Guinea pig herpes like virus is a gamma herpesvirus.

Guinea Pig Herpes-Like Virus (GPHLV) is a virus isolated from leukemic guinea pigs with herpes virus-like morphology described by Hsiung and Kaplow in 1969. GPHLV transformed embryonic cells from Syrian hamsters or rats, which were tumorigenic in adult animals. Herein, we present the genomic sequence of GPHLV strain LK40 as a reference for future molecular analysis. GPHLV has a broad host tropism and replicates efficiently in Guinea pig, Cat, and Green African Monkey-derived cell lines. GPHLV has a GC content of 35.45%. The genome is predicted to encode at least 75 open-reading frames (ORFs) with 84% (63 ORFs) sharing homology to human Kaposi Sarcoma Associated Herpes Virus (KSHV). Importantly, GPHLV encodes homologues of the KSHV oncogenes, vBCL2 (ORF16), vPK (ORF36), viral cyclin (v-cyclin, ORF72), the latency associated nuclear antigen (LANA, ORF73), and vGPCR (ORF74). GPHLV is a Rhadinovirus of Cavia porcellus, and we propose the formal name of Caviid gamma herpesvirus 1 (CaGHV-1). GPHLV can be a novel small animal model of Rhadinovirus pathogenesis with broad host tropism.

E3 Ubiquitin Ligases in Gammaherpesviruses and HIV: A Review of Virus Adaptation and Exploitation.

For productive infection and replication to occur, viruses must control cellular machinery and counteract restriction factors and antiviral proteins. Viruses can accomplish this, in part, via the regulation of cellular gene expression and post-transcriptional and post-translational control. Many viruses co-opt and counteract cellular processes via modulation of the host post-translational modification machinery and encoding or hijacking kinases, SUMO ligases, deubiquitinases, and ubiquitin ligases, in addition to other modifiers. In this review, we focus on three oncoviruses, Epstein-Barr virus (EBV), Kaposi's sarcoma herpesvirus (KSHV), and human immunodeficiency virus (HIV) and their interactions with the ubiquitin-proteasome system via viral-encoded or cellular E3 ubiquitin ligase activity.

Simian homologues of human herpesviruses and implications for novel viral introduction to free-living mountain gorillas.

The endangered mountain gorilla (Gorilla beringei beringei) in Rwanda, Uganda, and the Democratic Republic of Congo is frequently in contact with humans through tourism, research activities, and illegal entry of people into protected gorilla habitat. Herpesviruses, which are ubiquitous in primates, have the potential to be shared in any setting where humans and gorillas share habitat. Based on serological findings and clinical observations of orofacial ulcerated lesions resembling herpetic lesions, an alpha-herpesvirus resembling human herpes simplex virus type 1 (HSV-1) has long been suspected to be present in human-habituated mountain gorillas in the wild. While the etiology of orofacial lesions in the wild has not been confirmed, HSV-1 has been suspected in captively-housed mountain gorillas and confirmed in a co-housed confiscated Grauer's gorilla (Gorilla beringei graueri). To better characterize herpesviruses infecting mountain gorillas and to determine the presence/absence of HSV-1 in the free-living population, we conducted a population-wide survey to test for the presence of orally shed herpesviruses. DNA was extracted from discarded chewed plants collected from 294 individuals from 26 groups, and samples were screened by polymerase chain reaction using pan-herpesvirus and HSV-1-specific assays. We found no evidence that human herpesviruses had infected free-ranging mountain gorillas. However, we found gorilla-specific homologs to human herpesviruses, including cytomegaloviruses (GbbCMV-1 and 2), a lymphocryptovirus (GbbLCV-1), and a new rhadinovirus (GbbRHV-1) with similar characteristics (i.e., timing of primary infection, shedding in multiple age groups, and potential modes of transmission) to their human counterparts, human cytomegalovirus, Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus, respectively.

Leukemic histiocytic sarcoma in a captive common squirrel monkey (Saimiri sciureus) with Saimiriine Gammaherpesvirus 2 (Rhadinovirus), Saimiri sciureus lymphocryptovirus 2 (Lymphocryptovirus) and Squirrel monkey retrovirus (ß-Retrovirus) coinfection.

Hematopoietic neoplasia other than lymphoma and leukemia is uncommon among non-human primates. Herein, we provide the first evidence of occurrence of leukemic histiocytic sarcoma in a captive common squirrel monkey with Saimiriine Gammaherpesvirus 2 (Rhadinovirus), Saimiri sciureus lymphocryptovirus 2 (Lymphocryptovirus), and Squirrel monkey retrovirus (ß-Retrovirus) coinfection.

A Recombinant Rhesus Monkey Rhadinovirus Deleted of Glycoprotein L Establishes Persistent Infection of Rhesus Macaques and Elicits Conventional T Cell Responses.

A replication-competent, recombinant strain of rhesus monkey rhadinovirus (RRV) expressing the Gag protein of SIVmac239 was constructed in the context of a glycoprotein L (gL) deletion mutation. Deletion of gL detargets the virus from Eph family receptors. The ability of this gL-minus Gag recombinant RRV to infect, persist, and elicit immune responses was evaluated after intravenous inoculation of two Mamu-A*01+ RRV-naive rhesus monkeys. Both monkeys responded with an anti-RRV antibody response, and quantitation of RRV DNA in peripheral blood mononuclear cells (PBMC) by real-time PCR revealed levels similar to those in monkeys infected with recombinant gL+ RRV. Comparison of RRV DNA levels in sorted CD3+ versus CD20+ versus CD14+ PBMC subpopulations indicated infection of the CD20+ subpopulation by the gL-minus RRV. This contrasts with results obtained with transformed B cell lines in vitro, in which deletion of gL resulted in markedly reduced infectivity. Over a period of 20 weeks, Gag-specific CD8+ T cell responses were documented by major histocompatibility complex class I (MHC-I) tetramer staining. Vaccine-induced CD8+ T cell responses, which were predominantly directed against the Mamu-A*01-restricted Gag181-189CM9 epitope, could be inhibited by blockade of MHC-I presentation. Our results indicate that gL and the interaction with Eph family receptors are dispensable for the colonization of the B cell compartment following high-dose infection by the intravenous route, which suggests the existence of alternative receptors. Further, gL-minus RRV elicits cellular immune responses that are predominantly canonical in nature.IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) is associated with a substantial disease burden in sub-Saharan Africa, often in the context of human immunodeficiency virus (HIV) infection. The related rhesus monkey rhadinovirus (RRV) has shown potential as a vector to immunize monkeys with antigens from simian immunodeficiency virus (SIV), the macaque model for HIV. KSHV and RRV engage cellular receptors from the Eph family via the viral gH/gL glycoprotein complex. We have now generated a recombinant RRV that expresses the SIV Gag antigen and does not express gL. This recombinant RRV was infectious by the intravenous route, established persistent infection in the B cell compartment, and elicited strong immune responses to the SIV Gag antigen. These results argue against a role for gL and Eph family receptors in B cell infection by RRV in vivo and have implications for the development of a live-attenuated KSHV vaccine or vaccine vector.

Kaposi Sarcoma in Mantled Guereza.

We identified a novel Kaposi's sarcoma herpesvirus-related rhadinovirus (Colobine gammaherpesvirus 1) in a mantled guereza (Colobus guereza kikuyensis). The animal had multiple oral tumors characterized by proliferation of latent nuclear antigen 1-positive spindle cells and was not co-infected with immunosuppressive simian viruses, suggesting that it had Kaposi sarcoma caused by this novel rhadinovirus.

Gammaherpesvirus RNAs Come Full Circle.

After an adaptive immune response is mounted, gammaherpesviruses achieve persistence through the utilization of viral noncoding RNAs to craft a suitable host cell environment in an immunologically transparent manner. While gammaherpesvirus long noncoding RNAs (lncRNAs) and microRNAs have been recognized for some time and have been actively investigated, a recent spate of reports have now identified repertoires of the circular RNA (circRNA) class of noncoding RNAs in both the lymphocryptovirus and rhadinovirus genera of gammaherpesviruses. Despite the recent nature of these findings, the detection of circRNAs across viruses and viral gene expression programs, the conservation of some viral circRNAs, and their detection in the clinical setting already raises the spectrum of functional importance in gammaherpesvirus biology and associated malignancies. Here, we provide an overview of currently known gammaherpesvirus circular RNAs and discuss reported physical and contextual properties that may be germane to future functional studies. With the Epstein-Barr virus (EBV) circRNAome being the most extensively studied to date, our discussions will be weighted toward EBV circRNAs while also addressing circRNAs discovered in the rhesus macaque lymphocryptovirus (rLCV), the Kaposi's sarcoma herpesvirus (KSHV), and the murid gammaherpesvirus 68 (MHV68). We hope that this will help set the stage for future investigations into the functions and relevance of this new class of viral noncoding RNAs in infection and disease.

Rhesus Macaque Rhadinovirus Encodes a Viral Interferon Regulatory Factor To Disrupt Promyelocytic Leukemia Nuclear Bodies and Antagonize Type I Interferon Signaling.

Interferon (IFN) production and the subsequent induction of IFN-stimulated genes (ISGs) are highly effective innate strategies utilized by cells to protect against invading pathogens, including viruses. Critical components involved in this innate process are promyelocytic leukemia nuclear bodies (PML-NBs), which are subnuclear structures required for the development of a robust IFN response. As such, PML-NBs serve as an important hurdle for viruses to overcome to successfully establish an infection. Both Kaposi's sarcoma-associated herpesvirus (KSHV) and the closely related rhesus macaque rhadinovirus (RRV) are unique for encoding viral homologs of IFN regulatory factors (termed vIRFs) that can manipulate the host immune response by multiple mechanisms. All four KSHV vIRFs inhibit the induction of IFN, while vIRF1 and vIRF2 can inhibit ISG induction downstream of the IFN receptor. Less is known about the RRV vIRFs. RRV vIRF R6 can inhibit the induction of IFN by IRF3; however, it is not known whether any RRV vIRFs inhibit ISG induction following IFN receptor signaling. In our present study, we demonstrate that the RRV vIRF R12 aids viral replication in the presence of the type I IFN response. This is achieved in part through the disruption of PML-NBs and the inhibition of robust ISG transcription.IMPORTANCE KSHV and RRV encode a unique set of homologs of cellular IFN regulatory factors, termed vIRFs, which are hypothesized to help these viruses evade the innate immune response and establish infections in their respective hosts. Our work elucidates the role of one RRV vIRF, R12, and demonstrates that RRV can dampen the type I IFN response downstream of IFN signaling, which would be important for establishing a successful infection in vivo.

Comparative Analysis of Gammaherpesvirus Circular RNA Repertoires: Conserved and Unique Viral Circular RNAs.

Recent studies have identified circular RNAs (circRNAs) expressed from the Epstein-Barr virus (EBV) and Kaposi's sarcoma herpesvirus (KSHV) human DNA tumor viruses. To gain initial insights into the potential relevance of EBV circRNAs in virus biology and disease, we assessed the circRNAome of the interspecies homologue rhesus macaque lymphocryptovirus (rLCV) in a naturally occurring lymphoma from a simian immunodeficiency virus (SIV)-infected rhesus macaque. This analysis revealed rLCV orthologues of the latency-associated EBV circular RNAs circRPMS1_E4_E3a and circEBNA_U. Also identified in two samples displaying unusually high lytic gene expression was a novel rLCV circRNA that contains both conserved and rLCV-specific RPMS1 exons and whose backsplice junctions flank an rLCV lytic origin of replication (OriLyt). Analysis of a lytic infection model for the murid herpesvirus 68 (MHV68) rhadinovirus identified a cluster of circRNAs near an MHV68 lytic origin of replication, with the most abundant of these, circM11_ORF69, spanning the OriLyt. Lastly, analysis of KSHV latency and reactivation models revealed the latency associated circRNA originating from the vIRF4 gene as the predominant viral circRNA. Together, the results of this study broaden our appreciation for circRNA repertoires in the Lymphocryptovirus and Rhadinovirus genera of gammaherpesviruses and provide evolutionary support for viral circRNA functions in latency and viral replication.IMPORTANCE Infection with oncogenic gammaherpesviruses leads to long-term viral persistence through a dynamic interplay between the virus and the host immune system. Critical for remodeling of the host cell environment after the immune responses are viral noncoding RNAs that modulate host signaling pathways without attracting adaptive immune recognition. Despite the importance of noncoding RNAs in persistent infection, the circRNA class of noncoding RNAs has only recently been identified in gammaherpesviruses. Accordingly, their roles in virus infection and associated oncogenesis are unknown. Here we report evolutionary conservation of EBV-encoded circRNAs determined by assessing the circRNAome in rLCV-infected lymphomas from an SIV-infected rhesus macaque, and we report latent and lytic circRNAs from KSHV and MHV68. These experiments demonstrate utilization of the circular RNA class of RNAs across 4 members of the gammaherpesvirus subfamily, and they identify orthologues and potential homoplastic circRNAs, implying conserved circRNA functions in virus biology and associated malignancies.

Investigation of association between bovine viral diarrhoea virus and cervid herpesvirus type-1, and abortion in New Zealand farmed deer.

This study tested for association between bovine viral diarrhoea virus (BVDv) and cervid herpesvirus type-1 (CvHV-1) exposure and abortion in New Zealand farmed red deer. Rising two-year-old (R2, n = 22,130) and mixed-age (MA, n = 36,223) hinds from 87 and 71 herds, respectively, throughout New Zealand were pregnancy tested using ultrasound early in gestation (Scan-1) and 55-89 days later (Scan-2) to detect mid-term abortion. Sera from aborted and non-aborted hinds at Scan-2 were tested for BVDv and CvHV-1 using virus neutralisation tests. Available uteri from aborted hinds and from hinds not rearing a calf to weaning were tested by PCR for herpesvirus DNA. In herds with aborted hinds, 10.3% of 639 R2 and 17.2% of 302 MA hinds were sero-positive for BVDv and 18.6% of 613 R2 and 68.5% of 232 MA hinds were sero-positive for CvHV-1. There was no association between BVDv sero-status and abortion at animal level (R2 p = 0.36, MA p = 0.76) whereas CvHV-1 sero-positivity was negatively associated with abortion in MA hinds (p = 0.01) but not in R2 hinds (p = 0.36), MA). Eleven of 108 uteri from aborted R2 hinds but no MA hinds were positive for herpesvirus DNA. Vaginal samples from four R2 and one MA aborted hinds tested were negative for herpesvirus DNA. A Cervid Rhadinovirus type-2 (CRhV-2) was identified in seven PCR positive uteri samples. Findings suggest that BVDv and CvHV-1 may not be associated with abortion in R2 hinds, but association needs to be tested further in MA hinds. The role of CRhV-2 requires clarification.

An outbreak of malignant catarrhal fever in Sambar deer (Rusa unicolor) / Surto de febre catarral maligna em cervos Sambar (Rusa Unicolor)

Malignant catarrhal fever (MCF) is an infectious, pansystemic and highly fatal disease with wide geographic distribution. The species that are clinically prone to it include cattle, deer and bison. In Brazil, the disease in ruminants and deer is associated with the contact with sheep, especially during labor, when the fetal remains that are eliminated contain the ovine herpesvirus 2 (OvHV-2). The outbreak took place in a conservationist property in the city of Casimiro de Abreu/RJ, which hosted 23 Sambar deer, and, of these, 19 died, showing neurological signs. The deer lived in a location together with 15 male and female meat sheep. A female specimen of the Sambar deer (Rusa unicolor), aged approximately three years, which had presented with neurological clinical signs was referred to necropsy in the Setor de Anatomia Patológica at Universidade Federal Rural do Rio de Janeiro (SAP/UFRRJ). During necropsy, cerebrospinal fluid was sampled for analysis; fragments of several organs were fixated in 10% buffered formalin and processed for histopathological analysis. Fragments of occipital lobe, cerebellum and bulb were collected to perform the polymerase chain reaction (PCR). The diagnosis of this outbreak was based on epidemiological, clinical and pathological findings, and on the amplification of the OvHV-2 DNA through PCR. The histological changes were the base to confirm the MCF case and were characterized by degeneration of vascular endothelial cells, fibrinoid vasculitis, hyperplasia and necrosis of lymphoid organs. However, PCR was an important tool to confirm the diagnosis. MCF as an important disease with nervous symptomatology in deer.(AU)

A febre catarral maligna (FCM) é uma doença infecciosa, com distribuição geográfica ampla, pansistêmica e altamente fatal. As espécies clinicamente suscetíveis incluem bovino, cervo e bisão. No Brasil, a doença em ruminantes e cervídeos está associada ao contato com ovinos, principalmente durante o parto, no qual os envoltórios fetais eliminados contém, em suas secreções, o Herpesvírus ovino-2 (OvHV-2). O surto ocorreu em uma propriedade conservacionista no município de Casimiro de Abreu/RJ, que abrigava 23 cervos exóticos, onde foram registradas a morte de 19 destes, com sinais neurológicos. Os cervos habitavam em um piquete com 15 ovinos de corte, machos e fêmeas. Um exemplar de cervo sambar (Rusa unicolor), fêmea, com aproximadamente três anos de idade, que havia apresentado sinais clínicos neurológicos foi encaminhado para necropsia no Setor de Anatomia Patológica da Universidade Federal Rural do Rio de Janeiro (SAP/UFRRJ). Durante a necropsia foi realizada a coleta de líquido cefalorraquidiano e de fragmentos de lobo occipital, cerebelo e bulbo, para a realização de reação em cadeia da polimerase (PCR). Fragmentos de diversos órgãos foram fixados em formalina 10% tamponada e processados para a análise histopatológica. O diagnóstico do presente surto foi estabelecido com base nos achados epidemiológicos, clínicos, patológicos e na amplificação do DNA do OvHV-2 através da PCR. As alterações histológicas foram a base para confirmar o caso de FCM e caracterizaram-se por degeneração de células endoteliais vasculares, vasculite fibrinoide, hiperplasia dos órgãos linfoides. Contudo, a PCR foi uma ferramenta importante para a confirmação do diagnóstico. Ressalta-se a importância da FCM na lista dos diagnósticos diferenciais de doenças que cursam com sintomatologia nervosa em cervídeos.(AU)

Animal Models of Human Gammaherpesvirus Infections.

Humans are the only natural host of both Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV), and this strict host tropism has hampered the development of animal models of these human gammaherpesviruses. To overcome this difficulty and develop useful models for these viruses, three main approaches have been employed: first, experimental infection of laboratory animals [mainly new-world non-human primates (NHPs)] with EBV or KSHV; second, experimental infection of NHPs (mainly old-world NHPs) with EBV- or KSHV-related gammaherpesviruses inherent to respective NHPs; and third, experimental infection of humanized mice, i.e., immunodeficient mice engrafted with functional human cells or tissues (mainly human immune system components) with EBV or KSHV. These models have recapitulated diseases caused by human gammaherpesviruses, their asymptomatic persistent infections, as well as both innate and adaptive immune responses to them, facilitating the development of novel therapeutic and prophylactic measures against these viruses.

Encephalitis induced by a newly discovered ruminant rhadinovirus in a free-living Formosan sambar deer (Rusa unicolor swinhoei).

We documented a case of a free-living Formosan sambar deer (Rusa unicolor swinhoei) infected with a newly discovered ruminant Rhadinovirus (RuRv). Non-purulent encephalitis was the primary histological lesion of the sambar deer. We conducted nested PCR to screen for herpesvirus using generic primers targeting the DNA polymerase gene. In addition, we found that DNA polymerase gene of the sambar deer RuRv was present in the macrophage distributed in the Virchow Robin space with histopathologic lesions by chromogenic in-situ hybridization (CISH). The phylogenetic analysis indicated a high similarity between the viral sequence isolated from fallow deer and our case. This result suggests the possibility of cross-species transmission from other exotic Cervidae reservoir to the Formosan sambar deer.

Macaque homologs of Kaposi's sarcoma-associated herpesvirus (KSHV) infect germinal center lymphoid cells, epithelial cells in skin and gastrointestinal tract and gonadal germ cells in naturally infected macaques.

We developed a set of rabbit antisera to characterize infections by the macaque RV2 rhadinovirus homologs of KSHV. We analyzed tissues from rhesus and pig-tailed macaques naturally infected with rhesus rhadinovirus (RRV) or Macaca nemestrina rhadinovirus 2 (MneRV2). Our study demonstrates that RV2 rhadinoviruses have a tropism for epithelial cells, lymphocytes and gonadal germ cells in vivo. We observed latent infections in both undifferentiated and differentiated epithelial cells with expression of the latency marker, LANA. Expression of the early (ORF59) and late (glycoprotein B) lytic markers were detected in highly differentiated cells in epithelial ducts in oral, renal, dermal and gastric mucosal tissue as well as differentiated germ cells in male and female gonads. Our data provides evidence that epithelial and germ cell differentiation in vivo induces rhadinovirus reactivation and suggests that infected epithelial and germ cells play a role in transmission and dissemination of RV2 rhadinovirus infections in vivo.

ORF73 LANA homologs of RRV and MneRV2 contain an extended RGG/RG-rich nuclear and nucleolar localization signal that interacts directly with importin ß1 for non-classical nuclear import.

The latency-associated nuclear antigens (LANA) of KSHV and macaque RFHVMn, members of the RV1 rhadinovirus lineage, are closely related with conservation of complex nuclear localization signals (NLS) containing bipartite KR-rich motifs and RG-rich domains, which interact distinctly with importins α and ß1 for nuclear import via classical and non-classical pathways, respectively. RV1 LANAs are expressed in the nucleus of latently-infected cells where they inhibit replication and establish a dominant RV1 latency. Here we show that LANA homologs of macaque RRV and MneRV2 from the more distantly-related RV2 lineage, lack the KR-rich NLS, and instead have a large RG-rich NLS with multiple RG dipeptides and a conserved RGG motif. The RG-NLS interacts uniquely with importin ß1, which mediates nuclear import and accumulation of RV2 LANA in the nucleolus. The alternative nuclear import and localization of RV2 LANA homologs may contribute to the dominant RV2 lytic replication phenotype.

A Conserved Leucine Zipper Motif in Gammaherpesvirus ORF52 Is Critical for Distinct Microtubule Rearrangements.

Productive viral infection often depends on the manipulation of the cytoskeleton. Herpesviruses, including rhesus monkey rhadinovirus (RRV) and its close homolog, the oncogenic human gammaherpesvirus Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV8), exploit microtubule (MT)-based retrograde transport to deliver their genomes to the nucleus. Subsequently, during the lytic phase of the life cycle, the maturing viral particles undergo orchestrated translocation to specialized regions within the cytoplasm, leading to tegumentation, secondary envelopment, and then egress. As a result, we hypothesized that RRV might induce changes in the cytoskeleton at both early and late stages of infection. Using confocal imaging, we found that RRV infection led to the thickening and acetylation of MTs emanating from the MT-organizing center (MTOC) shortly after viral entry and more pronounced and diffuse MT reorganization during peak stages of lytic gene expression and virion production. We subsequently identified open reading frame 52 (ORF52), a multifunctional and abundant tegument protein, as being the only virally encoded component responsible for these cytoskeletal changes. Mutational and modeling analyses indicated that an evolutionarily conserved, truncated leucine zipper motif near the N terminus as well as a strictly conserved arginine residue toward the C terminus of ORF52 play critical roles in its ability to rearrange the architecture of the MT cytoskeleton. Taken together, our findings combined with data from previous studies describing diverse roles for ORF52 suggest that it likely binds to different cellular components, thereby allowing context-dependent modulation of function.IMPORTANCE A thorough understanding of the processes governing viral infection includes knowledge of how viruses manipulate their intracellular milieu, including the cytoskeleton. Altering the dynamics of actin or MT polymerization, for example, is a common strategy employed by viruses to ensure efficient entry, maturation, and egress as well as the avoidance of antiviral defenses through the sequestration of key cellular factors. We found that infection with RRV, a homolog of the human pathogen KSHV, led to perinuclear wrapping by acetylated MT bundles and identified ORF52 as the viral protein underlying these changes. Remarkably, incoming virions were able to supply sufficient ORF52 to induce MT thickening and acetylation near the MTOC, potentially aiding in the delivery viral genomes to the nucleus. Although the function of MT alterations during late stages of infection requires further study, ORF52 shares functional and structural similarities with alphaherpesvirus VP22, underscoring the evolutionary importance of MT cytoskeletal manipulations for this virus family.

Rhadinoviral interferon regulatory factor homologues.

Kaposi's sarcoma-associated herpesvirus (KSHV), or human herpesvirus 8 (HHV8) is a gammaherpesvirus and the etiological agent of Kaposi's sarcoma, primary effusion lymphoma and multicentric Castleman disease. The KSHV genome contains genes for a unique group of proteins with homology to cellular interferon regulatory factors, termed viral interferon regulatory factors (vIRFs). This review will give an overview over the oncogenic, antiapoptotic and immunomodulatory characteristics of KSHV and related vIRFs.

Detection of a novel gammaherpesvirus (genus Rhadinovirus) in wild muntjac deer in Northern Ireland.

This study represents the initial part of an investigation into the potential for non-native, wild, free-living muntjac deer (Muntiacus reevesi) to carry viruses that could be a threat to livestock. A degenerate PCR assay was used to screen a range of tissues from muntjac deer culled in Northern Ireland for the presence of herpesviral nucleic acids. This was followed by sequencing of PCR amplicons and phylogenetic analysis. We report the detection of a novel gammaherpesvirus most closely related to a type 2 ruminant rhadinovirus from mule deer. It remains to be determined if this new virus is pathogenic to deer or presents a risk to food security through the susceptibility of domestic livestock.

The Viral Bcl-2 Homologs of Kaposi's Sarcoma-Associated Herpesvirus and Rhesus Rhadinovirus Share an Essential Role for Viral Replication.

KS-Bcl-2 is a Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded viral Bcl-2 (vBcl-2) homolog which has apoptosis- and autophagy-inhibiting activity when expressed in transfected cells. However, little is known about its function during viral infection. As KS-Bcl-2 is expressed during the lytic replication cycle, we used constitutively lytic and inducibly lytic KSHV mutants to investigate the role of KS-Bcl-2 during the lytic cycle. We show that KSHV cannot complete the lytic replication cycle and produce infectious progeny in the absence of KS-Bcl-2, indicating that the protein is essential for KSHV replication. Replacement of the KS-Bcl-2 coding sequence, ORF16, by sequences encoding a potent cellular apoptosis and autophagy inhibitor, Bcl-XL, or the cytomegalovirus mitochondrial inhibitor of apoptosis, vMIA, did not rescue KSHV replication, suggesting that KS-Bcl-2 has a function that goes beyond apoptosis and autophagy inhibition. Strikingly, the vBcl-2 proteins of the related γ2-herpesviruses murine herpesvirus 68 and herpesvirus saimiri did not rescue the replication of a KS-Bcl-2 deletion mutant, but rhesus rhadinovirus (RRV) vBcl-2 did. Deletion of ORF16 from the RRV genome abrogated viral replication, but its replacement by KSHV ORF16 rescued RRV replication, indicating that the essential vBcl-2 function is conserved between these two primate rhadinoviruses. We further show that the KSHV and RRV Bcl-2 homologs localize to the mitochondria and nuclei of infected cells. Deletion of 17 amino acids from the N terminus of KS-Bcl-2 abrogates nuclear localization and KSHV replication, suggesting that KS-Bcl-2 might execute its essential function in the nuclei of infected cells.IMPORTANCE Several viruses express proteins homologous to cellular Bcl-2. Viral Bcl-2 proteins have functions similar to those of cellular Bcl-2: they can inhibit apoptosis, a form of programmed cell death, and autophagy, a self-degradative process for the disposal of dysfunctional or unwanted components. This study shows that the vBcl-2 proteins of KSHV and RRV differ from other vBcl-2 proteins in that they are essential for viral replication. The essential function is separate from the apoptosis- and autophagy-inhibiting activity but correlates with an unusual localization within the cell nucleus, suggesting that these proteins exert a novel function in the nucleus.

Conservation of the glycoprotein B homologs of the Kaposi׳s sarcoma-associated herpesvirus (KSHV/HHV8) and old world primate rhadinoviruses of chimpanzees and macaques.

The envelope-associated glycoprotein B (gB) is highly conserved within the Herpesviridae and plays a critical role in viral entry. We analyzed the evolutionary conservation of sequence and structural motifs within the Kaposi׳s sarcoma-associated herpesvirus (KSHV) gB and homologs of Old World primate rhadinoviruses belonging to the distinct RV1 and RV2 rhadinovirus lineages. In addition to gB homologs of rhadinoviruses infecting the pig-tailed and rhesus macaques, we cloned and sequenced gB homologs of RV1 and RV2 rhadinoviruses infecting chimpanzees. A structural model of the KSHV gB was determined, and functional motifs and sequence variants were mapped to the model structure. Conserved domains and motifs were identified, including an "RGD" motif that plays a critical role in KSHV binding and entry through the cellular integrin αVß3. The RGD motif was only detected in RV1 rhadinoviruses suggesting an important difference in cell tropism between the two rhadinovirus lineages.