Herpes Viruses II Gammaherpesviruses PDF

Medical Virology - Level H Lecture 19 Herpesviruses II -Gammaherpesviruses Professor Andrew Davidson E46 Biomedical Sciences Building [email protected] 19/11/24  Overview Epstein Barr virus (EBV) introd...

Medical Virology - Level H Lecture 19 Herpesviruses II -Gammaherpesviruses Professor Andrew Davidson E46 Biomedical Sciences Building [email protected] 19/11/24  Overview Epstein Barr virus (EBV) introduction and impact EBV primary and persistent infection EBV - cancer associations and potential mechanisms involved EBV and multiple sclerosis EBV vaccines Kaposi’s sarcoma virus (KSHV)  Intended Learning Outcomes. Describe the uniting features of human Gammaherpesviruses. Describe the epidemiology of EBV and recognise the diseases associated with EBV infection. Understand how EBV causes primary and persistent infections. Understand the EBV gene expression patterns in different stages of latency and their relationship to EBV induced cancers. Describe the evidence for the association of EBV infection and multiple sclerosis. Describe the epidemiology and diseases caused by KSHV infection.  Subfamily Gammaherpesvirinae wh humans for long time evolved a. is causelatent long en Gammaherpesviruses have a very restricted host range. - In vitro all members infect lymphoblastoid cells and some cause infection in epithelial or fibroblastic cells. Typically target B or T lymphocytes. Four genera – Lymphocryptovirus, Rhadinovirus, Percavirus and Macavirus genus – Lymphocryptovirus: mainly infect humans and non-human primates and includes human gammaherpesvirus 4 = Epstein Barr Virus – Rhadinovirus: mainly infect human and non-human primates and includes human gammaherpesvirus 8 = Kaposi’s Sarcoma Virus infection in program -important dsDNA genome - – EBV ~ 170 kbp, ~ 100 protein coding genes, also non-coding RNAs and miRNAs (>46) – KSHV ~ 165 kbp, at least 80 protein coding genes, also non-coding RNAs and miRNAs – In both cases linear dsDNA in particles but found as a closed circular dsDNA in the nucleus of persistently infected cells “episome”  Epstein Barr Virus Causes most common persistent asymptomatic virus infection in humans. Ubiquitous, infects 90-95% of the human population as a life long persistent infection. Mostly causes benign infections. First human tumour virus to be discovered (1964). Associated with a range of diseases – infectious mononucleosis (glandular fever) – human cancers (200,000 / year ; 1.8% of all cancer deaths) – multiple sclerosis Primarily found in the body as a latent infection of B cells. dsDNA genome completely sequenced in 1984.  Epidemiology Transmission by saliva. Globally, most people are infected by the age of 5-8. long covid could be reactivated EBr ? EBV infection at a young age typically asymptomatic. - In resource-rich environments EBV infection is frequently delayed until adolescence or early adulthood. Prevalence of infectious mononucleosis dependent on age of initial EBV infection in different countries. In many cases EBV associated cancers most prevalent in specific geographical areas.  EBV associated diseases Typically causes a subclinical persistent infection Primary Infection: - Infectious mononucleosis (IM) “kissing disease”, glandular fever - Chronic IM chronic disease/immune dysfunction - Fatal IM X-linked genetic T-cell defect Fatal lymphoproliferative (B-cell) disorders in various immunosuppressive conditions:. untreated HIV after organ transplant / AIDS affect people v/immonosuppression eg > - - associated wIB alls Burkitt’s lymphoma (BL): chromosome translocations, c-myc Hodgkin’s and non-Hodgkin’s lymphomas: 50% EBV positive Nasopharyngeal carcinoma (NPC): Gastric carcinomas: (EBV- associated gastric carcinoma), Natural killer (NK) / T cell lymphomas Multiple sclerosis: Direct association EBV: Structure Icosshedron  EBNA proteins EBV: dsDNA genome Antigens. Epstein Barrin Nuclear Fig. 3. Young et al (2016) Nat Rev Cancer v16:789-802 states latent Important progression. + cancer vimo of Linear form virion I Important in listic replication - lots of MicroRNAs and non coding Circular form RNAs. cell: episome > - genome circillarises in nucleus transcribed w/ diff promoters. genes -  EBV: Primary and persistent infection Viru needs to get into B cells which are main recevoir in In latent infected cells , Virus > - almost silent in some stages. the body. is few a net >produces no putersso very - a ↓ those alls as infected. infects epilthial alls First virus ↓ (difficult to model laboratory in good at evading host emmine response. passes through epithelial cells wel Or it allow can become in those periodically cells replicating > - understood. wont activated this is not well trancytosis ,. called process ↳ could be other viral infections event. stress ↓ ↳ could be reactivated they naive Balls do become comes into contact W/ ↳ When they cells ready to become more like plasma infects them. Secrete. antibodies ↓ > - Virus then produced in larger amounts , can to Mucosa lead to cancer could wells more infect epithelial cells > -> Infectedis Adenoids (tonsils) in these. cells (e. g. Symphoid nissue ↳ Virus can be secreted in Saliva at ↓ this point where it can infect other. centre germinal individuals. - Cells to more - B alls disseminate ↳ this During B cell , some become latent memory and vines They slowly proliferate cells for diration can resid in these can lifetime of individual of f controlled by Level of proliferation and NK all response Tall maintained by ↳ This balanced is. immune system good Fig. 1 Escalante (2022) Frontiers in Immunology v13:867918 EBV: Infection of primary target cells. There are a few Gp350/220 (two component - molecule Viral glycoproteins glycopaten is a on that helps vines enter surface of cells Balls + EBV that help. epithelial - A main vacune target. Virt enter host allo. CD35 CD21 , , EBV can also Neurophilin) and MHC Klass 11 all Utilise other interact /viral receptors on epithecial. proteins alls such as Ephrin Receptor Al Cas well as CD21 , Nueuropilin D The attachment protein gp350/220 and four core fusion glycoproteins—gB, gp42, and the gH/gL complex—are important for EBV entry into both epithelial cells and B-cells and targets for neutralizing antibodies Infectious mononucleosis (IM) - Glandular fever As age increases to young adult primary EBV infection more often causes IM. – Linked to host genetics. > - depending on HLA type > - higher predisposition to glandular fever. High replication of EBV in B cells in periphery and oral cavity. Clytic cycle) Up to 50% of resting memory B cells may be infected in acute phase of IM. Characterised by a rapid expansion in NK cells and CD8+ T cells. (swelling glands) of Strong inflammatory response and emergence of atypical lymphocytes (attack cells) on B – High fever, severe sore throat, swollen glands, extreme tiredness, ongoing tonsillitis – Recovery typically after 2-3 weeks but extreme tiredness can last for months (infectious for up to 7 weeks before symptoms) t reactivation could cause more  EBV: Primary and persistent infection study these -hard to processes I producea only preun ↓ enject Typically ↳ v rancyrosel · important in episome replication. no proteins is alls W/EBV , replicatein surtching a betwe e but different produced do RNA molecules produced immortalise them , is no viral proteins produced cells in lab then no antigen presentation immortalised eliminated alls to infection no mem B cells are different ① NK cells B by in body. of cells > lytic achiranaa ses - + can transcylose epithelium + Shed of vint > - many proteins produced are immune ·Typicales modulatory ↓ these cells would undergo apoplosis but LMPs are mimics these products which collection can - depending on of B cell proteins mainten. them are expressed involved in different of viral genes processes · is in a diffene all ↳can trigger a all the vires latency stated don't die. Initic stage > - expression lytic that activate of lots of genes production of vine particle Ballo+ from cello. B cells selection of genes Fig. 1. Munz (2019) Nat Rev Microbiology v17:693-700 > In other expressed > - EBNA proteins non-coding , RNAs , miRNAs  EBV: Primary and persistent infection Fig. 1 | Models of latent Epstein–Barr virus infection to reach viral persistence. Epstein–Barr virus (EBV) persists in circulating memory B cells without viral protein expression (latency 0). Only during homeostatic proliferation of these memory B cells is EBNA1 transiently expressed. After transfer across the mucosal epithelium from the saliva, the virus infects B cells in secondary lymphoid tissues such as the tonsils. This infection leads to Epstein–Barr nuclear antigen 2 (EBNA2)-dependent proliferation of infected cells. Infected memory B cells may differentiate directly into latency 0 after infection. Alternatively , EBV drives naive B cells into full latency III transformation (during which EBNA1, EBNA2, EBNA3A–EBNA3C, EBNA- LP, LMP1 and LMP2 are expressed) and this activation leads to their differentiation via latency IIa- expressing germinal centre B cells (in which EBNA1, LMP1 and LMP2 are expressed) to latency 0 memory B cells. This germinal centre differentiation pathway is thought to provide premalignant precursors of the EBV-associated diffuse large B cell lymphoma (DLBCL), Hodgkin’s lymphoma and Burkitt’s lymphoma. From circulating memory B cells, EBV reactivates lytic replication upon plasma cell differentiation and elevated lytic EBV replication can also be found in the EBV- associated plasmacytoma primary effusion lymphoma (PEL). This lytic reactivation most likely allows epithelial cell infection from the basolateral side for efficient shedding into the saliva and virus transmission. This epithelial cell infection gives rise to EBV- associated carcinomas, for example nasopharyngeal carcinoma (NPC). Expression of the viral non- coding RNAs(EBV- encoded small RNAs (EBERs), BART and BHRF1 microRNAs) is also depicted. EBNALP, EBNA eader peptide; LMP, latent membrane protein.  EBV: Latency In latently infected cells the genome is maintained as a transcriptionally silent genome. > - can be between 10-100 episomes in. alls The genome is circularised and if the cell divides then the virus genome is replicated and each daughter cell gets a copy of the virus. tether genome + division. helps ensue episome > - This is achieved by a virus protein called EBNA1 which binds to the virus genome and interacts with dividing chromatin. EBNA1 is amongst a group at least nine EBNA encoded proteins produced during various stages of latency, but it is the only EBV protein expressed in all types of latency.  Function of EBV latent proteins U. important for episane replication Some gene products promote cell growth others inhibit it. Farrell (2019) Ann Review of Pathology v14:29-53  Function of EBV latent non-coding RNAs EBV was the first human virus found to encode microRNAs viral (miRNAs) lots of transcription and translation of host cell mRNAs + also on gene expression itself. - of affects BART miRNAs -- 44 mature BART miRNAs -- Maintain latency by targeting EBV lytic genes, modulating LMP1 expression, targeting pro-apoptotic proteins, impairing host immune responses and inactivating pro-apoltic genes tumour suppressor genes (e g.. -- Can drive tumour growth in vivo BHRF1 miRNAs -- Three BHRF1 miRNAs are encoded -- Important for B cell transformation Interact /transiphon factors in nucleus : + sulovent innate emmie response. - EBV-encoded RNA 1 (EBER1) and EBER2 -- Are highly abundant non-coding RNAs -- Interact with a number of proteins and contribute to the activation of innate immunity.Young et al (2016) Nat Rev Cancer v16:789-802 Patterns of latent cycle gene expression in EBV. Latency III: – Required for B cell transformation: EBNA1, EBNA2, EBNA3A, EBNA3C, LP, LMP1, LMP2A, and BHFR1 miRNAS – Not required for B cell transformation: EBNA3B, EBER1, EBER2 and BART miRNAs Latency II: – EBNA1, LMP1, LMP2A, EBER1, EBER2 and BART miRNAs Latency I: – EBNA1, EBER1, EBER2 and BART miRNAs · Latenency O > - no proteins produced. From Farrell (2019) Ann Review of Pathology v14:29-53  Latency patterns and cancer. tumour look - Take lissue from ,. at mRNAs expressed Table 3: Farrell (2019) Ann Review of Pathology v14:29-53 Burkitt lymphoma (BL) - naturally in B cells you get Won gene rearrangements ocuring. immortalised EBV infects - cells are ↳ involved in discover mutations. carry different and cancer not vins of BL: aggressive non-Hodgkin B-cell lymphoma (1-5 %) Associated with EBV, HIV and chromosomal translocations resulting in c-myc oncogene overexpression. Endemic, sporadic and immunodeficiency types of BL. Endemic BL: coincident with malaria in equatorial Africa, Brazil, New Guinea etc - - sub Saharan africa Doctor Virologists Investigation led to discovery of EBV (Burkitt, Epstein, Barr, Achong) Endemic BL is nearly 100% EBV + Tumours are at a state of EBV latency Sporadic BL: is only 89% EBV +, but accounts for 40% of EBU blocks apoploors pediatric lymphomas. > - C-myc translocation- overexpression Chromosome cello wh translocation ↳ EBV proteins prevent apoptosis of cells with c-myc proliferat overexpression. - can occur in B cells - rearrangement Treatment: intensive chemotherapy and hospitalization (60- 90% long-term survival)  Burkitt lymphoma (BL) and EBV - Discovered EBV shortly before discovery moving 10 Bristol. Fellow of Royal Society > - - (1921 – 2024) Sir Epstein (FRS) Professor of Pathology at Bristol (1968-1985) Burkitt lymphoma (BL) and EBV discovery  Burkitt lymphoma (BL) and EBV - When they transporting no the were UR tissues , they discovery lr werehel a ↳ hissues formed some Humours spontaneous. is that printerated ↓ Vines Turous They found in viruses that resembled herpes  Nasopharyngeal carcinoma (NPC) Epithelial cell tumour associated with EBV latency, EBV almost always present in malignant epithelial cells. Found predominantly in SE Asia and southern China. Major health issue (2018: 129,000 new cases and 73,000 cases deaths). Co-factors: environment (diet, smoking etc) genetic predisposition (HLA type), fermented/salted fish EBV subtypes (?). ↳ cells Carcinoma · of epithelial  Nasopharyngeal carcinoma (NPC) Mechanism of cellular transformation not clear. Infection of epithelial cells in the laboratory does not immortalize cells or give rise to long term persistent infection. – cells lacking cyclin-dependent kinase inhibitors or overexpressing cyclin D1 can be persistently infected. – therefore, cells may already contain specific mutations before EBV transformation - cello have Nasopharyngeal carcinoma (NPC) already undergone - genetic environmental some form of damage > - initiating progression s cell a tumorigenic ↓ EBV infection is a prometer further driving nasophageal no allo a concery state  Nasopharyngeal carcinoma (NPC) Mechanism of cellular transformation not clear. Infection of epithelial cells in the laboratory does not immortalize cells or give rise to long term persistent infection. – cells lacking cyclin-dependent kinase inhibitors or overexpressing cyclin D1 can be persistently infected. – therefore, cells may already contain specific mutations before EBV transformation EBV genomes in cancer are clonal. EBV infection is detected in high-grade pre-invasive lesions in NPC but not in low- grade disease. Suggests that EBV infection must precede clonal selection of cells. Therefore likely that EBV only persistently infects cells that already have accumulated specific mutations. Expression of EBV genes is variable – latency II “like” – some of these genes (LMP1) often not expressed – whereas some lytic genes (BARF) are. Association of EBV lytic replication with clinical manifestations. ~higher Chanceifiniti a I U Fig. 5. Munz (2019) Nat Rev Microbiology v17:693-700  EBV and multiple sclerosis. Multiple sclerosis (MS): most common chronic inflammatory and neurodegenerative disease of the central nervous system (2.8 million people worldwide). cause of MS is complex and multifactorial: genetic susceptibility, environmental factors, lack of sun/vitamin D, smoking, obesity etc. For many years scientists have tried to associate the presence of infectious agents with disease. EBV a prime candidate and has been studied as a risk factor for MS different in many epidemiological studies. ↳ exposure to im anogens. But: – Difficult to establish causality – long period between disease initiation and clinical disease expression. – 95% of people infected with EBV - most of them do not develop MS.  EBV and MS: evidence Epidemiological Low rates of MS in areas with more childhood infections Increased risk of MS with a history of infectious mononucleosis Increased risk of MS with EBV seroconversion Decreased risk of MS in seronegative individuals Immunological Increased levels of EBV specific antibodies in MS MS risk alleles enriched control of EBV transcription control by EBNA2 Deficient cytotoxic T lymphocyte BV in MS EBV reactive OCBs (oligoclonal bands – immunoglobulin markers) Molecular mimicry between EBNA1 and CNS antigens Virological Increased shedding of EBV in saliva of paediatric patients with MS EBV BZLF1 (early lytic cycle protein) in MS lesions Pro-survival influence of EBV latency genes on memory B cells EBV loads correlate with T- bet+CXCR3+memory cells and IFNγ production Soldan and Lieberman (2022) Nat Rev Microbiology: doi: 10.1038/s41579-022-00770-5  EBV latest evidence Epidemiological evidence Bjornevick et al (2022) Science v375 – 10 million young adults in the US army surveyed over 20 years (1993-2013) – 801 individuals developed MS – Serological screening demonstrated a 32-fold increase of developing MS after EBV seroconversion – Only 1 person developed MS with no evidence of EBV infection – EBV infection necessary but insufficient for the development of MS What is the mechanism? Lanz et al (2022) Nature v603 – Antibodies from the CSF of MS patients recognize EBNA-1 and a host cellular CNS protein – “GlialCAM” – Immunisation of mice with an EBNA-1 peptide led to increased inflammation in the CNS – Molecular mimicry – But the cross-reactive antibodies only in 25% of MS patients so potentially other cross-reactive antibodies involved.  EBV vaccines Aiming to prevent / reduce the severity of infection with EBV. Reduce the incidence of infectious mononucleosis and the incidence of EBV-associated malignancies and autoimmune diseases. Vaccines in development for 40 years: 36 preclinical and 4 clinical trials Spurred on by recent findings linking EBV and MS. Vaccine development hindered by: – undefined correlates of immune protection – lack of an appropriate animal model – lack of knowledge regarding the ideal EBV antigens for vaccination – lack of knowledge regarding ideal vaccine delivery platform Number of new vaccines in phase I clinical trials (safety/immune response) Moderna mRNA vaccine (Jan 22). – targets four glycoprotein antigens on the virus particle – trial in 18–30 year old healthy adults NIH gp350-Ferritin nanoparticle vaccine (May 22) – gp350 present on the virus surface and virus-infected cells. – primary target for neutralizing antibodies  Kaposi‘s sarcoma virus (KHSV) One of the most recently discovered human tumour viruses (1994). Causative agent of all forms of Kaposi’s sarcoma (KS) in combination with impaired host immunity. KSHV can infect several different cell types, including endothelial, B cells, epithelial cells, dendritic cells, monocytes and fibroblasts. Latency can be established in B-cells and endothelial cells. repithelial allo KS tumours are of endothelial lineage – highly aggressive in immunosuppressed / AIDS patients Epidemiological forms of KS > immure - seresence. Cesarman et al (2019) Nature Reviews 5:9  KSHV seroprevalence ↳ host genetics ↳ environmental factors but also infections. ↳ virses not just HIV circulating diff Herpes vine Cesarman et al (2019) Nature Reviews 5:9  KHSV: Diseases Kaposi’s sarcoma endothelial cell cancer with an inflammatory component highly heterogenous histopathology Primary effusion lymphoma (PEL) B cell lymphoma that most commonly affects body cavities, including the peritoneal, pleural and pericardial cavities PEL tumour cells infected with KSHV and frequently EBV Multicentric Castleman disease (MCD) lymphoproliferative disorder presenting with generalized lymphadenopathy – infected cells have plasmablastic morphology symptoms are thought to be caused by the excessive production of inflammatory cytokines, such as IL-6 most cases occur in KSHV and HIV infection Treatment bolstering the immune system eg cART when HIV present different chemotherapy regimes KS tumours may however reoccur  Extra Reading Soldan, S and Lieberman, P.M. (2022) Epstein–Barr virus and multiple sclerosis. Nature Reviews Microbiology, https://doi.org/10.1038/s41579-022-00770-5 Farrell, P.J. (2019) Epstein–Barr virus and cancer. Annual Review of Pathology: Mechanisms of Disease v14:29-53 https://doi.org/10.1146/annurev-pathmechdis- 012418-013023 Münz, C. (2019) Latency and lytic replication in Epstein–Barr virus-associated oncogenesis. Nature Reviews Microbiology v17:691-700 https://doi.org/10.1038/s41579-019-0249-7 Young et al., (2016) Epstein–Barr virus: more than 50 years old and still providing surprises. Nature Reviews Cancer v16: 789-802 https://doi.org/10.1038/s41579-022- 00770-5 Cesarman et al. (2019) Kaposi sarcoma. Nature Reviews: Disease Primer 5:9 https://doi.org/10.1038/s41572-019-0060-9