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PubMed1993

Partial cloning of the genome of infectious hypodermal and haematopoietic necrosis virus, an unusual parvovirus pathogenic for penaeid shrimps; diagnosis of the disease using a specific probe.

The infectious hypodermal and haematopoietic necrosis virus (IHHNV), pathogenic for penaeid shrimp, is an icosahedral unenveloped particle, 22 nm in diameter, with an ssDNA linear genome, and proposed to be a member of the Parvoviridae. A large majority of minus-strand DNA is incorporated into the capsids compared to the plus-strand. A small amount of reannealed plus- and minus-strands (dsDNA) obtained after nucleic acid extraction was blunt-ended and cloned into the system pUC18/Escherichia coli strain DH5 alpha. Selected clones were studied and characterized using restriction enzymes. One of them, BQ31, was used to construct different sized probes labelled with digoxigenin-11-dUTP. These probes failed to hybridize with DNA of some insect parvoviruses and with DNA of a parvo-like virus of shrimp. They reacted strongly with dilutions of homogenized IHHNV-infected shrimp tissues and, conversely, did not react with uninfected shrimp tissues. They hybridized in situ, in sections of infected animals, labelling strongly the target cells and particularly the nuclear Cowdry type A inclusion body, which is the most diagnostic characteristics of this disease.

Animals↗

PubMed1994

Mapping of determinants of the host range for canine cells in the genome of canine parvovirus using canine parvovirus/mink enteritis virus chimeric viruses.

Feline panleukopenia virus (FPLV), mink enteritis virus (MEV) and canine parvovirus (CPV) are more than 98% similar in DNA and predicted amino acid sequences, but they show different host-cell specificities; CPV is able to replicate in canine cells in culture, whereas FPLV and MEV cannot or replicate only to a low titre. To map the genomic region responsible for the host range of CPV in vitro, CPV/MEV chimeric viruses were generated by transfecting infectious CPV/MEV chimeric plasmids into a cultured feline kidney cell line, and their host cell ranges were analysed. The 60 to 91 map units (m.u.) region of the CPV genome, which contains a part of the capsid protein (VP) gene encoding from amino acid 91 (in the VP2 sequence) to the carboxy terminus of VP protein, was required to impart the ability to replicate in canine cells to MEV, although the chimeric virus containing the 60 to 91 m.u. region of the CPV genome in the MEV background did not replicate in canine cells as efficiently as did CPV derived from the infectious plasmid of CPV. Not only the VP gene, but also a part of the NS gene of CPV were considered to participate in the full expression of the ability to replicate in canine cells. Within the 60 to 91 m.u. region, five of nine amino acid changes between MEV-Abashiri and CPV-Y1 were thought to be phylogenetically CPV-common; however, a recombinant virus containing all five amino acid changes of CPV in the MEV background replicated minimally in canine cells.

Animals↗

PubMed1995

A new genome type of human parvovirus B19 present in sera of patients with encephalopathy.

The possible involvement of human parvovirus B19 infection in encephalopathy has been reported. To determine the characteristics of B19 viruses involved in such cases, we molecularly cloned a part of the B19 DNAs derived from the sera of three patients with encephalopathy (B19 strains N80, N81 and N82), following amplification by PCR. The nucleotide (nt) sequences of the cloned DNAs (nt 3147-3405) were then determined. The nucleotide sequence of N80 was similar to that of the known genome type of group II. The nucleotide sequences of N81 and N82 were similar to each other, but distinctly different from those of other B19 strains reported previously. Almost the entire genome of strain N81 (nt 229-4812) was molecularly cloned following amplification by PCR. Analyses of the restriction site polymorphisms of the cloned N81 DNAs showed that N81 is distantly related to other B19 strains. Therefore, the two strains of N81 and N82 were defined as belonging to a new genome type, group V. Group V B19 virus has so far been isolated only from patients with encephalopathy.

Base Composition↗

PubMed1995

Morphology and antigenicity of recombinant B19 parvovirus capsids expressed in transfected COS-7 cells.

COS-7 cells transfected with parvovirus B19-simian virus 40 (SV40) hybrid vectors have previously been shown to express B19 structural proteins. In this study the morphology and antigenicity of B19 proteins expressed in these cells were investigated. At 84 h after transfection, approximately 10% of the COS-7 cells expressed B19 antigen, and the yield was equivalent to 2 x 10(3) to 2 x 10(5) B19 particles/transfected cell. The B19 proteins self-assembled into capsids that were morphologically and antigenically similar to native B19 virions, and could substitute for native antigen in a B19 IgM assay. Recombinant capsids lacking the recently described 11 kDa protein also resembled native virions.

Animals↗

PubMed1996

Genetic diversity of human parvovirus B19: sequence analysis of the VP1/VP2 gene from multiple isolates.

To evaluate the genetic variability of human parvovirus B19, the complete coding region of the VP1/VP2 structural proteins of 29 B19 isolates obtained from 25 infected patients were sequenced and compared with each other and with two previously published B19 isolates. The VP1/VP2 gene was amplified by PCR using B19-specific oligonucleotide primers and the amplification products were sequenced directly. Overall, the average nucleotide and predicted amino acid identity among B19 isolates was high. Sequential virus isolates from the same cases and isolates obtained from two cases linked by transmission in the same household were essentially identical. Sequence variation was minimal among isolates obtained from a single community-wide B19 outbreak, ranging between 0 and 10 (0.4%) base substitutions, although there appeared to be more than one genetic lineage circulating in the outbreak. A comparison with 18 additional isolates from distinct epidemiological settings found greater variability. These isolates differed from each other by between 11 (0.5%) and 112 (4.8%) base substitutions. B19 isolates from Xi'an, China, were significantly different from other isolates at both the nucleotide and amino acid levels, and were more closely related to a single isolate from Japan, obtained 10 years earlier, than to isolates from other countries. Isolates examined in this study included distinct genotypes from patients with similar clinical presentations and similar genotypes from patients with diverse clinical presentations. These data suggest that geographically defined genetic lineages of B19 may exist and that no particular B19 genotype was associated with a particular clinical outcome.

Adolescent↗

PubMed1996

Expression of muscovy duck parvovirus capsid proteins (VP2 and VP3) in a baculovirus expression system and demonstration of immunity induced by the recombinant proteins.

The gene encoding the muscovy duck parvovirus (DPV)-strain 89384 capsid proteins VP2 and VP3 was cloned in a baculovirus expression system and expressed in insect cells. The recombinant proteins were found to react with specific anti-DPV serum by Western blotting and to be located in the nucleus of insect cells (Sf9) as shown by immunofluorescence. Empty virus-like particles (VLPs) identical in size and appearance to DPV virions were observed by electron microscopy. The antigenicity and immunogenicity of the recombinant proteins were evaluated by ELISA and seroneutralization. Immunization of 3-week-old muscovy ducklings induced anti-DPV antibodies; neutralizing antibody titres were consistent with those observed in ducklings inoculated with a commercial inactivated vaccine. The way to develop these promising results is discussed.

Animals↗

PubMed1997

Establishment of a cell line expressing human parvovirus B19 non-structural protein from an inducible promoter.

Human parvovirus B19 non-structural (NS) protein is supposed to play a major role in B19 replication and transcription, and therefore in B19 pathogenicity. Constitutive expression of NS protein in stable cell lines has failed so far, presumably because of its cytotoxicity. To avoid this cytotoxic effect, we have cloned the NS gene in an Epstein-Barr virus episomal vector under the control of a steroid inducible promoter (5xGRE) and transfected this construction into HeLa cells. We obtained stable cell lines inducibly expressing high level of NS protein, with 50% of the cells demonstrating specific nucleo-cytoplasmic staining. In Western blot analysis, three B19 NS proteins (72, 68 and 60 kDa) were found but a unique NS transcript was detected by Northern blotting. The NS protein expressed in HeLa cell lines was demonstrated to be functional as it trans-activates the B19 P6 promoter. These cell lines might be major tools for further study and characterization of B19 NS protein.

Blotting, Western↗

PubMed1998

Induction of apoptosis in vitro and in vivo by H-1 parvovirus infection.

Apoptosis induced by H-1 parvovirus infection was investigated in C6 rat glioblastoma cells and in newborn rats. Apoptotic changes, such as chromatin condensation, the appearance of apoptotic nuclear bodies and oligonucleosomal DNA ladders, were observed in infected C6 cells 2 days after infection. Inhibitor assay results suggest that a caspase-3-dependent apoptosis activation pathway is induced by H-1 virus infection in C6 cells. Observations made in vivo revealed that the number of apoptotic cells increased in the infected cerebellum, coinciding with known virus infection sites.

Animals↗

PubMed2001

Circulating tumour necrosis factor-alpha and interferon-gamma are detectable during acute and convalescent parvovirus B19 infection and are associated with prolonged and chronic fatigue.

To investigate whether cytokine responses may have a bearing on the symptoms and outcome of parvovirus B19 infection, circulating cytokines were measured during acute infection (n=51), follow-up of acute infection (n=39) and in normal healthy controls (n=50). At acute B19 virus infection (serum anti-B19 IgM-positive), patients ranged in age from 4 to 54 years, with a mean age of 28.2 years. The male:female ratio was 1:4.1 and symptoms were rash (n=15), arthralgia (n=31), fatigue (n=8), lymphadenopathy (n=4), foetal hydrops (n=3), transient aplastic crisis (n=2), neutropenia (n=2), myelodysplasia (n=1), thrombocytopenia (n=1) and pancytopenia (n=1). Of these patients, 39 were contacted after a follow-up period of 2-37 months (mean of 22.5 months). In comparison with normal controls, detectable IL-6 was associated with acute B19 virus infection (26%; P=0.0003), but not with follow-up (6%; P=0.16). Detection of interferon (IFN)-gamma was associated with acute B19 virus infection (67%; P<0.0001) and follow-up (67%; P<0.0001). Detection of tumour necrosis factor (TNF)-alpha was associated with acute B19 virus infection (49%; P<0.0001) and follow-up (56%; P<0.0001). IL-1beta was detected in acute infection (20%), but not at follow-up. At acute B19 virus infection, detection of serum/plasma IL-6 was associated with rheumatoid factor (P=0.038) and IFN-gamma (> or =7 pg/ml) was associated with fatigue in those patients of > or =15 years of age (P=0.022). At follow-up, fatigue was associated with IFN-gamma (> or =7 pg/ml) and/or TNF-alpha (> or =40 pg/ml) (P=0.0275). Prolonged upregulation of serum IFN-gamma and TNF-alpha appears to represent a consistent host response to symptomatic B19 virus infection.

Acute Disease↗

PubMed2001

Evidence for evolution of canine parvovirus type 2 in Italy.

Two isolates of canine parvovirus (CPV) were obtained from dogs affected with severe haemorrhagic diarrhoea. Type 2b antigenic specificity was predicted by both antigenic analysis with monoclonal antibodies and PCR characterization with type-specific primers. Nevertheless, sequence analysis of the capsid protein-encoding gene revealed two amino acid changes. One of the changes affected position 426 (Asp to Glu), in a major antigenic site of the viral capsid, determining the replacement of a residue unique to CPV type 2b. The failure of established typing methods to distinguish this antigenic variant was overcome by the development of an RFLP assay.

Animals↗

PubMed2001

Divergent replication kinetics of two phenotypically different parvoviruses of rats.

Rat virus (RV) is an important infectious agent of laboratory rats because of its high prevalence and capacity to disrupt research. Additionally, RV infection serves as a model for characterizing virus-host interactions during acute, persistent and prenatal infection. Our research has examined the pathogenesis of two RV strains, RV-UMass and RV-Y. RV-UMass is more pathogenic, causes a higher level of persistent infection and transmits to the foetus after oronasal inoculation of the pregnant dam. To determine in vitro distinctions between the strains that may account for these differences and to provide a benchmark for characterizing virus replication in vivo, synchronized in vitro replication of both RV strains was defined and compared. The results demonstrated that RV replication has replicative intermediates, virus transcripts and proteins similar to those reported for the prototype parvovirus, minute virus of mice. However, the replicative cycle of RV-UMass was 12 h compared with 24 h for RV-Y, and RV-UMass and RV-Y differed in kinetics of virus DNA replication, transcription and protein accumulation. Additionally, in situ analysis correlated well with kinetics data as determined by Southern and Northern blot analysis. Sequence comparisons between the strains also determined coding differences that may contribute to phenotypic differences.

Animals↗

PubMed2001

Cellular transcription factors that interact with p6 promoter elements of parvovirus B19.

All transcripts of the human parvovirus B19 identified so far are regulated by a single promoter at map unit 6 of the viral genome, the so-called p6 promoter. This promoter is active in a wide variety of different cells. In order to identify cellular transcription factors involved in regulating promoter activity, we performed gel-retardation and supershift assays using the parts of the p6 promoter sequence shown previously to be protected in footprint experiments. Thereby, binding was demonstrated of the Oct-1 protein to an octamer motif within the p6 promoter and of the transcription factor Sp1 to three GC boxes. A specific preferential interaction of the factor Sp3 with one of these boxes was observed, indicating that the ratio Sp1:Sp3 may be involved in the regulation of promoter activity. Consensus sites for the regulatory protein YY1 are located close to the GC boxes and the octamer motif, to which this factor binds efficiently.

Antibodies↗

PubMed2002

A transgenic mouse model for non-immune hydrops fetalis induced by the NS1 gene of human parvovirus B19.

Human parvovirus B19 (B19) infection during pregnancy is associated with the adverse foetal outcome known as non-immune hydrops fetalis (NIHF). Although B19 is known to infect erythroid-lineage cells in vivo as well as in vitro, the mechanism leading to the occurrence of NIHF is not clear. To investigate the possible involvement of the B19 non-structural protein NS1 in NIHF, three independent lines of transgenic mice were generated that expressed NS1 under the control of the Cre-loxP system and the GATA1 promoter. Two of the three lines expressed NS1 in erythroid-lineage cells. Most of the transgenic mice died at the embryonic stage, some of which developed hydropic changes caused by severe anaemia at embryonic day 15.5 (E15.5). Histological examination of embryos at E15.5 showed significantly fewer erythropoietic islands in the liver parenchyma, whereas their hearts showed no abnormal signs, such as cardiomegaly and apoptotic cells. The NS1-transgenic mouse lines established here provide an animal model for human NIHF and suggest that NS1 plays a crucial role in the adverse outcome associated with intrauterine B19 infection in humans.

Animals↗

PubMed2002

No association between human parvovirus B19 and testicular germ cell cancer.

The incidence of testicular germ cell cancer, which is the most common cancer among young male adults, is increasing. The aetiology remains unknown, although a virus has been proposed. A previous study has shown a high prevalence of human parvovirus B19 (B19) DNA in the testes of patients with testicular germ cell tumours (85%) and suggested that B19 may play a role in tumour development. To address this question of causality, seroreactivity to B19 was studied among cases (n=80) and controls (n=241) using serum samples drawn before the onset of disease, in addition to an elucidation of the frequency of virus DNA in a retrospectively collected 2-year testicular carcinoma series. No association was found between B19 seropositivity and the risk of testicular cancer (odds ratio=1.03; 95% confidence interval=0.60-1.77) nor was there any dose-response relation (P for trend=0.53). This study did, however, confirm the observation that B19 DNA can be detected in testicular carcinoma tissue, as 4 of 24 cases were found to be positive, while no B19 DNA could be detected in the control cases. It is speculated that this finding may be due to susceptibility of the carcinoma cells to B19 virus owing to high-level expression of the viral receptor glycosphingolipid (Gb4) and possible other putative cellular factors resulting in a localized persistence initiated after the development of cancer.

Adult↗

PubMed2004

Parvovirus B19 infection in medical students during a hospital outbreak.

From March to May 2002, a parvovirus B19 (B19) outbreak was identified at a general hospital that serves as a teaching facility for the Universidad Autónoma de San Luis Potosí, Mexico. Medical students attending the hospital presented with symptoms suggestive of B19 infection. Previous studies have suggested that apparent hospital-related B19 outbreaks may be a reflection of B19 infection in the community. A study was undertaken to assess whether exposure to the hospital was a risk factor for B19 infection and to determine to what extent medical students were infected during this outbreak. The incidence of B19 infection in medical students attending the teaching hospital during the outbreak (n=211) was determined and compared to students not attending the hospital (n=96). To assess if a community-wide outbreak had occurred, 80 blood donors were also evaluated for the presence of B19 antibodies. Acute B19 infection was identified in 40 of 119 (33.6%) susceptible students attending the hospital and in 20 of 47 (42.6%) susceptible students not attending the hospital. The frequency of acute infection among susceptible blood donors was lower (9.5%) than in students, but higher than the rate expected during non-epidemic periods. Most infections (68.3%) were asymptomatic. Symptoms reported by infected subjects were not specific for B19 infection. Only 11.7% of subjects with acute infection fulfilled the clinical surveillance definition used to detect cases during the outbreak. In conclusion, hospital exposure was not associated to increased risk of B19 infection among medical students. Medical students may be at increased risk for acquiring and transmitting B19 infection during outbreaks.

Adolescent↗

PubMed2004

Advances in the biology, diagnosis and host-pathogen interactions of parvovirus B19.

Increased recognition of parvovirus B19 (B19), an erythrovirus, as a significant human pathogen that causes fetal loss and severe disease in immunocompromised patients has resulted in intensive efforts to understand the pathogenesis of B19-related disease, to improve diagnostic strategy that is deployed to detect B19 infection and blood-product contamination and, finally, to elucidate the nature of the cellular immune response that is elicited by the virus in diverse patient cohorts. It is becoming clear that at least three related erythrovirus strains (B19, A6/K71 and V9) are circulating in the general population and that viral entry into target cells is mediated by an expanding range of cellular receptors, including P antigen and beta-integrins. Persistent infection by B19 is emerging as a contributory factor in autoimmune disease, a hypothesis that is constrained by the detection of B19 in the skin of apparently healthy individuals. B19 infection during pregnancy may account for thousands of incidences of fetal loss per annum in Europe, North America and beyond, yet there is currently only minimal screening of pregnant women to assess serological status, and thereby risk of infection, upon becoming pregnant. Whilst major advances in diagnosis of B19 infection have taken place, including standardization of serological and DNA-based detection methodologies, blood donations that are targeted at high-risk groups are only beginning to be screened for B19 IgG and DNA as a means of minimizing exposure of at-risk patients to the virus. It is now firmly established that a Th1-mediated cellular immune response is mounted in immunocompetent individuals, a finding that should contribute to the development of an effective vaccine to prevent B19 infection in selected high-risk groups, including sickle-cell anaemics.

Anemia, Aplastic↗

PubMed2004

Parvovirus LuIII transducing vectors packaged by LuIII versus FPV capsid proteins: the VP1 N-terminal region is not a major determinant of human cell permissiveness.

Human cell lines are permissive for LuIII, a member of the rodent group of autonomous parvoviruses. However, LuIII vectors pseudotyped with feline panleukopaenia virus (FPV) capsid proteins can transduce feline cells but not human cells. Feline transferrin receptor (FelTfR) functions as a receptor for FPV. Transfection of Rh18A, a human rhabdomyosarcoma cell line, with FelTfR enabled transduction by vector with FPV capsid. This was not true of other human lines, suggesting restriction at some additional, post-entry, level(s) in human cells other than Rh18A. It seemed a reasonable hypothesis that a second blockage might be in nuclear delivery mediated by the N-terminal region of the minor capsid protein, VP1. We therefore generated virions containing an LuIII-luciferase genome, packaged using chimaeric VP1 molecules (N-terminal region of LuIII VP1, fused with body of FPV, and vice versa) together with the major capsid protein, VP2, of FPV or LuIII. The virions were tested for ability to transduce feline and human cells. Our hypothesis predicted that the N-terminal region of LuIII VP1 should allow transduction of human cells expressing FelTfR, while the FPV N-terminal region should not allow transduction of human cells (except for Rh18A). The experimental results did not bear out either of these predictions. Therefore, the VP1 N-terminal region appears not to be a major determinant of permissiveness for LuIII, versus FPV, capsid in human cells.

Amino Acid Sequence↗

PubMed2004

Attachment of bovine parvovirus to sialic acids on bovine cell membranes.

Although it has previously been shown that bovine parvovirus (BPV) attaches to the sialated glycoprotein glycophorin A on erythrocytes, the nature of virus-binding moieties on mammalian nucleated cells is less clear. Buffalo lung fibroblasts (Bu), primary bovine embryonic kidney cells, Madin-Darby bovine kidney cells and bovine embryonic trachea (EBTr) cells were assessed for molecules capable of binding BPV. Competition studies were carried out on both erythrocyte and nucleated cell targets using a variety of sialated compounds and sialic acid-negative compounds. Glycophorin A was found to inhibit BPV binding, while mucin exhibited low-level inhibition. These two sialated compounds also blocked attachment of BPV-modified microsphere carriers to the Bu cell membrane. Influenza A virus was used as a sialic acid competitor and interfered with BPV attachment to erythrocytes and replication in Bu cells. Significantly, the enzyme sialidase removed BPV-binding sites from Bu and EBTr cells. The binding sites could be reconstituted on sialidase-treated cells by the enzymes alpha-2,3-O-sialyltransferase and alpha-2,3-N-sialyltransferase. These results indicated that BPV can attach to sialic acid on cell membranes and that the sialylglycoproteins available for virus attachment appear to contain both N- and O-linked carbohydrate moieties, but that not all members of the sialic acid family can bind BPV. Moreover, there may be other moieties that can bind BPV, which may act as either primary or secondary receptors.

Animals↗