| structural analysis of proviral dna in simian foamy virus (lk-3)-infected cells. | proviral dna of the t-cell lymphotropic simian foamy virus strain lk-3 was characterized. in infected cells, multiple copies of unintegrated linear duplex viral dna of about 13 kbp length are present. nuclease s1 treatment of the dna generated two fragments of 6.5 and 6.0 kbp length that were cloned in phage and plasmid vectors. the proviral dna contains a single-stranded gap of 109 nucleotides. a dna fragment spanning the gap was cloned after completing the double strand by dna synthesis in vit ... | 1989 | 2558626 |
| isolation of a retrovirus and a herpesvirus from a captive california sea lion. | a non-oncogenic retrovirus was isolated from an explanted skin biopsy from a captive california sea lion (zalophus californianus) with a history of recurring skin lesions. the morphology of the viral particles in electron photomicrographs was characteristic of a foamy virus, a retrovirus in the subfamily spumavirinae. viral cytopathic effects consistent with foamy virus infection were observed in subsequent explants of skin and lymph nodes and co-cultivated peripheral blood leukocytes. the sea l ... | 1986 | 3012127 |
| detection and characterization of infectious dna intermediates of a primary foamy virus. | dna from human t-lymphoid (molt-4) and hamster kidney (bhk-21) cells infected with the t-lymphotropic simian foamy virus lk-3 was shown to be infectious, when assayed by transfection of bhk-21 cells. the proviral genome was further characterized by blot hybridization to a specific cdna probe, which had been prepared by reverse transcription in vitro using viral rna and rna-dependent dna polymerase present in cytoplasmic extracts of infected bhk-21 cells. this probe hybridized to a dna species of ... | 1986 | 3018132 |
| 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 cell ... | 1988 | 3130462 |
| 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, ... | 1984 | 6502141 |
| latent infection with feline syncytial virus of cell cultures prepared from the kidneys of new-born kittens. | feline syncytial virus infection was detected in 4 out of 30 secondary or tertiary cultures of kidney cells from new-born kittens. such infection was not detected in any primary cell culture. the syncytia-forming virus was readily transmissible by infected cells. one strain was transmissible to heterologous (bovine and canine) secondary cells, but did not infect mdbk and pk-15 cell lines. based on biochemical, untrastructural and serological characteristics, the virus was designated a member of ... | 1988 | 3354195 |
| isolation of novel human endogenous retrovirus-like elements with foamy virus-related pol sequence. | a new class of reverse transcriptase coding sequences was detected in reverse-transcribed rnas from human placenta by polymerase chain amplification with primers in highly conserved regions of the pol gene of mammalian retroviruses and retrotransposons. using one of these novel sequences as a probe to screen a human genomic library, we isolated retrovirus-like elements bordered by long terminal repeats and having a potential leucine trna primer-binding site. determination of the complete nucleot ... | 1995 | 7543594 |
| active foamy virus proteinase is essential for virus infectivity but not for formation of a pol polyprotein. | to analyze proteolytic processing of foamy (spuma) retroviruses, two mutations were generated in the presumed active-site triplet asp-ser-gly in the predicted proteinase (pr) region of the human foamy virus (hsrv). the mutations changed either the presumed catalytic aspartic acid residue to a catalytically incompetent alanine or the adjacent serine to a threonine found in most cellular and retroviral proteases at this position. both mutations were cloned into the full-length infectious hsrv dna ... | 1995 | 7474150 |
| human foamy virus and familial mediterranean fever in japan. | | 1995 | 7474216 |
| analysis of cross reactivity of retrovirus proteases using a vaccinia virus-t7 rna polymerase-based expression system. | we have used the vaccinia virus-t7 rna polymerase-based expression system for studies on the activity of proteases from various retroviruses on homologous and heterologous gag polyproteins in eukaryotic cells. proteases from human immunodeficiency virus (hiv) types 1 and 2, equine infectious anaemia virus, human t cell leukaemia virus type 1 and human spumavirus were produced and were shown to cleave their cognate gag substrates produced in trans. analysis of cross reactivity revealed that lenti ... | 1995 | 7561754 |
| internal transcriptional regulatory elements in hiv-1 and other retroviruses. | the transcriptional regulation of retroviruses plays an important role in their pathogenesis. cis-acting elements have been identified in the long terminal repeat (ltr) at the 5' extremity of the integrated provirus. these elements determine the rate and the site of transcription initiation and consist of arrays of binding sites for transcription factors. recent studies have demonstrated the presence of additional regulatory elements, located outside of the ltr, within the transcribed region of ... | 1995 | 7580829 |
| the multifaceted retrovirus. | i have attempted to illustrate the many different properties of retroviruses and their presence in a wide variety of animal species including humans. since the turn of this century, progress in the field of retrovirology has been noteworthy and many new and important scientific observations have been made (table 7). along the way, certain dogmas were replaced with new tenets. the recent recognition of retroviruses associated with human cancer and immunodeficiency places them into consideration a ... | 1986 | 3530440 |
| syncytium-forming virus of common marmosets (callithrix jacchus jacchus). | this communication describes the isolation and characterization of a new syncytium-forming virus of common marmosets (callithrix jacchus jacchus). the virus, isolated from skin explants and peripheral leukocytes of healthy animals, induced syncytia and subsequent cytolysis of several human, simian, and rodent fibroblastic cultures and induced a carrier state in mixed fibroblastic-epithelial or epithelial cell lines. cytoplasmic and nuclear viral antigen was demonstrated in infected cells by indi ... | 1981 | 6164648 |
| reverse transcriptase from simian foamy virus serotype 1: purification and characterization. | chromatography on heparin-sepharose, known for its affinity for nucleotide-binding polypeptides, was used to purify the viral rna-dependent dna polymerase (reverse transcriptase) from the core polypeptides of simian foamy virus type 1. this procedure allowed the recovery of highly purified enzyme with a high specific activity. the average molecular weight of this monomeric enzyme is 81,000 and is thus comparable to that found for other known primate retroviruses. reverse transcriptase activity o ... | 1982 | 6183451 |
| characterization of rnase h activity associated with reverse transcriptase in simian foamy virus type 1. | spumavirinae or foamy viruses have been shown to have a characteristic rna-dependent dna polymerase activity. we demonstrate here the existence of an rnase h activity that copurifies with the 81-kilodalton monomeric polypeptide, which carries the rna-dependent dna polymerase activity of simian foamy virus type 1. rnase h degrades rna hybrid substrates; however, it does not solubilize single-stranded rnas. inactivation assays with heat, high levels of bivalent cations, ethidium bromide, and sodiu ... | 1983 | 6191042 |
| characterization of a foamy virus isolated from cercopithecus aethiops lymphoblastoid cells. | a virus derived from cells of a lymphoblastoid line originating from the lymph node of a healthy african green monkey was characterized as a typical member of the foamy virus subgroup of retroviridae by its morphological, physicochemical, biological and biochemical properties (reverse transcriptase activity). besides the usual host range of foamy viruses, the isolated strain revealed a remarkable t-lymphotropism, distinguishing it from the prototypes of foamy viruses previously isolated from afr ... | 1983 | 6193403 |
| the prevalence of naturally occurring antibodies to human syncytial virus in east african populations. | a seroepidemiological study of naturally occurring antibodies to the human syncytial virus has been carried out by means of an indirect immunofluorescence test on 639 east africans, consisting of 493 normal ugandans, 66 kenyan patients with nasopharyngeal carcinoma (npc), and 80 kenyan and tanzanian patients with various other tumours or non-cancerous conditions. it was found that 3.4% of the normal individuals had antibodies to the virus and serial serum samples were available from 14 of these, ... | 1980 | 6245177 |
| seroepidemiology of human syncytial virus: antibody prevalence in the pacific. | a seroepidemiological survey of the human syncytial (foamy) virus was done by means of an indirect immunofluorescence test on 1,717 sera from nine different pacific island territories. the specificity of the reaction was verified by neutralization tests. the study indicated that the virus is ubiquitous in this part of the world, with no region being entirely free of antibody. the antibody prevalence ranged from a low of 1.2% in ponape to a high of 15.6% in the cook islands. the average prevalenc ... | 1980 | 6246030 |
| replication of human syncytium-forming virus in human cells: effect of certain biological factors and selective chemicals. | the growth characteristics of the human syncytium-forming virus (hsfv) were examined in several human cell lines of normal and malignant origins and composing of either fibroblastic or epithelial-like cells. virus production occurred only in the fibroblastic diploid cell lines: hef (human embryonic cells, flow #5,000) and hfdl #645 (human fetal diploid lung), but not in the epithelial-like heteroploid cell lines: ra (a continuous line of human amnion), #999 (human bone marrow), and kb (carcinoma ... | 1981 | 6264025 |
| the rna of the human syncytium-forming (foamy) virus. | human syncytium-forming (foamy) virus was labeled with 3h-uridine and banded isopycnically in sucrose gradients (buoyant density = 1.16 to 1.18 g/cm3). viral rna extracted from the banded virus was analyzed either by rate zonal separation in sucrose gradients or by polyacrylamide-agarose gel electrophoresis. the results indicated that purified hsfv contains a 60s rna component plus several smaller molecular weight rna components. on dissociation with heat, smaller rna structures were released fr ... | 1981 | 6264892 |
| simian foamy virus pseudotypes of vesicular stomatitis virus: production and use in sero-epidemiological investigations. | simian foamy virus (sfv) pseudotypes of vesicular stomatitis virus have been successfully produced and their host range characterized. the availability of these pseudotypes has permitted the development of a rapid, quantitative assay to measure neutralizing antibody titres to sfv that has proved useful in a sero-epidemiological study. | 1982 | 6279771 |
| [bovine syncytial virus--a review]. | | 1983 | 6316867 |
| evidence for superantigen activity of the bel 3 protein of the human foamy virus. | the human foamy virus is a complex retrovirus that codes for several regulatory bel genes in addition to the conventional gag, pol, and env genes. the bel 3 gene is located in the 3' part of the viral genome comparable to that of the superantigen of the mouse mammary tumor virus. superantigens bound to major histocompatibility complex (mhc) class ii molecules have been shown to stimulate t cells in a v beta-specific manner. the recombinant bel 3 protein purified to near homogeneity was assayed i ... | 1994 | 7528260 |
| stem cell factor binding to retrovirus primer binding site silencers. | using modified nuclear lysis and binding conditions, we have examined the binding of an embryonal carcinoma (ec) cell factor, binding factor a, to a stem cell-specific silencer which acts at the dna level and overlaps the moloney murine leukemia virus (m-mulv) proline primer binding site (pbs). following our protocol, we found that in vitro binding of factor a correlated with the in vivo activity of the m-mulv silencer. factor a bound specifically to the wild-type silencer element at room temper ... | 1995 | 7529329 |
| ultrastructural comparison of oncovirinae (type c), spumavirinae, and lentivirinae: three subfamilies of retroviridae found in farm animals. | the successive steps of maturation of seven retroviruses from five species of farm animals and one retrovirus from a mouse were compared in cell cultures. the viruses included three type c oncoviruses, one spumavirus, and three lentiviruses. although members of the 3 subfamilies shared some gross morphologic features such as budding on plasma membranes, core, and surface projections, differences were noted in the ultrastructural detail of these features. type c oncoviruses did not show any struc ... | 1984 | 6325793 |
| [neurotoxicity of human foamy virus in transgenic mice]. | human foamy virus (hfv) is a human retrovirus originally isolated from patients with various neoplastic and degenerative diseases. similarly to other human retroviruses, hfv encodes the three structural retroviral genes, gag, pol and env, and an additional region containing three open reading frames, bel-1 to bel-3. bel-1 activates transcription of the long terminal repeat of hfv and also of hiv. until today it has not been possible to identify hfv as the causative agent of any disease. in order ... | 1994 | 7533983 |
| human foamy virus infection activates class i major histocompatibility complex antigen expression. | we examined the effect of human foamy virus (hfv) infection on the expression of human major histocompatibility complex molecules. our data show that in vitro hfv infection of u373-mg glioblastoma cells results in increased expression of class i human leukocyte antigen (hla) and transcripts. transient transfection assays of plasmids containing the reporter gene chloramphenicol acetyl transferase driven by different 5' deletions of the hla-a11 class i promoter allowed identification of cis-acting ... | 1995 | 7534815 |
| mutational analysis of the reverse transcriptase and ribonuclease h domains of the human foamy virus. | human foamy or spuma virus (hfv) codes for a distinct set of pol gen products. to determine the minimal requirements for the hfv enzymatic activities, defined residues of the reverse transcriptase (rt) and ribo-nuclease h (rnase h) domain of the hfv pol gene were mutated by site-specific pcr mutagenesis. the mutant gene products were bacterially expressed, purified by ni2+ chelate affinity chromatography and characterised by western blotting. the enzymatic activities of the individual recombinan ... | 1995 | 7544460 |
| human foamy virus dna forms and expression in persistently infected dami megakaryocytic cells. | we have characterized human foamy virus (hfv) proviral dna and determined hfv expression in a persistent infection model, the dami megakaryocytic cell line. molecular studies were performed on parental persistently infected cells (dami-p), as well as on derived clones (dami-cl). we report that in these nonlytic and non-hfv producer cells, viral dna was found to be integrated into the cellular genome and that the few free proviral forms detected in dami-p cells were deleted in their 5' ltr. our m ... | 1995 | 7546910 |
| cell cycle dependence of foamy retrovirus infection. | in common with oncoviruses but unlike the lentivirus human immunodeficiency virus type 1, foamy (spuma) viruses require host cell proliferation for productive infection. we show that human immunodeficiency virus type 1 replicates in rd-cd4 cells regardless of the growth arrest condition of the cells, while murine leukemia virus is unable to infect growth-arrested rd-cd4 cells or cells progressing through a partial cell cycle that includes s phase but not mitosis. human foamy virus, like murine l ... | 1995 | 7474157 |
| activation of hiv transcription by human foamy virus in transgenic mice. | although infection by hiv-1 is the primary cause of aids, cofactorial agents of an infectious nature may be involved in the pathogenesis of the disease. the present work addresses the cofactorial potential of human foamy virus (hfv) in aids. it has been suggested that hfv seroprevalence reaches 5% in east africa, and hfv seroprevalence in east african patients suffering from aids and aids-related complex may be as high as 20%. although the pathogenic potential of hfv in humans has not yet been i ... | 1995 | 7603032 |
| recent insights into the biology of the human foamy virus. | human foamy virus (hfv) is a complex retrovirus with structural similarities to hiv and human t cell leukemia virus. there have been considerable advances in understanding the biology of hfv in cell cultures. however, viral behavior in vivo, and even viral detection, are still poorly understood. while hfv-transgenic mice develop neuromuscular disorders, attempts to associate hfv with a specific human disease have given inconclusive results. | 1995 | 7627455 |
| involvement of a spliced and defective human foamy virus in the establishment of chronic infection. | human foamy retrovirus (hfv) is found as two proviruses (hfv and delta hfv) which differ by a splice-induced deletion within the bel1 transactivator gene. the defective delta hfv (which lacks a functional bel1 but harbors an intronless bet gene) is predominantly found in nonlytic infections in vitro as well as in vivo. here, we show that infection of cell lines stably transduced by delta hfv dna with the highly lytic hfv leads to chronic infections characterized by an absence of lysis, a balance ... | 1995 | 7636968 |
| regulation of foamy virus gene expression. | | 1995 | 7648870 |
| haematological disorders associated with feline retrovirus infections. | feline oncornavirus and lentivirus infections have provided useful models to characterize the virus and host cell factors involved in a variety of marrow suppressive disorders and haematological malignancies. exciting recent progress has been made in the characterization of the viral genotypic features involved in felv-associated diseases. molecular studies have clearly defined the causal role of variant felv env gene determinants in two disorders: the t-lymphocyte cytopathicity and the clinical ... | 1995 | 7663052 |
| identification of an er retrieval signal in a retroviral glycoprotein. | | 1995 | 7664333 |
| endonucleolytic cleavages and dna-joining activities of the integration protein of human foamy virus. | the bacterial expression plasmids, pet3b and pet16b, that contain the integrase domain of the human foamy virus (hfv) reverse transcriptase were constructed and expressed in escherichia coli. the histidine-tagged hfv in protein was purified to near homogeneity by single-step ni2+ chelate affinity chromatography. hfv-specific proteins of 39 and 120 kda from virus-infected cells reacted with antisera raised against the recombinant in protein. purified recombinant hfv in protein was active as an en ... | 1993 | 7688824 |
| differential effects of ras and jun family members on complex retrovirus promoter activities. | infection by complex retroviruses such as visna-maedi, hiv1, htlv-i and hfv is generally not followed by particle production, but rather by a more or less prolonged latency period. knowledge of the mechanisms triggering an infectious cycle from the latent provirus(es) is of great importance in comprehending the appearance of the disease. it is currently admitted that cellular factors regulate viral expression. in this paper, we report the ability of ras, c-jun, jun-b and jun-d to diversely stimu ... | 1994 | 7709072 |
| [spontaneous contamination of primary green monkey kidney cell cultures by foamy virus]. | examinations of 1653 batches of green monkey kidney cell cultures revealed contamination with foamy virus (fv) in 243 (16%) batches. from some of these cultures 65 strains of virus belonging to two serotypes were isolated. tests on sera from 1122 monkeys revealed antibody to fv in 985 (87.8%) animals. no correlation between the presence of antibody in the serum and virus recovery from monkey kidney cell cultures was observed, however. this might be due either to the lack of the virus in the kidn ... | 1980 | 6254265 |
| absence of evidence for human spumaretrovirus sequences in patients with graves' disease. | | 1995 | 7712242 |
| biochemical characterization of simian foamy virus type i. | simian syncitium-forming ("foamy") virus type i (sfv1) was characterized biochemically. rna was extracted from purified virus either with 0.1 per cent sds or by the standard phenol-chloroform method. by both techniques a main component of 65-70s was found. denaturation of the 65-70s rna by heat resulted in a shift of the sedimentation coefficient mainly to a 30-35s component. electrophoresis on a composite polyacrylamide gel demonstrated the existence of three minor rna's: 8s, 5s and 4s respecti ... | 1981 | 6268018 |
| molecular biological characterization of the human foamy virus reverse transcriptase and ribonuclease h domains. | foamy viruses form a separate group of retroviruses encoding a pol protein with at least four domains based on comparative sequence alignments. the polymerase and ribonuclease h domains of the human foamy virus (hfv) pol gene were expressed in escherichia coli either individually or in combination. the histidine-tagged hfv fusion proteins were subsequently purified to near homogeneity by affinity ni2+ chelate column chromatography. the polymerase and rnase h activities were characterized by perf ... | 1995 | 7483284 |
| 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 i ... | 1987 | 2437243 |
| the gene expression of human foamy virus does not require a post-transcriptional transactivator. | human foamy virus (hfv) comprises a complex genomic organization of gag, pol, env, and several nonstructural genes such as bel1, bel2, bel3, bet, beo, and bes located between env and 3' ltr. among these viral nonstructural genes, bel1 appears to encode an essential transactivator of ltr-directed gene expression. to investigate the roles of the other nonstructural proteins for the viral replication, a series of proviral mutants were generated and tested for their in vitro replication. the mutatio ... | 1994 | 7522374 |
| the human foamy virus internal promoter is required for efficient gene expression and infectivity. | the human foamy or spumaretrovirus (hfv) is a complex retrovirus that codes for the three retroviral genes gag, pol, and env and the regulatory and accessory bel genes. a particular feature of hfv gene expression was recently described: not only does the hfv provirus contain the classical retroviral long terminal repeat promoter, a second functionally active promoter is present in the env gene upstream of the bel genes (m. löchelt, w. muranyi, and r. m. flügel, 1993, proc. natl. acad. sci. usa 9 ... | 1995 | 7831816 |
| characterization of the human spuma retrovirus integrase by site-directed mutagenesis, by complementation analysis, and by swapping the zinc finger domain of hiv-1. | the human spuma retrovirus or foamy virus integrase (hfv in) is an enzymatically active protein consisting of domains similar to other retroviral integrases: an amino-terminal hh-cc finger, a centrally located region with the conserved d, d-35-e protein motif required for catalytic activity and oligomerization, and at least one dna binding domain implicated in the 3' dna processing activity and integrase. recombinant, purified hfv in protein carrying 10 histidine residues displays a site-specifi ... | 1995 | 7852375 |
| a comparative study of higher primate foamy viruses, including a new virus from a gorilla. | few foamy (spuma) retroviruses have been investigated in molecular detail, despite their previous isolation from several mamalian species, including ten neutralization serotypes from various primates. here, we have studied a new gorilla foamy virus (sfv-gg) and investigated its functional and phylogenetic relationship to the human (hfv) and other primate foamy viruses, including that recently described in orangutans (sfv-11). nucleotide sequencing of pcr products obtained from the r/u5 region of ... | 1995 | 7871729 |
| phylogenetic analysis of primate foamy viruses by comparison of pol sequences. | the relationship between primate foamy viruses was determined by comparing a 425-bp dna segment obtained by pcr using primers homologous to highly conserved portions of the pol gene. the phylogenetic tree of 14 foamy viruses investigated reflects the relationship between their host species: a cluster of asian old world monkey foamy viruses including simian foamy virus (sfv) prototypes 1 and 2 (isolated from macaca cyclopsis) is separated from african old world foamy viruses including prototype s ... | 1995 | 7886963 |
| human foamy virus infection in myasthenia gravis. | | 1994 | 7906819 |
| identification and characterization of the bel 3 protein of human foamy virus. | the human foamy virus (hfv) is a complex retrovirus that contains several regulatory and auxiliary bel genes besides the gag, pol, and env genes. in contrast to the gene products of bel 1 and bel 2/bet that were identified previously, the bel 3 protein has not been described to date. here we report the identification of bel 3 in hfv-infected cells by immunoprecipitation, indirect immunofluorescence, and expression cloning under the control of a strong heterologous promoter. bel 3 was immunopreci ... | 1994 | 7917520 |
| absence of foamy virus dna in graves' disease. | a report on the high prevalence of foamy virus dna in lymphocytes from french patients with graves' disease prompted us to investigate a similar cohort of 41 german patients. using pcr amplification and southern blot hybridization, we detected foamy virus dna only in lymphocytes of two accidentally infected humans and five naturally infected monkeys, as well as in dna samples from four graves' disease patients investigated in the french study. however, we failed to detect foamy virus dna in peri ... | 1994 | 7917521 |
| reactivity of primate sera to foamy virus gag and bet proteins. | in order to establish criteria for the serodiagnosis of foamy virus infections we investigated the extent to which sera from infected individuals of human and primate origin react with structural and non-structural virus proteins in immunoblot assays. using lysates from infected cells as the source of virus antigen, antibodies were preferentially detected against the gag proteins and the non-structural bet protein. both the gag precursor molecules of 70 and 74k apparent m(r) and the cytoplasmic ... | 1994 | 7931149 |
| isolation of a new foamy retrovirus from orangutans. | we have isolated a new foamy virus from blood samples taken from two apparently healthy orangutans (pongo pygmaeus). the older orangutan has since died with encephalopathy after a brief acute illness, while the younger one, his grandson, remains well. these animals and 12 other orangutans had specific antibodies to foamy virus as measured by immunofluorescence. the new foamy virus and the antisera showed strong and specific neutralization, with only weak cross-reaction with other simian foamy vi ... | 1994 | 7933094 |
| structure and function of the long terminal repeat of the chimpanzee foamy virus isolates (sfv-6). | the complete long terminal repeat (ltr) nucleotide sequence of the chimpanzee foamy virus isolate sfv-6 was determined. its 1761-bp size makes it the longest ltr reported to date among all retroviruses. since the length of its ltr is similar to that of other simian isolates while its sequence homology is closer to that of hfv, sfv-6 genetic structure appears to be intermediate between simian and human foamy viruses. transient expression assays demonstrate that sfv-6 encodes a transactivator of v ... | 1994 | 7998839 |
| characterization of the internal promoter of simian foamy viruses. | simian and human foamy viruses (hfv and sfv), genetically related members of the spumavirus genus of retroviruses, have complex genome structures which encode the gag, pol, and env genes for virion proteins as well as additional open reading frames. one of these open reading frames is a viral transactivator, encoded by genes designated taf for sfv and bel-1 for hfv, which augments transcription directed by the long terminal repeat (ltr) through cis-acting targets in the u3 domain of the ltr. rec ... | 1994 | 8035481 |
| nuclear localization of foamy virus gag precursor protein. | all foamy viruses give rise to a strong nuclear staining when infected cells are reacted with sera from infected hosts. this nuclear fluorescence distinguishes foamy viruses from all other retroviruses. the experiments reported here indicate that the foamy virus gag precursor protein is transiently located in the nuclei of infected cells and this is the likely reason for the typical foamy virus nuclear fluorescence. by using the vaccinia virus expression system, a conserved basic sequence motif ... | 1994 | 8035493 |
| simian foamy virus type 1 contains a second promoter located at the 3' end of the env gene. | simian foamy virus type 1 (sfv-1) is a member of a distinct subfamily of retroviruses that possess a complex genome organization as well as complex means of regulating gene expression. this virus encodes a transcriptional transactivator (taf) that dramatically increases gene expression directed by the viral long terminal repeat. in this report, the identification of a second promoter which is significantly transactivated by sfv-1 taf is described. the second promoter is located at the 3' end of ... | 1994 | 8116246 |
| the bel1 protein of human foamy virus contains one positive and two negative control regions which regulate a distinct activation domain of 30 amino acids. | the bel1 transactivator is essential for the replication of human foamy virus (hfv). to define the functional domains of hfv bel1, we generated random missense mutations throughout the entire coding sequence of bel1. functional analyses of 24 missense mutations have revealed the presence of at least two functional domains in bel1. one domain corresponds to a basic amino acid-rich motif which acts as a bipartite nuclear targeting sequence. a second, central domain corresponds to a presumed effect ... | 1994 | 8139046 |
| analysis of the 5' long terminal repeat of bovine syncytial virus. | four molecular clones of the bovine syncytial virus (bsv) were determined to be replication competent by the initiation of cytopathic infections and production of viable virus following transfection of viral dna into permissive cells. the nucleotide (nt) sequence of the 5' long terminal repeat (ltr) of the infectious clone, bsv-11, was determined and analyzed to identify regions common to retroviral ltrs and elements with the potential for involvement in transcriptional regulation. | 1994 | 8163193 |
| isolation, cloning, and sequencing of simian foamy viruses from chimpanzees (sfvcpz): high homology to human foamy virus (hfv). | several independent isolates of simian foamy viruses (sfv) were recovered from chimpanzee b-cell lines. one isolate, designated sfvcpz, was molecularly cloned and sequenced. in addition, the genome of sfv type 6 (sfv-6), an independent chimpanzee foamy virus isolate, was partially cloned. the sfvcpz provirus is 13,246 base pairs (bp) long. it is flanked by long terminal repeats (ltrs) and encodes the genes gag, pol, env, the transcriptional transactivator taf, and a second 3' open reading frame ... | 1994 | 8184531 |
| genetic analysis indicates that the human foamy virus bel-1 protein contains a transcription activation domain of the acidic class. | human foamy virus encodes a nuclear regulatory protein, termed bel-1, that serves as a potent activator of viral transcription. mutational analysis has identified a small, discrete activation domain within bel-1 that is highly active in both higher and lower eukaryotic cells. here, we demonstrate that the activation domain of bel-1 is highly dependent on the ada2 transcriptional adaptor for biological activity in yeast cells, a property previously shown to be a hallmark of the vp16 class of acid ... | 1994 | 8189518 |
| human spumaretrovirus antibody reactivity in multiple sclerosis. | the role of human spumaretrovirus (hsrv) infections in the pathogenesis of multiple sclerosis (ms) was investigated with recombinant hsrv env-specific enzyme-linked immunosorbent assay. the presence of hsrv antibodies was determined in pairs of serum and cerebrospinal fluid (csf) samples from 60 ms patients. in 7 of these patients serial serum and csf samples were obtained in relation to the clinical activity of the disease during a period of 2 years. no increased antibody reactivity was demonst ... | 1994 | 8195818 |
| evaluation of cofactor effect of feline syncytium-forming virus on feline immunodeficiency virus infection. | although feline immunodeficiency virus (fiv) and the unrelated retrovirus feline leukemia virus (felv) are associated with acquired immune deficiency in cats, experimental and field evidence indicates that coinfection with both viruses may lead to more serious disease syndrome. a third feline retrovirus, feline syncytium-forming virus (fesfv), which is far more prevalent than either fiv or felv and is considered nonpathogenic in nature, is consistently coisolated from sick, fiv-infected cats. to ... | 1993 | 8391229 |
| markers of foamy virus infections in monkeys, apes, and accidentally infected humans: appropriate testing fails to confirm suspected foamy virus prevalence in humans. | foamy viruses (fvs) persist in healthy individuals of various mammalian species, including nonhuman primates. laboratory markers of fv infection are (1) virus in throat epithelium or peripheral blood lymphocytes (pbls), (2) proviral dna sequences in pbls and various solid organs, and (3) antibodies reactive to viral antigens on western blots, in radioimmunoprecipitation tests, and in immunofluorescence assays. using pcr and serological tests, we readily detected fv markers in naturally infected ... | 1995 | 7734189 |
| absence of evidence for infection with the human spuma retrovirus in an outbreak of menière-like vertiginous illness in wyoming, usa. | | 1994 | 8203206 |
| human spumaretrovirus in the etiology of sudden hearing loss. | | 1994 | 8203207 |
| establishment of carrier-state infection of a feline renal cell line with feline syncytial virus. | although feline syncytial virus (fsv) is normally highly cytopathogenic in crandell feline kidney cells, a non-cytopathic persistent infection was established in the cells after cocultivation of the initially infected cells with uninfected cells 4 times. more than 90% of the persistently infected cells were positive for fsv antigen, and electron microscopy showed that the culture produced morphologically normal fsv. virus from the carrier culture was infectious, however, the titer of the virus f ... | 1995 | 7756428 |
| replicating foamy virus-based vectors directing high level expression of foreign genes. | replication-competent retroviral vectors (pfov-1 to -3 and -7) were constructed on the basis of an infectious human foamy virus molecular clone which has deletions in the u3 region of the long terminal repeat and in the 3' region of the genome, previously identified to be nonessential for virus replication in vitro. the cat and luciferase indicator genes were expressed as c-terminal fusion proteins to 215 amino acids of the viral bet protein in the pfov-1 vector. introduction of the foot-and-mou ... | 1995 | 7793069 |
| expression of the human foamy virus bel-1 transactivator in insect cells. | the human foamy virus (hfv) bel-1 transactivator protein was expressed in insect cells by a recombinant baculovirus. for the generation of the recombinant baculovirus, acbel-1, the bel-1 gene of an hfv mutant was used, that bears truncations in the bel-1 overlapping bel-2 open reading frame. acbel-1 infected sf9 cells produced high amounts of recombinant protein of the same electrophoretic mobility (36 kd) as bel-1 expressed in mammalian cells. the baculovirus expressed bel-1 protein was readily ... | 1993 | 8266722 |
| transient immunosuppressive effect induced in rabbits and mice by the human spumaretrovirus prototype hfv (human foamy virus). | spumaviruses (foamy viruses) constitute one of the three retroviral genera isolated from man. although spumaviruses have not been clearly linked to a given pathology in humans and other infected species, it is well established that they lead in vivo to chronic infections without detectable viral expression. we thought it of interest to investigate certain aspects of the pathology induced in laboratory animals by human foamy virus (hfv). in this work, we demonstrate that hfv infection of rabbits ... | 1993 | 8284516 |
| transcriptional mapping of the 3' end of the bovine syncytial virus genome. | the bovine syncytial virus, a member of the retroviral subfamily spumavirinae, causes a persistent, asymptomatic infection in cattle. nucleotide sequence analysis of the viral genome revealed two overlapping reading frames in the 3' region, traditionally occupied by accessory-function genes in other complex retroviruses. in order to analyze the transcripts from the accessory-gene region, we designed oligonucleotide primers complementary to sequences within the 5' and 3' long terminal repeats (lt ... | 1994 | 8289332 |
| the human foamy virus internal promoter directs the expression of the functional bel 1 transactivator and bet protein early after infection. | the human foamy virus or spumaretrovirus (hfv) is a complex retrovirus that has the capacity to code not only for the three retroviral genes gag, pol, and env but, in addition, for at least three bel genes. the hfv provirus contains two different and functionally active promoters: the classical retroviral promoter in the 5' long terminal repeat and a recently identified second promoter in the env gene upstream of the bel genes. both promoter/enhancers are strongly dependent on the hfv transcript ... | 1994 | 8289367 |
| transcriptional trans activators of human and simian foamy viruses contain a small, highly conserved activation domain. | the bel-1 protein of human foamy virus is a potent transcriptional trans activator of its homologous long terminal repeat promoter element. here, we demonstrate that bel-1 can also efficiently activate gene expression when targeted to a heterologous promoter by fusion to the dna-binding motif of the yeast gal4 protein. analysis of a series of deletion mutants of bel-1 generated in this hybrid protein context suggests the presence of a single transcription activation domain that is fully containe ... | 1993 | 8411385 |
| functional dissection of the human spumaretrovirus transactivator identifies distinct classes of dominant-negative mutants. | the bel1 gene of human spumaretrovirus (hsrv) codes for a 300-amino-acid nuclear protein, termed bel1, that can strongly activate transcription from the cognate long terminal repeat (ltr) by at least 200-fold. bel1 can also activate human immunodeficiency virus type 1 (hiv-1) ltr expression. by using site-directed mutagenesis, we have identified distinct regions of bel1 essential for hsrv ltr activation. the amino-terminal 55 residues, which comprise a highly acidic region followed by a short ba ... | 1993 | 8380068 |
| simian foamy virus type 3 (sfv-3) in latently infected vero cells: reactivation by demethylation of proviral dna. | cell cultures latently infected with simian foamy virus type 3 (sfv-3) were established by suppressing lytic infection in vero cells with 3'-azido-3'-deoxythymidine (azt) and homologous antibodies (african green monkey serum immune to sfv-3). the resulting cell line, designated vero-l, was shown to contain at least one copy per cell of sfv-3 dna stably integrated at a defined site of the host cell genome. sequencing of 669 bp at the integration site did not identify a coding region and revealed ... | 1993 | 8380669 |
| human spumaretrovirus in the etiology of sudden hearing loss. | the etiology of sudden sensorineural hearing loss, so called sudden deafness, has for long puzzled researchers. recently we have studied the possibility that a hitherto relatively unknown retrovirus group consisting of human spumaretroviridae (hsrv) might be the causative agent of sudden deafness. during the last 3 months we have screened about 30 cases of sudden deafness. in 4 of them antibodies against hsrv were detected. three of them had suffered from a flu-like condition about 2 weeks befor ... | 1993 | 8382898 |
| functional organization of the bel-1 trans activator of human foamy virus. | human foamy virus encodes a 300-amino-acid nuclear regulatory protein termed bel-1 that is required for human foamy virus replication in culture. bel-1 is a potent trans-activator of gene expression directed by the homologous hfv long terminal repeat as well as the long terminal repeat of human immunodeficiency virus type 1. we have used mutational analysis to define several discrete functional domains within bel-1. the c-terminal approximately 50 amino acids of bel-1 are shown to be essential f ... | 1993 | 8383217 |
| multiple positive and negative cis-acting elements that mediate transactivation by bel1 in the long terminal repeat of human foamy virus. | the bel1 protein of human foamy virus (hfv), a retrovirus, regulates expression of the gene linked to the hfv long terminal repeat (ltr) and is essential for viral gene expression. the mechanism of action of the bel1 protein is unknown, but its action is mediated through the u3 region of the ltr. to determine which u3 sequences are critical for transactivation by bel1, a series of hybrid vectors consisting of a mutant hfv ltr and the chloramphenicol acetyltransferase gene were constructed and te ... | 1993 | 8383244 |
| human foamy virus proteins accumulate in neurons and induce multinucleated giant cells in the brain of transgenic mice. | human foamy virus (hfv) is a retrovirus encoding structural genes and, like human immunodeficiency virus and human t cell leukemia virus i, several ancillary reading frames collectively termed the be1 genes. we have previously shown that hfv transgenic mice develop an encephalopathy with neuronal loss in hippocampus and cerebral cortex. we have now raised and characterized rabbit antisera to various recombinant portions of gag, pol, env, and bel-1, the viral trans-activator. immunoreactivity for ... | 1993 | 8386440 |
| retrovirus infections of the nervous system. | mammalian retroviruses of all three subfamilies infect the nervous system. the leukemia viruses (oncovirinae) and lentiviruses (lentivirinae, eg, human immunodeficiency virus) cause serious disease, while the foamy viruses (spumavirinae) have not yet been shown to cause any disease. this review illustrates these diseases by referring particularly to three viruses: the human and murine leukemia viruses (human t-cell leukemia-lymphoma virus type i and murine leukemia virus), and the human immunode ... | 1993 | 8386955 |
| investigation of retroviral involvement in chronic fatigue syndrome. | within the last few years significant efforts have been made to identify objective reliable diagnostic markers from individuals with chronic fatigue syndrome (cfs). we report the absence of a previously described retroviral marker (htlv-ii gag) in a blinded study of cfs cases. even with excellent reproducible sensitivities, this marker failed in repeated attempts to distinguish cases from controls. in addition, four other retroviruses (simian t cell leukaemia virus, human spumavirus, bovine leuk ... | 1993 | 8387909 |
| infectious proviral clones of chimpanzee foamy virus (sfvcpz) generated by long pcr reveal close functional relatedness to human foamy virus. | infectious proviral clones of simian foamy virus isolated from chimpanzee (sfvcpz) were generated by long pcr. two overlapping fragments representing the complete provirus were amplified from genomic dna of infected cells. four 8.8-kbp amplimers extending from base 1 of the provirus into the env gene and five 4.45-kbp amplimers reaching from env to the end of the 3'-ltr were cloned into pcr ii. subsequently, the proviral fragments were combined in a chessboard manner to generate 20 plasmids cont ... | 1995 | 8553577 |
| human foamy virus polypeptides: identification of env and bel gene products. | human foamy virus (hfv) proteins were identified in human cells cultured in vitro by immunoprecipitation and immunoblotting with specific antisera. among several viral polypeptides, four glycoproteins of approximately 160, 130, 70, and 48 kda were identified in hfv-infected cells. gp130 was shown to represent the intracellular env precursor, and gp70 and gp48 were shown to represent the external and transmembrane env proteins, respectively. the nature of gp160, which shares sequences with the en ... | 1993 | 8388512 |
| human foamy virus replication: a pathway distinct from that of retroviruses and hepadnaviruses. | human foamy virus (hfv) is the prototype of the spumavirus genus of retroviridae. in all other retroviruses, the pol gene products, including reverse transcriptase, are synthesized as gag-pol fusion proteins and are cleaved to functional enzymes during viral budding or release. in contrast, the pol protein of hfv is translated from a spliced messenger rna and lacks gag domains. infectious hfv particles contain double-stranded dna similar in size to full-length provirus, suggesting that reverse t ... | 1996 | 8599113 |
| the foamy virus family: molecular biology, epidemiology and neuropathology. | the family of foamy viruses designates a group of retroviruses which share a specific morphology and provoke characteristic cytopathic effects in cultured cells. like htlv and hiv, foamy viruses are complex viruses encoding a number of ancillary genes in addition to gag, pol and env, including a transcriptional transactivator. foamy viruses are endemic in various primate species, and human foamy viruses (hfv) have been isolated from patients with various neoplastic and degenerative diseases. des ... | 1993 | 8389200 |
| regulation of expression and pathogenic potential of human foamy virus in vitro and in transgenic mice. | | 1996 | 8608720 |
| the carboxy-terminal transcription enhancement region of the human spumaretrovirus transactivator contains discrete determinants of the activator function. | the bel1 gene of human spumaretrovirus (hsrv) encodes a 300-amino-acid nuclear protein termed bel1 that is a potent activator of transcription from the cognate long terminal repeat (ltr). bel1 can also efficiently activate the human immunodeficiency virus type 1 (hiv-1) ltr. we have previously shown that the amino-terminal 227-residue region (minimal activator region) of bel1 can activate the hsrv ltr at low levels and that two distinct domains within the carboxy-terminal 73 residues, from resid ... | 1993 | 8389909 |
| identification of pol-related gene products of human foamy virus. | human foamy virus pol gene fragments were molecularly cloned into a procaryotic expression vector. the expression pattern of the cloned fragments and nucleotide sequence analysis of the 5' pol gene region revealed that in hfv the protease (pr) is located in the pol open reading frame. purified recombinant proteins were used to generate antibodies in rats. in immunoblot assay, using infected cells as antigen, a precursor protein with an apparent molecular mass (m(r)) of 127k was identified by ant ... | 1993 | 8390761 |
| regulatory elements in the long terminal repeat (ltr) of simian foamy virus type 3 (sfv-3). | simian foamy virus type 3 (sfv-3) is a retrovirus that has a complex genome organization and encodes two open reading frames (orf-1 and orf-2) in addition to the genes coding for gag, pol, and env. in this report, we demonstrate that orf-1 of sfv-3 encodes a transcriptional transactivator designated taf (transactivator of foamy virus) which augments gene expression directed by the viral long terminal repeat (ltr). the taf responsive elements have been mapped to the u3 region of the ltr, between ... | 1993 | 8390763 |
| functional domains of the simian foamy virus type 1 transcriptional transactivator (taf). | the genome of simian foamy virus type 1 encodes a transcriptional transactivator (taf) that dramatically elevates gene expression directed by the viral long terminal repeat. in this report, we describe the functional domains of simian foamy virus type 1 taf. several taf mutants and fusion proteins of taf and the dna-binding domain of the saccharomyces cerevisiae transcriptional transactivator gal4 were used in this study. taf contains two potent activation domains. one of the activation domains ... | 1993 | 8392601 |
| [amyotrophic lateral sclerosis--indications of increased antiretroviral seroreactivity without obvious epidemiology]. | of 25 male and 13 female patients diagnosed as sporadic cases of amyotrophic lateral sclerosis between 1989 and 1992, 17 had reproducible serum antibodies against human foamy virus (hfv = human spuma retrovirus, hsrv). hfv-positive als patients had higher igg3 concentrations than hfv-negatives (p < 0.05) and competed better on maedi-visna retroviral antigen than hfv-negatives or controls (p < 0.05), but did not differ otherwise. two hfv-positive patients were living in the same building; two oth ... | 1993 | 8392664 |
| a defective human foamy provirus generated by pregenome splicing. | foamy viruses are a group of retroviruses of complex structure which were thought to be non-pathogenic. the recent demonstration of neurological diseases in mice transgenic for human foamy virus (hfv) and the high prevalence of hfv sequences in graves' disease question this idea. by pcr, we have detected hfv sequences with a non-random deletion in the bel1 transactivator gene in other autoimmune conditions. sequence analysis revealed that this deleted area corresponds to the excision of a known ... | 1993 | 8223453 |
| amyotrophic lateral sclerosis an enigmatic disease with b-cellular and anti-retroviral immune responses. | the most frequent sporadic adult motor neuron disease, amyotrophic lateral sclerosis, affects more men, follows no epidemiologic pattern, and was long considered a pure spinal cord disorder. it now becomes evident that the disease is characterized by spinal, cerebral and extra-neuromuscular changes including b-cellular responses and ultrastructural skin alterations. do these parameters identify subgroups or correlate with the male preponderance of the disease? | 1993 | 8252177 |
| possible role of human foamy virus in graves' disease. | human foamy virus (hfv) is a member of the retroviral family of spumaretrovirinae. in addition to the three retroviral structural genes, gag, pol and env, hfv also contains regulatory sequences, called bel. foamy viruses have been previously associated with human thyroid disease, notably dequervain's thyroiditis. in indirect immunofluorescence tests we have demonstrated the reactivity of the thyroid glands of 7/7 patients with graves' disease and antibodies to hfv gag proteins. no reactivity was ... | 1993 | 8407236 |
| foamy viruses. | foamy viruses share complex genome organization with lentiviruses and certain oncoviruses. the open reading frame 3' of env encodes a transcriptional transactivator. distinct responsive sequences were identified in the long terminal repeats (ltrs) of simian (sfv-1 and sfv-3) and human foamy viruses (hfv). transactivation of heterologous ltrs was described including those of simian and human immunodeficiency viruses. foamy viruses persist for the whole lifetime in infected hosts (primates, cats, ... | 1993 | 8407246 |
| analysis of the role of the bel and bet open reading frames of human foamy virus by using a new quantitative assay. | we have constructed a bhk-21-derived indicator cell line containing a single integrated copy of the beta-galactosidase (beta-gal) gene under control of the human foamy virus (hfv) long terminal repeat promoter (from -533 to +20). these foamy virus-activated beta-gal expression (fab) cells can be used in a quantitative assay to measure the infectious titer of hfv. our results show that the fab assay is 50 times more sensitive than determination of the virus titer by the end-point dilution method. ... | 1993 | 8411364 |
| increase in the basal transcriptional activity of the human foamy virus internal promoter by the homologous long terminal repeat promoter in cis. | the human foamy or spumaretrovirus hfv is a complex and exogenous retrovirus that encodes several bel genes besides the three classical retroviral genes gag, pol, and env. hfv was recently reported to contain two functionally active promoters that are both strongly trans-activated by the hfv trans-activator protein bel 1. the occurrence of a second internal cap site underscores the complexity of the hfv genome. we have analysed whether there is interference between the hfv long terminal repeat p ... | 1993 | 8414976 |
| inability of retroviral tests to identify persons with chronic fatigue syndrome, 1992. | chronic fatigue syndrome (cfs) is characterized by prolonged, debilitating fatigue. although the cause of cfs unknown, cdc and researchers in other organizations have been investigating whether infection with a previously unidentified retrovirus might be an etiologic factor. based on reports suggesting that retroviral infection with a human t-lymphotropic virus type 2 (htlv-ii)-like retrovirus or a spumavirus might be associated with cfs, some research and commercial laboratories developed assay ... | 1993 | 8446093 |
| identification of human endogenous retroviruses with complex mrna expression and particle formation. | retroviruses comprise strains with considerable disease potential in animals and humans. in addition to exogenous strains transmitted horizontally, endogenous proviruses are transmitted through the germ line. some of these endogenous retroviruses can be pathogenic in mice and possibly in other animal species. they may also be considered as mobile genetic elements with the potential to produce mutations. in humans, genomic dna contains numerous endogenous retroviral sequences detected by their pa ... | 1993 | 8506289 |
| foamy virus vectors. | human foamy virus (hfv) is a retrovirus of the spumavirus family. we have constructed vectors based on hfv that encode neomycin phosphotransferase and alkaline phosphatase. these vectors are able to transduce a wide variety of vertebrate cells by integration of the vector genome. unlike vectors based on murine leukemia virus, hfv vectors are not inactivated by human serum, and they transduce stationary-phase cultures more efficiently than murine leukemia virus vectors. these properties, as well ... | 1996 | 8523528 |