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At least 19 recordsLinked to original sources

PubMed1997

Comparison of the complete sequence of feline spumavirus with those of the primate spumaviruses reveals a shorter gag gene.

The complete nucleotide sequence of the provirus of feline foamy virus (FeFV), strain F-17, was determined, and compared to the available data for human and simian spumaviruses. In addition to the usual retroviral gag, pol and env genes, two open reading frames are present between the env gene and the 3'-LTR, as in the simian spumaviruses, the first being the putative transactivator. The gag gene is predicted to encode a precursor protein of only 53 kDa compared to 70 kDa for simian spumaviruses and a doublet of 70/74 kDa for human spumavirus. The gag gene contains conserved splice acceptor and donor sites suggesting that, like human foamy virus, FeFV expresses its pol gene using a spliced mRNA. The poland envgenes showed greater sequence similarity to their counterparts in the primate spumaviruses than the gag gene and additional open reading frames.

Amino Acid Sequence↗

PubMed2002

Survival of spumavirus, a primate retrovirus, in laboratory media and water.

The persistence of a previously characterized spumavirus strain (strain SV-522) was investigated utilizing various laboratory media and waters, including Eagle's minimal essential medium (EMEM) plus 0% fetal bovine serum (EMEM-0%), EMEM-2%, EMEM-10%, Chlamydia transport medium (CTM), phosphate-buffered saline, distilled, estuarine, and marine water, human serum, and the germicides, ethyl alcohol (70%) and sodium hypochlorite (10%). Experiments were performed at 4 degrees C and/or 23 degrees C. Infectivity endpoints were determined in stock aliquots upon initiation of testing and then after 3, 5, 7, and 10 days. The virus was reisolated from all diluents after 5 days at 23 degrees C and in EMEM-10% after 7 days. The virus was detected in CTM, EMEM-2%, EMEM-10%, and estuarine and marine waters after 7 days at 4 degrees C. Differences in the persistence of the virus may be ascribed to temperature and organic load. Water ionic strengths (e.g., estuarine vs. marine water) had no effect on modifying persistence of viral particles. Infectivity of spumavirus was undetectable after 30 s in 70% ethanol or 10% sodium hypochlorite. After 30 min at 23 degrees C, spumavirus infectivity in normal but not heat-inactivated human serum increased by almost 100-fold. Persistence of infectivity of primate spumavirus after 7 days in media and waters, and the agent's infectious potential in the human host, emphasize a need for cautious recognition during the manipulation of primate cells/organs and in the handling of primates themselves.

Animals↗

PubMed2003

Biphasic DNA synthesis in spumaviruses.

Spumaviruses are complex retroviruses whose replication cycle resembles that of hepadnaviruses, especially by a late-occurring reverse transcription step. The possible existence of an early reverse transcription as observed in other retroviruses was not documented. Using real-time quantitative PCR, we addressed directly the kinetics of DNA synthesis during spumavirus infection. An early phase of viral DNA synthesis developed until 3 h postinfection, followed by a second phase, culminating 10 h postinfection. Both phases were abolished by the reverse transcriptase inhibitor 3'-azido-3'-deoxythymidine. Similar to other retroviruses, circular forms of viral DNA harboring two long terminal repeats were mainly found in the nucleus of infected cells. Interestingly, a fraction of these circular forms were detected in the cytoplasm and in extracellular virions, a feature shared with hepadnaviruses. Combined with packaging of both viral DNA and RNA genomes in virions, early and late reverse transcription might allow spumavirus to maximize its genome replication.

Animals↗

PubMed1992

Human spumavirus antibodies in sera from African patients.

Serum samples collected from patients with a wide variety of diseases from African and other countries were tested for antibodies to the human spumaretrovirus (HSRV). A spumaviral env-specific ELISA was employed as screening test. Out of 3020 human sera screened, 106 were found to be positive (3.2%). While the majority of patients' sera from Europe (1581) were negative, 26 were positive (1.6%). Sera from healthy adult blood donors (609), from patients with multiple sclerosis (48), Graves' disease (45), and chronic fatigue syndrome (41) were negative or showed a very low prevalence for spumaviral env antibodies. A higher percentage of seropositives (6.3%) were found among 1338 African patients from Tanzania, Kenya, and Gabon. Out of 1180 patients from Tanzania, 708 suffered from tumors, 75 from AIDS, and 128 had gynecological problems; 51 of the Tanzanian patients were HSRV seropositive (4.3%). A particularly high percentage of 16.6% seropositives were identified among nasopharyngeal carcinoma patients (NPC) from Kenya and Tanzania consistent with results reported 10 years ago. However, 20 nasopharyngeal carcinoma patients from Malaysia were HSRV-seronegative. In selected cases, sera from seropositive individuals were reacted with proteins from HSRV-infected cells in vitro. HSRV env- and gag-specific antibodies were specifically detected by these sera in Western blots. The results indicate spumavirus infections in human patients with various diseases at a relatively low prevalence worldwide; in African patients, however, the prevalence of spumavirus infections is markedly higher.

Africa↗

PubMed1990

Specific enzyme-linked immunosorbent assay for the detection of antibodies to the human spumavirus.

Recombinant plasmid clones were constructed harbouring the central domains of the outer membrane protein and the transmembrane protein of the env gene of human spumaretrovirus (HSRV). The corresponding fusion proteins were expressed in E. coli, purified and used subsequently to produce antibodies against the HSRV env proteins in rabbits. The authenticity of the bacterially produced domain of the HSRV env proteins was shown by radioimmunoprecipitation of the viral env glycoprotein from HSRV-infected human cells with rabbit antibodies raised against the recombinant antigens. The recombinant viral antigens were used to establish a sensitive and spumavirus-specific enzyme-linked immunosorbent assay (ELISA). This anti HSRV antibody ELISA makes it possible to screen human sera for the presence of spumavirus infections.

Animals↗

PubMed1997

Characterization of the genome of feline foamy virus and its proteins shows distinct features different from those of primate spumaviruses.

The genome of the feline foamy virus (FeFV) isolate FUV was characterized by molecular cloning and nucleotide sequence analysis of subgenomic proviral DNA. The overall genetic organization of FeFV and protein sequence comparisons of different FeFV genes with their counterparts from other known foamy viruses confirm that FeFV is a complex foamy virus. However, significant differences exist when FeFV is compared with primate foamy viruses. The FeFV Gag protein is smaller than that of the primate spumaviruses, mainly due to additional MA/CA sequences characteristic of the primate viruses only. Gag protein sequence motifs of the NC domain of primate foamy viruses assumed to be involved in genome encapsidation are not conserved in FeFV. FeFV Gag and Pol proteins were detected with monospecific antisera directed against Gag and Pol domains of the human foamy virus and with antisera from naturally infected cats. Proteolytic processing of the FeFV Gag precursor was incomplete, whereas more efficient proteolytic cleavage of the pre125Pro-Pol protein was observed. The active center of the FeFV protease contains a Gln that replaces an invariant Gly residue at this position in other retroviral proteases. Functional studies on FeFV gene expression directed by the promoter of the long terminal repeat showed that FeFV gene expression was strongly activated by the Bell/Tas transactivator protein. The FeFV Bell/Tas transactivator is about one-third smaller than its counterpart of primate spumaviruses. This difference is also reflected by a limited sequence similarity and only a moderate conservation of structural motifs of the different foamy virus transactivators analyzed.

Amino Acid Sequence↗

PubMed1987

Enhanced production of a human spumavirus (Retroviridae) in semi-permissive cell cultures after treatment with 5-azacytidine.

Infection by a human spumavirus of human foetal diploid lung (HFDL) cells was found to be productive with virus titres ranging from 10(3) to 10(5) p.f.u./ml. In contrast, infection of recovered amnion (RA) aneuploid cells resulted in a persistent infection with less than 100 p.f.u./ml infectious virus produced. The decreased sensitivity of RA cells to the spumavirus was not due to the failure of virus to penetrate into the cell since infectious virus was not produced even after transfection of infectious proviral DNA. The effect of 5-azacytidine, an inhibitor of DNA methylation, on virus replication was examined. Whereas virus production in HFDL cells was not affected, there was a 100-fold increase in virus yield in RA cells treated with the drug for at least 48 h and maximum virus yields were obtained 4 days post-infection.

Azacitidine↗

PubMed1988

Epidemiological studies of bovine spumavirus.

Bovine spumavirus (BSV) infection is shown to be endemic in some herds in north Queensland. The virus was readily isolated from leucocytes of the majority of mature cattle which were BSV antibody positive (BSV reactors) in the agar gel precipitin test (AGPT). Calves born to dams which were BSV reactors showed no BSV antibody or circulatory leucocyte-associated BSV (CLAB) at birth, but became BSV reactors following ingestion of colostrum, and maintained such evidence of passive immunity until 3-5 months of age. Experimental infection of dams with BSV at 5-7 months of gestation did not cause foetal infection. In groups of young animals at pasture, segregated by age and sex, no evidence of BSV infection occurred, following loss of passive immunity, until 18-24 months of age. At this time, occasional members of some groups (both male and female) became BSV reactors and showed CLAB. At approximately 24 months old, following mixing in groups with older cows, and single-sire mating, 34% of heifers became BSV reactors within 10 weeks. A herd survey indicated 85% of 2-3-year-old cows to be BSV reactors; thereafter, the percentage of reactors declined gradually with increasing age. Using BSV grown in cell culture, transmission of infection by throat spray was the most successful route, 7 of 7 (100%) of susceptible cattle becoming BSV reactors within 8 weeks of spraying. Using the intravenous route, only 2 of 5 (40%) susceptible cattle became BSV reactors, and swabbing of cell culture virus into the prepuce or vagina did not result in infection of 4 BSV-susceptible animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Detection of immunological tolerance to bovine spumavirus (BSV) with evidence for salivary excretion and spread of BSV from the tolerant animal.

A group of 17 Friesian-Holstein steers held in individual pens was examined for evidence of infection with bovine spumavirus (BSV). Serum was examined for specific antibody by 2 serological procedures, and circulatory leucocytes and throat swabs were examined for the presence of circulatory leucocyte-associated BSV (CLAB) and saliva-associated BSV (SAB). Initial tests showed that 7 of the 17 steers had specific antibody to BSV by both serological procedures, and a further steer developed such antibody during the first 3 months of holding the animals in single contiguous pens. All 8 of these specific antibody-positive steers were CLAB positive and SAB negative. Nine steers showed no specific antibody to BSV by either of the 2 serological procedures; 8 of these 9 steers showed no evidence of CLAB or SAB. The exception was one steer which was CLAB- and SAB-positive at each of 30 samplings taken over a period of 9 months observation, whilst remaining specific-antibody free. This steer was classed as immunologically tolerant of BSV, and epidemiological data suggested that lateral spread of infection had originated from this animal through the agency of saliva.

Animals↗

PubMed1988

Evidence for a gapped linear duplex DNA intermediate in the replicative cycle of human and simian spumaviruses.

Two forms of linear DNAs have been found in simian (SFV1) and human (HSRV) spumaviruses: a linear duplex unsensitive to nuclease S1 and a sensitive structure with a single-stranded gap. Two nuclease S1 sensitive sites, mapping at the same position for both viruses, have been identified in the gapped structure. Using different molecular subgenomic clones of HSRV as probes in Southern blot analysis, one S1 site was localized in the 3'LTR and the other near the middle of the molecule at about 6.5 kbp from the 5' end of the viral genome. The latter site was shown to correspond to a single stranded region within the linear duplex DNA. Nucleotide sequence analysis revealed that the polypurine tract (PPT) usually found at the 5' boundary of the 3'LTR of retroviruses, is duplicated in HSRV at the 3' end of the pol gene, near the gap. This suggests that the synthesis of plus strand DNA is discontinuous, generating the gap.

Animals↗

PubMed1991

Further characterization of the gapped DNA intermediates of human spumavirus: evidence for a dual initiation of plus-strand DNA synthesis.

We recently reported the presence of linear duplex DNA intermediates with a gap in the middle of the molecules in the replicative cycle of human (HSRV) and simian (SFV1) spumaviruses. The polypurine tract (PPT), at the 5' boundary of the 3' long terminal repeat, was found to be duplicated in the gap region. By molecular analysis of HSRV proviral DNA with region- and strand-specific probes, we have now determined that the gap is located on plus-strand DNA and that it is 120 bases long with the 3' end mapping at the duplicated PPT site. Kinetic analysis of proviral DNA provided evidence that the gap did not result from processing of a complete, full-length DNA molecule. These data strongly suggest that plus-strand DNA synthesis is initiated at both PPT sites.

Base Sequence↗

PubMed1999

Molecular characterization of proteolytic processing of the Gag proteins of human spumavirus.

Spumaviruses, or foamy viruses, express Gag proteins that are incompletely processed by the viral protease in cell cultures. To delineate the proteolytic cleavage sites between potential Gag subdomains, recombinant human spumaretrovirus (HSRV) Gag proteins of different lengths were expressed, purified by affinity chromatography, and subjected to HSRV protease assays. HSRV-specific proteolytic cleavage products were isolated and characterized by Western blotting. Peptides spanning potential cleavage sites, as deduced from the sizes of the proteolytic cleavage products, were chemically synthesized and assayed with HSRV protease. The cleaved peptides were then subjected to mass spectrometry. In control experiments, HSRV protease-deficient mutant proteins were used to rule out unspecific processing by nonviral proteases. The cleavage site junctions identified and the calculated sizes of the cleavage products were in agreement with those of the authentic cleavage products of the HSRV Gag proteins detectable in viral proteins from purified HSRV particles and in virus-infected cells. The biological significance of the data was confirmed by mutational analysis of the cleavage sites in a recombinant Gag protein and in the context of the infectious HSRV DNA provirus.

Animals↗

PubMed1999

[The retroviral spumaviruses: new data in retrovirology].

Spumaviruses or foamy viruses belong to the Retroviridae family. Their genomic structure enables to classify them among the complex retroviruses like lentiviruses and the T leukemia viruses. These viruses, discovered 40 years ago, present a large cellular tropism and although highly lytic in vitro, they seem to be innocuous in vivo. However, recent fascinating findings on foamy viruses bring new important biological aspects of general interest for the field of retrovirology and show that these viruses are at the crossroads between retroviruses and pararetroviruses.

Cytoskeleton↗

PubMed1997

Nonhuman primate spumavirus infections among persons with occupational exposure--United States, 1996.

Nonhuman primate (NHP) species used in biomedical research may be infected with a variety of retroviruses including simian immunodeficiency virus (SIV), simian spumaviruses (i.e., simian foamy viruses [SPV]), simian T-lymphotrophic viruses (STLV), and/or simian type D retroviruses. All of these retroviruses cause life-long infections in NHPs, and some are transmissible through sexual contact, blood, or breast-feeding. Following the detection of SIV infection in a worker with occupational exposure to SIV, in 1993 CDC and the National Institutes of Health conducted an anonymous serosurvey using stored specimens collected from U.S. workers with similar exposures. SIV seroreactivity was present in three (0.6%) of 427 stored serum samples. As a result of this finding, in 1993 CDC implemented a voluntary testing and counseling surveillance program to link specific exposures or health outcomes with the SIV serostatus of persons with potential occupational exposure to SIV. In 1995, the linked surveillance program was expanded to include voluntary testing and counseling for exposure to SFV, STLV and simian type D retroviruses. As of November 20, 1996, samples from 231 of the participating volunteer workers had been tested for SFV; infection was documented in three (1.3%). This report presents laboratory findings and case descriptions of these three infections, which indicate that SFV from NHPs can persistently infect exposed humans and may or may not cause disease or be transmitted among humans.

Animals↗

PubMed1984

Human spumavirus replication in human cells.

It was previously reported that the replication of the human syncytium-forming virus (HSFV), a spumavirus, occurred only in fibroblast-like cell lines (human fetal diploid lung #645 [HFDL]) but not in epithelial-like lines (recovered amnion) [RA]. Factors that may be involved in such a phenomenon were the subject of this investigation. While both permissive (HFDL) and nonpermissive (RA) cell lines supported the replication of several representative animal viruses and adsorbed HSFV equally well, immunofluorescent staining of HSFV antigens revealed markedly fewer fluorescing cells in nonpermissive cultures. Infectious center assays of infected nonpermissive cells indicated the formation of significantly fewer infectious centers. The rate of DNA synthesis was markedly greater in the permissive cell lines. In addition, in the permissive cell line, the amount of proviral DNA revealed by the Hirt procedure and isopycnic banding in CsCl was significantly increased and was infectious as determined by the calcium phosphate-DMSO transfection assay. These results indicate that resistance of HSFV infection in nonpermissive cell cultures is probably an intracellular event.

Amnion↗

PubMed1988

Spumaviruses isolated from sources containing agents of non-A, non-B (NANB) hepatitis do not cause NANB hepatitis.

Serum and liver tissue containing infective non-A, non-B hepatitis virus were shown to contain a retrovirus-like agent that replicated when inoculated into chimpanzee liver cell cultures in vitro. The virus appeared to assemble its core particles in association with tubular structures reminiscent of those characteristically seen in non-A, non-B hepatitis virus-infected chimpanzee liver in vivo, and produced syncytial cytopathic effects in a number of continuous and a primary mammalian liver cells. The agents were neutralized by acute and convalescent sera from human and chimpanzee cases of non-A, non-B hepatitis, as well as by antisera against simian spumavirus type 7, but not type 6. Aluminum chloride failed to abolish viral infectivity. There was no evidence of virus replication or hepatitis in chimpanzees inoculated with a seventh passage of one of the isolates. Thus the data suggest that the isolates are not causally related to non-A, non-B hepatitis, as was previously postulated.

Aluminum↗

PubMed1992

No evidence for spumavirus or oncovirus infection in relapsing-remitting multiple sclerosis.

Polymerase chain reaction analysis was used to investigate the possible role of human spumaretrovirus and oncoretroviruses (human T-cell lymphotropic virus types I [HTLV-I] and II [HTLV-II]) in multiple sclerosis. Eleven patients with relapsing-remitting multiple sclerosis in exacerbation and 11 normal blood donors were included in the study. Cerebrospinal fluid cells, peripheral blood mononuclear cells, and plasma were cocultured with allogeneic mononuclear cells for 6 weeks. Cultured cells were subjected to polymerase chain reaction analysis with primers selected for the pol and gag (human spumaretrovirus), pol and env (HTLV-I), and pol (HTLV-II) genes. Polymerase chain reaction was negative in all patient and blood donor control samples, whereas positive controls were consistently reactive with high sensitivity. No culture exhibited cytopathic effects and supernatants were negative for reverse transcriptase activity. Thus, our results do not support a role for these retroviruses in the pathogenesis of multiple sclerosis.

Adult↗

PubMed1992

Bacterial expression of the capsid antigen domain and identification of native gag proteins in spumavirus-infected cells.

A bacterial expression plasmid containing the central part of the gag gene of the human spumaretrovirus (HSRV) was constructed and expressed in E. coli. The expected protein product consisting of the complete region of the HSRV capsid antigen and part of the matrix protein was expressed in relatively large amounts. Polyclonal antisera raised against this recombinant protein were used to identify authentic gag precursors of 78 and 74 kDa and processed gag proteins of 60, 58, and 33 kDa in HSRV-infected human embryonal fibroblast cells by radioimmunoprecipitation. The recombinant antigen will be useful for the detection of antibodies against HSRV gag proteins in human sera.

Antigens, Viral↗