang and Moore used representational difference analysis, or RDA, to find KSHV by comparing KS tumor tissue from an AIDS patient to his own unaffected tissue. The idea behind this experiment was that if a virus causes KS, the genomic DNA in the two samples should be precisely identical except for DNA belonging to the virus. In their initial RDA experiment, they isolated two small DNA fragments that represented less than 1% of the actual viral genome. These fragments were similar (but still distinct from) the known herpevirus sequences, indicating the presence of a new virus. Starting from these fragments, this research team was then able to sequence the entire genome of the virus less than two years later.[ citation needed ]
The discovery of this herpesvirus sparked considerable controversy and scientific in-fighting until sufficient data had been collected to show that indeed KSHV was the causative agent of Kaposi's sarcoma. [11] The virus is now known to be a widespread infection of people living in sub-Saharan Africa; intermediate levels of infection occur in Mediterranean populations (including Lebanon, Saudi Arabia, Italy, and Greece) and low levels of infection occur in most Northern European and North American populations. Gay and bisexual men are more susceptible to infection (through still unknown routes of sexual transmission) whereas the virus is transmitted through non-sexual routes in developing countries.[ citation needed ]
KSHV is a herpesvirus, and is a large double-stranded DNA virus with a protein covering that packages its nucleic acids, called the capsid, which is then surrounded by an amorphous protein layer called the tegument, and finally enclosed in a lipid envelope derived in part from the cell membrane. KSHV has a genome which is approximately 165,000 nucleic acid bases in length. The viral genome consists of a ~145 kilobase-long unique region, encoding all of expressed viral genes, which is flanked by ~20-30 kilobases of terminal repeat sequences. [12] Each terminal repeat unit is 801 bp in length, has 85% G+C content and is oriented in a repetitive head-to-tail fashion. KSHV is a rhadinovirus, a Herpes genus remarkable since it has stolen numerous genes from host cells including, in the case of KSHV, genes that encode for complement-binding protein, IL-6, BCL-2, cyclin-D, a G protein-coupled receptor, interferon regulatory factor and Flice inhibitory protein (FLIP), as well as DNA synthesis proteins including dihydrofolate reductase, thymidine kinase, thymidylate synthetase, DNA polymerase and many others. While no other human tumor virus possesses these same genes, other tumor viruses target the same cellular pathways illustrating that at a basic level, all tumor viruses appear to attack the same cellular control pathways, so-called tumor suppressor pathways.[ citation needed ]
Crucial for the entry of KSHV into cells [13] are the EPH receptor A2, [14] Hrs, [15] TSG101, [16] and a few integrins (whose identity has yet to be confirmed). [17] After infection, the virus enters into lymphocytes via macropinosomes.[ citation needed ] Once the virus newly infects a cell, the lipid membrane is shed and the virion travels to the nucleus. The viral genome is released where it circularizes into an episome through a poorly understood process that appears to involve homologous recombination of the terminal repeats.[ citation needed ] The viral episome is chromatinized upon entry into the host cell nucleus. [18]
After entry, the virus typically remains in a latent ("quiet") state. Only a subset of genes that are encoded in the KSHV latency associated region (KLAR) are expressed during latency, including latency-associated nuclear antigen (LANA), vFLIP, vCyclin and 12 microRNAs. Latency is the hallmark of all KSHV-associated etiologies known to date including all KSHV-associated oncogenesis. It has been shown that both protein coding genes such as LANA and noncoding genes (microRNAs) encoded in KLAR are important for KSHV associated tumorigenesis. To study the functions of microRNAs, a detailed protocol of bacmid mutagenesis and a complete set of cell-lines carrying microRNA deletion mutants have been established and are available as a resource to researchers. [19] Additionally, it has been shown that vFLIP and vCyclin interfere with the TGF-β signaling pathway indirectly by inducing the oncogenic host mir17-92 cluster. [20] These observations represents a novel mechanism that may be important for KSHV tumorigenesis and angiogenesis, a hallmark of KS.[ citation needed ]
During latency, LANA is the only viral protein that is required for viral replication, which is carried out by the host replication machinery. LANA tethers the viral DNA to cellular chromosomes, inhibits p53 and retinoblastoma protein and suppresses viral genes needed for full virus production and assembly ("lytic replication"). Why only a subset of virus genes expressed during latency is not fully understood. But it has been shown that the latency associated gene expression can be explained in part by a characteristic epigenetic state that KSHV episome acquires during latency. LANA plays an important role during latency, regulating both host and virus transcripts and binding to multiple active promoters; it also associates with the host protein hSET1 that creates H3K4me3 marks in chromatin. [21]
Various signals such as inflammation may provoke the virus to enter into lytic replication. The primary viral protein responsible for the switch between latent and lytic replication is known as the ORF50 Replication Transactivation Activator (RTA). When cell signaling conditions activate the generation of RTA, it in turn activates synthesis of a stereotypic cascade of secondary and tertiary viral proteins that ultimately make components of the virus capsid and also the DNA synthesis enzymes required to replicate the virus genome. [22] During lytic replication, it is believed that the virus genome is replicated as a continuous linear molecule off of an episome (so-called rolling circle model). As each unit genome is replicated, it is cut within the terminal repeat region, and then packaged into a virus particle (virion). The virus then becomes enveloped with a lipid membrane as it transits the nucleus and the cytoplasm to exit the cell. Thus, whereas KSHV genome is circular in the nucleus of latently infected cells, it is packaged into infectious viruses as a linear molecule. When the virus enters into lytic replication, thousands of virus particles can be made from a single cell, which usually results in death of the infected cell.[ citation needed ]
It was discovered in 2020 that infection with the SARS-CoV-2 virus, the virus which causes COVID-19, may induce the lytic reactivation of KSHV in the human body, causing the herpes virus to cease latency and begin the formation of cancerous cells. Further, it was discovered that some medications used to treat the infection with SARS-CoV-2, namely Nafamostat and Azithromycin, ended up promoting the production of mature virions, "... potentially inducing KSHV lytic reactivation." [23]
The mechanisms by which the virus is contracted are not well understood. Healthy individuals can be infected with the virus and show no signs or symptoms, due to the immune system's ability to keep the infection in check. Infection is of particular concern to the immunocompromised. Cancer patients receiving chemotherapy, AIDS patients, and organ transplant patients are all at a high risk of showing signs of infection.[ citation needed ].
Recent advances in sequencing technologies have uncovered that virus is chromatinized during latency. It has also been shown that virus encoded microRNA manipulates and interacts not only with host mRNA but also deregulate host long non-coding RNA (lncRNA). [24] More recently, circularRNAs (circRNAs) are recently discovered in both EBV and KSHV [25] [26] [27]
Infection with this virus is thought to be lifelong, but a healthy immune system will keep the virus in check. Many people infected with KSHV will never show any symptoms. Kaposi's sarcoma occurs when someone who has been infected with KSHV becomes immunocompromised due to AIDS, medical treatment, or, very rarely, aging.
KSHV is a known causative agent of four diseases: [4] [28]
In the 1970s, the global prevalence rate for HHV-8 was 2 to 10%. [29] The seroprevalence of HHV-8 varies significantly geographically and infection rates in northern European, southeast Asian, and Caribbean countries are between 2-4%, [30] in Mediterranean countries at approximately 10%, and in sub-Saharan African countries at approximately 40%. [31] In South America, infection rates are low in general but are high among Amerindians. [32] Even within individual countries, significant variation can be observed across different regions, with infection rates of about 19.2% in Xinjiang compared to about 9.5% in Hubei, China. [33] Although seroprevalence has been consistently shown to increase with age in a linear manner, [33] [34] [35] [36] countries with high infection rates may see higher seroprevalence in younger age groups. [37] Educational level has shown an inverse correlation with infection rates. [34] [35] Individuals infected with HIV-1 or genital warts are generally more likely to be co-infected with HHV-8. [31] [33] [38]
In countries with low seroprevalence, HHV-8 is primarily limited to AIDS and KS patients. [39] In countries with high seroprevalence, infection is frequent in childhood, [40] indicating a likely mother-to-child transmission by saliva. [41] [42] In a Zambian survey, all children with KS had mothers who were positive for HHV-8, whereas not all children whose mothers had KS were HHV-8 positive. [43] In another Zambian survey, 13.8% of children were seropositive for HHV-8 by age 4. [44] Seroprevalence has not been shown to vary significantly because of gender or marital status. [36]
The most recent common ancestor of this virus in the Mediterranean, Iran, and Xinjiang, China, has been estimated to have evolved 29,872 years (95% highest probability density 26,851–32,760 years) ago. [45] the most recent common ancestor for viruses isolated in Xinjiang was 2037 years (95% highest probability density 1843–2229 years) ago. Given the historical links between the Mediterranean and Xinjiang during the Roman period it seems likely that this virus was introduced to Xinjiang along the Silk Road. The mutation rate was estimated to be 3.44×10−6 substitutions per site per year (95% highest probability density 2.2×10−6 to 4.71×10−6). However, the global distribution of different genotypes of KSHV and the potential transmission path need further studies.[ citation needed ]
Typing of isolates is based on the variable K1 membrane protein. Six types are recognised (A–F). [46]
Since persons infected with KSHV will asymptomatically give the virus, caution should be used by sex partners in having unprotected sex and activities where saliva might be shared during sexual activity. Prudent advice is to use condoms when needed and avoid deep kissing with partners who may have KSHV infections.
Kaposi's sarcoma is usually a localized tumor that can be treated either surgically or through local irradiation. Chemotherapy with drugs such as liposomal anthracyclines or paclitaxel may be used, particularly for invasive disease. Antiviral drugs, such as ganciclovir, that target the replication of herpesviruses such as KSHV have been used to successfully prevent development of Kaposi's sarcoma, [47] although once the tumor develops these drugs are of little or no use. For patients with AIDS-KS, the most effective therapy is highly active antiretroviral therapy to reduce HIV infection. [48] AIDS patients receiving adequate anti-HIV treatment may have up to a 90% reduction in Kaposi's sarcoma occurrence.
Although KSHV affects the host immune system, there is ample chance for clinical intervention to recover this change. One challenge is overexpression inhibitory of target cell repress immune. Under longtime inflammation stimulation, the target cell becomes unable to respond, which leads to an exhausted phenotype. The activation immunotherapies can revive and enhance immune cell function. Comparing to other immunotherapies, therapies targeting the anti-programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) has been a great success. Because of KSHV infection, the monocytes increase the expression of PD-1, which is an inhibitory molecule, and cause immune escape in many tumor types. There is high PD-1 expression in NK cells from KS-HIV patients and cause exhausted phenotype. The anti-PD-1 antibody, (nivolumab or pembrolizumab), demonstrated a significant antitumor effect. Nivolumab is currently an ongoing phase I clinical trial, and Pembrolizumab has shown its function in treatment for HIV and KS patients in phase I and is in a phase II trial for treatment. A thalidomide analog medicine – Pomalidomide was also granted by the FDA in 2011. Pomalidomide was shown to recover the expression of MHC-1, which help cell display intracellular proteins to cytotoxic T cells, and it also can repress the expression of PD-L1 and increase the CD8+ T cell killing. [49]
KSHV encodes for ~90 genes and multiple non-coding RNAs, such as microRNAs. [50] The "ORF" genes are named based on genome position of the homologous genes in the first rhadinovirus described, herpesvirus saimiri. The "K" genes are unique to KSHV, Some KSHV genes have well-characterized functions, while others remain uncharacterized.[ citation needed ]
ORF2 – dihydrofolate reductase
ORF8 – gB – envelope glycoprotein involved in viral entry
ORF9 – Pol8 – DNA polymerase required for viral DNA replication
ORF10 – regulates RNA export and responses to type I IFNs
ORF16 – vBcl2
ORF18, ORF24, ORF30, ORF31, ORF34, ORF66 – viral transcription factors required for the expression of late genes
ORF21 – vTK – thymidine kinase
ORF22 – gH – envelope glycoprotein involved in viral entry
ORF23 – uncharacterized
ORF25, ORF26 and ORF65 – capsid proteins
ORF33 – involved in viral particle formation
ORF34 – unclear function
ORF35 – unclear function, mutant does not express early viral genes
ORF36 – vPK – viral protein kinase with multiple roles in replication cycle
ORF37 – SOX – dual function protein – DNase activity required for genome packaging and RNase activity regulates host gene expression
ORF38 – involved in viral particle formation
ORF39 – gM – envelope glycoprotein
ORF40 and ORF41 – helicase and primase – DNA replication
ORF42 – uncharacterized
ORF45 – tegument protein, binds and prevents dephosphorylation of p90 ribosomal S6 kinases (RSKs) and ERK for modulate the ERK/RSK MAPK signaling pathway
ORF47 – gL – envelope glycoprotein involved in viral entry
ORF49 – may be required for viral gene expression
ORF50 – RTA, replication and transcription activator – the major transcription factor driving lytic KSHV reactivation
ORF52 – KicGAS – tegument protein required for formation of virions and inhibition of cGAS DNA sensing
ORF53 – gN – envelope glycoprotein
ORF55 – uncharacterized
ORF57 – MTA – regulates RNA stability, export and translation of viral genes
ORF59 – PF–8 – polymerase processivity factor, accessory subunit of viral DNA polymerase
ORF67 and ORF69 – nuclear egress
ORF70 – thymidylate synthase
ORF72 – vCyclin
ORF73 – LANA, latency-associated nuclear antigen– tethers genome to chromosome during latency, also regulates host gene expression. A cytoplasmic form of LANA may inhibit activation of immune responses.
ORF74 – vGPCR
ORF75 – FGARAT
PAN, polyadenylated nuclear RNA – non–coding linear and circular RNAs
miRNAs (mirKs) – viral microRNAs expressed during latency to regulate proliferation and cell death
K1 – involved in oncogenesis
K2 – Interleukin 6 homolog, Q2HRC7
K3 and K5 – ubiquitin E3 ligases – regulates antigen presentation
K4 – vCCL2 – chemokine
K4.1 – vCCL3 – chemokine
K8 – transcriptional repressor – modulates chromatin
K8.1 – envelope glycoprotein
K9 – vIRF1, viral interferon regulatory factor 1
K10 – vIRF4. A circular RNA (circRNA) is also generated from this locus.
K10.5 – vIRF3 (initially designated LANA2), is expressed during latency in PEL cell lines, but is also a bona fide lytic factor, like all of the vIRFs. [51]
K11 – vIRF2
K12 – kaposin
K13 – vFLIP
The Epstein–Barr virus (EBV), formally called Human gammaherpesvirus 4, is one of the nine known human herpesvirus types in the herpes family, and is one of the most common viruses in humans. EBV is a double-stranded DNA virus. Epstein–Barr virus (EBV) is the first identified oncogenic virus, that is a virus that can cause cancer. EBV establishes permanent infection in humans. It causes infectious mononucleosis and is also tightly linked to many malignant diseases (cancers). Various vaccine formulations underwent testing in different animals or in humans. However, none of them were able to prevent EBV infection and no vaccine has been approved to date.
Rhadinovirus is a genus of viruses in the order Herpesvirales, in the family Herpesviridae, in the subfamily Gammaherpesvirinae. Humans and other mammals serve as natural hosts. There are 12 species in this genus. Diseases associated with this genus include: Kaposi's sarcoma, primary effusion lymphoma and multicentric Castleman's disease, caused by Human gammaherpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV). The term rhadino comes from the Latin fragile, referring to the tendency of the viral genome to break apart when it is isolated.
An oncovirus or oncogenic virus is a virus that can cause cancer. This term originated from studies of acutely transforming retroviruses in the 1950–60s, when the term oncornaviruses was used to denote their RNA virus origin. With the letters RNA removed, it now refers to any virus with a DNA or RNA genome causing cancer and is synonymous with tumor virus or cancer virus. The vast majority of human and animal viruses do not cause cancer, probably because of longstanding co-evolution between the virus and its host. Oncoviruses have been important not only in epidemiology, but also in investigations of cell cycle control mechanisms such as the retinoblastoma protein.
Primary effusion lymphoma (PEL) is classified as a diffuse large B cell lymphoma. It is a rare malignancy of plasmablastic cells that occurs in individuals that are infected with the Kaposi's sarcoma-associated herpesvirus. Plasmablasts are immature plasma cells, i.e. lymphocytes of the B-cell type that have differentiated into plasmablasts but because of their malignant nature do not differentiate into mature plasma cells but rather proliferate excessively and thereby cause life-threatening disease. In PEL, the proliferating plasmablastoid cells commonly accumulate within body cavities to produce effusions, primarily in the pleural, pericardial, or peritoneal cavities, without forming a contiguous tumor mass. In rare cases of these cavitary forms of PEL, the effusions develop in joints, the epidural space surrounding the brain and spinal cord, and underneath the capsule which forms around breast implants. Less frequently, individuals present with extracavitary primary effusion lymphomas, i.e., solid tumor masses not accompanied by effusions. The extracavitary tumors may develop in lymph nodes, bone, bone marrow, the gastrointestinal tract, skin, spleen, liver, lungs, central nervous system, testes, paranasal sinuses, muscle, and, rarely, inside the vasculature and sinuses of lymph nodes. As their disease progresses, however, individuals with the classical effusion-form of PEL may develop extracavitary tumors and individuals with extracavitary PEL may develop cavitary effusions.
Patrick S. Moore is an American virologist and epidemiologist who co-discovered together with his wife, Yuan Chang, two different human viruses causing the AIDS-related cancer Kaposi's sarcoma and the skin cancer Merkel cell carcinoma. Moore and Chang have discovered two of the seven known human viruses causing cancer. The couple met while in medical school together and were married in 1989 while they pursued fellowships at different universities.
Yuan Chang is a Taiwanese-born American virologist and pathologist who co-discovered together with her husband, Patrick S. Moore, the Kaposi's sarcoma-associated herpesvirus (KSHV) and Merkel cell polyomavirus, two of the seven known human oncoviruses.
Human herpesvirus 6 (HHV-6) is the common collective name for human betaherpesvirus 6A (HHV-6A) and human betaherpesvirus 6B (HHV-6B). These closely related viruses are two of the nine known herpesviruses that have humans as their primary host.
HHV Latency Associated Transcript is a length of RNA which accumulates in cells hosting long-term, or latent, Human Herpes Virus (HHV) infections. The LAT RNA is produced by genetic transcription from a certain region of the viral DNA. LAT regulates the viral genome and interferes with the normal activities of the infected host cell.
Herpesviridae is a large family of DNA viruses that cause infections and certain diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word ἕρπειν, referring to spreading cutaneous lesions, usually involving blisters, seen in flares of herpes simplex 1, herpes simplex 2 and herpes zoster (shingles). In 1971, the International Committee on the Taxonomy of Viruses (ICTV) established Herpesvirus as a genus with 23 viruses among four groups. As of 2020, 115 species are recognized, all but one of which are in one of the three subfamilies. Herpesviruses can cause both latent and lytic infections.
Viral transformation is the change in growth, phenotype, or indefinite reproduction of cells caused by the introduction of inheritable material. Through this process, a virus causes harmful transformations of an in vivo cell or cell culture. The term can also be understood as DNA transfection using a viral vector.
Gammaherpesvirinae is a subfamily of viruses in the order Herpesvirales and in the family Herpesviridae. Viruses in Gammaherpesvirinae are distinguished by reproducing at a more variable rate than other subfamilies of Herpesviridae. Mammals serve as natural hosts. There are 43 species in this subfamily, divided among 7 genera with three species unassigned to a genus. Diseases associated with this subfamily include: HHV-4: infectious mononucleosis. HHV-8: Kaposi's sarcoma.
Murid gammaherpesvirus 68 (MuHV-68) is an isolate of the virus species Murid gammaherpesvirus 4, a member of the genus Rhadinovirus. It is a member of the subfamily Gammaherpesvirinae in the family of Herpesviridae. MuHV-68 serves as a model for study of human gammaherpesviruses which cause significant human disease including B-cell lymphoma and Kaposi's sarcoma. The WUMS strain of MuHV-68 was fully sequenced and annotated in 1997, and the necessity of most of its genes in viral replication was characterized by random transposon mutagenesis.
Merkel cell polyomavirus was first described in January 2008 in Pittsburgh, Pennsylvania. It was the first example of a human viral pathogen discovered using unbiased metagenomic next-generation sequencing with a technique called digital transcriptome subtraction. MCV is one of seven currently known human oncoviruses. It is suspected to cause the majority of cases of Merkel cell carcinoma, a rare but aggressive form of skin cancer. Approximately 80% of Merkel cell carcinoma (MCC) tumors have been found to be infected with MCV. MCV appears to be a common—if not universal—infection of older children and adults. It is found in respiratory secretions, suggesting that it might be transmitted via a respiratory route. However, it has also been found elsewhere, such as in shedded healthy skin and gastrointestinal tract tissues, thus its precise mode of transmission remains unknown. In addition, recent studies suggest that this virus may latently infect the human sera and peripheral blood mononuclear cells.
The latency-associated nuclear antigen (LANA-1) or latent nuclear antigen is a Kaposi's sarcoma-associated herpesvirus (KSHV) latent protein initially found by Moore and colleagues as a speckled nuclear antigen present in primary effusion lymphoma cells that reacts with antibodies from patients with KS. It is the most immunodominant KSHV protein identified by Western-blotting as 222–234 kDa double bands migrate slower than the predicted molecular weight. LANA has been suspected of playing a crucial role in modulating viral and cellular gene expression. It is commonly used as an antigen in blood tests to detect antibodies in persons that have been exposed to KSHV.
Kaposi's sarcoma (KS) is a type of cancer that can form masses on the skin, in lymph nodes, in the mouth, or in other organs. The skin lesions are usually painless, purple and may be flat or raised. Lesions can occur singly, multiply in a limited area, or may be widespread. Depending on the sub-type of disease and level of immune suppression, KS may worsen either gradually or quickly. Except for Classical KS where there is generally no immune suppression, KS is caused by a combination of immune suppression and infection by Human herpesvirus 8.
Large B-cell lymphoma arising in HHV8-associated multicentric Castleman's disease is a type of large B-cell lymphoma, recognized in the WHO 2008 classification. It is sometimes called the plasmablastic form of multicentric Castleman disease. It has sometimes been confused with plasmablastic lymphoma in the literature, although that is a dissimilar specific entity. It has variable CD20 expression and unmutated immunoglobulin variable region genes.
Eva Henriette Gottwein is a virologist and Associate Professor of Microbiology-Immunology at Northwestern University Feinberg School of Medicine in Chicago, Illinois. The main focus of her research is the role of viral miRNAs involved in herpesviral oncogenesis. Gottwein is member of Robert H. Lurie Comprehensive Cancer Center of Northwestern University. Her contributions as a member include the focus on how encoded miRNAs target and function in the human oncogenic herpesvirus Kaposi's sarcoma-associated herpesvirus known as KSHV.
Human herpes viruses, also known as HHVs, are part of a family of DNA viruses that cause several diseases in humans. One of the most notable functions of this virus family is their ability to enter a latent phase and lay dormant within animals for extended periods of time. The mechanism that controls this is very complex because expression of viral proteins during latency is decreased a great deal, meaning that the virus must have transcription of its genes repressed. There are many factors and mechanisms that control this process and epigenetics is one way this is accomplished. Epigenetics refers to persistent changes in expression patterns that are not caused by changes to the DNA sequence. This happens through mechanisms such as methylation and acetylation of histones, DNA methylation, and non-coding RNAs (ncRNA). Altering the acetylation of histones creates changes in expression by changing the binding affinity of histones to DNA, making it harder or easier for transcription machinery to access the DNA. Methyl and acetyl groups can also act as binding sites for transcription factors and enzymes that further modify histones or alter the DNA itself.
Dean Hamilton Kedes is an American scientist in the field of virology and current director of the medical scientist training program at the University of Virginia school of medicine.
HSV epigenetics is the epigenetic modification of herpes simplex virus (HSV) genetic code.