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suboptimal porcine endogenous retrovirus infection in non-human primate cells: implication for preclinical xenotransplantation.porcine endogenous retrovirus (perv) poses a potential risk of zoonotic infection in xenotransplantation. preclinical transplantation trials using non-human primates (nhp) as recipients of porcine xenografts present the opportunity to assess the zoonosis risk in vivo. however, perv poorly infects nhp cells for unclear reasons and therefore nhp may represent a suboptimal animal model to assess the risk of perv zoonoses. we investigated the mechanism responsible for the low efficiency of perv-a in ...201020949092
epigenetic regulation on the 5'-proximal cpg island of human porcine endogenous retrovirus subgroup a receptor 2/gpr172b.porcine endogenous retroviruses (pervs) have been considered one of the major risks of xenotransplantation from pigs to humans. perv-a efficiently utilizes human perv-a receptor 2 (hupar-2)/gpr172b to infect human cells; however, there has been no study on the regulation mechanisms of hupar-2/gpr172b expression. in this study, we examined the expression of hupar-2/gpr172b from the standpoint of epigenetic regulation and discussed the risks of perv-a infection in xenotransplantation. quantitative ...201020951222
long-term absence of porcine endogenous retrovirus infection in chronically immunosuppressed patients after treatment with the porcine cell-based academic medical center bioartificial liver.clinical use of porcine cell-based bioartificial liver (bal) support in acute liver failure as bridging therapy for liver transplantation exposes the patient to the risk of transmission of porcine endogenous retroviruses (pervs) to human. this risk may be enhanced when patients receive liver transplant and are subsequently immunosuppressed. as further follow-up of previously reported patients (di nicuolo et al. 2005), an assessment of perv infection was made in the same patient population pharma ...201021158944
identification of full-length proviral dna of porcine endogenous retrovirus from chinese wuzhishan miniature pigs inbred.existence of porcine endogenous retrovirus (perv) hinders pigs to be used in clinical xenotransplantation to alleviate the shortage of human transplants. chinese miniature pigs are potential organ donors for xenotransplantation in china. however, so far, an adequate level of information on the molecular characteristics of perv from chinese miniature pigs has not been available. we described here the cloning and characterization of full-length proviral dna of perv from chinese wuzhishan miniature ...201019070900
a newly cloned pig dolichyl-phosphate mannosyl-transferase for preventing the transmission of porcine endogenous retrovirus to human cells.porcine endogenous retrovirus (perv) is a major problem associated with successful clinical xenotransplantation. in our previous study, reducing the high mannose type of n-glycan content proved to be very effective in downregulating perv infectivity. in this study, dolichyl-phosphate mannosyltransferase (d-p-m), an enzyme related to the early stages of n-linked sugar synthesis was studied. the pig cdna of the encoding d-p-m was newly isolated. the rna interference (sirna) for the d-p-m was appli ...201019912589
unusual permeability of porcine endogenous retrovirus subgroup a through membrane filters.in xenotransplantation from pigs to humans, a bio-artificial endocrine pancreas (bio-aep), in which pancreatic endocrine cells are encapsulated within a semipermeable membrane of 100 nm pore size, has been developed. we evaluated the permeability of porcine endogenous retroviruses (pervs) through membrane filters using a pseudotype virus (lacz(perv-a)) containing a viral core derived from murine leukemia virus and an envelope (env) from perv subgroup a. contrary to our expectations, lacz(perv-a) ...201019915326
regulation of porcine endogenous retrovirus release by porcine and human tetherins.the risk of transmission of porcine endogenous retrovirus (perv) is one of the major safety issues in xenotransplantation. human tetherin, recently described as an antiviral protein able to inhibit the release of enveloped viruses, and its porcine homologue were shown to inhibit perv release from producer cells, establishing themselves as candidate molecules to suppress perv production in porcine xenografts by animal engineering.201020015985
no evidence of porcine endogenous retrovirus in patients with type 1 diabetes after long-term porcine islet xenotransplantation.xenotransplantation is a promising alternative for donor shortage to ameliorate physiologic and metabolic disorders. the major concern for xenotransplant is the risk of zoonosis mainly by the porcine endogenous retrovirus (perv), presentation in the piglet genome. twenty-three patients with type 1 diabetes were transplanted with porcine islets using collagen-generating devices which were implanted subcutaneously in the anterior wall of the abdomen. clinical characteristics and metabolic tests we ...201020029803
critical issues related to porcine xenograft exposure to human viruses: lessons from allotransplantation.xenotransplantation of tissues from swine into humans poses the threat of bidirectional transfer of porcine or human microorganisms to the recipient or to the xenograft, respectively. this review focuses on recipient-derived infection. recent data are reviewed that assess the susceptibility of porcine cells to human viruses. on the basis of the experience in allotransplantation, potential consequences for the xenograft are discussed.201020061950
an effective method for the quantitative detection of porcine endogenous retrovirus in pig tissues.xenotransplantation shows great promise for providing a virtually limitless supply of cells, tissues, and organs for a variety of therapeutical procedures. however, the potential of porcine endogenous retrovirus (perv) as a human-tropic pathogen, particularly as a public health risk, is a major concern for xenotransplantation. this study focus on the detection of copy number in various tissues and organs in banna minipig inbreed (bmi) from 2006 to 2007 in west china hospital, sichuan university. ...201020108128
expression of complement regulatory protein on porcine endogenous retrovirus (perv) depends on molecular size.expression of complement regulatory proteins (crp) on pig cells is an effective means to avoid hyperacute rejection. however, pig endogenous retrovirus (perv) from pig cells transfected with crp may acquire resistance to human serum (hs). the present study investigated the size limitations of the transfected crp that can be easily expressed and function on perv particles. cdnas of various sized daf(cd55)s, including single-, double-, triple-, tetra-, as well as 2.1- and 2.2-daf, were prepared. p ...201020226243
real-time quantitative polymerase chain reaction with sybr green i detection for estimating copy numbers of porcine endogenous retrovirus from chinese miniature pigs.porcine endogenous retrovirus (perv) in the pig genome represents a potential infectious risk in xenotransplantation. chinese miniature pigs have been considered to be potential organ donors in china. however, an adequate level of information on perv from chinese miniature pigs has not been available. we established an sybr green i-based real-time quantitative polymerase chain reaction (pcr) assay for estimating copy numbers of perv integrated in the host genome. the assay was 100-fold more sens ...201020620553
characterisation of a human cell-adapted porcine endogenous retrovirus perv-a/c.porcine endogenous retroviruses (pervs) pose a potential risk for xenotransplantation using pig cells, tissues or organs. a special threat comes from viruses generated by recombination between human-tropic perv-a and ecotropic perv-c. serial passages of a recombinant perv-a/c on human 293 cells resulted in increased infectious titers and a multimerization of transcription factor binding sites in the viral long terminal repeat (ltr). in contrast to the ltr, the sequence of the env gene did not ch ...201020657519
simultaneous detection and subtyping of porcine endogenous retroviruses proviral dna using the dual priming oligonucleotide system.the purpose of this study was to develop a multiplex pcr that can detect porcine endogenous retrovirus (perv) proviral genes (pol, enva, envb, envc) and porcine mitochondrial dna, using a dual priming oligonucleotide (dpo) system. the primer specifically detected the perv proviral genes pol, enva, envb, envc, and porcine mitochondrial dna only in samples of pig origin. the sensitivity of the primer was demonstrated by simultaneous amplification of all 5 target genes in as little as 10 pg of pig ...201020706036
analysis of the molecular and regulatory properties of active porcine endogenous retrovirus gamma-1 long terminal repeats in kidney tissues of the nih-miniature pig.the pig genome contains the gamma 1 family of porcine endogenous retroviruses (pervs), which are a major obstacle to the development of successful xenotransplantation from pig to human. long terminal repeats (ltrs) found in pervs are known to be essential elements for the control of the transcriptional activity of single virus by different transcription factors (tfs). to identify transcribed perv ltr elements, rt-pcr and dna sequencing analyses were performed. twenty-nine actively transcribed lt ...201020811814
molecular characterization of long terminal repeat of porcine endogenous retroviruses in chinese pigs.pigs offer an unlimited source of xenografts for humans. however, vertically transmitted porcine endogenous retrovirus (perv) poses an infectious risk in the course of pig-to-human transplantation. in this study, we characterized perv long terminal repeat (ltr) sequences from three species of chinese pigs banna minipig inbred (bmi), wu-zhi-shan pig (wzsp), and neijiang pig (njp-a), and compared them with those of known pervs (perv-a, perv-b, perv-c, perv-nih, and 293-perv-43). genomic dna extrac ...201020822308
[receptors for animal retroviruses].diseases caused by animal retroviruses have been recognized since 19th century in veterinary field. most livestock and companion animals have own retroviruses. to disclose the receptors for these retroviruses will be useful for understanding retroviral pathogenesis, developments of anti-retroviral drugs and vectors for human and animal gene therapies. of retroviruses in veterinary field, receptors for the following viruses have been identified; equine infectious anemia virus, feline immunodefici ...200920218331
comparison of the age-related porcine endogenous retrovirus (perv)expression using duplex rt-pcr.porcine endogenous retroviruses (pervs) are members of family retroviridae, genus gamma retrovirus, and transmitted by both horizontally and vertically like other endogenous retroviruses (ervs). perv was initially described in the 1970s having inserted its gene in the host genome of different pig breeds, and three classes, perv-a, perv-b, and perv-c are known. the therapeutic use of living cells, tissues, and organs from animals called xenotransplantation might relieve the limited supply of allo ...200919934597
studies on long-term infection of human cells with porcine endogenous retrovirus.a major concern in pig-to-human xenotransplantations is the potential risk of transmission of porcine endogenous retroviruses (pervs) integrated in the pig genome. our previous work has shown that perv provirus genes and gag protein can be detected in human embryonic kidney hek-293 cells during a long-term infection with perv (yu et al., transplant. proc. 37, 496-499, 2005). in this study, we continued studying the long-term (>6 months) perv infection of hek-293 cells. the results showed no sign ...200919941398
investigation of porcine endogenous retrovirus in the conservation population of ningxiang pig.porcine endogenous retrovirus (perv) varies between pig breeds. screening and analysis of perv in putative pig breeds may provide basic parameters to evaluate the biological safety of xenotransplantation from pigs to humans. in this study, perv was investigated among the conservation population of the ningxiang pig. the result revealed that the genotype of perv distribution was subtype a, 100%; subtype b, 100%; and subtype c, 100%. the env sequences of perv-a and -b showed 11 clones detected by ...200920005405
identification of two distinct structural regions in a human porcine endogenous retrovirus receptor, hupar2, contributing to function for viral entry.of the three subclasses of porcine endogenous retrovirus (perv), perv-a is able to infect human cells via one of two receptors, hupar1 or hupar2. characterizing the structure-function relationships of the two hupar receptors in perv-a binding and entry is important in understanding receptor-mediated gammaretroviral entry and contributes to evaluating the risk of zoonosis in xenotransplantation.200919144196
no in vivo infection of triple immunosuppressed non-human primates after inoculation with high titers of porcine endogenous retroviruses.porcine endogenous retroviruses (pervs) released from pig tissue can infect selected human cells in vitro and therefore represent a safety risk for xenotransplantation using pig cells, tissues, or organs. although pervs infect cells of numerous species in vitro, attempts to establish reliable animal models failed until now. absence of perv transmission has been shown in first experimental and clinical xenotransplantations; however, these trials suffered from the absence of long-term exposure (tr ...200919243559
distribution and expression of porcine endogenous retroviruses in multi-transgenic pigs generated for xenotransplantation.multi-transgenic pigs produced for use in xenotransplantation have to be screened for the presence and expression of porcine endogenous retroviruses (perv) to select animals with low perv load. the production of transgenic pigs may also be associated with the integration of the transgene adjacent to or into the locus of a perv provirus, potentially leading to an enhanced virus expression.200919392721
inhibition of porcine endogenous retrovirus (perv) replication by hiv-1 gene expression inhibitors.porcine endogenous retrovirus (perv) is persistently integrated into the host genomic dna as a provirus and released from a variety of porcine cells. perv infects a certain range of human cells, which is a major concern in xenotransplantation. therefore, the use of viral gene expression inhibitors could be envisaged, if they reduce perv production from porcine organs and minimize viral transmission to human recipients. in the present study, four hiv-1 gene expression inhibitors were examined for ...200919414036
porcine endogenous retrovirus and other viruses in xenotransplantation.potential transmission of zoonotic porcine viruses is a major safety issue in xenotransplantation. this review will first summarize recent studies involving transmission and control of the major concern, porcine endogenous retrovirus (perv). second, the potential for zoonotic transfer and safety measures required against other viruses of concern will be discussed.200919469034
characterization of the replication-competent porcine endogenous retrovirus class b molecular clone originated from korean domestic pig.xenotransplantation from pigs offers an opportunity to resolve the shortage of human organs. the porcine endogenous retrovirus (perv) cannot be eliminated because of its presence in the germline dna. three subgroups of the replication-competent perv (perv-a, perv-b, and perv-c) have been identified in pigs. we constructed a molecular clone of perv-b from a korean domestic pig bac clone containing perv genomes, and its replication competency was characterized in human cells. the pol region of per ...200919543822
production of transgenic pigs that express porcine endogenous retrovirus small interfering rnas.the presence of multiple copies of porcine endogenous retrovirus (perv) within the pig genome, and the demonstration that replication competent perv, that infect human cells in culture, can be isolated from pig cells, directly impacts the drive towards the development of pigs for xenotransplantation. the development of technology to produce pigs that do not propagate perv has the potential to facilitate the development of xenotransplantation products for human use, and as such, is the focus of t ...200919566656
porcine endogenous retrovirus released by a bioartificial liver infects primary human cells.porcine endogenous retrovirus (perv) remains a safety risk in pig-to-human xenotransplantation. there is no evidence of in vivo productive infection in humans because perv is inactivated by human serum. however, perv can infect human cell lines and human primary cells in vitro and inhibit human immune functions.200919686312
the international xenotransplantation association consensus statement on conditions for undertaking clinical trials of porcine islet products in type 1 diabetes-- executive summary.the international xenotransplantation association islet xenotransplantation consensus statement describes the conditions for undertaking clinical trials of porcine islet products in type 1 diabetes. chapter 1 reviews the key ethical requirements and progress toward the definition of an international regulatory framework for clinical trials of xenotransplantation. chapters 2 to 7 provide in depth and agreed-upon recommendations on source pigs, pig islet product manufacturing and release testing, ...200919799759
the international xenotransplantation association consensus statement on conditions for undertaking clinical trials of porcine islet products in type 1 diabetes--chapter 2: source pigs.an islet xenotransplantation product includes live cells from a non-human source, in this study, a pig source. a live product cannot be subjected to conventional disinfection, and therefore the source pig must be depleted of infectious agents that can transmit to the recipient and cause disease. among other requirements, regulatory guidances specify that donor animals fulfill the designated pathogen-free (dpf) status. donor pigs fulfilling dpf status are generally bred and maintained in biosecur ...200919799761
the international xenotransplantation association consensus statement on conditions for undertaking clinical trials of porcine islet products in type 1 diabetes--chapter 5: strategies to prevent transmission of porcine endogenous retroviruses.xenotransplantation using porcine cells, tissues, or organs may offer a potential solution for the shortage of allogeneic human organs. prior to the clinical use of porcine xenotransplants, three main hurdles must be overcome: immunologic rejection, physiologic incompatibility, and risk of transmission of porcine pathogens. designated pathogen-free breeding of pigs can prevent transmission of most porcine microbes. however, this is not possible in the case of porcine endogenous retroviruses (per ...200919799764
polymerase chain reaction in detection of porcine endogenous retrovirus (perv) from porcine tissues.pigs offer an unlimited source of xenografts for humans. the use of transplants from animal origin offers a potential solution to the limited supply of human organs and tissues. however, like many other mammalian species, pigs harbor porcine endogenous retrovirus (perv), which are encoded in their genomic dna and are assumed to have been integrated into the porcine germline. the ability of perv to infect human cells in vitro has heightened safety concerns regarding the transmission of perv to pi ...200923100752
genome areas with high gene density and cpg island neighborhood strongly attract porcine endogenous retrovirus for integration and favor the formation of hot spots.porcine endogenous retroviruses (perv) are members of the gammaretrovirus genus and display integration preferences around transcription start sites, a finding which is similar to the preferences of the murine leukemia virus (mlv). our new genome-wide analysis of the integration profile of a recombinant perv (perv a/c), enabled us to examine more than 1,900 integration sites and identify 224 integration hot spots. investigation of the possible genome features involved in hot-spot formation revea ...200919036816
progress towards clinical xenotransplantation.xenotransplantation has progressed from early heroic experiments on the path to meet the ever increasing demands of tissue and organ transplantation in patients with end-stage organ failure. the pig species is regarded as the most promising donor species. however, due to the evolutionary distance, innovative approaches are to be developed to permit life-supporting function in humans. transplantation of organs from non-human primates has increased our knowledge on rejection mechanisms and provide ...200817981539
reappraisal of biosafety risks posed by pervs in xenotransplantation.donor materials of porcine origin could potentially provide an alternative source of cells, tissues or whole organs for transplantation to humans, but is hampered by the health risk posed by infection with porcine viruses. although pigs can be bred in such a way that all known exogenous microorganisms are eliminated, this is not feasible for all endogenous pathogens, such as the porcine endogenous retroviruses (pervs) which are present in the germline of pigs as proviruses. upon transplantation, ...200817987669
knockdown of porcine endogenous retrovirus (perv) expression by perv-specific shrna in transgenic pigs.xenotransplantation using porcine cells, tissues or organs may be associated with the transmission of porcine endogenous retroviruses (pervs). more than 50 viral copies have been identified in the pig genome and three different subtypes of perv were released from pig cells, two of them were able to infect human cells in vitro. rna interference is a promising option to inhibit perv transmission.200818333912
no transmission of porcine endogenous retroviruses (pervs) in a long-term pig to rat xenotransplantation model and no infection of immunosuppressed rats.xenotransplantation from pig to humans may be associated with the risk of transmission of porcine endogenous retroviruses (pervs) that are present in the genome of all pigs and that infect human cells in vitro. however, it remains unclear whether pervs infect transplant recipients in vivo and, if so, whether they are pathogenic. it is therefore essential to perform in vivo infection studies in animal models.200818344940
functional hierarchy of two l domains in porcine endogenous retrovirus (perv) that influence release and infectivity.the porcine endogenous retrovirus (perv) gag protein contains two late (l) domain motifs, pppy and p(f/s)ap. using viral release assays we demonstrate that pppy is the dominant l domain involved in perv release. pfap represents a novel retroviral l domain variant and is defined by abnormal viral assembly phenotypes visualized by electron microscopy and attenuation of early perv release as measured by viral genomes. psap is functionally dominant over pfap in early perv release. psap virions are 3 ...200818355887
is porcine endogenous retrovirus (perv) transmission still relevant?xenotransplantation using porcine cells or organs may be associated with the risk of transmission of zoonotic microorganisms. porcine endogenous retroviruses (pervs) pose a potentially high risk because they are integrated into the genome of all pigs and perv-a and perv-b at least, which are present in all pigs, can infect human cells. however, perv transmission could not be demonstrated in the first recipients of clinical xenotransplantation or after numerous experimental pig-to-non-human prima ...200818374136
porcine endogenous retrovirus transmission characteristics from a designated pathogen-free herd.previously, a strategy for monitoring pigs intended for cell transplantation was developed and successfully applied to several representative herds in new zealand. a better understanding of porcine viruses' epidemiology in new zealand has been achieved, and, as a result, a designated pathogen-free (dpf) herd has been chosen as a good candidate for xenotransplantation. this herd is free of all infectious agents relevant to xenotransplantation. the presented study of pig endogenous retrovirus (per ...200818374137
retrotransposition: another obstacle for xenotransplantation?to overcome the shortage of human organs for transplantation, pigs are considered as xenogeneic donors. however, primarily immunological and virological barriers exist. one of the main virological obstacles, represented by the presence of functional and infectious porcine endogenous retroviruses (perv) in the genome of the pigs, may be excluded by conventional breeding. in contrast, there are truncated proviral sequences that have the capacity to retrotranspose, causing insertional mutagenesis i ...200818374139
analysis of natural recombination in porcine endogenous retrovirus envelope genes.human tropic porcine endogenous retroviruses (pervs) are the major concern in zoonosis for xenotransplantation because pervs cannot be eliminated by specific pathogen-free breeding. recently, a perv a/c recombinant with perv-c bearing perv-a gp70 showed a higher infectivity (approximately 500-fold) to human cells than perv-a. additionally, the chance of recombination between pervs and hervs is frequently stated as another risk of xenografting. overcoming zoonotic barriers in xenotransplantation ...200818388481
no infection with porcine endogenous retrovirus in recipients of acellular porcine aortic valves: a two-year study.engineered tissue heart valves may become a promising therapeutics for heart valve disease. compared with synthetic materials, acellular porcine scaffolds are considered as suitable matrices for tissue-engineered heart valves for the mechanical and structural properties of native tissue. whether acellular porcine scaffolds can cause infection in recipients with porcine endogenous retrovirus (perv) is critical for evaluating the safety of transplantation of tissue-engineered heart valves based on ...200818447885
identification of residues outside of the receptor binding domain that influence the infectivity and tropism of porcine endogenous retrovirus.identification of determinants of human tropism of porcine endogenous retrovirus (perv) is critical to understanding the risk of transmission of perv to recipients of porcine xenotransplantation products. previously, we showed that a chimeric envelope cdna encoding the 360 n-terminal residues of the human-tropic perv envelope class a (perv-a) su and the 130 c-terminal residues of the pig-tropic perv-c su and all of tm (perv-a/c) showed a 100-fold decrease in infectivity titer on human cells (m. ...200818508891
recombinant porcine endogenous retroviruses (perv-a/c): a new risk for xenotransplantation?pervs are integrated in the genome of all pigs. some of them infect human cells and represent therefore a potential risk for xenotransplantation using pig cells or organs. three replication-competent subtypes have been described, perv-a, perv-b and perv-c. whereas perv-a and perv-b are polytropic viruses and infect, among others, human cells, perv-c is an ecotropic virus, infecting only pig cells. recombinant perv-a/c are able to infect human cells, they are characterised by high-titre replicati ...200818584115
strategies to enhance the safety profile of xenotransplantation: minimizing the risk of viral zoonoses.pig-to-human xenotransplantation has taken steps closer to reality through advances in animal engineering to address immunological as well as microbial problems. the most highlighted problem in xenotransplantation safety has been the potential risk for zoonotic infection mediated by porcine endogenous retroviruses. safety issues regarding viral zoonosis, particularly porcine endogenous retroviruses, are summarized and commented upon.200818685301
existence of proviral porcine endogenous retrovirus in fresh and decellularised porcine tissues.swine are expected to be utilized as xenograft donors for both whole organ and cellular transplantation. a major concern in using porcine organs for transplantation is the potential of transmission of porcine endogenous retrovirus (perv). tissue-engineered or decellularised heart valves have already been implanted in humans and have been marketed by certain companies after food and drug administration (fda) approval. the aim of this study was to examine the existence of porcine endogenous retrov ...200818695319
progress and prospects: genetic engineering in xenotransplantation.in this review, we summarize the work published over the last 2 years using genetic modifications of animals in the field of xenotransplantation. genetic engineering of the donor has become a powerful tool in xenotransplantation, both for the inactivation of one particular porcine gene and for the addition of human genes with the goal of overcoming xenogeneic barriers. we summarize the work relative to the knockout of the alpha1,3-galactosyltransferase gene, followed by genetic engineering aimed ...200818762806
absence of transmission of potentially xenotic viruses in a prospective pig to primate islet xenotransplantation study.shortage of human donor organs for transplantation has prompted usage of animals as an alternative donor source. pigs are the most acceptable candidate animals but issues of xenozoonoses remain. despite careful monitoring of designated pathogen free pigs there is still a risk that their tissues may carry infectious agents. thus xenotransplantation requires extensive pre-clinical study on safety of the graft especially for those viruses that are either potentially oncogenic and/or immunosuppressi ...200818814261
absence of replication of porcine endogenous retrovirus and porcine lymphotropic herpesvirus type 1 with prolonged pig cell microchimerism after pig-to-baboon xenotransplantation.porcine endogenous retrovirus (perv), porcine cytomegalovirus (pcmv), and porcine lymphotropic herpesvirus (plhv) are common porcine viruses that may be activated with immunosuppression for xenotransplantation. studies of viral replication or transmission are possible due to prolonged survival of xenografts in baboon recipients from human decay-accelerating factor transgenic or alpha-1,3-galactosyltransferase gene knockout miniature swine. ten baboons underwent xenotransplantation with transgeni ...200818829759
no evidence for perv release by islet cells from german landrace pigs.islet cells from pig could be used as an alternative to the current treatment of diabetic patients. however, xenotransplantation from pig to humans may be associated with the risk of transmission of porcine endogenous retroviruses (pervs) that are present in the genome of all pigs and infect human cells in vitro. although transplantation of pig islet cells for treatment of diabetes may be not accompanied by immunosuppression that may facilitate virus survival, since islets will be used encapsula ...200819034225
porcine endogenous retrovirus (perv) and its transmission characteristics: a study of the new zealand designated pathogen-free herd.previously a strategy for monitoring of pigs intended for cell transplantation was developed and successfully applied to several representative herds in new zealand. a designated pathogen-free (dpf) herd has been chosen as a good candidate for xenotransplantation. this herd has previously tested free of infectious agents relevant to xenotransplantation and we present here an in depth study of porcine endogenous retrovirus (perv) transmission. a panel of assays that describes the constraints for ...200819364075
transmission of porcine endogenous retrovirus to human cells in nude mouse.xenotransplantation is associated with the risk of porcine endogenous retrovirus (perv) transmission, since it has been shown that perv can infect human cells in vitro (specke et al., virology 285, 177-180, 2001). we evaluated the possibility of perv infection of human cells in nude mice model. porcine kidney cells pk15 carrying perv and human liver cancer cells smmc-7721 were injected separately into the right and left axilla of nude mice, respectively. two months later, pig cytochrome oxidase ...200819143483
large-scale survey of porcine endogenous retrovirus in chinese miniature pigs.we conducted a large-scale survey on the existence and expression status of porcine endogenous retrovirus (perv) in seven breeds of chinese miniature pigs. genotyping of perv was examined by pcr using type-specific primers according to the env genotyping method. the presence and expression status of viral gag, pol and env genes were further analyzed in wuzhishan pigs (wzsp) and bama minipigs (bmp). the results showed that perv existed in all 348 genomic dna samples. the genotype distribution was ...200817689611
lack of cross-species transmission of porcine endogenous retrovirus (perv) to transplant recipients and abattoir workers in contact with pigs.this study investigated the potential transmission of porcine endogenous retrovirus (perv) to solid-organ transplant recipients and abattoir workers in contact with pigs. blood samples were obtained from volunteer healthy blood donors (group a; n=33); pig-breeding farmers who had undergone a liver transplant (group b; n=14); and pig abattoir workers (group c; n=49). a second blood sample was obtained 1 year after the first sample from 10 of the abattoir workers (group d). tests included investig ...200717713442
the restriction of zoonotic perv transmission by human apobec3g.the human apobec3g protein is an innate anti-viral factor that can dominantly inhibit the replication of some endogenous and exogenous retroviruses. the prospects of purposefully harnessing such an anti-viral defense are under investigation. here, long-term co-culture experiments were used to show that porcine endogenous retrovirus (perv) transmission from pig to human cells is reduced to nearly undetectable levels by expressing human apobec3g in virus-producing pig kidney cells. inhibition occu ...200717849022
[potential risk of porcine endogenous retrovirus cross-species transmission in neonatal pig islets under xenotransplanted condition].to evaluate the potential risk of porcine endogenous retrovirus (perv) cross-species transmission xenotransplanted with microencapsulated neonatal pig islets (npis).200718007064
[cloning and bioinformatics analysis of sla-dr genes in hunan shaziling pigs].in order to clone class ii dra and drb genes of swine leukocyte antigen (sla) in hunan shaziling pigs, to analyze their characteristics and polymorphism and to provide immunological basic parameters for xenotransplantation from pigs to humans. sla-dra and sla-drb genes in two shaziling pigs with the absence of porcine endogenous retrovirus (perv) env-c were amplified by rt-pcr, cloned into pucm-t vectors, sequenced and analyzed through blast in ncbi and related software in expasy. the obtained s ...200718065385
differential resistance to cell entry by porcine endogenous retrovirus subgroup a in rodent species.the risk of zoonotic infection by porcine endogenous retroviruses (perv) has been highlighted in the context of pig-to-human xenotransplantation. the use of receptors for cell entry often determines the host range of retroviruses. a human-tropic perv subgroup, perv-a, can enter human cells through either of two homologous multitransmembrane proteins, hupar-1 and hupar-2. here, we characterised human pars and their homologues in the perv-a resistant rodent species, mouse and rat (mupar and ratpar ...200718081925
lack of evidence for perv expression after apoptosis-mediated horizontal gene transfer between porcine and human cells.evidence for porcine endogenous retrovirus (perv) infection of human cells has provoked a public health debate over the proposed use of porcine xenografts to alleviate the worldwide shortage of human allografts. nevertheless, the potential relevance of perv transmission by apoptosis-mediated horizontal dna transfer, a documented means of infection-independent retrovirus delivery, appears to have been overlooked in this discussion. to examine the hypothesis that apoptotic cell death during porcin ...200717214701
functional epitopes on porcine endogenous retrovirus envelope protein interacting with neutralizing antibody combining sites.porcine cell and organ transplantation provides promise for maintaining normal physiological conditions in patients with end-stage organ failure. the approach however poses serious risk of transmitting pig pathogens to humans. among many potential pathogens, porcine endogenous retroviruses (perv) are of particular concern due to their ubiquitous nature in pigs and capability of infecting human cells. major antigenic determinants and receptor binding domains on perv remain unclear until now. two ...200717222436
transient transmission of porcine endogenous retrovirus to fetal lambs after pig islet tissue xenotransplantation.evidence for the in vivo transmission of porcine endogenous retrovirus (perv) from porcine xenografts to various recipient animals has been inconsistent. to characterize the contribution of the host immune system to the potential for perv transmission from pig islet tissue xenografts to host tissues, we examined two immunoincompetent animal models, thymectomizsed fetal lambs and nodscid mice. pig proislets were grafted into fetal lambs or adult nodscid mice. conventional, nested and real-time pc ...200717228325
novel method of decellularization of porcine valves using polyethylene glycol and gamma irradiation.recent tissue-engineered valves are in need of a breakthrough to overcome several limitations against clinical applications. we have developed a new method of decellularization using polyethylene glycol and gamma irradiation.200717383366
expression of porcine endogenous retroviruses (pervs) in melanomas of munich miniature swine (mms) troll.porcine endogenous retroviruses (pervs) are integrated in the genome of all pig breeds. since some of them are able to infect human cells, they might represent a risk for xenotransplantation using pig cells or organs. however, the expression and biological role of pervs in healthy pigs as well as in porcine tumours is largely unknown. since we and others have recently shown overexpression of a human endogenous retrovirus, herv-k, in human melanomas, we studied the expression of pervs in melanoma ...200717418507
selective inhibition of porcine endogenous retrovirus replication in human cells by acyclic nucleoside phosphonates.several anti-human immunodeficiency virus type 1 reverse transcriptase inhibitors were evaluated for their antiviral activities against porcine endogenous retrovirus in human cells. among the test compounds, zidovudine was found to be the most active. the order of potency was zidovudine > phosphonylmethoxyethoxydiaminopyrimidine = phosphonylmethoxypropyldiaminopurine > tenofovir > or = adefovir > stavudine.200717470654
three-yr follow-up of a type 1 diabetes mellitus patient with an islet xenotransplant.in order to alleviate the shortage of human donors, the use of porcine islets of langerhans for xenotransplantation in diabetic patients has been proposed as a solution. to overcome rejection, we have developed a procedure for protecting the islets by combining them with sertoli cells and placing them in a novel subcutaneous device, that generates an autologous collagen covering. a type 1 diabetic woman was closely monitored for 10 months, and then transplanted in two devices with two months of ...200717488384
some ethical issues regarding xenotransfusion.the use of porcine red blood cells has recently been proposed as a possible solution to the shortage of blood for human transfusion.200717489861
pre-screening of miniature swine may reduce the risk of transmitting human tropic recombinant porcine endogenous retroviruses.it has been reported that peripheral blood mononuclear cells from miniature swine are capable of transmitting human tropic porcine endogenous retrovirus (perv) recombinants to both human and pig cells. it has been suggested that these recombinants are exogenous and/or driven by one or more critical loci present in the pig genome.200717489862
[clinical xenotransplantation].the growing numerical gap between the number of patients and available human donor organs have led to a revival interest in xenotransplantation. this review will mainly focus on the clinical affairs of xenotransplantation and the project of producing the gene modified pigs. trials, designed to overcome xenogenic rejection by the expression of human complement regulatory protein (crp), such as daf (cd55), on the pig organ and knocking out the alpha-gal epitope(galalpha1-3galbeta1-4glcnac-r), whic ...200717603258
no evidence of perv infection in healthcare workers exposed to transgenic porcine liver extracorporeal support.clinical xenotransplantation holds great promise by providing one solution to the shortage of human organs for transplantation, while also posing a potential public health threat by facilitating transmission of infectious disease from source animals to humans. one potential vector for infectious disease transmission is healthcare workers (hcw) who are involved in administering xenotransplantation procedures.200717669172
long-term survival of neonatal porcine islets in nonhuman primates by targeting costimulation pathways.we evaluated the ability of neonatal porcine islets to engraft and restore glucose control in pancreatectomized rhesus macaques. although porcine islets transplanted into nonimmunosuppressed macaques were rapidly rejected by a process consistent with cellular rejection, recipients treated with a cd28-cd154 costimulation blockade regimen achieved sustained insulin independence (median survival, >140 days) without evidence of porcine endogenous retrovirus dissemination. thus, neonatal porcine isle ...200616501570
phylogeny, recombination and expression of porcine endogenous retrovirus gamma2 nucleotide sequences.endogenous retroviral sequences in the pig genome represent a potential infectious risk in xenotransplantation. porcine endogenous retrovirus (perv) gamma sequences described to date have been classified into several families. the known infectious, human-tropic pervs have been assigned to the perv gamma1 subfamilies a, b and c. high copy numbers and full-length clones have also been observed for an additional family, designated perv gamma2. the aim of this study was to examine the perv gamma2 fa ...200616528048
detection of perv by polymerase chain reaction and its safety in bioartificial liver support system.to establish a method detecting porcine endogenous retrovirus (perv) in china experimental minipigs and to evaluate the safety of perv in three individuals treated with bioartificial liver support systems based on porcine hepatocytes.200616534887
mice transgenic for a human porcine endogenous retrovirus receptor are susceptible to productive viral infection.porcine endogenous retrovirus (perv) is considered one of the major risks in xenotransplantation. no valid animal model has been established to evaluate the risks associated with perv transmission to human patients by pig tissue xenotransplantation or to study the potential pathogenesis associated with perv infection. in previous work we isolated two genes encoding functional human perv receptors and proved that introduction of these into mouse fibroblasts allowed the normally nonpermissive mous ...200616537582
a novel strategy for preventing perv transmission to human cells by remodeling the viral envelope glycoprotein.porcine endogenous retrovirus (perv) released from pig cells is a main problem associated with clinical xenotransplantation. in a previous study, we demonstrated that the high mannose type of n-glycan of the envelope glycoprotein is closely related to perv infectivity with respect to human cells. in this study, we addressed the effects of reducing the high mannose type of n-glycan on perv infectivity.200616756569
[research of porcine endogenous retrovirus in shaziling pigs].to provide basic parameters of evaluating the biological safety of xenotransplantation from pig to human, ear tissues from 31 individuals were randomly collected from a shazi ling pig population. pcr and rt-pcr were performed to detect porcine endogenous retrovirus (perv) proviral dna and mrna respectively. the sensitivity of the pcr was evaluated using a positive control. to study tissue distribution, rt-pcr of pol, gag and env was performed in the kidney, heart, liver, lung and spleen of 3 ind ...200616825165
journey from hepatocyte transplantation to hepatic stem cells: a novel treatment strategy for liver diseases.acute liver failure (alf) carries high morbidity and mortality (>80%) even in the best centres. orthotopic liver transplantation (oltx) is the only viable approach to the treatment of alf. this has significantly improved the survival in these patients. the major limitations of oltx are non availability of the donor liver, requirement of a major surgical procedure, high cost and longterm immunosuppression. isolated hepatocyte transplantation is emerging as an appealing method for the treatment of ...200616873904
porcine endogenous retrovirus integration sites in the human genome: features in common with those of murine leukemia virus.porcine endogenous retroviruses (perv) are a major concern when porcine tissues and organs are used for xenotransplantation. perv has been shown to infect human cells in vitro, highlighting a potential zoonotic risk. no pathology is associated with perv in its natural host, but the pathogenic potential might differ in the case of cross-species transmission and can only be inferred from knowledge of related gammaretroviruses. we therefore investigated the integration features of the perv dna in t ...200616928752
phylogenetic analysis of porcine endogenous retroviruses expressed in chinese pigs based on envelope sequences.the promise of successful clinical xenotransplantation is now offset by the potential risk of transmission of porcine endogenous retrovirus (perv). perv consists of three subtypes according to the varieties of env sequences. we analyzed perv subtypes in two species of chinese pigs (banna minipig inbred, bmi, and wu-zhi-shan pig, wzsp). positive a and b were detected while positive c was absent in the analyzed chinese pigs. the polymerase chain reaction products were then cloned into a pgem-t vec ...200616980057
the lack of inhibition of porcine endogenous retrovirus by small interference rna designed from the long terminal regions.xenotransplantation from pigs may offer a potential solution to the organ shortage. however, there remains the risk of xenoinfection by porcine endogenous retroviruses (pervs) that cannot be eliminated by breeding pigs under specified pathogen-free conditions. rna interference is a new method to inhibit the expression of a specific gene. here, we designed two sirnas from the long terminal repeat of perv. our results showed that these sirnas had no inhibitory effects. the possible reasons for thi ...200616980058
in vivo screening of porcine endogenous retrovirus in chinese banna minipig inbred.the risk of porcine endogenous retrovirus (perv) infection is one of the major barriers in clinical trials of pig-to-human xenotransplantation. previous experiments showed that perv could infect many types of human and nonhuman primate cells, but there is no reported evidence of in vivo infection. in this study, extracted genomic dna from tissues of seventeen pigs was analyzed using specific sequence primers for gag, pol, and env. the results suggested that perv exist in the genomes of all tissu ...200616980059
isolation and characterization of an infectious replication-competent molecular clone of ecotropic porcine endogenous retrovirus class c.xenotransplantation of pig organs is complicated by the existence of polytropic replication-competent porcine endogenous retroviruses (perv) capable of infecting human cells. the potential for recombination between ecotropic perv-c and human-tropic perv-a and perv-b adds another level of infectious risk. proviral perv-c were characterized in max-t cells derived from d/d haplotype miniature swine. three proviruses were cloned from a genomic library. clone perv-c(1312) generated infectious particl ...200617005704
genomic presence of recombinant porcine endogenous retrovirus in transmitting miniature swine.the replication of porcine endogenous retrovirus (perv) in human cell lines suggests a potential infectious risk in xenotransplantation. perv isolated from human cells following cocultivation with porcine peripheral blood mononuclear cells is a recombinant of perv-a and perv-c. we describe two different recombinant perv-ac sequences in the cellular dna of some transmitting miniature swine. this is the first evidence of perv-ac recombinant virus in porcine genomic dna that may have resulted from ...200617081300
molecular characterization of the porcine endogenous retrovirus subclass a and b envelope gene from pigs.xenotransplantation of porcine organs has the potential to overcome the current critical shortage of allogenic organs for transplantation in humans. however, the existence of porcine endogenous retroviruses (pervs) presents a problem for the clinical use of xenografts from pigs. in an attempt to understand the molecular characteristics of pervs, we cloned the perv env gene from six pig breeds (ie, berkshire, duroc, landrace, yorkshire, and two types of miniature pigs) in korea. a total of 141 en ...200617112901
[porcine endogenous retrovirus in daweizi pigs in hunan].to detect porcine endogenous retrovirus (perv) in daweizi pigs and to provide basic parameters of evaluating the biological safety for xenotransplantation from pigs to humans.200617213579
induction of neutralizing antibody against human immunodeficiency virus type 1 (hiv-1) by immunization with gp41 membrane-proximal external region (mper) fused with porcine endogenous retrovirus (perv) p15e fragment.the membrane-proximal external region (mper) of hiv-1 gp41 is recognized by all three anti-hiv antibodies 2f5, 4e10 and z13 that were directly derived from aids patients and have broader anti-hiv neutralizing activities. thus, the mper has been the focus of anti-hiv vaccine design and development. however, it has been unsuccessful to generate anti-hiv neutralizing antibodies targeting this region. one possible reason is that the mper-containing immunogens have failed to maintain the correct conf ...200616143433
the infectivity and host range of the ecotropic porcine endogenous retrovirus, perv-c, is modulated by residues in the c-terminal region of its surface envelope protein.endogenous retroviral genetic material serves as a reservoir for the generation of retroviral pathogens by recombination between activated endogenous or exogenous infectious agents. some porcine tissues actively express infectious porcine endogenous retroviruses (pervs). of the three classes of perv characterized to date, two, perv-a and b, are capable of infecting human cells in vitro, whereas perv-c cannot. here, we demonstrate that the perv-c envelope surface protein (su) when disassociated f ...200616309725
variation of host cell tropism of porcine endogenous retroviruses expressed in chinese banna minipig inbred.a serious donor-organ shortage urges the use of animal donors to treat a wide appropriate variety of major health problems including organ failure and diabetes. however, the promise of clinical xenotransplantation is offset at the present time by the potential of a public health risk due to the cross-species transmission of pathogens from animal donors to human patients. in particular, the transmission of porcine endogenous retrovirus (perv) is a major concern. in this study, cell tropism of per ...200616407655
antibodies neutralizing feline leukaemia virus (felv) in cats immunized with the transmembrane envelope protein p15e.the feline leukaemia virus (felv) vaccines that are currently in wide use are generally poor inducers of virus-neutralizing antibodies, although such antibodies appear after recovering from challenge. however, the presence of neutralizing antibodies in cats recovering from natural felv infection clearly correlates with resistance to subsequent infection and passive transfer of antibodies can protect other animals. after demonstrating the induction of neutralizing antibodies in rats and goats imm ...200616423059
an69 hollow fiber membrane will reduce but not abolish the risk of transmission of porcine endogenous retroviruses.as the risk of porcine endogenous retrovirus (perv) infection is a major obstacle to the xenotransplantation of porcine tissue, we investigated whether an an69 hollow fibre membrane, used for islets of langerhans transplantation, could prevent the transfer of pervs and thus reduce the risk of perv infection. pk15 cells were used as a perv source. a specific and highly sensitive rcr was used for detection of a perv provirus dna (gag region) and a porcine mtdna. human u293 cells were incubated in ...200516454349
[intergration and epression of porcine endogenous retrovinus in the immortal cell line of banna minipig inberd line-mesenhymal stem cells].to detect the integration and expression of porcine endogenous retrovirus (perv) in the immortal cell line of banna minipig inbred line-mesenchymal stem cells (bmi-mscs).200516334548
pig islet xenotransplantation: activation of porcine endogenous retrovirus in the immediate post-transplantation period.porcine endogenous retroviruses (perv) are considered as the main infectious barrier in islet xenotransplantation. perv has been shown to infect, but not to cause symptomatic disease in mice after islet transplantation. in vivo activation of perv have so far not been examined. expression of perv was examined in adult and fetal porcine islets with or without the presence of known retroviral inducers or after transplantation to rats.200516202068
[effects of modified acellularization process on porcine endogenous retroviruses in porcine aorta valves].to study the effect of modified acellularization process on porcine endogenous retrovirus (perv) in porcine aorta valves (pavs).200516253188
the use of pancreas biopsy scoring provides reliable porcine islet yields while encapsulation permits the determination of microbiological safety.for clinical xenogenic islet transplantation to be successful, several requirements must be met. among them is a sizeable and reliable source of fully functional and microbiologically safe islets. the inherent variability among porcine pancreases, with respect to islet yield, prompted us to develop a biopsy score technique to determine the suitability of each pancreas for islet isolation processing. the biopsy score consists of an assessment of five variables: warm ischemia time, pancreas color, ...200516285251
intraperitoneal alginate-encapsulated neonatal porcine islets in a placebo-controlled study with 16 diabetic cynomolgus primates.a nonhuman primate model of diabetes is valuable for assessing porcine pancreatic islet transplants that might have clinical benefits in humans.200516298643
characterization of a monoclonal antibody specific to the gag protein of porcine endogenous retrovirus and its application in detecting the virus infection.the porcine endogenous retrovirus (perv) has drawn extensive attention recently, due to the widespread use of biomaterials of porcine origin in organ transplantation. this virus is present in all pig strains and has been demonstrated to be capable of infecting human cells in vitro. therefore, it is imperative to develop a highly sensitive and specific immunoassay for clinical surveillance in patients receiving xenotransplantation. we describe here the generation of a monoclonal antibody (mab) na ...200515681064
absence of perv infection in baboons after transgenic porcine liver perfusion.xenotransplantation offers great promise to supplement the shortage of human organs available for transplant, but cross-species infection is a substantial concern. porcine endogenous retrovirus (perv), in particular, is thought to pose a risk as a potential pathogen to humans. we evaluated whether perv is capable of infecting nonhuman primates in vivo after extracorporeal porcine liver perfusion (eclp).200515734478
transplantation of neonatal porcine islets and sertoli cells into nonimmunosuppressed nonhuman primates.a mexican group reported transplantation of cocultured neonatal porcine islets and sertoli cells resulting in insulin independence in nonimmunosuppressed type 1 diabetes patients. we have transplanted similar islets alone (naked islets) or cocultured islets with sertoli cells (islet/sertoli cells) into an omental site and other locations of seven nondiabetic, nonimmunosuppressed, nonhuman primates. porcine endogenous retrovirus was not detected in recipient blood 8 weeks after porcine islet graf ...200515808684
long-term effects on hek-293 cell line after co-culture with porcine endogenous retrovirus.xenotransplantation of pig organs, tissues, and cells bears the risk of interspecies transmission of porcine endogenous retrovirus (perv). to evaluate the long-term effect of perv infection on human cells, human embryonic kidney cell line hek-293 cells were co-cultured with perv produced by the porcine kidney pk15 cell line for 24 hours and the infected hek-293 cells were continually cultured for 6 months. perv-gag, pol gene and gag protein were detected in infected hek-293 cells by pcr and immu ...200515808688
the effect of complement regulatory protein expression on pig endothelial cells to porcine endogenous retrovirus lyses by human sera.expression of human complement regulatory proteins (crp) on pig endothelial cells (pec) has been useful to avoid hyperacute rejection by human sera. on the other hand, porcine endogenous retrovirus (perv) from pec transfectants with crp may acquire resistance to human sera. in this study, we investigated the effects of the transfected crp on perv neutralization and/or lysis by human sera.200515808690
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