Pathogenesis of Bohle iridovirus infection in Krefft's freshwater turtle hatchlings (Emydura macquarii krefftii).

Ranaviruses have been detected in over 12 families of reptiles including many genera of turtles, tortoises, and terrapins, but the pathogenesis of these infections is still poorly understood. Krefft's river turtle hatchlings (N = 36; Emydura macquarii krefftii) were inoculated intramuscularly with Bohle iridovirus (BIV, Ranavirus, isolate) or saline, and euthanized at 9 timepoints (3 infected and 1 control per timepoint) over a 24-day period. Samples of lung, liver, kidney, and spleen were collected for quantitative polymerase chain reaction (PCR); internal organs, skin, and oral cavity samples were fixed for histopathological examination. The earliest lesions, at 8 days postinoculation (dpi), were lymphocytic inflammation of the skin and fibrinoid necrosis of regional vessels at the site of inoculation, and mild ulcerative necrosis with lymphocytic and heterophilic inflammation in the oral, nasal, and tongue mucosae. Fibrinonecrotic foci with heterophilic inflammation were detected in spleen and gonads at 16 dpi. Multifocal hepatic necrosis, heterophilic inflammation, and occasional basophilic intracytoplasmic inclusion bodies were observed at 20 dpi, along with ulcerative lymphocytic and heterophilic tracheitis and bronchitis. Tracheitis, bronchitis, and rare bone marrow necrosis were present at 24 dpi. Of the viscera tested for ranaviral DNA by PCR, the liver and spleen had the highest viral loads throughout infection, and thus appeared to be major targets of viral replication. Testing of whole blood by qPCR was the most-effective ante-mortem method for detecting ranaviral infection compared with oral swabs. This study represents the first time-dependent pathogenesis study of a ranaviral infection in turtles.

Viruses Infecting the European Catfish (Silurus glanis).

In aquaculture, disease management and pathogen control are key for a successful fish farming industry. In past years, European catfish farming has been flourishing. However, devastating fish pathogens including limiting fish viruses are considered a big threat to further expanding of the industry. Even though mainly the ranavirus (Iridoviridea) and circovirus (Circoviridea) infections are considered well- described in European catfish, more other agents including herpes-, rhabdo or papillomaviruses are also observed in the tissues of catfish with or without any symptoms. The etiological role of these viruses has been unclear until now. Hence, there is a requisite for more detailed information about the latter and the development of preventive and therapeutic approaches to complete them. In this review, we summarize recent knowledge about viruses that affect the European catfish and describe their origin, distribution, molecular characterisation, and phylogenetic classification. We also highlight the knowledge gaps, which need more in-depth investigations in the future.

Pigeon adenovirus and pigeon torque teno virus associated with acute multifocal hepatic necrosis in pigeons in Queensland, Australia.

In 2018, an outbreak resulting in deaths of 28 breeding pigeons was reported north of Brisbane, Australia. The affected birds had runny nasal discharge and poor body condition. Two birds were submitted to Biosecurity Sciences Laboratory, Brisbane, for investigation. A range of diagnostic tests excluded a number of known pathogens, and no virus was isolated in cell culture. Histopathological examination revealed severe acute multifocal necrosis in the liver with eosinophilic intranuclear inclusions in hepatocytes and Kupffer cells. High-throughput sequencing (HTS) revealed full-length sequences for pigeon adenovirus 1 (PiAd-A) and pigeon torque teno virus (PTTV). This report indicates concomitant PiAd-1and PTTV infections in Australian pigeons.

Bid is involved in apoptosis induced by Chinese giant salamander iridovirus and contributes to the viral replication in an amphibian cell line.

Bid is a pro-apoptotic BH3-only member of the Bcl-2 superfamily that functions to link the extrinsic apoptotic pathway and the mitochondrial amplification loop of the intrinsic pathway. In this study, the expression and functions of Chinese giant salamander (Andrias davidianus) Bid (AdBid) were investigated. The AdBid cDNA sequence contains an open reading frame (ORF) of 576 nucleotides, encoding a putative protein of 191 aa. AdBid possesses the conserved BH3 interacting domain and shared 34-52% sequence identities with other amphibian Bid. mRNA expression of AdBid was most abundant in muscle. The expression level of AdBid in Chinese giant salamander muscle, kidney and spleen significantly increased after Chinese giant salamander iridovirus (GSIV) infection. Additionally, a plasmid expressing AdBid was constructed and transfected into the Chinese giant salamander muscle cell line (GSM cells). The morphology and cytopathic effect (CPE) and apoptotic process in AdBid over-expressed GSM cells was significantly enhanced during GSIV infection compared with that in control cells. Moreover, a higher level of the virus major capsid protein (MCP) gene copies and protein synthesis was confirmed in the AdBid over-expressed cells. These results indicated that AdBid played a positive role in GSIV induced apoptosis and the viral replication. This study may contribute to the better understanding on the infection mechanism of iridovirus-induced apoptosis.

Torque teno virus in liver diseases: On the way towards unity of view.

The review presents the data accumulated for more than 20 years of research of torque teno virus (TTV). Its molecular genetic structure, immunobiology, epidemiology, diagnostic methods, possible replication sites, and pathogenicity factors are described. TTV is a virus that is frequently detectable in patients with different viral hepatitides, in cases of hepatitis without an obvious viral agent, as well as in a healthy population. There is evidence suggesting that biochemical and histological changes occur in liver tissue and bile duct epithelium in TTV monoinfection. There are sufficient histological signs of liver damage, which confirm that the virus can undergo a replicative cycle in hepatocytes. Along with this, cytological hybridization in TTV-infected cells has shown no substantial cytopathic (cell-damaging) effects that are characteristic of pathogenic hepatotropic viruses. Studying TTV has led to the evolution of views on its role in the development of human pathology. The first ideas about the hepatotropism of the virus were gradually reformed as new data became available on the prevalence of the virus and its co-infection with other viruses, including the viruses of the known types of hepatitides. The high prevalence of TTV in the human population indicates its persistence in the body as a virome and a non-pathogenic virus. It has recently been proposed that the level of TTV DNA in the blood of patients undergoing organ transplantation should be used as an endogenous marker of the body's immune status. The available data show the polytropism of the virus and deny the fact that TTV can be assigned exclusively to hepatitis viruses. Fortunately, the rare detection of the damaging effect of TTV on hepatic and bile duct epithelial cells may be indirect evidence of its conditionally pathogenic properties. The ubiquity of the virus and the variability of its existence in humans cannot put an end to its study.

High prevalence of subclinical frog virus 3 infection in freshwater turtles of Ontario, Canada.

Ranaviruses have been associated with chelonian mortality. In Canada, the first two cases of ranavirus were detected in turtles in 2018 in Ontario, although a subsequent survey of its prevalence failed to detect additional positive cases. To confirm the prevalence of ranavirus in turtles in Ontario, we used a more sensitive method to investigate if lower level persistent infection was present in the population. Here we report results via a combination of qPCR, PCR, Sanger sequencing and genome sequencing from turtles from across Ontario, with no clinical signs of illness. We found 2 positives with high viral load and 5 positives with low viral load. Histopathology found subtle histological changes. DNA sequences identified two types of frog virus 3 (FV3), and genome sequencing identified a ranavirus similar to wild-type FV3. Our results show that the virus has been present in Ontario's turtles as subclinical infections.

Function and Regulation of Nuclear DNA Sensors During Viral Infection and Tumorigenesis.

IFI16, hnRNPA2B1, and nuclear cGAS are nuclear-located DNA sensors that play important roles in initiating host antiviral immunity and modulating tumorigenesis. IFI16 triggers innate antiviral immunity, inflammasome, and suppresses tumorigenesis by recognizing double-stranded DNA (dsDNA), single-stranded DNA (ssDNA), damaged nuclear DNA, or cooperatively interacting with multiple tumor suppressors such as p53 and BRCA1. hnRNPA2B1 initiates interferon (IFN)-α/ß production and enhances STING-dependent cytosolic antiviral signaling by directly binding viral dsDNA from invaded viruses and facilitating N6 -methyladenosine (m6A) modification of cGAS, IFI16, and STING mRNAs. Nuclear cGAS is recruited to double-stranded breaks (DSBs), suppresses DNA repair, and promotes tumorigenesis. This review briefly describes the nuclear functions of IFI16, hnRNPA2B1, and cGAS, and summarizes the transcriptional, post-transcriptional, and post-translational regulation of these nuclear DNA sensors.

First detection and genetic characterization of a novel kirkovirus from a dead thoroughbred mare in northern Xinjiang, China, in 2018.

BACKGROUND: In May 2018, a 8 year old thoroughbred mare died at an equestrian club in Changji, Xinjiang, China. The horse had been imported from the United States in 2013. She became pregnant in December 2016 but, after foaling, gradually lost weight and died in May 2018. This study aim to identify the pathogen, who cause of horse death, using virome. RESULTS: We have identified an Equ1-like virus from the fecal virome of a dead thoroughbred mare in China. Full genomic sequencing and phylogenetic analysis of the virus, tentatively named "kirkovirus Cj-7-7", showed that it was closely related to kirkovirus Equ1 and clustered together with po-circo-like viruses 21, 22, 41, and 51, suggesting that it should be assigned to the proposed family "Kirkoviridae". An epidemiological investigation showed that kirkovirus Cj-7-7 circulates in horses of northern Xinjiang and may specifically infect intestinal cells. CONCLUSIONS: Our findings demonstrate the genetic diversity and geographic distribution of Kirkoviruses, and the prevalence of Kirkovirus Cj-7-7 in Xinjiang, China.

Chinese Giant Salamander (Andrias davidianus) Iridovirus Infection Leads to Apoptotic Cell Death through Mitochondrial Damage, Caspases Activation, and Expression of Apoptotic-Related Genes.

Chinese giant salamander iridovirus (GSIV) is the causative pathogen of Chinese giant salamander (Andrias davidianus) iridovirosis, leading to severe infectious disease and huge economic losses. However, the infection mechanism by GSIV is far from clear. In this study, a Chinese giant salamander muscle (GSM) cell line is used to investigate the mechanism of cell death during GSIV infection. Microscopy observation and DNA ladder analysis revealed that DNA fragmentation happens during GSIV infection. Flow cytometry analysis showed that apoptotic cells in GSIV-infected cells were significantly higher than that in control cells. Caspase 8, 9, and 3 were activated in GSIV-infected cells compared with the uninfected cells. Consistently, mitochondria membrane potential (MMP) was significantly reduced, and cytochrome c was released into cytosol during GSIV infection. p53 expression increased at an early stage of GSIV infection and then slightly decreased late in infection. Furthermore, mRNA expression levels of pro-apoptotic genes participating in the extrinsic and intrinsic pathway were significantly up-regulated during GSIV infection, while those of anti-apoptotic genes were restrained in early infection and then rose in late infection. These results collectively indicate that GSIV induces GSM apoptotic cell death involving mitochondrial damage, caspases activation, p53 expression, and pro-apoptotic molecules up-regulation.

Accelerated Metabolite Levels of Aerobic Glycolysis and the Pentose Phosphate Pathway Are Required for Efficient Replication of Infectious Spleen and Kidney Necrosis Virus in Chinese Perch Brain Cells.

Glucose is a main carbon and energy source for virus proliferation and is usually involved in the glycolysis, pentose phosphate pathway (PPP), and tricarboxylic acid cycle (TCA cycle) pathways. In this study, we investigated the roles of glucose-related metabolic pathways during the replication of infectious spleen and kidney necrosis virus (ISKNV), which has caused serious economic losses in the cultured Chinese perch (Siniperca chuatsi) industry. We found that ISKNV infection enhanced the metabolic pathways of the PPP and the TCA cycle at the early stage of the ISKNV infection cycle and enhanced the glycolysis pathway at the late stage of the ISKNV infection cycle though the comprehensive analysis of transcriptomics, proteomics, and metabolomics. The advanced results proved that ISKNV replication induced upregulation of aerobic glycolysis at the late stage of ISKNV infection cycle and aerobic glycolysis were required for ISKNV multiplication. In addition, the PPP, providing nucleotide biosynthesis, was also required for ISKNV multiplication. However, the TCA cycle involving glucose was not important and necessary for ISKNV multiplication. The results reported here provide new insights into viral pathogenesis mechanism of metabolic shift, as well as antiviral treatment strategies.

Dose-dependent morbidity of freshwater turtle hatchlings, Emydura macquarii krefftii, inoculated with Ranavirus isolate (Bohle iridovirus, Iridoviridae).

Ranaviral infections cause mass die-offs in wild and captive turtle populations. Two experimental studies were performed to first determine the susceptibility of an Australian turtle species (Emydura macquarii krefftii) to different routes of infection and second examine the effect of viral titre on the morbidity in hatchlings. All inoculation routes (intracoelomic, intramuscular and oral) produced disease, but the clinical signs, histopathology and time to onset of disease varied with the route. The median infectious and lethal doses for intramuscularly inoculated hatchlings were 102.52 (1.98-2.93) and 104.43 (3.81-5.19) TCID50 ml-1, respectively. Clinical signs began 14 to 29 days post-inoculation and the median survival time was 22 days (16-25) across all dose groups. For every 10-fold increase in dose, the odds of developing any clinical signs or severe clinical signs increased by 3.39 [P<0.01, 95 % confidence interval (CI): 1.81-6.36] and 3.71 (P<0.01, 95 % CI: 1.76-7.80), respectively. Skin lesions, previously only reported in ranaviral infection in lizards, were observed in the majority of intramuscularly inoculated hatchlings that developed ranaviral disease. The histological changes were consistent with those in previous reports for reptiles and consisted of necrosis at or near the site of injection, in the spleen, liver and oral cavity. Systemic inflammation was also observed, predominantly affecting necrotic organs. The estimates reported here can be used to model ranaviral disease and quantify and manage at-risk populations.

Isolation and Characterization of a Ranavirus Associated with Disease Outbreaks in Cultured Hybrid Grouper (♀ Tiger Grouper Epinephelus fuscoguttatus × â™‚ Giant Grouper E. lanceolatus) in Guangxi, China.

An outbreak of suspected iridovirus disease in cultured hybrid grouper (♀Tiger Grouper Epinephelus fuscoguttatus × â™‚ Giant Grouper Epinephelus lanceolatus) occurred in the Guangxi Province in July, 2018. In this study, grouper iridovirus Guangxi (SGIV-Gx) was isolated from diseased hybrid grouper that were collected from Guangxi. Cytopathic effects were observed and identified in grouper spleen cells that were incubated with diseased tissue homogenates after 24 h, and the effects increased at 48 h postinfection. The transmission electron microscopy results showed that viral particles that were about 200 nm in diameter with hexagonal profiles were present in the cell cytoplasm of suspected virus-infected cells. The presence of SGIV-Gx (accession number: MK107821) was identified by polymerase chain reaction (PCR) and amplicon sequencing, which showed that this strain was most closely related to Singapore grouper iridovirus (AY521625.1). The detection of SGIV-Gx infection was further supported by novel aptamer (Q2c)-based detection technology. The effects of temperature and pH on viral infectivity were analyzed by using reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) and cell culture. The results indicated that SGIV-Gx was resistant to exposure to pH levels 5, 7, and 7.5 for 1 h, but its infectivity was remarkably lower at pH levels 3 and 10 after 1 h. The analyses showed that SGIV-Gx was stable for 1 h at 4°C and 25°C but was inactivated after 1 h at 40, 50, and 60°C.

First report of megalocytivirus (iridoviridae) in cultured bluegill sunfish, Lepomis macrochirus, in China.

The bluegill sunfish, Lepomis macrochirus, is an important aquacultural and recreational species in southern China because of its excellent taste, rapid growth rate, and good looks. At present, few pathogens are known to affect the bluegill sunfish. However, an iridovirus-like disease recently caused heavy losses to the bluegill sunfish aquaculture industry in Guangdong, China. We report that a virus, designated BSMIV-SD-20171020, was isolated from diseased bluegill sunfish in China. The isolate was efficiently propagated in a Chinese perch brain (CPB) cell line. The cytopathic effect was observed, the MCP gene PCR amplified, and the virus observed with electron microscopy. Its viral titer in CPB cells reached 104.13 TCID50 mL-1. The mortality rate was 100% when bluegill sunfish were challenged with BSMIV-SD-20171020 at a dose of 103.13 TCID50/fish. A histopathological examination revealed basophilic hypertrophied cells in the intestine, liver, and spleen. A nucleotide sequence alignment and phylogenetic analysis of the major capsid protein revealed that isolate BSMIV-SD-20171020 is the species Infectious spleen and kidney necrosis virus (ISKNV), in the genus Megalocytivirus.

Metagenomic analysis of DNA viruses from posttransplant lymphoproliferative disorders.

Posttransplant lymphoproliferative disorders (PTLDs), 50%-80% of which are strongly associated with Epstein-Barr virus (EBV), carry a high morbidity and mortality. Most clinical/epidemiological/tumor characteristics do not consistently associate with worse patient survival, so our aim was to identify if other viral genomic characteristics associated better with survival. We extracted DNA from stored paraffin-embedded PTLD tissues at our center, identified viral sequences by metagenomic shotgun sequencing (MSS), and analyzed the data in relation to clinical outcomes. Our study population comprised 69 PTLD tissue samples collected between 1991 and 2015 from 60 subjects. Nucleotide sequences from at least one virus were detected by MSS in 86% (59/69) of the tissues (EBV in 61%, anelloviruses 52%, gammapapillomaviruses 14%, CMV 7%, and HSV in 3%). No viruses were present in higher proportion in EBV-negative PTLD (compared to EBV-positive PTLD). In univariable analysis, death within 5 years of PTLD diagnosis was associated with anellovirus (P = 0.037) and gammapapillomavirus (P = 0.036) detection by MSS, higher tissue qPCR levels of the predominant human anellovirus species torque teno virus (TTV; P = 0.016), T cell type PTLD, liver, brain or bone marrow location. In multivariable analyses, T cell PTLD (P = 0.006) and TTV PCR level (P = 0.012) remained significant. In EBV-positive PTLD, EBNA-LP, EBNA1 and EBNA3C had significantly higher levels of nonsynonymous gene variants compared to the other EBV genes. Multiple viruses are detectable in PTLD tissues by MSS. Anellovirus positivity, not EBV positivity,was associated with worse patient survival in our series. Confirmation and extension of this work in larger multicenter studies is desirable.

Pathogenesis of Bohle Iridovirus (Genus Ranavirus) in Experimentally Infected Juvenile Eastern Water Dragons ( Intellagama lesueurii lesueurii).

Juvenile eastern water dragons ( Intellagama lesueurii lesueurii) are highly susceptible to infection with Bohle iridovirus (BIV), a species of ranavirus first isolated from ornate burrowing frogs in Townsville, Australia. To investigate the progression of BIV infection in eastern water dragons, 11 captive-bred juveniles were orally inoculated with a dose of 104.33 TCID50 and euthanized at 3, 6, 8, 10, 12, and 14 days postinfection (dpi). Viral DNA was detected via polymerase chain reaction (PCR) in the liver, kidney, and cloacal swabs at 3 dpi. Mild lymphocytic infiltration was observed in the submucosa and mucosa of the tongue and liver at 3 dpi. Immunohistochemistry (IHC) first identified viral antigen in foci of splenic necrosis and in hepatocytes with intracytoplasmic inclusion or rare single-cell necrosis at 6 dpi. By 14 dpi, positive IHC labeling was found in association with lesions in multiple tissues. Selected tissues from an individual euthanized at 14 dpi were probed using in situ hybridization (ISH). The ISH labeling matched the location and pattern detected by IHC. The progression of BIV infection in eastern water dragons, based on lesion severity and virus detection, appears to start in the spleen, followed by the liver, then other organs such as the kidney, pancreas, oral mucosa, and skin. The early detection of ranaviral DNA in cloacal swabs and liver and kidney tissue samples suggests these to be a reliable source of diagnostic samples in the early stage of disease before the appearance of clinical signs, as well as throughout the infection.

Mortality from scale drop disease in farmed Lates calcarifer in Southeast Asia.

In Southeast Asia, a new disease called scale drop disease (SDD) caused by a novel Megalocytivirus (SDDV) has emerged in farmed Asian sea bass (Lates calcarifer) in Singapore, Malaysia and Indonesia. We received samples from an Eastern Thai province that also showed gross signs of SDD (loss of scales). Clinical samples of 0.2-1.1 kg L. calcarifer collected between 2016 and 2018 were examined for evidence of SDDV infection. Histopathology was similar to that in the first report of SDDV from Singapore including necrosis, inflammation and nuclear pyknosis and karyorrhexis in the multiple organs. Intracytoplasmic inclusion bodies were also observed in the muscle tissue. In a density-gradient fraction from muscle extracts, TEM revealed enveloped, hexagonal megalocytiviral-like particles (~100-180 nm). By PCR using primers derived from the Singaporean SDDV genome sequence, four different genes were amplified and sequenced from the Thai isolate revealing 98.7%-99.9% identity between the two isolates. Since viral inclusions were rarely observed, clinical signs and histopathology could not be used to easily distinguish between SDD caused by bacteria or SDDV. We therefore recommend that PCR screening be used to monitor broodstock, fry and grow-out fish to estimate the current impact of SDDV in Southeast Asia and to prevent its spread.

FATAL RANAVIRUS INFECTION IN A GROUP OF ZOO-HOUSED MELLER'S CHAMELEONS (TRIOCEROS MELLERI).

A group of five juvenile Meller's chameleons (Trioceros melleri) experienced 100% mortality over a period of 1 mo due to ranavirus infection. The index case was found dead without premonitory signs. The three subsequent cases presented with nonspecific clinical signs (lethargy, decreased appetite, ocular discharge) and were ultimately euthanatized. The final case died after initially presenting with skin lesions. Postmortem examination revealed thin body condition in all five animals and mild coelomic effusion and petechiae affecting the tongue and kidneys of one animal. Microscopically, all animals had multifocal necrosis of the spleen, liver, and kidney; four of five animals had necrosis of the nasal cavity; and two of five had necrosis of adrenal tissue, bone marrow, and skin. Numerous basophilic intracytoplasmic inclusions were present in the liver of all animals and nasal mucosa of three of the five animals. Consensus polymerase chain reaction for herpesvirus and adenovirus were negative, whereas ranavirus quantitative polymerase chain reaction was positive. Virus isolation followed by whole genome sequencing and Bayesian phylogenetic analysis classified the isolates as a strain of frog virus 3 (FV3) most closely related to an FV3 isolate responsible for a previous outbreak in the zoo's eastern box turtle (Terrapene carolina carolina) group. This case series documents the first known occurrence of ranavirus-associated disease in chameleons and demonstrates the potential for interspecies transmission between chelonian and squamate reptiles.

Phylogenomic characterization of two novel members of the genus Megalocytivirus from archived ornamental fish samples.

The genus Megalocytivirus is the most recently described member of the family Iridoviridae; as such, little is known about the genetic diversity of this genus of globally emerging viral fish pathogens. We sequenced the genomes of 2 megalocytiviruses (MCVs) isolated from epizootics involving South American cichlids (oscar Astronotus ocellatus and keyhole cichlid Cleithracara maronii) and three spot gourami Trichopodus trichopterus sourced through the ornamental fish trade during the early 1990s. Phylogenomic analyses revealed the South American cichlid iridovirus (SACIV) and three spot gourami iridovirus (TSGIV) possess 116 open reading frames each, and form a novel clade within the turbot reddish body iridovirus genotype (TRBIV Clade 2). Both genomes displayed a unique truncated paralog of the major capsid protein gene located immediately upstream of the full-length parent gene. Histopathological examination of archived oscar tissue sections that were PCR-positive for SACIV revealed numerous cytomegalic cells characterized by basophilic intracytoplasmic inclusions within various organs, particularly the anterior kidney, spleen, intestinal lamina propria and submucosa. TSGIV-infected grunt fin (GF) cells grown in vitro displayed cytopathic effects (e.g. cytomegaly, rounding, and refractility) as early as 96 h post-infection. Ultrastructural examination of infected GF cells revealed unenveloped viral particles possessing hexagonal nucleocapsids (120 to 144 nm in diameter) and electron-dense cores within the cytoplasm, consistent with the ultrastructural morphology of a MCV. Sequencing of SACIV and TSGIV provides the first complete TRBIV Clade 2 genome sequences and expands the known host and geographic range of the TRBIV genotype to include freshwater ornamental fishes traded in North America.

Identification and genomic characterization of a novel CRESS DNA virus from a calf with severe hemorrhagic enteritis in China.

In this study, a novel circular replication-associated protein (Rep)-encoding single stranded (CRESS) DNA virus was discovered in diarrheic sample of a calf with severe hemorrhagic enteritis. The virus, named Bo-Circo-like virus CH, has a circular genome with 3909 nucleotides (nt). Six putative open reading frames (ORFs) were identified, including Rep, capsid (Cap) and four proteins of unknown function. Both the genome size and the number as well as the organization of encoded ORFs, Bo-Circo-like virus CH is most closely related to Po-Circo-like virus 21 detected in pig faeces. A preliminary survey using specific primers for the Rep region showed that 5.3% (4/75) of diarrheic samples were positive for Bo-Circo-like virus, and all 42 healthy samples were negative. In conclusion, our results indicate that Bo-Circo-like virus CH may represent a new virus in bovine. Further investigation is needed to determine the relationship between the virus infection and diarrhea.

An alloherpesvirus infection of European perch Perca fluviatilis in Finland.

The order Herpesvirales includes viruses that infect aquatic and terrestrial vertebrates and several aquatic invertebrates (i.e. mollusks), and share the commonality of possessing a double-stranded DNA core surrounded by an icosahedral capsid. Herpesviruses of the family Alloherpesviridae that infect fish and amphibians, including channel catfish virus and koi herpesvirus, negatively impact aquaculture. Here, we describe a novel herpesvirus infection of wild European perch from lakes in Finland. Infected fish exhibited white nodules on the skin and fins, typically in the spring when prevalence reached nearly 40% in one of the sampled lakes. Transmission electron microscopic examination of affected tissues revealed abundant nuclear and cytoplasmic virus particles displaying herpesvirus morphology. Degenerate PCR targeting a conserved region of the DNA polymerase gene of large DNA viruses amplified a 520 bp product in 5 of 5 affected perch skin samples tested. Phylogenetic analysis of concatenated partial DNA polymerase and terminase (exon 2) gene sequences produced a well-supported tree grouping the European perch herpesvirus with alloherpesviruses infecting acipenserid, esocid, ictalurid, and salmonid fishes. The phenetic analysis of the European perch herpesvirus partial DNA polymerase and terminase nucleotide gene sequences ranged from 34.6 to 63.9% and 39.6 to 59.6% to other alloherpesviruses, respectively. These data support the European perch herpesvirus as a new alloherpesvirus, and we propose the formal species designation of Percid herpesvirus 2 (PeHV2) to be considered for approval by the International Committee on Taxonomy of Viruses.