Macrodendritic ulcerative keratitis and conjunctival lymphoid hyperplasia in horses with equine herpesvirus-2 and equine herpesvirus-5 infections

OBJECTIVE

The aim of this study was to describe the clinical, confocal microscopic, histologic, and virologic features of horses with macrodendritic ulcerative keratitis and conjunctival lymphoid hyperplasia associated with equine herpesvirus-2 and equine herpesvirus-5 infection.

ANIMAL STUDIED

Four foals with bilateral ocular disease.

PROCEDURES

Complete ophthalmic examination was performed for each horse, and corneal samples were collected for cytology and microbiologic evaluation, including virus isolation and molecular diagnostics for the equine herpesviruses. In vivo confocal microscopy examination of the cornea was performed in two horses. Conjunctival biopsies for histopathology were collected from two horses with nodular conjunctival thickening.

RESULTS

Each horse had bilateral, large, superficial dendritic corneal ulcerations that covered extensive regions of the corneal surface. Corneal in vivo confocal microscopy examination in two horses detected inflammatory cells and populations of morphologically abnormal corneal epithelial cells adjacent to the ulcerations. The abnormal epithelial cells included round, relatively small, hyperreflective cells intermixed with elongated, enlarged, hyperreflective cells. Equine herpesvirus-2 was isolated from corneal samples of 2 horses and detected by PCR assay in the other two horses. Equine herpesvirus-5 was also detected by PCR assay in three of the horses. Conjunctival histopathology identified predominantly lymphocytic infiltrates. The macrodendrites and conjunctival masses resolved with topical antiviral therapy (cidofovir or idoxuridine) in all horses and did not recur.

CONCLUSIONS AND CLINICAL RELEVANCE

The equine gammaherpesviruses may be associated with the development of macrodendritic ulcerative keratitis and conjunctival lymphocytic masses in foals. In vivo confocal microscopy of horses with macrodendrites revealed similar findings to other host species with herpetic dendritic keratitis.

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.

Molecular detection of murine gammaherpesvirus 68 (MHV-68) in Haemaphysalis concinna ticks collected in Slovakia

Murine gammaherpesvirus 68 (MHV-68) is a natural pathogen of murid rodents, which serve as hosts to Haemaphysalis concinna ticks. The occurrence of MHV-68 was investigated in a total of 47 H. concinna adult ticks collected on the vegetation in Gabčíkovo, situated in south-western Slovakia (47º54´0´´N, 17º35´0´´E), from May 2013 to May 2014. DNA from ticks was purified and screened by nested PCR targeting ORF50 of MHV-68 and the copy number of virus genome in ticks was determined by a real-time PCR assay specific for ORF65. The MHV-68 incidence in questing ticks was 38.3% (18/47) and the virus genome copy number per tick varied from 2x102 to 9.6x103. In this study, MHV-68 was documented for the first time in H. concinna ticks. Results expand previous data describing the occurrence of MHV-68 in Ixodes ricinus and Dermacentor reticulatus ticks collected in Slovakia, supporting the hypothesis that MHV-68 might be a newfound pathogen in ticks.

CD8+ T cell evasion mandates CD4+ T cell control of chronic gamma-herpesvirus infection

Gamma-herpesvirus infections are regulated by both CD4⁺ and CD8⁺ T cells. However clinical disease occurs mainly in CD4⁺ T cell-deficient hosts. In CD4⁺ T cell-deficient mice, CD8⁺ T cells control acute but not chronic lung infection by Murid Herpesvirus-4 (MuHV-4). We show that acute and chronic lung infections differ in distribution: most acute infection was epithelial, whereas most chronic infection was in myeloid cells. CD8⁺ T cells controlled epithelial infection, but CD4⁺ T cells and IFNγ were required to control myeloid cell infection. Disrupting the MuHV-4 K3, which degrades MHC class I heavy chains, increased viral epitope presentation by infected lung alveolar macrophages and allowed CD8⁺ T cells to prevent disease. Thus, viral CD8⁺ T cell evasion led to niche-specific immune control, and an essential role for CD4⁺ T cells in limiting chronic infection.

Gamma-herpesviruses chronically infect most people. While infection is usually asymptomatic, disease occurs if the immune system is weakened. Understanding how immune control normally works should provide a basis for preventing disease. In mice, CD8⁺ T cells can control acute gamma-herpesvirus infection but not chronic infection. We show that acute and chronic infections involve different cell types. CD8⁺ T cells controlled epithelial cell infection, which predominated acutely, but they could not control chronic macrophage infection unless viral immune evasion was disabled. Instead CD4⁺ T cells were required. Thus, viral evasion made host defence cell type-specific: CD8⁺ T cells controlled epithelial cell infection; CD4⁺ T cells controlled macrophage infection; and comprehensive control required both T cell subsets.

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.

Isolation of Equine Herpesvirus–2 from the Lung of an Aborted Fetus

This study describes the isolation of equine herpesvirus–2 (EHV-2) from the lung of an aborted equine fetus in Argentina. The isolated virus was confirmed as EHV-2 by indirect immunofluorescence using a rabbit anti–EHV-2 polyclonal antiserum and by virus-neutralization test using an equine polyclonal antibody against EHV-2. Restriction endonuclease DNA fingerprinting with BamHI also confirmed the identity of the virus as EHV-2. Furthermore, viral nucleic acid was detected by polymerase chain reaction from the original lung sample and from the DNA obtained from cells infected with the virus isolate. This work constitutes the first reported isolation of EHV-2 from an aborted equine fetus. The presence of EHV-2 in the lung of the aborted fetus would indicate that this virus is capable of crossing the placental barrier. However, no cause–effect relationship was established between the EHV-2 isolate and the abortion.

Detection of Murine Herpesvirus 68 (MHV-68) in Dermacentor reticulatus Ticks

Murid herpesvirus 4 (MuHV 4) strain 68 (MHV-68) is a natural pathogen of murid rodents, which serves as hosts to Dermacentor reticulatus ticks. These ticks are known to transmit multiple pathogens, which can cause diseases in humans and animals. Recently, the detection of MHV-68 antibodies in the blood of animals living in the same biotope as virus-infected mice has suggested the role of ticks in pathogen circulation in nature. Herein, to identify MHV-68 in D. reticulatus ticks, DNA samples from 432 adults were collected at two sites in southwestern Slovakia from 2011 to 2014. Samples were examined by polymerase chain reaction (PCR), targeting ORF50 of MHV-68. Ignoring season and locality, we have found 25.9 % of the male and 44.9 % of the female ticks to be positive. Within ticks collected in Vojka, 40 % (125/312) became positive, at a rate of approximately 6.8 times higher in spring than in autumn (66 vs 9.7 %). In addition, in the spring, 1.4 times more females were positive than males. Within ticks collected in Gabčíkovo, 23.3 % (28/120) became positive, with positive females being twice as frequent. The infecting virus was identified by analyzing amplified products via sequencing and restriction fragment length polymorphism (RFLP) analyses. Using an explantation/co-cultivation procedure, we examined the salivary glands, intestines, and ovaries of five females for live MHV-68. In all organs of two ticks, we identified a virus capable of replication in mammalian cells. This is the first report of MHV-68 detection in D. reticulatus ticks and of a live virus in their organs. Findings encourage further study to determine whether this potential arbovirus, found in salivary glands, is transmissible. It further supports the hypothesis regarding the mediating role of ticks in MHV-68 circulation in nature.

Herpesvirus delivery to the murine respiratory tract

Herpesvirus transmission is sporadic, and infection may be asymptomatic or present only with secondary lesions after dissemination. Consequently host entry remains ill-understood. Experimental infections can be informative, but depend on inoculations that are inherently artificial and so need validation. Mice are a widely used experimental host. Alert mice inhale readily small (5 μl) liquid volumes, and Indian ink, luciferase or radiolabel delivered thus distributed to the nasopharynx and oropharynx. Murid Herpesvirus-4 or Herpes simplex virus type 1 delivered thus infected only the nose, arguing that host entry is nasal rather than oral. Marker or virus delivery to the lung depended on general anesthesia and a large inoculum volume (30 μl), and so needs further validation of physiological relevance. While lungs could be infected at lower doses than the upper respiratory tract, tracking experiments showed that nasal inocula pass mostly into the oropharynx, even when restricted to 1 μl. Thus, the relative inefficiency of experimental upper respiratory tract infection was attributable to limited liquid retention in this site. Nonetheless low volume intranasal delivery to alert mice provides a convenient way to model experimentally an apparently natural mode of herpesvirus host entry.

Macaque homologs of EBV and KSHV show uniquely different associations with simian AIDS-related lymphomas

Two gammaherpesviruses, Epstein-Barr virus (EBV) (Lymphocryptovirus genus) and Kaposi's sarcoma-associated herpesvirus (KSHV) (Rhadinovirus genus) have been implicated in the etiology of AIDS-associated lymphomas. Homologs of these viruses have been identified in macaques and other non-human primates. In order to assess the association of these viruses with non-human primate disease, archived lymphoma samples were screened for the presence of macaque lymphocryptovirus (LCV) homologs of EBV, and macaque rhadinoviruses belonging to the RV1 lineage of KSHV homologs or the more distant RV2 lineage of Old World primate rhadinoviruses. Viral loads were determined by QPCR and infected cells were identified by immunolabeling for different viral proteins. The lymphomas segregated into three groups. The first group (n = 6) was associated with SIV/SHIV infections, contained high levels of LCV (1–25 genomes/cell) and expressed the B-cell antigens CD20 or BLA.36. A strong EBNA-2 signal was detected in the nuclei of the neoplastic cells in one of the LCV-high lymphomas, indicative of a type III latency stage. None of the lymphomas in this group stained for the LCV viral capsid antigen (VCA) lytic marker. The second group (n = 5) was associated with D-type simian retrovirus-2 (SRV-2) infections, contained high levels of RV2 rhadinovirus (9–790 genomes/cell) and expressed the CD3 T-cell marker. The third group (n = 3) was associated with SIV/SHIV infections, contained high levels of RV2 rhadinovirus (2–260 genomes/cell) and was negative for both CD20 and CD3. In both the CD3-positive and CD3/CD20-negative lymphomas, the neoplastic cells stained strongly for markers of RV2 lytic replication. None of the lymphomas had detectable levels of retroperitoneal fibromatosis herpesvirus (RFHV), the macaque RV1 homolog of KSHV. Our data suggest etiological roles for both lymphocryptoviruses and RV2 rhadinoviruses in the development of simian AIDS-associated lymphomas and indicate that the virus-infected neoplastic lymphoid cells are derived from different lymphocyte lineages and differentiation stages.

The incidence of Kaposi's sarcoma (KS) and non-Hodgkin's lymphoma increased in conjunction with the epidemic of HIV disease and AIDS. These malignancies are now known to be associated with secondary infections with a gammaherpesvirus; KS, with the Kaposi's sarcoma-associated herpesvirus (KSHV) and lymphoma, with both KSHV and Epstein-Barr virus (EBV). Similar AIDS-related malignancies have been observed in monkeys with simian AIDS and monkey gammaherpesviruses related to KSHV and EBV have been implicated in the development of disease. The study of monkey models of AIDS-related malignancies provides important approaches for understanding the role of gammaherpesviruses in AIDS-related tumorigenesis. Here we have used a combined molecular and immunological approach to identify, quantitate and localize infections of gammaherpesviruses in AIDS-associated lymphomas in macaques. We found high levels of macaque viruses related to EBV and KSHV in the tumor cells of distinct types of macaque lymphomas, suggesting that the virus-infected tumor cells belong to different lymphocyte lineages and differentiation stages.

Experimental infection of laboratory-bred bank voles (Myodes glareolus) with murid herpesvirus 4

MuHV-4 is a natural pathogen of rodents of the genus Apodemus (e.g., wood mice, yellow-necked mice) and Myodes glareolus (bank voles). We report experimental MuHV-4 infection of bank voles in comparison with infection of A. sylvaticus (wood mice) and BALB/c mice. Like in wood mice, the level of productive replication in the lungs of bank voles was significantly lower than in BALB/c mice. In contrast to other hosts, however, the level of latent infection in the lung and spleen of bank voles was extremely low. These findings, together with those of previous studies, suggest that bank voles are an occasional and inefficient host for MuHV-4.

Molecular detection of murine herpesvirus 68 in ticks feeding on free-living reptiles

The MHV-68 (designed as Murid herpesvirus 4 (MuHV 4) strain 68) isolated from two rodents, Myodes glareolus and Apodemus flavicollis, is considered as a natural pathogen of free-living murid rodents. Recently, the detection of MHV antibodies in the blood of animals living in the same biotope as MHV-infected mice has suggested that ticks may have a role in the transmission of this pathogen. Ixodes ricinus is one the most abundant tick species in Europe known to transmit multiple pathogens causing human and animal diseases. In this study, nymphs and larvae feeding on 116 individuals of a temperate lizard species-the green lizard Lacerta viridis captured in the Slovak Karst National Park, were examined for MHV-68. The specific sequence of virion glycoprotein 150 was amplified in DNA individually isolated from I. ricinus ticks using single-copy sensitive nested polymerase chain reaction. MHV-68 was detected in ten of 649 nymphs and in five of 150 larvae, respectively. We found that 9.6% of green lizards fed at least one MHV-68-infected immature tick. Occurrence of MHV-68 within all ticks tested was 1.8%. This study is first to show that immature I. ricinus ticks feeding on free-living lizards in a Central European region could be infected with gammaherpesvirus (MHV-68), naturally infecting free-living murid rodents. Our results provide evidence supporting the hypothesis that ticks may play a mediating role in circulation of MHV-68 in nature.

Longitudinal patterns of viremia and oral shedding of rhesus rhadinovirus and retroperitoneal fibromatosis herpesviruses in age-structured captive breeding populations of rhesus Macaques (Macaca mulatta)

Rhesus rhadinovirus (RRV) and retroperitoneal fibromatosis herpesvirus (RFHV), 2 closely related γ2 herpesviruses, are endemic in breeding populations of rhesus macaques at our institution. We previously reported significantly different prevalence levels, suggesting the transmission dynamics of RRV and RFHV differ with regard to viral shedding and infectivity. We designed a longitudinal study to further examine the previously observed differences between RRV and RFHV prevalence and the potential influence of age, season, and housing location on the same 90 rhesus macaques previously studied. Virus- and host-genome-specific real-time PCR assays were used to determine viral loads for both RRV and RFHV in blood and saliva samples collected at 6 time points over an 18-mo period. Proportions of positive animals and viral load in blood and saliva were compared between and within viruses by age group, location, and season by using 2-part longitudinal modeling with Bayesian inferences. Our results demonstrate that age and season are significant determinants, with age as the most significant factor analyzed, of viremia and oral shedding for both RRV and RFHV, and these pathogens exhibit distinctly different patterns of viremia and oral shedding over time within a single population.

Prevalence of viremia and oral shedding of rhesus rhadinovirus and retroperitoneal fibromatosis herpesvirus in large age-structured breeding groups of rhesus macaques (Macaca mulatta)

We performed a cross-sectional study to estimate the prevalence of 2 gamma-2-herpesviruses, rhesus rhadinovirus (RRV) and retroperitoneal fibromatosis herpesvirus (RFHV), in breeding colonies of rhesus macaques. Of 90 animals selected for sampling, 73 (81%) were positive for RRV, which was detected only in blood in 22 (24%), only in saliva in 15 (16%), and in both blood and saliva in 36 (40%). Detection of RRV DNA in blood and saliva was significantly higher in animals younger than 2 y. In comparison, RFHV was detected in 40 (44%) of the 90 animals: only in blood in 5 (6%), only in saliva in 26 (29%), and in both blood and saliva in 9 (10%). Dual infection was detected in 38 (42%) animals; RFHV was only detected in coinfections. The mean RRV genome copy number in blood was significantly higher than that for RFHV. Age was a significant predictor of RRV copy number in blood and RFHV copy number in saliva. Of the 90 animals, 88 (98%) were positive for rhadinoviral antibodies on an immunofluorescent assay. Both RRV and RFHV are highly endemic in socially housed breeding colonies of rhesus macaques, and their patterns of infection are similar to that for the betaherpesvirus rhesus cytomegalovirus.

Myocarditis in newborn wild-type BALB/c mice infected with the murine gamma herpesvirus MHV-68

OBJECTIVES

Animal models of human Epstein-Barr virus (EBV) infection include EBV infection of primates and infection of mice with MHV-68, a further gamma herpesvirus (gamma-HV). We aimed at extending the MHV-68 model to study gamma-HV-related cardiac disease.

METHODS

Newborn wild-type BALB/c- (n=107), wild-type C57BL/6- (n=17) and immunodeficient B6-(Rag1) mice (n=18) were infected by nasal inoculation and evaluated for histopathological changes as well as tissue viral loads.

RESULTS

From day 5 on BALB/c mice showed myocardial viral replication. Whereas focal inflammation occurred simultaneously, necrosis was first observed 9 days post-infection. The maximum rates of necrosis (40%) and of focal inflammation (33%) were found after 10 to 12 and 33 to 35 days, respectively. Some animals developed persistent viral activity and inflammation throughout the observation period of three months. Inflammation was mainly related to T cell infiltrates. Although C57BL/6 mice also showed myocardial inflammation, necrosis was not found suggesting differences in the susceptibility to the virus in distinct mouse strains. In immunodeficient animals higher myocardial viral loads were observed compared to wild-type mice but no cardiac lesions, which suggests that the antiviral immune response contributed to the lesions.

CONCLUSIONS

The model system presented here is the first to allow detailed studies on cardiac disease caused by gamma-HV infections and may facilitate the development of more specific treatment options for human cardiac EBV infection.

Discovery of herpesviruses in bats

Seven novel gammaherpesviruses (GHV) and one novel betaherpesvirus were discovered in seven different European bat species (order Chiroptera, family Vespertilionidae) with a pan-herpesvirus PCR assay, targeting the DNA polymerase (DPOL) gene. The sequences of six bat GHV were similarly related to members of the gammaherpesvirus genera Percavirus and Rhadinovirus. The seventh GHV was related to the porcine lymphotropic herpesvirus 1 (genus Macavirus). The betaherpesvirus appeared to be a distant relative of human cytomegalovirus. For three bat GHV a 3.6 kbp locus was amplified and sequenced, spanning part of the glycoprotein B gene and the majority of the DPOL gene. In phylogenetic analysis, the three bat GHV formed a separate clade with similar distance to the Percavirus and Rhadinovirus clades. These novel viruses are the first herpesviruses to be described in bats.

Malignant catarrhal fever-like lesions associated with ovine herpesvirus-2 infection in three goats

This is the first description of malignant catarrhal fever-like lesions associated with ovine herpesvirus-2 (OvHV-2) infection in goats with central nervous symptoms. The diagnosis was based on typical histological lesions characterized by systemic lymphohistiocytic and fibrinoid vasculitis and confirmed by polymerase chain reaction and subsequent phylogenetic analysis of the detected OvHV-2 sequences.

Sequence analysis of the equid herpesvirus 2 chemokine receptor homologues E1, ORF74 and E6 demonstrates high sequence divergence between field isolates

Equid herpesvirus 2 (EHV-2), in common with other members of the subfamily Gammaherpesvirinae, encodes homologues of cellular seven-transmembrane receptors (7TMR), namely open reading frames (ORFs) E1, 74 and E6, which each show some similarity to cellular chemokine receptors. Whereas ORF74 and E6 are members of gammaherpesvirus-conserved 7TMR gene families, E1 is currently unique to EHV-2. To investigate their genetic variability, EHV-2 7TMRs from a panel of equine gammaherpesvirus isolates were sequenced. A region of gB was sequenced to provide comparative sequence data. Phylogenetic analysis revealed six 'genogroups' for E1 and four for ORF74, which exhibited approximately 10-38 and 11-27 % amino acid difference between groups, respectively. In contrast, E6 was highly conserved, with two genogroups identified. The greatest variation was observed within the N-terminal domains and other extracellular regions. Nevertheless, analysis of the number of non-synonymous (d(N)) and synonymous (d(S)) substitutions per site generally supported the hypothesis that the 7TMRs are under negative selective pressure to retain functionally important residues, although some site-specific positive selection (d(N)>d(S)) was also observed. Collectively, these data are consistent with transmembrane and cytoplasmic domains being less tolerant of mutations with adverse effects upon function. Finally, there was no evidence for genetic linkage between the different gB, E1, ORF74 and E6 genotypes, suggesting frequent intergenic recombination between different EHV-2 strains.

Comparison of ovine herpesvirus 2 genomes isolated from domestic sheep (Ovis aries) and a clinically affected cow (Bos bovis)

The rhadinovirus Ovine herpesvirus 2 (OvHV-2) is the causative agent of sheep-associated malignant catarrhal fever. OvHV-2 primarily affects ruminants and has a worldwide distribution. In this study, a composite sequence of OvHV-2 genomic DNA isolated from nasal secretions of sheep experiencing virus-shedding episodes was determined and compared with the sequence of OvHV-2 DNA isolated from a lymphoblastoid cell line derived from a clinically affected cow. The study confirmed the OvHV-2 sequence information determined for the cell line-isolated DNA and showed no apparently significant changes in the OvHV-2 genome during passage through a clinically susceptible species with subsequent maintenance in vitro. Amino acid identity between the predicted open reading frames (ORFs) of the two genomes was 94-100%, except for ORF73, which had an identity of 83%. Polymorphism in ORF73 was due primarily to variability in the G/E-rich repetitive central region of the ORF.

Sequence analysis of the regions flanking terminal repeats of the genome of umava isolate of murine gammaherpesvirus

The umava isolate of murine gammaherpesvirus (MHV-umava) slightly differs from Murine gammaherpesvirus 68 (MHV-68) and two other isolates of murine gammaherpesvirus (MHV), MHV-76 and MHV-72 in some biological properties. To identify the region(s) in the MHV-umava genome responsible for this phenomenon, we compared the sequences flanking terminal repeats (TRs) of the MHV-umava genome with those of MHV-68, MHV-76 and MHV-72. Restriction and sequence analyses revealed in MHV-umava as compared to MHV-68 approximately 9.3 kbp deletion at the left end of the genome and approximately 1.5 kbp deletion at the right end of the genome. While the approximately 9.3 kbp deletion was similar to that in MHV-76, the approximately 1.5 kbp deletion was unique for MHV-umava.

RFHVMn ORF73 is structurally related to the KSHV ORF73 latency-associated nuclear antigen (LANA) and is expressed in retroperitoneal fibromatosis (RF) tumor cells

Retroperitoneal fibromatosis herpesvirus (RFHV), the macaque homolog of the human rhadinovirus, Kaposi's sarcoma-associated herpesvirus (KSHV), was first identified in retroperitoneal fibromatosis (RF) tumor lesions of macaques with simian AIDS. We cloned and sequenced the ORF73 latency-associated nuclear antigen (LANA) of RFHVMn from the pig-tailed macaque. RFHVMn LANA is structurally analogous to KSHV ORF73 LANA and contains an N-terminal serine-proline-rich region, a large internal glutamic acidic-rich repeat region and a conserved C-terminal domain. RFHVMn LANA reacts with monoclonal antibodies specific for a glutamic acid-proline dipeptide motif and a glutamic acid-glutamine-rich motif in the KSHV LANA repeat region. Immunohistochemical and immunofluorescence analysis revealed that RFHVMn LANA is a nuclear antigen which is highly expressed in RF spindloid tumor cells. These data suggest that RFHV LANA is an ortholog of KSHV LANA and will function similarly to maintain viral latency and play a role in tumorigenicity in macaques.

Temporal detection of equine herpesvirus infections of a cohort of mares and their foals

The objectives of this study were to estimate the prevalence of equine herpesviruses (EHV) 1-5 in the nasal secretions (NS) of a cohort of 12 mares and their foals from birth to 6 months of age, estimate the prevalence of EHV-1-5 infection of peripheral blood mononuclear cells (PBMC) of selected foals, and investigate phylogenetic relationships amongst the various strains of EHV-2 and 5. Virus-specific PCR assays were used to detect EHV-1-5 in NS and PBMC. A homologous portion of the glycoprotein B (gB) gene of the various strains of EHV-2 and 5 was sequenced and compared. EHV-2, 4, and 5 were all detected in NS from the horses, but only EHV-4 was associated with respiratory disease (P=0.005). EHV-2 and 5 infections were both common, but foals shed EHV-2 in their NS earlier in life than EHV-5 (P=0.01). Latent EHV-2 and 5 infections were detected in the PBMC of 75 and 88%, respectively, of the foals at approximately 6 months of age. The strains of EHV-2 shed in the NS of individual horses were more genetically heterogeneous than the strains of EHV-5 (95.5-99.3% versus 98.8-99.3% nucleotide identity, respectively). One-month-old foals typically shed strains of EHV-2 that were identical to those infecting their dams whereas older foals often shed virus strains that were different from those of their dams. Although herpesvirus infections were ubiquitous in this cohort of horses, there were distinct clinical consequences and clear epidemiological differences between infections with the different viruses.

Occurrence of ovine herpesvirus type-2 infection in sheep and cattle in Samsun Province, Turkey

July 2004, a cow with clinical signs of ovine herpesvirus type-2 infection which is known as sheep associated malignant catarrhal fever (SA-MCF) was reported in Samsun Province in Turkey. Blood samples were collected from the suspected cow, 10 sheep housed with it, and from 150 healthy sheep and 29 healthy cattle randomly selected from different places in Samsun Province. Nested polymerase chain reaction (n-PCR) was used to detect ovine herpesvirus type-2 (OvHV-2) DNA in the suspected cow and competitive- ELISA (c-ELISA) kits were used to detect antibodies against OvHV-2. The suspected cow was found to be n-PCR positive and c-ELISA negative. The serological results were as follows: All 10 (100%) of sheep housed with the suspected cow and 18 of 29 (62%) of the randomly selected cattle were found seropositive. All 150 randomly selected healthy sheep were seronegative. The overall percentage of seropositivity was 14.7% (28/190). OvHV-2 DNA was detected in the peripheral blood leucocyte (PBL) samples of the cow and of the 10 sheep housed with the suspected cow.

Prevalence of equine herpesvirus type 2 (EHV-2) DNA in ocular swabs and its cell tropism in equine conjunctiva

Equine herpes virus 2 (EHV-2), a gamma(2)-herpesvirus, is common in horses of all ages. Its role as a primary pathogen is unclear but there is an association between EHV-2, respiratory disease and keratoconjunctivitis. The purpose of this study was to gain more information on the prevalence of EHV-2 DNA in conjunctival swabs from horses with and without ocular disease and to define the anatomical site and cell type harbouring viral genome or antigen. By polymerase chain reaction (PCR) 22 out of 77 (28.6%) ocular swabs of clinically healthy and only 4 out of 48 (8.3%) samples from diseased horses were positive. To define the main virus reservoir ocular tissue from 13 randomly selected horses without pathological evidence of ocular disease were analysed by nested PCR. In two horses optic nerve, lacrimal gland and conjunctiva, in further two cases lacrimal gland and conjunctiva and in four horses the conjunctiva only were EHV-2 PCR positive. For specifying the target cell we focused on conjunctivae and selected 3 out of 15 clinically healthy slaughterhouse horses positive for EHV-2 by PCR. In situ hybridisation on sections of these paraffin embedded conjunctivae localized viral genome in histiocyte-like cells of the submucosa. Immunohistochemical staining with an EHV-2 or S100 specific polyclonal antiserum demonstrated that Langerhans cells were co-localized in the same region of the sample section where virus positive cells were detected. Furthermore, we concluded that detection of viral antigen revealed a productive virus infection.

Infection and persistence of rhesus monkey rhadinovirus in immortalized B-cell lines

Similar to its close relative human herpesvirus 8, rhesus monkey rhadinovirus (RRV) persists predominantly in B cells of its natural host. Rhesus monkey B-cell lines immortalized by the Epstein-Barr-related virus from rhesus monkeys (rhEBV) were used as targets for infection by RRV. These cultured B cells were susceptible to infection by RRV and continued to produce low titers of RRV for months of continuous culture. Infection by RRV did not detectably alter the growth rates of these B-cell lines when it was measured at standard or reduced serum concentrations. Depending on the cell line, 5 to 40% of the B cells stained positive for the RRV genome by fluorescence in situ hybridization (FISH). Most RRV-positive cells showed a fine punctate nuclear staining pattern consistent with latent infection, while a small minority of cells (0.2 to 1%) contained large, intensely staining nuclear foci consistent with productive, replicative infection. Greater than 90% of the cells were rhEBV genome positive in a pattern consistent with latent infection, and again only a small minority of cells showed a productive, replicative staining pattern. Dual, two-color FISH staining revealed coinfection of numerous cells with both RRV and rhEBV, but productive replication of RRV and rhEBV was always observed in separate cells, never in the same cell. Thus, productive replication of RRV is unlinked to that of rhEBV; factors that influence activation to productive replication act separately on RRV and rhEBV, even within the same cell. The percentage of B cells expressing green fluorescent protein (GFP) early after infection with a recombinant RRV containing a GFP reporter gene was dose dependent and at a low multiplicity of infection increased progressively over time until 14 to 17 days after infection. These results establish a naturalistic cell culture system for the study of infection and persistence by RRV in rhesus monkey B cells.

Mass spectrometric analyses of purified rhesus monkey rhadinovirus reveal 33 virion-associated proteins

The repertoire of proteins that comprise intact gammaherpesviruses, including the human pathogen Kaposi's sarcoma-associated herpesvirus (KSHV), is likely to have critical functions not only in viral structure and assembly but also in the early stages of infection and evasion of the host's rapidly deployed antiviral defenses. To develop a better understanding of these proteins, we analyzed the composition of rhesus monkey rhadinovirus (RRV), a close phylogenetic relative of KSHV. Unlike KSHV, RRV replicates to high titer in cell culture and thus serves as an effective model for studying primate gammaherpesvirus structure and virion proteomics. We employed two complementary mass spectrometric approaches and found that RRV contains at least 33 distinct virally encoded proteins. We have assigned 7 of these proteins to the capsid, 17 to the tegument, and 9 to the envelope. Of the five gammaherpesvirus-specific tegument proteins, three have no known function. We also found three proteins not previously associated with a purified herpesvirus and an additional seven that represent new findings for a member of the gamma-2 herpesviruses. Detergent extraction resulted in particles that contained six distinct tegument proteins in addition to the expected capsid structural proteins, suggesting that this subset of tegument components may interact more directly with or with higher affinity for the underlying capsid and, in turn, may play a role in assembly or transport of viral or subviral particles during entry or egress.

Antibodies against bovine herpesvirus 4 are highly prevalent in wild African buffaloes throughout eastern and southern Africa

Bovine herpesvirus 4 (BoHV-4) has been isolated from cattle throughout the world. Interestingly, a survey of wild African buffaloes mainly from the Maasai Mara Game Reserve in Kenya revealed that 94% of the animals tested had anti-BoHV-4 antibodies [Rossiter, P.B., Gumm, I.D., Stagg, D.A., Conrad, P.A., Mukolwe, S., Davies, F.G., White, H., 1989. Isolation of bovine herpesvirus-3 from African buffaloes (Syncerus caffer). Res. Vet. Sci. 46, 337-343]. These authors also proposed that the serological antigenic relationship existing between BoHV-4 and alcelaphine herpesvirus 1 (AlHV-1) could confer to BoHV-4 infected buffaloes a protective immune response against lethal AlHV-1 infection. In the present study, we addressed two questions related to Rossiter et al. paper. Firstly, to investigate the role of the African buffalo as a natural host species of BoHV-4, the seroprevalence of anti-BoHV-4 antibodies was analysed in wild African buffaloes throughout eastern and southern Africa. A total of 400 sera was analysed using two complementary immunofluorescent assays. These analyses revealed that independently of their geographical origin, wild African buffaloes exhibit a seroprevalence of anti-BoHV-4 antibodies higher than 68%. This result is by far above the seroprevalence generally observed in cattle. Our data are discussed in the light of our recent phylogenetic study demonstrating that the BoHV-4 Bo17 gene has been acquired from a recent ancestor of the African buffalo. Secondly, we investigated the humoral antigenic relationship existing between BoHV-4 and AlHV-1. Our results demonstrate that among the antigens expressed in AlHV-1 infected cells, epitope(s) recognised by anti-BoHV-4 antibodies are exclusively nuclear, suggesting that the putative property of BoHV-4 to confer an immune protection against AlHV-1 relies on a cellular rather than on a humoral immune response.

Whole-genome transcription profiling of rhesus monkey rhadinovirus

Rhesus monkey rhadinovirus (RRV) and Kaposi's sarcoma-associated herpesvirus (KSHV; also called human herpesvirus 8) belong to the gamma-2 grouping of herpesviruses. RRV and KSHV share a high degree of sequence similarity, and their genomes are organized in a similar fashion. RRV serves as an excellent animal model system to study the gamma herpesvirus life cycle both in vitro and in vivo. We have developed a high-sensitivity, high-throughput, high-specificity real-time quantitative reverse transcriptase-based PCR assay for RRV and have used this assay to profile transcription from the whole RRV genome during de novo productive infection of rhesus fibroblasts. Using this assay, we demonstrate that the genome-wide transcription profile for RRV closely parallels the genome-wide transcription profile for KSHV.

Shedding of ovine herpesvirus 2 in sheep nasal secretions: the predominant mode for transmission

Ovine herpesvirus 2 (OvHV-2), the major causative agent of malignant catarrhal fever in ruminant species worldwide, has never been propagated in vitro. Using real-time PCR, a striking, short-lived, peak of viral DNA, ranging from 10(5) to over 10(8) copies/2 microg of DNA, was detected in nasal secretions from over 60.7% of adolescent sheep (n = 56) at some point during the period from 6 to 9 months of age. In contrast, only about 18% of adult sheep (n = 33) experienced a shedding episode during the study period. The general pattern of the appearance of viral DNA in nasal secretions was a dramatic rise and subsequent fall within 24 to 36 h, implying a single cycle of viral replication. These episodes occurred sporadically and infrequently, but over the 3-month period most of the 56 lambs (33, or 60.7%) experienced at least one episode. No corresponding fluctuations in DNA levels were found in either peripheral blood leukocytes or plasma. In a DNase protection assay, complete, enveloped OvHV-2 virions were demonstrated in the nasal secretions of all sheep examined during the time when they were experiencing an intense shedding episode. OvHV-2 infectivity in nasal secretions was also demonstrated by aerosolization of the secretions into OvHV-2-negative sheep. The data herein show that nasal shedding is the major mode of OvHV-2 transmission among domestic sheep and that adolescents represent the highest risk group for transmission.

Development of a real-time QPCR assay for the detection of RV2 lineage-specific rhadinoviruses in macaques and baboons

BACKGROUND

Two distinct lineages of rhadinoviruses related to Kaposi's sarcoma-associated herpesvirus (KSHV/HHV8) have been identified in macaques and other Old World non-human primates. We have developed a real-time quantitative PCR (QPCR) assay using a TaqMan probe to differentially detect and quantitate members of the rhadinovirus-2 (RV2) lineage. PCR primers were derived from sequences within ORF 60 and the adjacent ORF 59/60 intergenic region which were highly conserved between the macaque RV2 rhadinoviruses, rhesus rhadinovirus (RRV) and Macaca nemestrina rhadinovirus-2 (MneRV2). These primers showed little similarity to the corresponding sequences of the macaque RV1 rhadinoviruses, retroperitoneal fibromatosis herpesvirus Macaca nemestrina (RFHVMn) and Macaca mulatta (RFHVMm). To determine viral loads per cell, an additional TaqMan QPCR assay was developed to detect the single copy cellular oncostatin M gene.

RESULTS

We show that the RV2 QPCR assay is linear from less than 2 to more than 300,000 copies using MneRV2 DNA, and is non-reactive with RFHVMn DNA up to 1 billion DNA templates per reaction. RV2 loads ranging from 6 to 2,300 viral genome equivalent copies per 10(6) cells were detected in PBMC from randomly sampled macaques from the Washington National Primate Research Center. Screening tissue from other primate species, including another macaque, Macaca fascicularis, and a baboon, Papio cynocephalus, revealed the presence of novel rhadinoviruses, MfaRV2 and PcyRV2, respectively. Sequence comparison and phylogenetic analysis confirmed their inclusion within the RV2 lineage of KSHV-like rhadinoviruses.

CONCLUSIONS

We describe a QPCR assay which provides a quick and sensitive method for quantitating rhadinoviruses belonging to the RV2 lineage of KSHV-like rhadinoviruses found in a variety of macaque species commonly used for biomedical research. While this assay broadly detects different RV2 rhadinovirus species, it is unreactive with RV1 rhadinovirus species which commonly co-infect the same primate hosts. We also show that this QPCR assay can be used to identify novel RV2 rhadinoviruses in different primate species.

Novel gamma-2-herpesvirus of the Rhadinovirus 2 lineage in gibbons

We obtained 475 nucleotides of the DNA polymerase gene of a novel human herpesvirus 8 homolog sequence in a gibbon. The finding of this new gibbon virus, which clusters with a related chimpanzee virus in the rhadinovirus 2 genogroup, suggests the existence of a novel γ-2-herpesvirus in humans.

Equine herpes virus 2 infection in horse populations in Poland

The prevalence of Equine herpesvirus 2 (EHV-2) infections in the horse populations in Poland was investigated. Peripheral blood leukocytes (PBLs) of 139 horses were tested. The animals were divided into four groups: clinically healthy horses, horses suffering from respiratory disorders, mares with a recent abortion and horses with diagnosed ataxia. Thirty-four virus isolates were obtained from leukocytes of the tested animals by cocultivation with equine dermal cells and were identified as EHV-2 by PCR using primers for the gB gene of EHV-2 and/or primers for the sequence located upstream of the gene homologous to the equine interleukin 10 (IL-10) gene. These results indicate that EHV-2 is prevalent in horse populations in Poland. As the virus was most frequently isolated from horses with respiratory disorders its etiological importance may be considered.

Detection of bovine gammaherpesviruses by a nested duplex PCR

The two bovine gammaherpesviruses (Alcelaphine herpesvirus 1, AlHV-1; Bovine herpesvirus 4, BoHV-4) are distributed worldwide in cattle populations. Since the animals are frequently infected latently with no or low seropositivity, a DNA based diagnostic method would be useful for surveys and detection of these viruses. In the present study a nested duplex PCR was established for the sensitive and specific simultaneous detection of both viruses. The primers were designed for the gene of the major capsid protein (ORF25). The assay did not amplify the capsid gene sequence of 10 related bovine herpesviruses and other gammaherpesviruses. The test was able to detect 1pfu (plaque forming unit) of AlHV-1 and BoHV-4. Among 146 clinical samples (lymph nodes and peripheral blood leukocytes, PBLs) 65 (44.52%) were found to be positives for AlHV-1 and 84 (57.53%) for BoHV-4. This nested duplex PCR assay could serve as a useful diagnostic method for rapid, sensitive, specific simultaneous detection of the two bovine gammaherpesviruses.

Novel Kaposi's sarcoma-associated herpesvirus homolog in baboons

Kaposi's sarcoma (KS) and lymphoproliferative diseases induced by KS-associated herpesvirus (KSHV/human herpesvirus 8) cause substantial morbidity and mortality in human immunodeficiency virus-infected individuals. To understand KSHV biology it is useful to investigate closely related rhadinoviruses naturally occurring in nonhuman primates. Here we report evidence for a novel KSHV homolog in captive baboon species (Papio anubis and other). Using degenerate PCR we identified a novel rhadinovirus, PapRV2, that has substantial sequence identity to two essential KSHV genes, the viral polymerase and thymidylate synthase. A subset of animals exhibited detectable PapRV2 viral load in peripheral blood mononuclear cells. Extensive serological analysis of nearly 200 animals in the colony demonstrated that the majority carried cross-reacting antibodies that recognize KSHV or macaque rhadinovirus antigens. Seroreactivity increased with age, similar to the age-specific prevalence of KSHV in the human population. This establishes baboons as a novel resource to investigate rhadinovirus biology, which can be developed into an animal model system for KSHV-associated human diseases, vaccine development, and therapy evaluation.

The wood mouse is a natural host for Murid herpesvirus 4

Infection of laboratory mice by the Murid herpesvirus 4 (MHV-4) is a much studied model system for gammaherpesvirus pathogenesis. Little, however, is known about its natural host range, epidemiology and pathogenesis outside the laboratory. We have studied MHV-4 infection in free-living murids in the UK. Using a combination of serology and PCR analysis, we found that MHV-4 was endemic in wood mice (Apodemus sylvaticus) but not in two species of voles (Clethrionomys glareolus, Microtus agrestis). The sites of detection of viral DNA were the lungs and, less commonly, the spleen, emphasizing the importance of the former in virus persistence during natural infection and confirming similar data in laboratory mice.

The mouse is not permissive for equine herpesvirus 2 (EHV-2), however viral DNA persisted in lung and spleen depending on the inoculation route

BALB/c mice were inoculated with 3 EHV-2 low passage isolates. After intranasal inoculation, viral DNA was detected by virus-specific nested PCR in the lung up to day 30 post inoculation and in nasal turbinates till day 7. In trigeminal ganglia, olfactory bulb, brain and lymph nodes viral DNA was randomly shown by PCR. After intraperitoneal inoculation viral DNA was present in lymphoid tissues. The spleen was PCR positive up to day 30 and showed a splenomegaly. Clinical signs, virus replication and viraemia, were not observed and no virus strain-specific differences were obvious. Control mice inoculated with equine herpesvirus 4 were PCR negative in all tissues.

Enhanced atherogenesis is not an obligatory response to systemic herpesvirus infection in the apoE-deficient mouse: comparison of murine gamma-herpesvirus-68 and herpes simplex virus-1

Viral and bacterial infectious agents have been implicated in the etiology of atherosclerosis. We have previously shown that a gamma-herpesvirus can accelerate atherosclerosis in the apolipoprotein E-deficient (apoE-/-) mouse. To address whether a virally induced systemic immune response is sufficient to trigger enhanced atheroma formation, we infected apoE-/- mice with murine gamma-herpesvirus-68 (MHV-68) or herpes simplex virus-1 (HSV-1). In this study, we show that both viruses were able to induce a cell-mediated and humoral immune response in the apoE-/- mouse, which was sustained over a period of 24 weeks. Although intranasal or intraperitoneal infection with MHV-68 induced similar levels of virus-specific IgG1 and IgG2a antibodies in the serum of apoE-/- mice, those infected with HSV-1 showed higher anti-HSV-1 IgG2a compared with IgG1 antibody levels. In addition, viral message was not detected in the aortas of HSV-1-infected animals, whereas we have shown previously that MHV-68 mRNA can be detected in the aortas of infected mice as early as 5 days after infection. Compared with control mice, apoE-/- mice infected with MHV-68 showed accelerated atherosclerosis, whereas mice infected with HSV-1 did not. These data indicate that a systemic immune response to any particular infectious agent is insufficient to induce enhanced atherosclerosis in the apoE-/- mouse and point to specific infections or immune mechanisms that might be essential for virally enhanced atherogenesis.

Prevalence of equine herpesvirus types 2 and 5 in horse populations by using type-specific PCR assays

Equineherpesvirustypes 2 and 5 (EHV-2andEHV-5)have a rather unclearpathogenicity and distribution within the equid population. In order to gain more information on the prevalence of these two viruses, type-specific PCR assays were developed to detect viral DNA in nasal specimens and in peripheral blood leukocytes (PBLs) of adult horses and foals from various regions of Europe, i.e. Sweden, Hungary and the United Kingdom. In adult horses, the prevalence of EHV-2 in PBLs was up to 68% in Sweden and 71% in the United Kingdom. EHV-2 DNA was detected in the PBLs from all the foals tested in all countries and most (93%) of the nasal specimens also yielded positive results. The prevalence of EHV-5 DNA in the PBLs of foals in Hungary was 15 and 24% in adult horses in the United Kingdom. This observation was among the very few reports of the presence of EHV-5 in horses. In summary, the specific PCR assays revealed important data on the occurrence and distribution of EHV-2 and EHV-5 in large horse populations. The findings indicated that infection with EHV-5 occurred later than EHV-2 in foals. This study may contribute to a better understanding of the etiological role of these gammaherpesviruses in equine diseases.

Detection of equine herpesvirus type 2 (EHV-2) in horses with keratoconjunctivitis

The prevalence of EHV-2 in 27 horses with keratoconjunctivitis and 21 clinically healthy horses of different ages and stocks were analyzed. We demonstrated that EHV-2 was present in 12 keratoconjunctivitis cases as shown by nested PCR on ocular swabs. This is statistically more often than in the control group, where only two ocular swabs were EHV-2 positive. Cocultivation was successful on peripheral blood leukocytes of healthy and diseased horses but not on swabs. We isolated ten EHV-2 strains from diseased and nine from control horses, whereas 16 isolates showed different restriction enzyme patterns. The results of immunfluorescence and neutralization tests are predictory only in combination with the nested PCR data on ocular swabs. A successful antiviral treatment in nine out of 16 cases supports the aetiological role of EHV-2 in this ocular disease.

Identification of equine herpesvirus 3 (equine coital exanthema virus), equine gammaherpesviruses 2 and 5, equine adenoviruses 1 and 2, equine arteritis virus and equine rhinitis A virus by polymerase chain reaction

OBJECTIVE

To develop rapid (< 8 hour) tests using polymerase chain reaction (PCR) for the diagnosis of equine herpesvirus 3 (EHV3; equine coital exanthema virus), equine gammaherpesviruses 2 (EHV2) and EHV5, equine adenovirus 1 (EAdV1), EAdV2, equine arteritis virus (EAV), equine rhinitis A virus (ERAV; formerly equine rhinovirus 1)

DESIGN

Either single round or second round (seminested) PCRs were developed and validated.

METHODS

Oligonucleotide primers were designed that were specific for each virus, PCR conditions were defined and the specificity and sensitivity of the assays were determined. The application of the tests was validated using a number of independent virus isolates for most of the viruses studied. The PCRs were applied directly to clinical samples where samples were available.

RESULTS

We developed a single round PCR for the diagnosis of EHV3, a seminested PCR for EHV2 and single round PCRs for EHV5, EAdV1, EAdV2 and RT-PCRs for EAV and ERAV. The PCR primer sets for each virus were designed and shown to be highly specific (did not amplify any recognised non-target template) and sensitive (detection of minimal amounts of virus) and, where multiple virus isolates were available all isolates were detected.

CONCLUSION

The development and validation of a comprehensive panel of PCR diagnostic tests, predominantly for viruses causing equine respiratory disease, that can be completed within 8 hours from receipt of clinical samples, provides a major advance in the rapid diagnosis or exclusion diagnosis of these endemic equine virus diseases in Australia.

A novel gamma 2-herpesvirus of the Rhadinovirus 2 lineage in chimpanzees

Old World monkeys and, recently, African great apes have been shown, by serology and polymerase chain reaction (PCR), to harbor different gamma2-herpesviruses closely related to Kaposi's sarcoma-associated Herpesvirus (KSHV). Although the presence of two distinct lineages of KSHV-like rhadinoviruses, RV1 and RV2, has been revealed in Old World primates (including African green monkeys, macaques, and, recently, mandrills), viruses belonging to the RV2 genogroup have not yet been identified from great apes. Indeed, the three yet known gamma2-herpesviruses in chimpanzees (PanRHV1a/PtRV1, PanRHV1b) and gorillas (GorRHV1) belong to the RV1 group. To investigate the putative existence of a new RV2 Rhadinovirus in chimpanzees and gorillas we have used the degenerate consensus primer PCR strategy for the Herpesviral DNA polymerase gene on 40 wild-caught animals. This study led to the discovery, in common chimpanzees, of a novel gamma2-herpesvirus belonging to the RV2 genogroup, termed Pan Rhadino-herpesvirus 2 (PanRHV2). Use of specific primers and internal oligonucleotide probes demonstrated the presence of this novel gamma2-herpesvirus in three wild-caught animals. Comparison of a 1092-bp fragment of the DNA polymerase obtained from these three animals of the Pan troglodytes troglodytes subspecies, one from Gabon and the two others from Cameroon, revealed <1% of nucleotide divergence. The geographic colocalization as well as the phylogenetic "relationship" of the human and simian gamma2-herpesviruses support the model according to which herpesviruses have diversified from a common ancestor in a manner mediating cospeciation of herpesviruses with their host species. By demonstrating the existence of two distinct Rhadinovirus lineages in common chimpanzees, our finding indicates the possible existence of a novel human gamma2-herpesvirus belonging to the RV2 genogroup.

Characterization of RKZ isolate of ovine herpesvirus 1

Cytopathic effect (CPE) characterized mainly by foci of rounded cells was observed in cultures of primary plexus choroideus cells from healthy lamb following cryopreservation. It was possible to transmit the infectious agent to other primary cells of ovine origin by co-cultivation with infected cells. By indirect immunofluorescence microscopy it was found that high percentage of sheep (65-80% in 3 different herds from Slovakia) are infected with this infectious agent. Electron microscopy of cells with CPE revealed the presence of herpesvirus particles. Viral DNA was isolated from infected cells using pulse-field gel electrophoresis and further used as probe in Southern blot analysis. The probe reacted specifically only with DNA from cells infected with Ovine herpesvirus 1 (OvHV-1) but not with DNA of other ruminant herpesviruses. Some of the HindIII restriction fragments of DNA of the obtained OvHV-1 isolate denominated RKZ were cloned. Part of the H9 clone was sequenced identifying a gene that encoded a polypeptide homologous to conserved herpesvirus VP23 structural protein. From comparison of the sequence of this clone with VP23 sequences of other herpesviruses it was deduced that OvHV-1 might be classified within the Rhadinovirus genus of the Gammaherpesvirinae subfamily. The sequencing of the H9 clone of DNA of RKZ isolate enabled establishment of sensitive and highly specific polymerase chain reaction (PCR) assay for detection of OvHV-1.

A chimpanzee rhadinovirus sequence related to Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8: increased detection after HIV-1 infection in the absence of disease

OBJECTIVE

To look for a virus related to Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus 8 (HHV8) in chimpanzees and to investigate phylogenetic and biological similarities to KSHV.

METHODS

Peripheral blood mononuclear cell (PBMC) DNA samples from chimpanzees (Pan troglodytes troglodytes) were screened with newly designed consensus oligonucleotide primers for the DNA polymerase gene of KSHV-related gamma2-herpesviruses (rhadinoviruses). Samples from HIV-1-infected and -uninfected chimpanzees were screened with virus-specific primers. Antibodies to KSHV structural and latent antigens were measured by immunofluorescence, enzyme-linked immunosorbent assay (ELISA) and Western blot.

RESULTS

We identified 972 base pairs (bp) of a new viral DNA polymerase sequence with 81.6% (nucleotides) and 93.2% (protein) identity to that of KSHV/HHV8. It was detected in 15/37 (41%) animals experimentally infected with HIV-1, but only in one out of 30 uninfected animals (P<0.001). Antibodies were found by immunofluorescence to structural, but not latent, KSHV antigens in nearly all HIV-1-infected and uninfected animals.

CONCLUSION

Like man and two other Old World primate species, chimpanzees harbour a virus closely related to KSHV/HHV8, termed Pan troglodytes rhadinovirus-1 (PtRV-1). Like KSHV, PtRV-1 is more easily detected by polymerase chain reaction (PCR) in the PBMC of HIV-1-infected than of HIV-1-uninfected individuals, suggesting increased viral load. Despite the close phylogenetic relationship and biological similarities between KSHV and PtRV-1, Kaposi's sarcoma (KS) has not been reported in HIV-1-infected chimpanzees. PtRV-1 may lack some of the pathogenic determinants of KSHV, or humans and chimpanzees may differ in how they control the infection with their respective rhadinoviruses.

Common metastatic carcinoma of California sea lions (Zalophus californianus): evidence of genital origin and association with novel gammaherpesvirus

Tissues from 10 adult California sea lions (Zalophus californianus, seven females and three males) that had metastatic carcinoma in sublumbar area lymph nodes were examined histologically. A distinctive epithelial proliferative lesion interpreted as intraepithelial neoplasia was found in genital tracts of all ten animals; in vagina (5/7), cervix (7/7), uterus (3/7), penis (3/3) and prepuce (3/3). Intraepithelial neoplasia closely resembled metastatic carcinomas and was directly contiguous with invasive carcinoma in one animal. Rare eosinophilic intranuclear inclusion bodies were found in penile and preputial intraepithelial neoplasia (one animal), cervical intraepithelial neoplasia (one animal), invasive cervical carcinoma (one animal) and metastatic carcinoma (two animals). Electron microscopic examination of tissues from two sea lions (one with intraepithelial neoplasia and one with metastatic carcinoma) demonstrated viral particles consistent with a herpesvirus. An immunohistochemical stain for the latent membrane protein of Epstein-Barr virus was positive in intraepithelial neoplasia in one sea lion. Herpesvirus DNA sequences were detected by consensus primer polymerase chain reaction (PCR) in metastatic carcinomas from all four sea lions from which unfixed tumor samples were available. Results of sequencing were consistent with a novel gammaherpesvirus in the genus Rhadinovirus. DNA extracted from the four metastatic carcinomas also was tested for papillomavirus by Southern blot and PCR with consensus papillomavirus primers; all samples were negative by both methods. These findings support the genital origin of the sea lion carcinoma and implicate a novel gammaherpesvirus as a possible cause.

Experimental infection of rhesus and pig-tailed macaques with macaque rhadinoviruses

The recognition of naturally occurring rhadinoviruses in macaque monkeys has spurred interest in their use as models for human infection with Kaposi sarcoma-associated herpesvirus (human herpesvirus 8). Rhesus macaques (Macaca mulatta) and pig-tailed macaques (Macaca nemestrina) were inoculated intravenously with rhadinovirus isolates derived from these species (rhesus rhadinovirus [RRV] and pig-tailed rhadinovirus [PRV]). Nine rhadinovirus antibody-negative and two rhadinovirus antibody-positive monkeys were used for these experimental inoculations. Antibody-negative animals clearly became infected following virus inoculation since they developed persisting antibody responses to virus and virus was isolated from peripheral blood on repeated occasions following inoculation. Viral sequences were also detected by PCR in lymph node, oral mucosa, skin, and peripheral blood mononuclear cells following inoculation. Experimentally infected animals developed peripheral lymphadenopathy which resolved by 12 weeks following inoculation, and these animals have subsequently remained free of disease. No increased pathogenicity was apparent from cross-species infection, i.e., inoculation of rhesus macaques with PRV or of pig-tailed macaques with RRV, whether the animals were antibody positive or negative at the time of virus inoculation. Coinoculation of additional rhesus monkeys with simian immunodeficiency virus (SIV) isolate SIVmac251 and macaque-derived rhadinovirus resulted in an attenuated antibody response to both agents and shorter mean survival compared to SIVmac251-inoculated controls (155.5 days versus 560.1 days; P < 0.019). Coinfected and immunodeficient macaques died of a variety of opportunistic infections characteristic of simian AIDS. PCR analysis of sorted peripheral blood mononuclear cells indicated a preferential tropism of RRV for CD20(+) B lymphocytes. Our results demonstrate persistent infection of macaque monkeys with RRV and PRV following experimental inoculation, but no specific disease was readily apparent from these infections even in the context of concurrent SIV infection.

Rhesus rhadinovirus establishes a latent infection in B lymphocytes in vivo

Recent DNA sequence analysis indicates that rhesus rhadinovirus (RRV) is a member of the lymphotropic gamma-2 herpesvirus family. To determine if RRV is lymphotropic, peripheral blood mononuclear cells from naturally infected monkeys were separated by immunomagnetic bead depletion and analyzed for the presence of RRV by virus isolation and nested PCR. The recovery and consistent detection of RRV in the CD20(+)-enriched fraction clearly demonstrates that B lymphocytes are a major site of virus persistence.

A herpesvirus of rhesus monkeys related to the human Kaposi's sarcoma-associated herpesvirus

A herpesvirus that is related to but distinct from the Kaposi's sarcoma-associated herpesvirus (KSHV, or human herpesvirus 8) was isolated from rhesus monkeys. The sequence of 10.6 kbp from virion DNA revealed the presence of an interleukin-6 homolog similar to what is present in KSHV and a closer relatedness of the DNA polymerase and glycoprotein B reading frames to those of KSHV than to those of any other herpesvirus. This rhesus monkey herpesvirus replicated lytically and to high titers in cultured rhesus monkey fibroblasts. Antibody testing revealed a high prevalence for at least 10 years in our rhesus monkey colony and a high prevalence in two other colonies that were tested. Thus, rhesus monkeys naturally harbor a virus related to KSHV, which we have called RRV, for rhesus monkey rhadinovirus.

Kaposi's sarcoma-associated herpesvirus (KSHV or HHV8) in primary effusion lymphoma: ultrastructural demonstration of herpesvirus in lymphoma cells

Recent molecular evidence suggests an association with a new herpesvirus, Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8), and primary effusion lymphomas (PELs). PELs have a characteristic morphology, phenotype, and clinical presentation, with malignant effusions in the absence of a contiguous solid tumor mass. We have established a cell line (KS-1) from a KSHV-positive human immunodeficiency virus (HIV)-negative patient with pleural cavity-based lymphoma that was passaged into triple-immunodeficient BNX mice. In contrast to cell lines from body cavity-based lymphomas derived from HIV-positive individuals that contain both KSHV and Epstein Barr viral genome, these cells contain only KSHV, allowing for uncontaminated virologic studies. Ultrastructural examination identified malignant cells with features of late differentiating B cells (immunoblasts). Cells with viral cytopathic effect contained typical 110-nm intranuclear herpesvirus nucleocapsids and complete cytoplasmic virions, confirming the association of PEL with KSHV.

[Identification of the corn mosaic virus, a rhabdovirus, in Costa Rica]

Maize mosaic virus (MMV), a rhabdovirus, was identified associated to maize field plants, showing stunting and continuous chlorotic stripes uniformly distributed over the leaf blade. The virus was detected in field samples by agar-gel immunodifussion. Enveloped, bacilliform virus particles were observed by electron microscopy in thin sections of naturally infected leaf tissue.