The genome of goose hemorrhagic polyomavirus, a new member of the proposed subgenus Avipolyomavirus

Molecular analysis Polish isolates of goose hemorrhagic polyomavirus from geese and free-living birds

Goose haemorrhagic polyomavirus (GHPV) is the viral agent of hemorrhagic nephritis and enteritis of geese (HNEG), a lethal disease of goose. The study describes the results of a molecular analysis Polish isolates of GHPV from geese and free-living birds based on complete VP1 gene and VP2 gene sequences. The sequences were analyzed and aligned with different GHPV isolates sequences accessible in the GenBank database. This study indicates affiliation GHPV isolates from fee-living birds and GHPV isolates circulating in Polish goose flocks and around the world to the same genetic groups, which proves their evolutionary relationship and indicates the potential role of free-living birds as a source of infections for poultry.

Viral gene expression profile of goose haemorrhagic polyomavirus in susceptible primary cells

Routine culturing of goose haemorrhagic polyomavirus (GHPV) is cumbersome, and limited data are available about its replication and gene expression profile. In this study, goose embryo fibroblast cells were infected with GHPV for temporal measurement of the viral genome copy number and mRNA levels with quantitative PCR. Accumulation of small and large tumour antigen-encoding mRNAs was detected as early as 9 hours post-infection (hpi), while high level expression of the capsid protein encoding VP1-VP3, and ORF-X mRNAs was first detected at 24 hpi. Elevation of GHPV genome copy number was noted at 48 hpi. The results indicate that the gene expression profile of GHPV is similar to that described for mammalian polyomaviruses.RESEARCH HIGHLIGHTS GHPV was propagated in culture of primary goose embryo fibroblast cells.The transcription commenced before the onset of viral DNA replication.The transcription patterns of GHPV and mammalian polyomaviruses were comparable.

Molecular epidemiology and phylodynamics of goose haemorrhagic polyomavirus

Goose haemorrhagic polyomavirus (GHPV, or Anser anser polyomavirus 1) is a small dsDNA virus of the Polyomaviridae family. The virus infects the internal organs causing haemorrhagic nephritis and enteritis of geese that may be fatal for goslings. In this study, GHPV positivity was examined in goose and duck samples collected in Hungary between 2005 and 2019. In this period, 384 of the investigated 1,111 specimens were diagnosed as GHPV-positive by PCR assay. Twenty-two GHPV genomes were sequenced and subjected to phylogenetic and evolutionary analysis. Based on the sequence data, the mean evolutionary rates were estimated 6.57 × 10^-6 -5.82 × 10^-5  s/s/y for both GHPV complete genomes and individual genes, with negative selection acting on each gene. When GHPV VP1 sequences originating from wild birds were also included in the analyses, the nt and aa mutations inflated the substitution rate to 1.54 × 10^-4  s/s/y that may imply adaptation of the virus to novel host species. Our data suggested the co-circulation of various GHPV strains in Hungarian goose farms; the source of these may be persistently infected domesticated or migratory wild birds. Detection and characterization of GHPV in wild birds and domestic waterfowls may help to elaborate new strategies for more effective disease control and prevention.

Codon usage patterns of LT-Ag genes in polyomaviruses from different host species

Background

Polyomaviruses (PyVs) have a wide range of hosts, from humans to fish, and their effects on hosts vary. The differences in the infection characteristics of PyV with respect to the host are assumed to be influenced by the biochemical function of the LT-Ag protein, which is related to the cytopathic effect and tumorigenesis mechanism via interaction with the host protein.

Methods

We carried out a comparative analysis of codon usage patterns of large T-antigens (LT-Ags) of PyVs isolated from various host species and their functional domains and sequence motifs. Parity rule 2 (PR2) and neutrality analysis were applied to evaluate the effects of mutation and selection pressure on codon usage bias. To investigate evolutionary relationships among PyVs, we carried out a phylogenetic analysis, and a correspondence analysis of relative synonymous codon usage (RSCU) values was performed.

Results

Nucleotide composition analysis using LT-Ag gene sequences showed that the GC and GC3 values of avian PyVs were higher than those of mammalian PyVs. The effective number of codon (ENC) analysis showed host-specific ENC distribution characteristics in both the LT-Ag gene and the coding sequences of its domain regions. In the avian and fish PyVs, the codon diversity was significant, whereas the mammalian PyVs tended to exhibit conservative and host-specific evolution of codon usage bias. The results of our PR2 and neutrality analysis revealed mutation bias or highly variable GC contents by showing a narrow GC12 distribution and wide GC3 distribution in all sequences. Furthermore, the calculated RSCU values revealed differences in the codon usage preference of the LT-AG gene according to the host group. A similar tendency was observed in the two functional domains used in the analysis.

Conclusions

Our study showed that specific domains or sequence motifs of various PyV LT-Ags have evolved so that each virus protein interacts with host cell targets. They have also adapted to thrive in specific host species and cell types. Functional domains of LT-Ag, which are known to interact with host proteins involved in cell proliferation and gene expression regulation, may provide important information, as they are significantly related to the host specificity of PyVs.

Genomic analysis of Sheldrake origin goose hemorrhagic polyomavirus, China

Goose hemorrhagic polyomavirus (GHPV) is not a naturally occurring infection in geese in China; however, GHPV infection has been identified in Pekin ducks, a domestic duck species. Herein, we investigated the prevalence of GHPV in five domestic duck species (Liancheng white ducks, Putian black ducks, Shan Sheldrake, Shaoxing duck, and Jinyun Sheldrake) in China. We determined that the Jinyun Sheldrake duck species could be infected by GHPV with no clinical signs, whereas no infection was identified in the other four duck species. We sequenced the complete genome of the Jinyun Sheldrake origin GHPV. Genomic data comparison suggested that GHPVs share a conserved genomic structure, regardless of the host (duck or geese) or region (Asia or Europe). Jinyun Sheldrake origin GHPV genomic characterization and epidemiological studies will increase our understanding of potential heterologous reservoirs of GHPV.

Rapid detection of goose hemorrhagic polyomavirus using TaqMan quantitative real-time PCR

Due to low doses of infection, an efficient and sensitive virus detection method is necessary to detect low amounts of goose hemorrhagic polyomavirus (GHPV). In this study, we have developed a TaqMan real-time PCR (qPCR) specific assay for the detection of GHPV. Specificity assay showed no cross-reactions with other common waterfowl viruses. The standard curve had a linear correlation of 0.997 and efficiency of 99% between the cycle threshold value and the logarithm of the plasmids copy number. The possible lowest detectable concentration was 35.4 copies/μl; 100 times more sensitive than conventional PCR (detection limit, 3.54 × 10³ copies/μl). Domestic Jinyun Sheldrakes ducks and their embryonated eggs were found positive of GHPV infection which provides evidence of possible vertical transmission of GHPV.

Isolation of a novel polyomavirus, related to Japanese eel endothelial cell-infecting virus, from marbled eels, Anguilla marmorata (Quoy & Gaimard)

Marbled eels, Anguilla marmorata (Quoy & Gaimard), cultured in Taiwan exhibited haemorrhage and mortality in January 2012. The severely diseased eels bled from the gills and showed congestion of the central venous sinus of the gill filaments and haemorrhage throughout the body similar to viral endothelial cell necrosis of eel. In this study, a novel polyomavirus (AmPyV) was isolated from the diseased eels using the AMPF cell line established from the pectoral fin of healthy marbled eels. AmPyV was found to encode a long T-antigen orthologous gene. Phylogenetic analysis showed that AmPyV was closely related to Japanese eel endothelial cell-infecting virus. PCR assays revealed AmPyV infection throughout the systemic organs. AmPyV proliferated in the AMPF, EK-1 and EO-2 cells at temperatures 25-30 °C, and the progeny virus yields were 10(7.0) , 10(7.4) and 10(7.7) TCID50  mL(-1) , respectively. The purified virions were icosahedral particles, 70-80 nm in diameter. No clinical signs or mortality was observed among the eels injected with the virus; however, the virus was reisolated from the brain, eyes, kidneys, fins and gills of infected eels 2 month after injection. Our results suggest that AmPyV exhibits a latent infection. Pathogen of the disease needs to study further.

The Ancient Evolutionary History of Polyomaviruses

Polyomaviruses are a family of DNA tumor viruses that are known to infect mammals and birds. To investigate the deeper evolutionary history of the family, we used a combination of viral metagenomics, bioinformatics, and structural modeling approaches to identify and characterize polyomavirus sequences associated with fish and arthropods. Analyses drawing upon the divergent new sequences indicate that polyomaviruses have been gradually co-evolving with their animal hosts for at least half a billion years. Phylogenetic analyses of individual polyomavirus genes suggest that some modern polyomavirus species arose after ancient recombination events involving distantly related polyomavirus lineages. The improved evolutionary model provides a useful platform for developing a more accurate taxonomic classification system for the viral family Polyomaviridae.

Polyomaviruses are a family of DNA-based viruses that are known to infect various terrestrial vertebrates, including humans. In this report, we describe our discovery of highly divergent polyomaviruses associated with various marine fish. Searches of public deep sequencing databases unexpectedly revealed the existence of polyomavirus-like sequences in scorpion and spider datasets. Our analysis of these new sequences suggests that polyomaviruses have slowly co-evolved with individual host animal lineages through an established mechanism known as intrahost divergence. The proposed model is similar to the mechanisms through with other DNA viruses, such as papillomaviruses, are thought to have evolved. Our analysis also suggests that distantly related polyomaviruses sometimes recombine to produce new chimeric lineages. We propose a possible taxonomic scheme that can account for these inferred ancient recombination events.

Whole genome sequence of a goose haemorrhagic polyomavirus detected in Hungary

Goose haemorrhagic polyomavirus (GHPV) provoke haemorrhagic nephritis and enteritis of domestic geese. Outbreaks were detected in European countries and caused economic losses for goose keepers. Domestic ducks may be infected with GHPV without any signs typical for geese. The genomic organisation of some isolates was described but the gene functions and the pathomechanisms of the virus was not precisely defined. Here we describe the genome sequence and structure of GHPV of a goose from a Hungarian goose flock showing characteristics of the haemorrhagic nephritis and enteritis. The GHPV genome investigated in this study was 5252 bp long and was very similar (99% nucleotide identity) to sequences deposited in the GenBank. All the whole GHPV genomes possess the same ORFs in length, including the VP1, VP2, VP3, ORF-X, t and T tumour antigens. Amino acid changes are detected mainly in the putative ORF-X region. Data about the GHPV genome imply a conserved genomic structure among isolates from different countries. Genomic and epidemiological studies may help vaccine development efforts and identify potential heterologous reservoirs of GHPV.

Identification of a novel polyomavirus from vervet monkeys in Zambia

To examine polyomavirus (PyV) infection in wildlife, we investigated the presence of PyVs in Zambia with permission from the Zambia Wildlife Authority. We analysed 200 DNA samples from the spleens and kidneys (n = 100 each) of yellow baboons and vervet monkeys (VMs) (n = 50 each). We detected seven PyV genome fragments in 200 DNA samples using a nested broad-spectrum PCR method, and identified five full-length viral genomes using an inverse PCR method. Phylogenetic analysis of virally encoded proteins revealed that four PyVs were closely related to either African green monkey PyV or simian agent 12. Only one virus detected from a VM spleen was found to be related, with relatively low nucleotide sequence identity (74 %), to the chimpanzee PyV, which shares 48 % nucleotide sequence identity with the human Merkel cell PyV identified from Merkel cell carcinoma. The obtained entire genome of this virus was 5157 bp and had large T- and small t-antigens, and VP1 and VP2 ORFs. This virus was tentatively named vervet monkey PyV 1 (VmPyV1) as a novel PyV. Comparison with other PyVs revealed that VmPyV1, like chimpanzee PyV, had a longer VP1 ORF. To examine whether the VmPyV1 genome could produce viral proteins in cultured cells, the whole genome was transfected into HEK293T cells. We detected VP1 protein expression in the transfected HEK293T cells by immunocytochemical and immunoblot analyses. Thus, we identified a novel PyV genome from VM spleen.

Identification of MW polyomavirus, a novel polyomavirus in human stool

We have discovered a novel polyomavirus present in multiple human stool samples. The virus was initially identified by shotgun pyrosequencing of DNA purified from virus-like particles isolated from a stool sample collected from a healthy child from Malawi. We subsequently sequenced the virus' 4,927-bp genome, which has been provisionally named MW polyomavirus (MWPyV). The virus has genomic features characteristic of the family Polyomaviridae but is highly divergent from other members of this family. It is predicted to encode the large T antigen and small T antigen early proteins and the VP1, VP2, and VP3 structural proteins. A real-time PCR assay was designed and used to screen 514 stool samples from children with diarrhea in St. Louis, MO; 12 specimens were positive for MWPyV. Comparison of the whole-genome sequences of the index Malawi case and one St. Louis case demonstrated that the two strains of MWPyV varied by 5.3% at the nucleotide level. The number of polyomaviruses found in the human body continues to grow, raising the question of how many more species have yet to be identified and what roles they play in humans with and without manifest disease.

Pathological and epidemiological significance of goose haemorrhagic polyomavirus infection in ducks

Goose haemorrhagic polyomavirus (GHPV) is the viral agent of haemorrhagic nephritis enteritis of geese, a lethal disease of goslings. It was recently shown that GHPV can also be detected in Muscovy and mule ducks. The goal of the present study was to investigate the pathobiology of GHPV in ducks. In the first experiment, field isolates of GHPV from Muscovy or mule ducks were fully sequenced and compared with goose GHPV. These duck isolates were then used to inoculate 1-day-old goslings. Typical clinical signs and lesions of haemorrhagic nephritis enteritis of geese were reproduced, indicating that "duck-GHPV" isolates are virulent in geese. In the second experiment, 1-day-old and 21-day-old Muscovy ducklings were infected by a reference GHPV strain. In both cases, neither clinical signs nor histopathological lesions were observed. However, the virus was detected in cloacal bursae and sera, and serological responses were detected at 12 days post infection. These findings suggest firstly that one common genotype of GHPV circulates among ducks and geese, and secondly that ducks may be infected by GHPV but show no pathologic evidence of infection, whereas geese express clinical signs. GHPV infection should therefore be considered as being carried in ducks and of epidemiological relevance in cases of contact with goose flocks.

Taxonomical developments in the family Polyomaviridae

The Polyomaviridae Study Group of the International Committee on Taxonomy of Viruses (ICTV) has recommended several taxonomical revisions, as follows: The family Polyomaviridae, which is currently constituted as a single genus (Polyomavirus), will be comprised of three genera: two containing mammalian viruses and one containing avian viruses. The two mammalian genera will be designated Orthopolyomavirus and Wukipolyomavirus, and the avian genus will be named Avipolyomavirus. These genera will be created by the redistribution of species from the current single genus (Polyomavirus) and by the inclusion of several new species. In addition, the names of several species will be changed to reflect current usage.

Epizootic occurrence of haemorrhagic nephritis enteritis virus infection of geese

Recent outbreaks of haemorrhagic nephritis enteritis in geese flocks of 3 to 10 weeks in age in Hungary were investigated. Mortality varied between 4% and 67%. Affected birds generally died suddenly. Occasional clinical signs included tremors of the head and neck, subcutaneous haemorrhages and excretion of faeces containing partly digested blood. At necropsy the most frequent findings were a turgid wall and reddish mucosa of the intestines and reddish discolouration of the swollen kidneys, but oedema and haemorrhages of the subcutaneous connective tissue, hydropericardium and ascites were also seen. In subacute cases, visceral gout was frequently observed. Histological examination revealed zonal necrosis of the tubular epithelial cells with haemorrhages in the kidney. Other histological findings were serous hepatitis with fatty infiltration, necrotizing haemorrhagic enteritis and haemorrhages in the different organs including the brain. Experimental geese infected parenterally with crude liver and spleen homogenates prepared from diseased birds died after 8 to 20 days without premonitory signs, and had typical gross and histological lesions. Attempts to isolate cytopathic virus on different tissue cultures failed. The presence of polyomavirus was proven by polymerase chain reaction. Five isolates were further investigated by analysing their complete VP1 gene sequence. All tested strains were very closely related to each other on the basis of the nucleotide sequence, and they were identical at the deduced amino acid level.

Whole-genome characterization of a novel polyomavirus detected in fatally diseased canary birds

Polyomaviruses of birds are aetiological agents of acute inflammatory diseases in non-immunocompromised hosts, which is in contrast to mammalian polyomaviruses. VP4, an additional structural protein encoded by the viral genomes of the known avian polyomaviruses, has been suggested to contribute to pathogenicity through loss of cells following induction of apoptosis. Four distinct bird polyomaviruses have been identified so far, which infect crows, finches, geese and parrots. Using broad-spectrum PCR, a novel polyomavirus, tentatively designated canary polyomavirus (CaPyV), was detected in diseased canary birds (Serinus canaria) that died at an age of about 40 days. Intranuclear inclusion bodies were found in the liver, spleen and kidneys. The entire viral genome was amplified from a tissue sample using rolling-circle amplification. Phylogenetic analysis of the genome sequence indicated a close relationship between CaPyV and other avian polyomaviruses. Remarkably, an ORF encoding VP4 could not be identified in the CaPyV genome. Therefore, the mechanism of pathogenicity of CaPyV may be different from that of the other avian polyomaviruses.

Recombinant subunit vaccine elicits protection against goose haemorrhagic nephritis and enteritis

Outbreaks of haemorrhagic nephritis and enteritis of geese (HNEG) have been reported in goose flocks in Hungary, Germany and France since 1969. HNEG is characterized by high morbidity and mortality rates in geese 3 to 10 weeks of age. The causative agent of HNEG is the goose haemorrhagic polyomavirus (GHPV), which has a circular double-stranded DNA genome encoding the structural proteins VP1, VP2 and VP3. In vitro culture of GHPV has been problematic, so the baculovirus system was used to construct a recombinant virus expressing the VP1 gene of GHPV under control of the polyhedrin promoter in Sf9 insect cells. The expression and the identity of recombinant goose polyomavirus VP1 in the crude Sf9 cell extracts were confirmed by mass spectrometry. Experimental oil-emulsion vaccines containing two different doses of antigen were prepared using this crude extract. Goslings were vaccinated either once at 1 day old or twice by boosting 18 days after the primary vaccination, and were challenged with a virulent polyomavirus isolate at 5 weeks of age. A single injection of either vaccine dose induced 95% protection against challenge. Using the booster vaccination regimen, 100% protection was achieved with either vaccine dose.

Pathology of goose haemorrhagic polyomavirus infection in goose embryos

Goose embryos were infected with goose haemorrhagic polyomavirus (GHPV) onto the chorioallantoic membrane (CAM) in order to examine the effect of GHPV on the embryos and to obtain data on whether embryos could develop into infected, virus-shedding goslings, as well as to present an accurate biological method for virus titration. The reported method of infection could offer a possibility to express the virus titre as the median embryo infective dose (EID(50)). As a special pathological feature of the disease, extensive cerebral haemorrhages were observed, which protruded the skullcap in many cases. Some embryos infected with 10(1.25) or 10(0.25) EID(50)/0.2 ml were able to hatch; however, they were in poor physical condition and died by post-hatching day 4 showing haemorrhagic nephritis and enteritis of geese. Virus shedding was revealed by polymerase chain reaction. The ability of some of the infected goose embryos to hatch may indicate the potency of GHPV to spread vertically, although this needs further study for confirmation.

Generation of virus-like particles consisting of the major capsid protein VP1 of goose hemorrhagic polyomavirus and their application in serological tests

Goose hemorrhagic polyomavirus (GHPV) is the causative agent of hemorrhagic nephritis and enteritis of geese (HNEG), a fatal disease of young geese with high mortality rates. GHPV cannot be efficiently propagated in tissue culture. To provide antigens for diagnostic tests and vaccines, its major structural protein VP1 was recombinantly expressed in Sf9 insect cells and in the yeast Saccharomyces cerevisiae. As demonstrated by density gradient centrifugation and electron microscopy, GHPV-VP1 expressed in insect cells formed virus-like particles (VLPs) with a diameter of 45 nm indistinguishable from infectious polyomavirus particles. However, efficiency of VLP formation was low as compared to the monkey polyomavirus SV-40-VP1. In yeast cells, GHPV-VP1 alone formed smaller VLPs, 20 nm in diameter. Remarkably, co-expression of GHPV-VP2 resulted in VLPs with a diameter of 45 nm. All three types of GHPV-VLPs were shown to hemagglutinate chicken erythrocytes. ELISA and hemagglutination inhibition tests using the VLPs as antigen detected GHPV-specific antibodies in up to 85.7% of sera derived from flocks with HNEG but in none of the sera of a clinically healthy flock. However, GHPV-specific antibodies were also detected in sera from two other flocks without HNEG indicating a broad distribution of GHPV due to subclinical or unrecognised infections.

Comparing phylogenetic codivergence between polyomaviruses and their hosts

Seventy-two full genomes corresponding to nine mammalian (67 strains) and two avian (5 strains) polyomavirus species were analyzed using maximum likelihood and Bayesian methods of phylogenetic inference. Our fully resolved and well-supported (bootstrap proportions > 90%; posterior probabilities = 1.0) trees separate the bird polyomaviruses (avian polyomavirus and goose hemorrhagic polyomavirus) from the mammalian polyomaviruses, which supports the idea of spitting the genus into two subgenera. Such a split is also consistent with the different viral life strategies of each group. Simian (simian virus 40, simian agent 12 [Sa12], and lymphotropic polyomavirus) and rodent (hamster polyomavirus, mouse polyomavirus, and murine pneumotropic polyomavirus [MPtV]) polyomaviruses did not form monophyletic groups. Using our best hypothesis of polyomavirus evolutionary relationships and established host phylogenies, we performed a cophylogenetic reconciliation analysis of codivergence. Our analyses generated six optimal cophylogenetic scenarios of coevolution, including 12 codivergence events (P < 0.01), suggesting that Polyomaviridae coevolved with their avian and mammal hosts. As individual lineages, our analyses showed evidence of host switching in four terminal branches leading to MPtV, bovine polyomavirus, Sa12, and BK virus, suggesting a combination of vertical and horizontal transfer in the evolutionary history of the polyomaviruses.

Characterization of two novel polyomaviruses of birds by using multiply primed rolling-circle amplification of their genomes

Polyomaviruses are small nonenveloped particles with a circular double-stranded genome, approximately 5 kbp in size. The mammalian polyomaviruses mainly cause persistent subclinical infections in their natural nonimmunocompromised hosts. In contrast, the polyomaviruses of birds--avian polyomavirus (APV) and goose hemorrhagic polyomavirus (GHPV)--are the primary agents of acute and chronic disease with high mortality rates in young birds. Screening of field samples of diseased birds by consensus PCR revealed the presence of two novel polyomaviruses in the liver of an Eurasian bullfinch (Pyrrhula pyrrhula griseiventris) and in the spleen of a Eurasian jackdaw (Corvus monedula), tentatively designated as finch polyomavirus (FPyV) and crow polyomavirus (CPyV), respectively. The genomes of the viruses were amplified by using multiply primed rolling-circle amplification and cloned. Analysis of the FPyV and CPyV genome sequences revealed a close relationship to APV and GHPV, indicating the existence of a distinct avian group among the polyomaviruses. The main characteristics of this group are (i) involvement in fatal disease, (ii) the existence of an additional open reading frame in the 5' region of the late mRNAs, and (iii) a different manner of DNA binding of the large tumor antigen compared to that of the mammalian polyomaviruses.

A Survey of Avian Polyomavirus (APV) Infection in Imported and Domestic Bred Psittacine Birds in Japan

Although birds infected with avian polyomavirus (APV) subclinically could be a source of infection, no epidemiological studies of APV in psittacine birds have been reported in Japan. In the present study, we investigated subclinical morbidity rate of APV in imported and domestically bred psittacine birds by polymerase chain reaction (PCR). Of 402 live birds from which blood or feather samples were taken between April, 2003 and March, 2004, 11 (2.7%) were found to be APV positive. The DNA sequences of the APV t/T antigen region were determined for five APV-positive randomly selected samples and were found to be conserved.

Complete nucleotide sequence of polyomavirus SA12

The Polyomaviridae have small icosahedral virions that contain a genome of approximately 5,000 bp of circular double-stranded DNA. Polyomaviruses infect hosts ranging from humans to birds, and some members of this family induce tumors in test animals or in their natural hosts. We report the complete nucleotide sequence of simian agent 12 (SA12), whose natural host is thought to be Papio ursinus, the chacma baboon. The 5,230-bp genome has a genetic organization typical of polyomaviruses. Sequences encoding large T antigen, small t antigen, agnoprotein, and the viral capsid proteins VP1, VP2, and VP3 are present in the expected locations. We show that, like its close relative simian virus 40 (SV40), SA12 expresses microRNAs that are encoded by the late DNA strand overlapping the 3' end of large T antigen coding sequences. Based on sequence comparisons, SA12 is most closely related to BK virus (BKV), a human polyomavirus. We have developed a real-time PCR test that distinguishes SA12 from BKV and the other closely related polyomaviruses JC virus and SV40. The close relationship between SA12 and BKV raises the possibility that these viruses circulate between human and baboon hosts.

Haemorrhagic nephritis and enteritis of geese: pathomorphological investigations and proposed pathogenesis

Haemorrhagic nephritis and enteritis of geese as a new disease was first described in Hungary in 1969. The authors identified the causative agent of the outbreaks occurring in 1969 as a polyomavirus by PCR in 2001. In order to study the pathogenesis of the virus, one-day-old goslings were infected with tissue homogenate that tested positive for polyomavirus by PCR. Morphological, light and transmission electron microscopic (TEM) examinations have revealed that goose haemorrhagic polyomavirus replicates in the endothelial cells of the blood vessels and capillaries of diseased birds. Infection causes damage and necrosis of the endothelial cells. The virus was not observed in the parenchymal cells. Oedema and haemorrhages found throughout the body may be due to the dysfunction or functional deficiency of endothelial cells damaged by the virus.

Novel polyomavirus detected in the feces of a chimpanzee by nested broad-spectrum PCR

In order to screen for new polyomaviruses in samples derived from various animal species, degenerated PCR primer pairs were constructed. By using a nested PCR protocol, the sensitive detection of nine different polyomavirus genomes was demonstrated. The screening of field samples revealed the presence of a new polyomavirus, tentatively designated chimpanzee polyomavirus (ChPyV), in the feces of a juvenile chimpanzee (Pan troglodytes). Analysis of the region encoding the major capsid protein VP1 revealed a unique insertion in the EF loop of the protein and showed that ChPyV is a distinct virus related to the monkey polyomavirus B-lymphotropic polyomavirus and the human polyomavirus JC polyomavirus.

A survey to detect subclinical polyomavirus infections of captive psittacine birds in Germany

Infections of avian polyomavirus (APV) are known to cause fatal disease in a wide range of psittacine and non-psittacine birds. Here, we present a survey to investigate the existence of subpopulation of persistent or subclinically infected parrots inside the population of captive psittacine birds in Germany. DNA was isolated from feathers of 85 symptom-free birds from 20 different genera (all psittaciformes) taken from 30 different breeders from all over Germany. The presence of APV was analysed by performing polymerase chain reaction assays (PCR). APV was detected in none of the samples, indicating that the existence of a subpopulation of captive psittacine birds having a persistent APV infection in Germany seems to be relatively low.

Pathology of spontaneous and experimental infections by Goose haemorrhagic polyomavirus

Haemorrhagic nephritis enteritis of geese (HNEG) is a fatal disease of geese aged from 3 to 12 weeks. The causative virus, Goose haemorrhagic polyomavirus (GHPV), is a member of the Polyomaviridae family We examined goslings either spontaneously or experimentally infected with GHPV. Tissues were sampled for histology, GHPV DNA detection and electron microscopy. Clinical signs and gross lesions observed in experimentally infected goslings were largely consistent with those noticed in field cases. Histological examination showed that, in the acute phase of HNEG, GHPV replicates in almost all the tissues with a particular tropism for endothelial and lymphoid cells. Haemorrhagic foci were widespread in many tissues, including brain. Ultrastructural features were largely consistent with other polyomavirus infections, with accumulation of virions in the nucleus. Non-typical, double-membraned organelles were observed in the cytoplasm. GHPV DNA distribution was widespread in tissues of infected birds, from day 5 post-infection. GHPV therefore induces a systemic disease in its host, leading to severe vascular dysfunction and immunosuppressive B-cell depletion.

Nuclear localization of avian polyomavirus structural protein VP1 is a prerequisite for the formation of virus-like particles

Virions of polyomaviruses consist of the major structural protein VP1, the minor structural proteins VP2 and VP3, and the viral genome associated with histones. An additional structural protein, VP4, is present in avian polyomavirus (APV) particles. As it had been reported that expression of APV VP1 in insect cells did not result in the formation of virus-like particles (VLP), the prerequisites for particle formation were analyzed. To this end, recombinant influenza viruses were created to (co)express the structural proteins of APV in chicken embryo cells, permissive for APV replication. VP1 expressed individually or coexpressed with VP4 did not result in VLP formation; both proteins (co)localized in the cytoplasm. Transport of VP1, or the VP1-VP4 complex, into the nucleus was facilitated by the coexpression of VP3 and resulted in the formation of VLP. Accordingly, a mutant APV VP1 carrying the N-terminal nuclear localization signal of simian virus 40 VP1 was transported to the nucleus and assembled into VLP. These results support a model of APV capsid assembly in which complexes of the structural proteins VP1, VP3 (or VP2), and VP4, formed within the cytoplasm, are transported to the nucleus using the nuclear localization signal of VP3 (or VP2); there, capsid formation is induced by the nuclear environment.