Publications

comparison of growth and differentiation of fetal and adult rhesus monkey mesenchymal stem cells.	the goal of this study was to compare the growth and differentiation potential of fetal and adult rhesus monkey (macaca mulatta) mesenchymal stem cells (rhmscs). rhmscs were obtained from healthy early third-trimester fetal (n = 3) and adult (n = 3) rhesus monkey bone marrow. fetal rhmscs were plated at 10, 50, 100, or 1,000 cells/cm(2) in medium containing 10% or 20% infant monkey serum (ims) or fetal bovine serum (fbs). fetal rhmscs grown at 1,000 cells/cm(2) in 20% fbs showed faster growth ra ...	2006	16646667
foamy virus capsid assembly occurs at a pericentriolar region through a cytoplasmic targeting/retention signal in gag.	foamy viruses (fv) are unusual retroviruses that differ in many aspects of their life cycle from the orthoretroviruses such as human immunodeficiency virus. similar to mason-pfizer monkey virus (mpmv), fv assemble into capsids intracellularly. the capsids are then transported to a cellular membrane for acquisition of envelope (env) glycoproteins and budding. however, unlike mpmv, budding of fv is dependent upon the presence of env. previous work suggested that fv env proteins are localized to th ...	2006	16749903
isolation and partial characterization of bovine foamy virus from polish cattle.	the first isolation and partial characterization of bovine foamy virus (bfv), also known as bovine syncytial virus, in poland is described. this virus was isolated by co-cultivation of peripheral blood leukocytes from infected cattle with permissive cf2th cells. the new isolate, called bfv100 was identified using several techniques: electron microscopy, western blotting, pcr and sequencing of a part of the gag and pol/env genes. based on syncytia induction, antigenic determinants, primer binding ...	2006	17203737
risk assessment: a model for predicting cross-species transmission of simian foamy virus from macaques (m. fascicularis) to humans at a monkey temple in bali, indonesia.	contact between humans and nonhuman primates (nhps) frequently occurs at monkey temples (religious sites that have become associated with free-ranging populations of nhps) in asia, creating the potential for nhp-human disease transmission. in march 2003 a multidisciplinary panel of experts participated in a workshop designed to model the risk of nhp-human pathogen transmission. the panel developed a risk assessment model to describe the likelihood of cross-species transmission of simian foamy vi ...	2006	16900504
expanded tissue targets for foamy virus replication with simian immunodeficiency virus-induced immunosuppression.	foamy viruses (fv) are the oldest known genus of retroviruses and have persisted in nonhuman primates for over 60 million years. fv are efficiently transmitted, leading to a lifelong nonpathogenic infection. transmission is thought to occur through saliva, but the detailed mechanism is unknown. interestingly, this persistent infection contrasts with the rapid cytopathicity caused by fv in vitro, suggesting a host defense against fv. to better understand the tissue specificity of fv replication a ...	2006	16378969
role and mechanism of action of the apobec3 family of antiretroviral resistance factors.		2006	16414984
simian foamy virus infection by whole-blood transfer in rhesus macaques: potential for transfusion transmission in humans.	cross-species infection of humans with simian foamy virus (sfv) has been reported in european and north american nonhuman primate (nhp) handlers, primarily due to wound injuries involving infected animals in research centers and zoos. additionally, african hunters have been found to be infected with sfv by exposure to body fluids, blood, or tissues of infected nhps in the wild. the persistence of infectious virus in peripheral blood mononuclear cells (pbmnc) and the recent identification of some ...	2006	16934071
construction and characterization of efficient, stable and safe replication-deficient foamy virus vectors.	as serious side effects affected recent virus-mediated gene transfer studies, novel vectors with improved safety profiles are urgently needed. in the present study, replication-deficient retroviral vectors based on feline foamy virus (ffv) were constructed and analyzed. the novel ffv vectors are devoid of almost the complete env gene plus the internal promoter - accessory bel gene cassette including the gene for the viral transcriptional transactivator bel1/tas. in these bel1/tas-independent vec ...	2007	17203107
foamy virus vectors: an awaited alternative to gammaretro- and lentiviral vectors.	the first vectors derived from foamy viruses were established over ten years ago. until now only used and further developed by a handful of investigators these vectors have been shown to be promising tools for the gene transfer into haematopoietic stem cells. several inherent features of foamy virus-derived vectors, such as the high efficiency in targeting cd34-positive stem cells, a favourable integration profile, and the apathogenic nature of the parental virus, indicate that they are superior ...	2007	17969559
ubiquitin-dependent virus particle budding without viral protein ubiquitination.	an essential step in the release of an extracellular enveloped virus particle is a budding event that ultimately separates virion and host cell membranes. for many enveloped viruses, membrane fission requires the recruitment of the class e vacuolar protein sorting (vps) machinery by short, virally encoded peptide sequences termed "late-budding" or "l" domains. some l-domain peptide sequences (e.g., psap) bind directly to components of class e vps machinery, whereas others (e.g., ppxy) access it ...	2007	18056634
ledgf/p75 interacts with divergent lentiviral integrases and modulates their enzymatic activity in vitro.	transcriptional co-activator ledgf/p75 is the major cellular interactor of hiv-1 integrase (in), critical to efficient viral replication. in this work, a series of ins from the betaretrovirus, gammaretrovirus, deltaretrovirus, spumavirus and lentivirus retroviral genera were tested for interaction with the host factor. none of the non-lentiviral ins possessed detectable affinity for ledgf in either pull-down or yeast two-hybrid assays. in contrast, all lentiviral ins examined, including those fr ...	2007	17158150
acetylation of the foamy virus transactivator tas by pcaf augments promoter-binding affinity and virus transcription.	it was shown recently that retrovirus transactivators interact with transcriptional coactivators, such as histone acetyltransferases (hats). foamy viruses (fvs) direct gene expression from the long terminal repeat and from an internal promoter. the activity of both promoters is strictly dependent on the dna-binding transactivator tas. recently, it was shown that tas interacts with the hats p300 and pcaf. based on these findings, it is demonstrated here that pcaf has the ability to acetylate tas ...	2007	17170459
characterization of blood-borne transmission of simian foamy virus.	simian foamy virus (sfv) is an endemic, nonhuman primate (nhp) retrovirus that is transmitted to individuals who work with or hunt nhps. the cross-species transmission of simian retroviruses is believed to be the etiology of human immunodeficiency virus and human t-lymphotropic virus infections in humans. although sfv is not pathogenic in the native host, the shared ancestry with other simian retroviruses has brought into question the potential for acquired pathogenicity after cross-species tran ...	2007	17207245
serological detection systems for identification of cows shedding bovine foamy virus via milk.	the biology of foamy viruses, their mode of transmission and disease potential in their natural host and after interspecies transmission are largely unknown. to gain insights into the prevalence of bovine foamy virus (bfv) and its zoonotic potential, enzyme-linked immunosorbent assays (elisas) were established to determine antibody responses against gag, env, and the non-structural protein bet in bovine serum and milk. in polish cattle, strong gag reactivity was most frequent (41.5%) and strongl ...	2007	17408715
centrosomal latency of incoming foamy viruses in resting cells.	completion of early stages of retrovirus infection depends on the cell cycle. while gammaretroviruses require mitosis for proviral integration, lentiviruses are able to replicate in post-mitotic non-dividing cells. resting cells such as naive resting t lymphocytes from peripheral blood cannot be productively infected by retroviruses, including lentiviruses, but the molecular basis of this restriction remains poorly understood. we demonstrate that in g0 resting cells (primary fibroblasts or perip ...	2007	17530924
recombinant human foamy virus, a novel vector for neurological disorders gene therapy, drives production of gad in cultured astrocytes.	human foamy virus (hfv), with its nonpathogenic nature and several unique features for gene transfer, is a promising vector system for neurological disorders gene therapy. the question of whether hfv vectors can be developed for the expression of therapeutic genes in primary astrocytes of the brain may be of interest. first, efficient expression for foreign genes, which is critical for the potentials of hfv-derived vector in gene therapy, was successfully demonstrated in rat-cultured astrocytes ...	2007	17579580
detection and analysis of bovine foamy virus infection by an indicator cell line.	to determine the infectivity and replication strategy of bovine foamy virus (bfv) in different cultured cells using the bfv indicator cell line (bicl) system.	2007	17588335
effective inhibition of hepatitis b virus replication by small interfering rnas expressed from human foamy virus vectors.	rna interference (rnai) mediated by double- stranded small interfering rna (sirna) is a novel mechanism of sequence-specific, post-transcriptional gene silencing. there has been much research into the use of rnai for the treatment of human diseases. many viruses, including hepatitis b virus (hbv), are susceptible to inhibition by this mechanism. however, for rnai to be efficacious therapeutically, effective rnai targeting sequences and a suitable delivery system are required. in this study, we e ...	2007	17334648
foamy-virus-mediated gene transfer to canine repopulating cells.	foamy virus (fv) vectors are particularly attractive gene-transfer vectors for stem-cell gene therapy because they form a stable transduction intermediate in quiescent cells and can efficiently transduce hematopoietic stem cells. here, we studied the use of fv vectors to transduce long-term hematopoietic repopulating cells in the dog, a clinically relevant large animal model. mobilized canine peripheral blood (pb) cd34+ cells were transduced with an enhanced green fluorescent protein (egfp)-expr ...	2007	16968897
correct capsid assembly mediated by a conserved yxxlgl motif in prototype foamy virus gag is essential for infectivity and reverse transcription of the viral genome.	unlike other retrovirus gag proteins, the prototype foamy virus (pfv) p71(g)(ag) protein is not processed into mature matrix (ma), capsid (ca), and nucleocapsid (nc) subunits. little information about sequence motifs involved in fv capsid assembly and release is available. the recent analysis of candidate l-domain motifs in pfv gag identified an evolutionarily conserved yxxl sequence motif with a potential function in capsid assembly. here we provide support for the hypothesis that this motif do ...	2007	17229703
apobec-mediated viral restriction: not simply editing?	the apobec family of cytidine deaminases inhibit the mobility of diverse retroviruses, retrotransposons and other viruses. initial reports proposed that these effects were due to the dna editing capabilities of these enzymes; however, many recent studies have provided evidence suggesting that apobec proteins can inhibit these elements by several mechanisms, including editing-dependent and editing-independent processes. investigating these modes of action and the potential contribution that each ...	2007	17303427
role of the foamy virus pol cleavage site in viral replication.	foamy virus pol precursor protein processing by the viral protease occurs at only one site, releasing a protease-reverse transcriptase and an integrase protein. to examine whether the cleavage of the pol precursor protein is necessary for enzymatic activities and efficient viral replication, several mutations were generated around the cleavage site. all cleavage site mutants synthesize wild-type levels of pol precursor protein. mutants containing more than two amino acid substitutions around the ...	2007	17344283
unique integration profiles in a canine model of long-term repopulating cells transduced with gammaretrovirus, lentivirus, or foamy virus.	recent advances have allowed for improved retrovirus-mediated gene transfer, and therapeutic benefits have been described in patients. these successes have shown the potential of hematopoietic stem cell (hsc) gene therapy, but treatment-related leukemia and benign expansion of gene-modified clones have shifted the attention toward safety. the delayed onset of adverse events in gene therapy clinical trials emphasizes the importance of long-term integration site studies in large animal models. we ...	2007	17518616
transduction of human embryonic stem cells by foamy virus vectors.	human embryonic stem cells (hescs) are important tools for the study of stem cell biology and may ultimately be used in cellular therapies and regenerative medicine. for hescs to achieve their potential, stable genetic modification of the hesc genome will be required. here we have studied the transduction of hescs by vectors based on foamy virus (fv), an integrating retrovirus with no known pathogenicity. we find that hescs and also escs derived from rhesus monkeys can be efficiently transduced ...	2007	17622243
in vitro fidelity of the prototype primate foamy virus (pfv) rt compared to hiv-1 rt.	we compared the in vitro fidelity of wild-type human immunodeficiency virus type-1 (hiv-1) reverse transcriptase (rt) and the prototype foamy virus (pfv) rt. both enzymes had similar error rates for single nucleotide substitutions; however, pfv rt did not appear to make errors at specific hotspots, like hiv-1 rt. in addition, pfv rt made more deletions and insertions than hiv-1 rt. although the majority of the missense errors made by hiv-1 rt and pfv rt are different, relatively few of the mutat ...	2007	17631930
guanine tetrad and palindromic sequence play critical roles in the rna dimerization of bovine foamy virus.	retroviruses are unique in having a diploid genome. however, the rna sequences and structures that link the two rna molecules are different. to identify the dimer linkage site of bovine foamy virus (bfv), complementary dnas were used to interfere with rna dimerization of bfv. we found that two sites, designated si and sii, within a 53-base rna fragment, were essential for bfv dimerization in vitro. si consists of a potential guanine tetrad (ggggc), which overlaps the primer binding site, while s ...	2007	17712597
foamy virus vectors expressing anti-hiv transgenes efficiently block hiv-1 replication.	gene therapy has the potential to control human immunodeficiency virus (hiv) in patients who do not respond to traditional antiviral therapy. in this study, we tested foamy virus (fv) vectors expressing three anti-hiv transgenes, both individually and in a combination vector. the transgenes tested in this study are revm10, a dominant negative version of the viral rev protein, sh1, a short hairpin rna directed against a conserved overlapping sequence of tat and rev, and membrane-associated c46 (m ...	2008	17955023
successful treatment of canine leukocyte adhesion deficiency by foamy virus vectors.	recent successes in treating genetic immunodeficiencies have demonstrated the therapeutic potential of stem cell gene therapy. however, the use of gammaretroviral vectors in these trials led to insertional activation of nearby oncogenes and leukemias in some study subjects, prompting studies of modified or alternative vector systems. here we describe the use of foamy virus vectors to treat canine leukocyte adhesion deficiency (clad). four of five dogs with clad that received nonmyeloablative con ...	2008	18157138
a novel human foamy virus mediated gene transfer of gad67 reduces neuropathic pain following spinal cord injury.	neuropathic pain is a long-lasting clinical problem that is often refractory to medical management. gene transfer of specific genes for therapeutic benefit offers a novel approach to the treatment of neuropathic pain. in this study, we tested whether the transfer of the glutamic acid decarboxylase (gad) gene to dorsal root ganglion (drg) cells would attenuate below-injury level central neuropathic pain after spinal cord injury (sci) by using a novel human foamy virus (hfv) vector to achieve rele ...	2008	18180106
ifp35 is involved in the antiviral function of interferon by association with the viral tas transactivator of bovine foamy virus.	interferon-induced proteins (ifps) exert multiple functions corresponding to diverse interferon signals. however, the intracellular functions of many ifps are not fully characterized. here, we report that ifp35, a member of the ifp family with a molecular mass of 35 kda, can interact with the bovine tas (btas) regulatory protein of bovine foamy virus (bfv). the interaction involves nid2 (ifp35/nmi homology domain) of ifp35 and the central domain of btas. the overexpression of ifp35 disturbs the ...	2008	18305040
intranasal immunization of mice with a formalin-inactivated bovine respiratory syncytial virus vaccine co-formulated with cpg oligodeoxynucleotides and polyphosphazenes results in enhanced protection.	as respiratory syncytial virus (rsv) targets the mucosal surfaces of the respiratory tract, induction of both systemic and mucosal immunity will be critical for optimal protection. in this study, the ability of an intranasally delivered, formalin-inactivated bovine rsv (fi-brsv) vaccine co-formulated with cpg oligodeoxynucleotides (odn) and polyphosphazenes (pp) to induce systemic and mucosal immunity, as well as protection from brsv challenge, was evaluated. intranasal immunization of mice with ...	2008	18089749
dimerization of btas is required for the transactivational activity of bovine foamy virus.	the btas protein of bovine foamy virus (bfv) is a 249-amino-acid nuclear regulatory protein which transactivates viral gene expression directed by the long terminal repeat promoter (ltr) and the internal promoter (ip). here, we demonstrate the btas protein forms a dimeric complex in mammalian cells by using mammalian two hybrid systems and cross-linking assay. functional analyses with deletion mutants reveal that the region of 46-62aa is essential for dimer formation. furthermore, our results sh ...	2008	18448144
a premature termination codon mutation at the c terminus of foamy virus gag downregulates the levels of spliced pol mrna.	foamy viruses (fv) comprise a subfamily of retroviruses. orthoretroviruses, such as human immunodeficiency virus type 1, synthesize gag and pol from unspliced genomic rna. however, fv pol is expressed from a spliced mrna independently of gag. fv pol splicing uses a 3' splice site located at the 3' end of gag, resulting in a shared exon between gag and pol. previously, our laboratory showed that c-terminal gag premature termination codon (ptc) mutations in the 3' shared exon led to greatly decrea ...	2008	18057244
complex effects of foamy virus central purine-rich regions on viral replication.	similar to the lentiviruses family of retroviruses, foamy viruses (fvs) contain purine-rich sequences located in the center of the genome. their function on viral replication or vector transfer remains elusive, although dual initiation of plus-strand reverse transcription has been suggested. to elucidate the physical nature of the central region of the prototype fv (pfv) genome, we performed 3' and 5' race experiments. our results revealed that the pfv genome contains a centrally located gap in ...	2008	18078974
is feline foamy virus really apathogenic?	feline foamy virus (ffv) is a retrovirus commonly found in cats. it is generally thought to be apathogenic, making it a suitable candidate as a gene therapy vector. however, there have been reports of association of ffv with chronic progressive arthritis and a cofactor effect with feline immunodeficiency virus. this study investigated experimental ffv infection and whether this was associated with signs of disease. eight young specific pathogen free cats were inoculated intramuscularly with ffv. ...	2008	18342375
foamy virus vectors come of age.		2008	18362918
azt resistance of simian foamy virus reverse transcriptase is based on the excision of aztmp in the presence of atp.	azidothymidine (azt, zidovudine) is one of the few nucleoside inhibitors known to inhibit foamy virus replication. we have shown previously that up to four mutations in the reverse transcriptase gene of simian foamy virus from macaque (sfvmac) are necessary to confer high resistance against azt. to characterize the mechanism of azt resistance we expressed two recombinant reverse transcriptases of highly azt-resistant sfvmac in escherichia coli harboring three (k211i, s345t, e350k) or four mutati ...	2008	18096624
deoxynucleoside triphosphate incorporation mechanism of foamy virus (fv) reverse transcriptase: implications for cell tropism of fv.	here, we investigated the pre-steady-state deoxynucleoside triphosphate (dntp) incorporation kinetics of primate foamy virus (pfv) reverse transcriptase (rt) in comparison with those of hiv-1 and mulv rts. pfv rt displayed a drastic reduction in primer extension at low dntp concentrations where hiv-1 rt remains highly active, indicating a low dntp binding affinity in the case of pfv rt. indeed, kinetic analysis showed that, as observed with mulv rt, pfv rt exhibits approximately 10 to 80 times l ...	2008	18508890
characterization of nuclear localization signals of the prototype foamy virus integrase.	to analyse the potential karyophilic activity of prototype foamy viruses (pfvs), we expressed the pfv integrase (in) and its mutants as fusion proteins with enhanced green fluorescence protein. the subcellular localization of the fusion proteins was investigated by fluorescence microscopy. the pfv in was found to be karyophilic and targeted the fusion protein to the nucleus. mutational analyses demonstrated that the pfv in contains a potent but non-transferable nuclear localization signal (nls) ...	2008	18559938
functional nucleotides of u5 ltr determining substrate specificity of prototype foamy virus integrase.	in order to study functional nucleotides in prototype foamy virus (pfv) dna on specific recognition by pfv integrase (in), we designed chimeric u5 long terminal repeat (ltr) dna substrates by exchanging comparative sequences between human immunodeficiency virus type-1 (hiv-1) and pfv u5 ltrs, and investigated the 3'-end processing reactivity using hiv-1 and pfv ins, respectively. hiv-1 in recognized the nucleotides present in the fifth and sixth positions at the 3'-end of the substrates more spe ...	2008	18600045
chromatin tethering of incoming foamy virus by the structural gag protein.	retroviruses hijack cellular machineries to productively infect their hosts. during the early stages of viral replication, proviral integration relies on specific interactions between components of the preintegration complex and host chromatin-bound proteins. here, analyzing the fate of incoming primate foamy virus, we identify a short domain within the c-terminus of the structural gag protein that efficiently binds host chromosomes, by interacting with h2a/h2b core histones. while viral particl ...	2008	18627573
overnight transduction with foamyviral vectors restores the long-term repopulating activity of fancc-/- stem cells.	fanconi anemia (fa) is a complex genetic disorder characterized by congenital abnormalities, bone marrow failure, and myeloid malignancies. identification of 13 fa genes has been instrumental to explore gene transfer technologies aimed at correction of autologous fa-deficient stem cells. to date, 3 human fa stem cell gene therapy trials with standard 4-day transduction protocols using gammaretroviral vectors failed to provide clinical benefit. in addition, 2- to 4 day ex vivo manipulation of bon ...	2008	18684868
the c terminus of foamy retrovirus gag contains determinants for encapsidation of pol protein into virions.	foamy viruses (fv) differ from orthoretroviruses in many aspects of their replication cycle. a major difference is in the mode of pol expression, regulation, and encapsidation into virions. orthoretroviruses synthesize pol as a gag-pol fusion protein so that pol is encapsidated into virus particles through gag assembly domains. however, as fv express pol independently of gag from a spliced mrna, packaging occurs through a distinct mechanism. fv genomic rna contains cis-acting sequences that are ...	2008	18715914
establishment of an indicator cell line to quantify bovine foamy virus infection.	a cell line derived from baby hamster kidney (bhk-21) cells was transfected with the enhanced green fluorescent protein gene driven by the bovine foamy virus (bfv) long terminal repeat (ltr) to establish a bfv indicator cell line (bicl). among 48 clones, one clone was chosen for its little constitutive enhanced green fluorescent protein (egfp) expression and high level of egfp expression after activation by bfv infection. by detecting the egfp expression of the bfv indicator cell line, the titer ...	2008	18720504
the usefulness of a perfect parasite.		2008	18802996
restriction of foamy viruses by primate trim5alpha.	foamy viruses (fvs) are unconventional retroviruses with a replication strategy that is significantly different from orthoretroviruses and bears some homology to that of hepadnaviruses. although some cellular proteins, such as apobec3, have been reported to block fvs, no restriction by trim5alpha has been described to date. the sensitivity of three fv isolates of human-chimpanzee or prototypic (pfv), macaque (sfvmac), and feline (ffv) origin to a variety of primate trim5alphas was therefore test ...	2008	18367529
replication in a superficial epithelial cell niche explains the lack of pathogenicity of primate foamy virus infections.	foamy viruses (fvs) are ancient retroviruses that are ubiquitous in nonhuman primates (nhps). while fvs share many features with pathogenic retroviruses, such as human immunodeficiency virus, fv infections of their primate hosts have no apparent pathological consequences. paradoxically, fv infections of many cell types in vitro are rapidly cytopathic. previous work has shown that low levels of proviral dna are found in most tissues of naturally infected rhesus macaques, but these proviruses are ...	2008	18400853
subviral particle release determinants of prototype foamy virus.	glycoproteins of several viruses have the capacity to induce release of noninfectious, capsidless particulate structures containing only the viral glycoprotein. such structures are often called subviral particles (svp). foamy viruses (fvs), a special type of retroviruses with a replication strategy combining features of both orthoretroviruses and hepadnaviruses, express a glycoprotein (env) which has the ability to induce svp release. however, unlike human hepatitis b virus, prototype fv (pfv) n ...	2008	18684814
mutations in the amino terminus of foamy virus gag disrupt morphology and infectivity but do not target assembly.	foamy viruses (fvs) assemble using pathways distinct from those of orthoretroviruses. fv capsid assembly takes place near the host microtubule-organizing center (mtoc). assembled capsids then migrate by an unknown mechanism to the trans-golgi network to colocalize with the fv glycoprotein, env. interaction with env is required for fv capsid egress from cells; the amino terminus of fv gag contains a cytoplasmic targeting/retention signal that is responsible for targeting assembly to the mtoc. a m ...	2008	18434404
a one-step sybr green i-based product-enhanced reverse transcriptase assay for the quantitation of retroviruses in cell culture supernatants.	pcr-enhanced reverse transcriptase assays (pert) are sensitive tools for the detection of retroviruses in biological samples. the adaptation of real-time pcr techniques based on fluorescent probes (f-pert) has added a reliable quantitative capacity to the assay. in the interest of economy and time, the sybr green i-based real-time detection system was used to establish a convenient one-step pert assay (sg-pert). this assay can be completed in 2h, is linear over six orders of magnitude and can be ...	2009	19022294
functional and structural characterization of the integrase from the prototype foamy virus.	establishment of the stable provirus is an essential step in retroviral replication, orchestrated by integrase (in), a virus-derived enzyme. until now, available structural information was limited to the ins of human immunodeficiency virus type 1 (hiv-1), avian sarcoma virus (asv) and their close orthologs from the lentivirus and alpharetrovirus genera. here, we characterized the in vitro activity of the prototype foamy virus (pfv) in from the spumavirus genus and determined the three-dimensiona ...	2009	19036793
foamy virus as a gene transfer vector to the central nervous system.	engineered foamy virus (fv) vectors have been lauded for their superior safety profiles and stable integration patterns compared to their gammaretroviral counterparts. the drawback has been the belief that fv incorporation is cell cycle-dependent, thereby limiting its utility in post-mitotic tissues such as the central nervous system. in this brief communication, we challenged this theory by examining fv in vivo. we injected equal titers of fv and lentivirus (lv) into the adult rat brain and fou ...	2009	19052632
transduction of human neural progenitor cells with foamy virus vectors for differentiation-dependent gene expression.	neural progenitor cells are potential vehicles for delivery of therapeutic agents into the brain. differentiation-dependent promoters may be useful to target the therapeutic transgene expression to specific neural cell types. here we explored the potential of vectors based on the foamy virus (fv) for genetic engineering of neural progenitor cells. we demonstrate that fv vectors can mediate stable long-term constitutive expression of the enhanced green fluorescent protein (egfp) in neural progeni ...	2009	19052634
activity of tar in inducible inhibition of hiv replication by foamy virus vector expressing sirnas under the control of hiv ltr.	in this report we describe foamy virus vectors with conditional expression of short interfering rnas (sirnas) in hiv infected cells. short hairpin rnas (shrnas) based on two targets in the 5' end of the untranslated region and one in the rev gene flanked with 5' and 3' microrna 30 (mir30) sequences were synthesized and placed under the control of an hiv promoter for tat-mediated expression. hiv permissive cells were transduced with foamy virus vectors containing each hybrid shrna expression cass ...	2009	19110017
generation of an improved foamy virus vector by dissection of cis-acting sequences.	in contrast to other retroviruses, foamy viruses (fvs) generate their pol protein precursor independently of the gag protein from a spliced mrna. the exact mechanism of pol protein incorporation into the viral capsid is poorly understood. previously, we showed that pol encapsidation critically depends on the packaging of (pre-) genomic rna and identified two distinct signals within the cis-acting sequences (casi and casii), pol encapsidation sequences (pesi and pesii), which are required for pol ...	2009	19141459
accuracy estimation of foamy virus genome copying.	foamy viruses (fvs) are the most genetically stable viruses of the retrovirus family. this is in contrast to the in vitro error rate found for recombinant fv reverse transcriptase (rt). to investigate the accuracy of fv genome copying in vivo we analyzed the occurrence of mutations in hek 293t cell culture after a single round of reverse transcription using a replication-deficient vector system. furthermore, the frequency of fv recombination by template switching (ts) and the cross-packaging abi ...	2009	19348676
molecular dissection of the prototype foamy virus (pfv) rna 5'-utr identifies essential elements of a ribosomal shunt.	the prototype foamy virus (pfv) is a nonpathogenic retrovirus that shows promise as a vector for gene transfer. the pfv (pre)genomic rna starts with a long complex leader that can be folded into an elongated hairpin, suggesting an alternative strategy to cap-dependent linear scanning for translation initiation of the downstream gag open reading frame (orf). we found that the pfv leader carries several short orfs (sorfs), with the three 5'-proximal sorfs located upstream of a structural element. ...	2009	19638424
foamy virus vectors for gene transfer.	foamy virus (fv) vectors are efficient gene delivery vehicles that have shown great promise for gene therapy in preclinical animal models. fvs or spumaretroviruses are not endemic in humans, but are prevalent in nonhuman primates and in other mammals. they have evolved means for efficient horizontal transmission in their host species without pathology. fv vectors have several unique properties that make them well suited for therapeutic gene transfer including a desirable safety profile, a broad ...	2009	19743892
macroevolution of complex retroviruses.	retroviruses can leave a "fossil record" in their hosts' genomes in the form of endogenous retroviruses. foamy viruses, complex retroviruses that infect mammals, have been notably absent from this record. we have found an endogenous foamy virus within the genomes of sloths and show that foamy viruses were infecting mammals more than 100 million years ago and codiverged with their hosts across an entire geological era. our analysis highlights the role of evolutionary constraint in maintaining vir ...	2009	19762636
importance of the major splice donor and redefinition of cis-acting sequences of gutless feline foamy virus vectors.	foamy virus vectors are potent alternatives to lenti- and gamma-retroviral vectors for gene therapy. to construct and optimize gutless feline foamy virus (ffv) replication-deficient (rd) vectors, viral elements essential for optimal efficient marker gene transduction were characterized and fine-mapped and packaging clones constructed. for these purposes, new gag and pol expression clones which allow efficient expression of packaging proteins and vectors carrying deletions in coding and non-codin ...	2009	19775717
bfv activates the nf-kappab pathway through its transactivator (btas) to enhance viral transcription.	multiple families of viruses have evolved sophisticated strategies to regulate nuclear factor-kappab (nf-kappab) signaling, which plays a pivotal role in diverse cellular events, including virus-host interactions. in this study, we report that bovine foamy virus (bfv) is able to activate the nf-kappab pathway through the action of its transactivator, btas. both cellular ikkbeta and ikappabalpha also participate in this activation. in addition, we demonstrate that btas induces the processing of p ...	2010	20178883
transcription factor ap1 modulates the internal promoter activity of bovine foamy virus.	foamy virus contains two promoters, which are the canonical long terminal repeat (ltr) promoter and the internal promoter (ip). fv gene expression was considered to initiate at the internal promoter. however, little was known about how basal transcription of ip was triggered by the host cellular factors. previous studies found some cellular proteins could affect hfv viral replication, but it was no known whether the ap1 signal pathway was involved in the activation of viral replication or not. i ...	2010	19853631
dual transgene expression by foamy virus vectors carrying an endogenous bidirectional promoter.	several gene therapy applications require the transfer and simultaneous expression of multiple genes in the same cell. in this study, we analyzed the potential for coordinated expression of an endogenous bidirectional promoter located on chromosome x, which controls the expression of the heterogeneous nuclear ribonucleoprotein h2 (hnrnph2) and alpha-galactosidase (gla) genes. the promoter was cloned in both transcriptional orientations in a foamy virus (fv) vector backbone, whereas the enhanced ...	2010	19907502
the foamy virus genome remains unintegrated in the nuclei of g1/s phase-arrested cells, and integrase is critical for preintegration complex transport into the nucleus.	foamy viruses are a member of the spumavirus subfamily of retroviruses with unique mechanisms of virus replication. foamy virus replication is cell cycle dependent; however, the genome is found in the nuclei of cells arrested in the g(1)/s phase. despite the presence of genome in the nuclei of growth-arrested cells, there is no viral gene expression, thus explaining its dependency on cell cycle. this report shows that the foamy virus genome remains unintegrated in g(1)/s phase-arrested cells. th ...	2010	20032182
biophysical and enzymatic properties of the simian and prototype foamy virus reverse transcriptases.	the foamy virus pol protein is translated independently from gag using a separate mrna. thus, in contrast to orthoretroviruses no gag-pol precursor protein is synthesized. only the integrase domain is cleaved off from pol resulting in a mature reverse transcriptase harboring the protease domain at the n-terminus (pr-rt). although the homology between the pr-rts from simian foamy virus from macaques (sfvmac) and the prototype foamy virus (pfv), probably originating from chimpanzee, exceeds 90%, s ...	2010	20113504
species-specific inhibition of foamy viruses from south american monkeys by new world monkey trim5{alpha} proteins.	foamy virus evolution closely parallels that of the host species, indicating virus-host coadaptation. we studied simian foamy viruses (sfvs) from common marmosets, spider monkeys, and squirrel monkeys, new world monkey (nwm) species that share geographic ranges. the trim5alpha protein from each of these nwm species inhibited the replication of at least one of the sfvs associated with the other two species but did not affect the replication of its own sfv. thus, trim5alpha has potentially shaped ...	2010	20130055
early reverse transcription is essential for productive foamy virus infection.	although viral rna constitutes the majority of nucleic acids packaged in virions, a late occurring step of reverse transcription leads to the presence of infectious viral cdna in foamy virus particles. this peculiarity distinguishes them from the rest of the retroviral family.	2010	20552014
characterization of biochemical properties of feline foamy virus integrase.	in order to study biochemical properties, the integrase (in) protein of feline foamy virus (ffv) was over-expressed from escherichia coli, purified by two-step chromatography; talon column and heparin column, and characterized in biochemical aspects. for the three enzymatic reactions of the 3' -processing, strand transfer, and disintegration activities, mn2+ ion was essentially required as a cofactor. interestingly, co2+ and zn2+ ions were found to act as effective cofactors, while other transit ...	2010	20622493
foamy virus nuclear rna export is distinct from that of other retroviruses.	most retroviruses express all of their genes from a single primary transcript. in order to allow expression of more than one gene from this rna, differential splicing is extensively used. cellular quality control mechanisms retain and degrade unspliced or partially spliced rnas in the nucleus. two pathways have been described that explain how retroviruses circumvent this nuclear export inhibition. one involves a constitutive transport element in the viral rna that interacts with the cellular mrn ...	2010	21159877
analysis of bovine foamy virus btas mrna transcripts during persistent infection.	foamy virus (fv) is an unconventional retrovirus that possesses a complex genome and a special mechanism for gene expression regulation. the genome encodes transcriptional protein tas which is found to regulate both the internal promoter (ip) and the long terminal repeat promoter (ltr). however, the detailed mechanism of tas-mediated gene expression remains unknown. in this study, we provided the first evidence for the temporal production and utilization of four different bovine foamy virus (bfv ...	2010	19911263
production of foamy virus vector and transduction of hematopoietic cells.	foamy viruses (fvs), or spumaviruses, are nonpathogenic retroviruses that have been developed as integrating viral vectors. this protocol presents methods for producing high-titer fv vector stocks, free of contaminating replication-competent retrovirus, to be used for transducing hematopoietic stem cells. fv vector stocks are produced by transfecting 293 cells, harvesting and filtering the culture medium, and concentrating vector virions by ultracentrifugation. the resulting stocks are free of r ...	2010	20810629
role of neutralizing antibodies in controlling simian foamy virus transmission and infection.	human infections with simian foamy viruses (sfvs) have been reported after occupational and nonoccupational exposure to infected animals and their tissues, blood, and body fluids, although there is no evidence for human-to-human transmission. we previously demonstrated sfv transmission in monkeys by blood transfusion with whole blood from one donor animal that had a low neutralizing antibody (nab) endpoint titer, whereas blood transfusion from a second donor monkey that had a high nab titer fail ...	2010	19719470
bovine foamy virus transactivator btas interacts with cellular relb to enhance viral transcription.	viruses are obligate intracellular parasites that depend on cellular machinery for their efficient transcription and replication. in a previous study we reported that bovine foamy virus (bfv) is able to activate the nuclear factor κb (nf-κb) pathway through the action of its transactivator btas to enhance viral transcription. however, the mechanism used by nf-κb to enhance bfv transcription remains elusive. to address this question, we employed a yeast two-hybrid assay to screen for btas-interac ...	2010	20844054
preparation of bfv gag antiserum and preliminary study on cellular distribution of bfv.	viruses (e.g. human immunodeficiency virus, human simplex virus and prototype foamy virus) are obligate intracellular parasites and therefore depend on the cellular machinery for cellular trafficking. bovine foamy virus (bfv) is a member of the spumaretrovirinae subfamily of retroviruses, however, details of its cellular trafficking remain unknown. in this study, we cloned the bfv gag gene into prokaryotic expression vector pet28a and purified the denaturalized gag protein. the protein was used ...	2010	20960308
foamy virus: an available vector for gene transfer in neural cells and other nondividing cells.	foamy viruses (fvs) are classified to a subfamily of retrovirus presented in a wide range of hosts. none of fvs has been found to associate with any diseases in their native hosts. such a unique biological character of fvs makes it suitable for the development of vectors for gene transfer. however, it is still controversial whether foamy virus vectors (fv vectors) can be applied to the central nervous system (cns). in this review, we summarize the studies of fv vectors, which have been used for ...	2010	20969536
functional interchangeability of late domains, late domain cofactors and ubiquitin in viral budding.	the membrane scission event that separates nascent enveloped virions from host cell membranes often requires the escrt pathway, which can be engaged through the action of peptide motifs, termed late (l-) domains, in viral proteins. viral ptap and ypdl-like l-domains bind directly to the escrt-i and alix components of the escrt pathway, while ppxy motifs bind nedd4-like, hect-domain containing, ubiquitin ligases (e.g. wwp1). it has been unclear precisely how ubiquitin ligase recruitment ultimatel ...	2010	20975941
the mechanism of retroviral integration from x-ray structures of its key intermediates.	to establish productive infection, a retrovirus must insert a dna replica of its genome into host cell chromosomal dna. this process is operated by the intasome, a nucleoprotein complex composed of an integrase tetramer (in) assembled on the viral dna ends. the intasome engages chromosomal dna within a target capture complex to carry out strand transfer, irreversibly joining the viral and cellular dna molecules. although several intasome/transpososome structures from the dde(d) recombinase super ...	2010	21068843
novel functions of prototype foamy virus gag glycine- arginine-rich boxes in reverse transcription and particle morphogenesis.	prototype foamy virus (pfv) gag lacks the characteristic orthoretroviral cys-his motifs that are essential for various steps of the orthoretroviral replication cycle, such as rna packaging, reverse transcription, infectivity, integration, and viral assembly. instead, it contains three glycine-arginine-rich boxes (gr boxes) in its c terminus that putatively represent a functional equivalent. we used a four-plasmid replication-deficient pfv vector system, with uncoupled rna genome packaging and st ...	2010	21106749
nonintegrating foamy virus vectors.	foamy viruses (fvs), or spumaviruses, are integrating retroviruses that have been developed as vectors. here we generated nonintegrating foamy virus (nifv) vectors by introducing point mutations into the highly conserved dd35e catalytic core motif of the foamy virus integrase sequence. nifv vectors produced high-titer stocks, transduced dividing cells, and did not integrate. cells infected with nifv vectors contained episomal vector genomes that consisted of linear, 1-long-terminal-repeat (1-ltr ...	2010	20592072
identification and functional characterization of btas transactivator as a dna-binding protein.	the genome of bovine foamy virus (bfv) encodes a transcriptional transactivator, namely btas, that remarkably enhances gene expression by binding to the viral long-terminal repeat promoter (ltr) and internal promoter (ip). in this report, we characterized the functional domains of bfv btas. btas contains two major functional domains: the n-terminal dna-binding domain (residues 1-133) and the c-terminal activation domain (residues 198-249). the complete btas responsive regions were mapped to the ...	2010	20615521
progress and prospects: foamy virus vectors enter a new age.	foamy viruses, distantly related to the major subfamily of retroviruses, orthoretroviruses that include oncoviruses (for example, murine leukemia virus (mlv)) and lentiviruses (human immunodeficiency virus (hiv)), are endemic in mammalian species, but not in human populations. humans infected by accidental or occupational exposure remain well. the virus is not transmitted to others, nor is it associated with any disease. these features added to its broad host range, efficient transduction of pro ...	2010	20631802
structural studies of the catalytic core of the primate foamy virus (pfv-1) integrase.	retroviral integrases are vital enzymes in the viral life cycle and thus are important targets for antiretroviral drugs. the structure of the catalytic core domain of the integrase from human foamy virus, which is related to hiv-1, has been solved. the structure of the protein is presented in two different crystal forms, each containing several molecules in the asymmetric unit, with and without the essential manganese or magnesium ion, and the structures are compared in detail. this allows regio ...	2010	20693659
minimal size of prototype foamy virus integrase for nuclear localization.	we have reported previously that the prototype foamy virus (pfv) integrase (in) has a strong nuclear localization signal (nls) in its c-terminal domain, in particular in a region of aa 306-334 including highly karyophilic arginines or lysines at positions 308, 313, 318, 324, and 329. in this study, we used various mutants of the c-terminal domain to further analyze its karyophilic determinants. plasmids expressing these mutants fused to maltose binding protein (mbp) and enhanced green fluorescen ...	2011	21692567
tracking of specific integrant clones in dogs treated with foamy virus vectors.	vector integration can lead to proto-oncogene activation and malignancies during hematopoietic stem cell gene therapy. we previously used foamy virus vectors to deliver the cd18 gene under the control of an internal murine stem cell virus promoter and successfully treated dogs with canine leukocyte adhesion deficiency. here we have tracked the copy numbers of 11 specific proviruses found in these animals for 36-42 months after transplantation, including examples within or near proto-oncogenes, t ...	2011	20738155
structural biology of retroviral dna integration.	three-dimensional macromolecular structures shed critical light on biological mechanism and facilitate development of small molecule inhibitors. clinical success of raltegravir, a potent inhibitor of hiv-1 integrase, demonstrated the utility of this viral dna recombinase as an antiviral target. a variety of partial integrase structures reported in the past 16 years have been instrumental and very informative to the field. nonetheless, because integrase protein fragments are unable to functionall ...	2011	21216426
treatment of canine leukocyte adhesion deficiency by foamy virus vectors expressing cd18 from a pgk promoter.	proto-oncogene activation caused by retroviral vector integration can cause malignancies in gene therapy trials. this has led investigators to search for less genotoxic vectors with minimal enhancer activity and a decreased risk of influencing neighboring chromosomal gene expression after integration. we previously showed that foamy virus (fv) vectors expressing the canine cd18 gene from an internal murine stem cell virus (mscv) promoter could cure canine leukocyte adhesion deficiency (lad). her ...	2011	21228879
structural insights into the retroviral dna integration apparatus.	retroviral replication depends on successful integration of the viral genetic material into a host cell chromosome. virally encoded integrase, an enzyme from the dde(d) nucleotidyltransferase superfamily, is responsible for the key dna cutting and joining steps associated with this process. insights into the structural and mechanistic aspects of integration are directly relevant for the development of antiretroviral drugs. recent breakthroughs have led to biochemical and structural characterizat ...	2011	21277766
basic residues in the foamy virus gag protein.	foamy virus (fv) capsid proteins have few lysines. basic residues are almost exclusively represented by arginines indicating positive selective pressure. to analyze the possible functions of this peculiarity, we mutated an infectious molecular clone of the prototypic fv (pfv) to harbor lysines in the gag protein at arginine-specifying positions and analyzed various aspects of the fv replication cycle. the majority of mutants replicated equally as well in permanent cell cultures as the original w ...	2011	21289113
immunological properties of the transmembrane envelope protein of the feline foamy virus and its use for serological screening.	the transmembrane envelope (tm) proteins of retroviruses are used as antigen in diagnostic immunoassays and they represent a conserved target for neutralizing antibodies. to analyze the situation in infections with the feline foamy virus (ffv), its recombinant tm protein was produced and used for elisa and western blot analyses. screening sera from 404 german cats showed that 39% reacted against the tm protein, the same infection rate was determined using the gag protein. epitope mapping showed ...	2011	21316070
genetic correction of x-linked chronic granulomatous disease with novel foamy virus vectors.	the x-linked form of chronic granulomatous disease (x-cgd) results from mutations in the cybb gene encoding gp91(phox), the larger subunit of the oxidase flavocytochrome b(558). affected individuals suffer from recurrent life-threatening infections due to impaired superoxide production by reduced nicotinamide adenine dinucleotide phosphate (nadph) oxidase in phagocytes. novel foamy virus vectors expressing the human codon-optimized gp91(phox) were evaluated for the genetic correction of the dise ...	2011	21426924
[the progress in research on foamy virus tas protein].		2011	21528546
tetherin inhibits prototypic foamy virus release.	abstract: background: tetherin (also known as bst-2, cd317, and hm1.24) is an interferon- induced protein that blocks the release of a variety of enveloped viruses, such as retroviruses, filoviruses and herpesviruses. however, the relationship between tetherin and foamy viruses has not been clearly demonstrated. results: in this study, we found that tetherin of human, simian, bovine or canine origin inhibits the production of infectious prototypic foamy virus (pfv). the inhibition of pfv by huma ...	2011	21529378
lysine acetylation sites in bovine foamy virus transactivator btas are important for its dna binding activity.	cellular acetylation signaling is important for viral gene regulation, particularly during the transactivation of retroviruses. the regulatory protein of bovine foamy virus (bfv), btas, is a transactivator that augments viral gene transcription from both the long terminal repeat (ltr) promoter and the internal promoter (ip). in this study, we report that the histone acetyltransferase (hat), p300, specifically acetylates btas both in vivo and in vitro. further studies demonstrated that btas acety ...	2011	21813148
prototype foamy virus gag nuclear localization: a novel pathway among retroviruses.	gag nuclear localization has long been recognized as a hallmark of foamy virus (fv) infection. two required motifs, a chromatin-binding site (cbs) and a nuclear localization signal (nls), both located in glycine-arginine-rich box ii (grii), have been described. however, the underlying mechanisms of gag nuclear translocation are largely unknown. we analyzed prototype fv (pfv) gag nuclear localization using a novel live-cell fluorescence microscopy assay. furthermore, we characterized the nuclear ...	2011	21715475
pattern of seroreactivity against feline foamy virus proteins in domestic cats from germany.	the prevalence of feline foamy virus (ffv, spumaretrovirinae) in naturally infected domestic cats ranges between 30 and 80% ffv positive animals depending on age, sex and geographical region analyzed. two serotypes have been reported for ffv designated fuv7-like and f17/951-like. serotype-specific neutralization has been shown to correlate with sequence divergence in the surface (su) domain of the envelope protein (env). we analyzed a serum collection of 262 domestic cat sera from germany using ...	2011	21724269
a new indicator cell line established to monitor bovine foamy virus infection.	in order to improve the accuracy for quantitating the bovine foamy virus (bfv) in vitro, we developed a baby hamster kidney cell (bhk)-21-derived indicator cell line containing a plasmid that encodes the firefly luciferase driven by the bfv long terminal repeat promoter (ltr, from -7 to 1012). the bfv titer could be determined by detecting the luciferase expression since the viral trans-activator btas protein activates the promoter activity of the ltr. one clone, designated bfvl, was selected fr ...	2011	21979571
orthoretroviral-like prototype foamy virus gag-pol expression is compatible with viral replication.	abstract: background: foamy viruses (fvs) unlike orthoretroviruses express pol as a separate precursor protein and not as a gag-pol fusion protein. a unique packaging strategy, involving recognition of briding viral rna by both pol precursor and gag as well as potential gag-pol protein interactions, ensures pol particle encapsidation. results: several prototype fv (pfv) gag-pol fusion protein constructs were generated to examine whether pfv replication is compatible with an orthoretroviral-like ...	2011	21843316