scholarly journals Packaging of Endogenous Retroviral Sequences in Retroviral Vectors Produced by Murine and Human Packaging Cells

1998 ◽  
Vol 72 (4) ◽  
pp. 2671-2676 ◽  
Author(s):  
Clive Patience ◽  
Yasuhiro Takeuchi ◽  
Francois-Loic Cosset ◽  
Robin A. Weiss
Keyword(s):  
Cell Lines ◽  
Leukemia Virus ◽  
Retroviral Vectors ◽  
Endogenous Retrovirus ◽  
Endogenous Retroviruses ◽  
Human Endogenous Retrovirus ◽  
Target Cells ◽  
Gag Proteins ◽  
Packaging Cell ◽  
Vector Particles

ABSTRACT Interaction of retrovirus vectors and endogenous retroviruses present in packaging cell lines and target cells may result in unwanted events, such as the formation of recombinant viruses and the mobilization of therapeutic vectors. Using sensitive reverse transcriptase PCR assays, we investigated human and murine gene therapy packaging cell lines for incorporation of endogenous retrovirus transcripts into murine leukemia virus (MLV) vector particles and, conversely, whether vector genomes are incorporated into human endogenous retrovirus (HERV) particles. VL30 endogenous retrovirus sequences were efficiently packaged in particles produced by the murine AM12 packaging system. For every seven MLV-derived β-galactosidase (β-Gal) vector genomes present in the particles, one copy of VL30 was also packaged. Although human FLY packaging cells expressed several classes of HERV transcripts (HERV-K, HuRT, type C, and RTVL-H), none was detectable in the MLV vector particles released from the cells. Nonspecific packaging of the MLV Gag-Pol expression vector transcripts was detected in the FLY virions at a low level (1 in 17,000 sequences). These findings indicate that human packaging cells produce retrovirus particles far less contaminated by endogenous viral sequences than murine packaging cells. Human teratocarcinoma cells (GH cells), which produce HERV-K particles, were transduced with an MLV-derived β-Gal vector. Although both HERV-K and RTVL-H sequences were found in association with the particles, β-Gal transcripts were not detected, indicating that HERV Gag proteins do not efficiently package MLV-based vectors.

The potential of retroviral vectors to cotransfer human endogenous retroviruses (HERVs) from human packaging cell lines

Gene ◽  
2007 ◽  
Vol 390 (1-2) ◽  
pp. 175-179 ◽  
Author(s):  
Udo Zeilfelder ◽  
Oliver Frank ◽  
Sandra Sparacio ◽  
Ulrike Schön ◽  
Valerie Bosch ◽  
...  
Keyword(s):  
Cell Lines ◽  
Retroviral Vectors ◽  
Endogenous Retroviruses ◽  
Human Endogenous Retroviruses ◽  
Packaging Cell

scholarly journals Human endogenous retrovirus-W envelope (syncytin) is expressed in both villous and extravillous trophoblast populations

2006 ◽  
Vol 87 (7) ◽  
pp. 2067-2071 ◽  
Author(s):  
A. Muir ◽  
A. M. L. Lever ◽  
A. Moffett
Keyword(s):  
Cell Lines ◽  
First Trimester ◽  
Endogenous Retrovirus ◽  
Endogenous Retroviruses ◽  
Extravillous Trophoblast ◽  
Human Endogenous Retrovirus ◽  
Human Trophoblast ◽  
Human Endogenous Retroviruses ◽  
Normal Tissues ◽  
Villous Trophoblast

The placenta is unique amongst normal tissues in transcribing numerous different human endogenous retroviruses at high levels. In this study, RT-PCR and immunohistochemistry were used to investigate the expression of syncytin in human trophoblast. Syncytin transcripts were found in first-trimester trophoblast cells with both villous and extravillous phenotypes and also in the JAR and JEG-3 choriocarcinoma cell lines. Syncytin protein was detected in villous trophoblast and in all extravillous trophoblast subpopulations of first- and second-trimester placental tissues. It was also present in ectopic trophoblast from tubal implantations. This study confirms that syncytin is expressed widely by a variety of normal human trophoblast populations, as well as choriocarcinoma cell lines.

scholarly journals Human endogenous retrovirus transcription profiles of the kidney and kidney-derived cell lines

2011 ◽  
Vol 92 (10) ◽  
pp. 2356-2366 ◽  
Author(s):  
Sonja Haupt ◽  
Michele Tisdale ◽  
Michelle Vincendeau ◽  
Mary Anne Clements ◽  
David T. Gauthier ◽  
...  
Keyword(s):  
Cell Culture ◽  
Cell Line ◽  
Cell Lines ◽  
Kidney Tissue ◽  
Human Kidney ◽  
Endogenous Retrovirus ◽  
Endogenous Retroviruses ◽  
Human Endogenous Retrovirus ◽  
Tissue Samples ◽  
Transcription Pattern

The human genome comprises approximately 8–9 % of human endogenous retroviruses (HERVs) that are transcribed with tissue specificity. However, relatively few organs have been examined in detail for individual differences in HERV transcription pattern, nor have tissue-to-cell culture comparisons been frequently performed. Using an HERV-specific DNA microarray, a core HERV transcription profile was established for the human kidney comparing 10 tissue samples. This core represents HERV groups expressed uniformly or nearly so in non-tumour kidney tissue. The profiles obtained from non-tumour tissues were compared to 10 renal tumour tissues (renal cell carcinoma, RCC) derived from the same individuals and additionally, to 22 RCC cell lines. No RCC cell line or tumour-specific differences were observed, suggesting that HERV transcription is not altered in RCC. However, when comparing tissue transcription to cell line transcription, there were consistent differences. The differences were irrespective of cancer state and included cell lines derived from non-tumour kidney tissue, suggesting that a specific alteration of HERV transcription occurs when establishing cell lines. In contrast to previous publications, all known HERV-derived tumour antigens, including those identified in RCC, were expressed both in multiple RCC cell lines and several non-tumour tissue-derived cell lines, a result that contrasts with findings from patient samples. The results establish the core kidney transcription pattern of HERVs and reveal differences between cell culture lines and tissue samples.

scholarly journals Human Endogenous Retrovirus Type K (HERV-K) Particles Package and Transmit HERV-K–Related Sequences

2015 ◽  
Vol 89 (14) ◽  
pp. 7187-7201 ◽  
Author(s):  
Rafael Contreras-Galindo ◽  
Mark H. Kaplan ◽  
Derek Dube ◽  
Marta J. Gonzalez-Hernandez ◽  
Susana Chan ◽  
...  
Keyword(s):  
Human Genome ◽  
Reverse Transcription ◽  
Peripheral Blood Lymphocytes ◽  
Endogenous Retrovirus ◽  
Endogenous Retroviruses ◽  
Human Endogenous Retrovirus ◽  
Breast Cancer Cell Lines ◽  
Target Cells ◽  
Virus Particles ◽  
Cellular Genome

ABSTRACTHuman endogenous retroviruses (HERV) make up 8% of the human genome. While the youngest of these retroviruses, HERV-K(HML-2), termed HK2, is able to code for all viral proteins and produce virus-like particles, it is not known if these virus particles package and transmit HK2-related sequences. Here, we analyzed the capacity of HK2 for packaging and transmitting HK2 sequences. We created an HK2 probe, termed Bogota, which can be packaged into HK2 viruses, and transfected it into cells that make HK2 particles. Supernatants of the transfected cells, which contained HK2 viral particles, then were added to target cells, and the transmissibility of the HK2 Bogota reporter was tracked by G418 resistance. Our studies revealed that contemporary HK2 virions produced by some teratocarcinoma and breast cancer cell lines, as well as by peripheral blood lymphocytes from lymphoma patients, can package HK2 Bogota probes, and these viruses transmitted these probes to other cells. After transmission, HK2 Bogota transcripts undergo reverse transcription, a step impaired by antiretroviral agents or by introduction of mutations into the probe sequences required for reverse transcription. HK2 viruses were more efficiently transmitted in the presence of HK2 Rec or HIV-1 Tat and Vif. Transmitted Bogota probes formed episomes but did not integrate into the cellular genome. Resistance to integration might explain the relatively low number of HK2 insertions that were acquired during the last 25 million years of evolution. Whether transient transmission of modern HK2 sequences, which encode two putative oncoproteins, can lead to disease remains to be studied.IMPORTANCERetroviruses invaded the genome of human ancestors over the course of millions of years, yet these viruses generally have been inactivated during evolution, with only remnants of these infectious sequences remaining in the human genome. One of these viruses, termed HK2, still is capable of producing virus particles, although these particles have been regarded as being noninfectious. Using a genetic probe derived from HK2, we have discovered that HK2 viruses produced in modern humans can package HK2 sequences and transmit them to various other cells. Furthermore, the genetic sequences packaged in HK2 undergo reverse transcription. The transmitted probe circularized in the cell and failed to integrate into the cellular genome. These findings suggest that modern HK2 viruses can package viral RNA and transmit it to other cells. Contrary to previous views, we provide evidence of an extracellular viral phase of modern HK2 viruses. We have no evidence of sustained, spreading infection.

scholarly journals Human Endogenous Retroviral Long Terminal Repeat Sequences as Cell Type-Specific Promoters in Retroviral Vectors

2009 ◽  
Vol 83 (23) ◽  
pp. 12643-12650 ◽  
Author(s):  
Ulrike Schön ◽  
Olivia Diem ◽  
Laura Leitner ◽  
Walter H. Günzburg ◽  
Dixie L. Mager ◽  
...  
Keyword(s):  
Transcriptional Control ◽  
Leukemia Virus ◽  
Cell Types ◽  
Retroviral Vectors ◽  
Endogenous Retrovirus ◽  
Human Endogenous Retrovirus ◽  
Cell Type ◽  
Specific Expression ◽  
Hybrid Vectors ◽  
Cell Type Specific

ABSTRACT The human genome contains more than half a million human endogenous retrovirus (HERV) long terminal repeats (LTRs) that can be regarded as mobile regulatory modules. Many of these HERV LTRs have been recruited during evolution as transcriptional control elements for cellular gene expression. We have cloned LTR sequences from two HERV families, HERV-H and HERV-L, differing widely in their activity and tissue specificity into a murine leukemia virus (MLV)-based promoter conversion vector (ProCon). Various human cell lines were infected with the HERV-MLV hybrid vectors, and cell type-specific expression of the reporter gene was compared with the promoter specificity of the corresponding HERV LTRs in transient-transfection assays. Transcription start site analysis of HERV-MLV hybrid vectors revealed preferential use of the HERV promoter initiation site. Our data show that HERV LTRs function in the context of retroviral vectors in certain cell types and have the potential to be useful as cell type-specific promoters in vector construction.

scholarly journals Presence of a Shared 5′-Leader Sequence in Ancestral Human and Mammalian Retroviruses and Its Transduction into Feline Leukemia Virus

2017 ◽  
Vol 91 (20) ◽  
Author(s):  
Junna Kawasaki ◽  
Maki Kawamura ◽  
Yoshiharu Ohsato ◽  
Jumpei Ito ◽  
Kazuo Nishigaki
Keyword(s):  
Leukemia Virus ◽  
Rapid Evolution ◽  
Viral Disease ◽  
Endogenous Retrovirus ◽  
Middle Part ◽  
Endogenous Retroviruses ◽  
Feline Leukemia Virus ◽  
Human Endogenous Retrovirus ◽  
Content Type ◽  
Genetic Feature

ABSTRACT Recombination events induce significant genetic changes, and this process can result in virus genetic diversity or in the generation of novel pathogenicity. We discovered a new recombinant feline leukemia virus (FeLV) gag gene harboring an unrelated insertion, termed the X region, which was derived from Felis catus endogenous gammaretrovirus 4 (FcERV-gamma4). The identified FcERV-gamma4 proviruses have lost their coding capabilities, but some can express their viral RNA in feline tissues. Although the X-region-carrying recombinant FeLVs appeared to be replication-defective viruses, they were detected in 6.4% of tested FeLV-infected cats. All isolated recombinant FeLV clones commonly incorporated a middle part of the FcERV-gamma4 5′-leader region as an X region. Surprisingly, a sequence corresponding to the portion contained in all X regions is also present in at least 13 endogenous retroviruses (ERVs) observed in the cat, human, primate, and pig genomes. We termed this shared genetic feature the commonly shared (CS) sequence. Despite our phylogenetic analysis indicating that all CS-sequence-carrying ERVs are classified as gammaretroviruses, no obvious closeness was revealed among these ERVs. However, the Shannon entropy in the CS sequence was lower than that in other parts of the provirus genome. Notably, the CS sequence of human endogenous retrovirus T had 73.8% similarity with that of FcERV-gamma4, and specific signals were detected in the human genome by Southern blot analysis using a probe for the FcERV-gamma4 CS sequence. Our results provide an interesting evolutionary history for CS-sequence circulation among several distinct ancestral viruses and a novel recombined virus over a prolonged period. IMPORTANCE Recombination among ERVs or modern viral genomes causes a rapid evolution of retroviruses, and this phenomenon can result in the serious situation of viral disease reemergence. We identified a novel recombinant FeLV gag gene that contains an unrelated sequence, termed the X region. This region originated from the 5′ leader of FcERV-gamma4, a replication-incompetent feline ERV. Surprisingly, a sequence corresponding to the X region is also present in the 5′ portion of other ERVs, including human endogenous retroviruses. Scattered copies of the ERVs carrying the unique genetic feature, here named the commonly shared (CS) sequence, were found in each host genome, suggesting that ancestral viruses may have captured and maintained the CS sequence. More recently, a novel recombinant FeLV hijacked the CS sequence from inactivated FcERV-gamma4 as the X region. Therefore, tracing the CS sequences can provide unique models for not only the modern reservoir of new recombinant viruses but also the genetic features shared among ancient retroviruses.

scholarly journals A Human Endogenous Retrovirus Suppresses Translation of an Associated Fusion Transcript, PLA2L

1998 ◽  
Vol 72 (7) ◽  
pp. 6164-6168 ◽  
Author(s):  
Paul E. Kowalski ◽  
Dixie L. Mager
Keyword(s):  
Cell Lines ◽  
Fusion Transcript ◽  
Endogenous Retrovirus ◽  
Full Length ◽  
Endogenous Retroviruses ◽  
Human Endogenous Retrovirus ◽  
Stem Loop ◽  
Teratocarcinoma Cell ◽  
Reading Frame ◽  
High Level

ABSTRACT Human endogenous retroviruses (HERVs) are repetitive, noninfectious chromosomal elements degenerated from exogenous retroviruses. The HERV-H family is composed of approximately 1,000 elements which are dispersed throughout the human genome. We have shown previously that an HERV-H element splices into a downstream locus, termed PLA2L, which has a large open reading frame (ORF) containing two domains with phospholipase A2 homology. Over half of the putative 5′ untranslated region (5′ UTR) of the resulting fusion transcript is derived from HERV-H long-terminal-repeat and internal sequences. As 5′ UTRs are known to modulate translation initiation, we tested for possible effects upon gene expression at the translation level due to the 5′ fusion with HERV-H sequences. No PLA2L protein was detected in teratocarcinoma cell lines in which PLA2L mRNA is abundantly expressed. In addition, despite a high level of transcription, no protein synthesis was detected when the full-length PLA2L cDNA was expressed in COS cells. Upon removal of the 5′-terminal HERV-H sequences, PLA2L protein was seen in transfectants. The 5′ UTR contains both small ORFs and a strong predicted RNA secondary structure, both of which have been shown to contribute to translation suppression. The HERV-H sequences, combined with a unique PLA2L 5′ UTR sequence, form a predicted RNA stem-loop that has a stability greater than that proposed to negatively affect translation. Interestingly, this stem-loop is abolished when the HERV-H sequences are removed. We hypothesize that the PLA2L 5′ HERV-H sequences function as an abnormally long and complex 5′ UTR, resulting in suppression of translation in both teratocarcinoma cell lines and full-length cDNA transfectants. This is the first known example of a endogenous retrovirus integration affecting expression of a heterologous human gene at the translational level.

scholarly journals HERV-K Gag RNA and Protein Levels Are Elevated in Malignant Regions of the Prostate in Males with Prostate Cancer

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 449
Author(s):  
Simin D. Rezaei ◽  
Joshua A. Hayward ◽  
Sam Norden ◽  
John Pedersen ◽  
John Mills ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cell Lines ◽  
Endogenous Retrovirus ◽  
Human Endogenous Retrovirus ◽  
Normal Prostate ◽  
Tissue Samples ◽  
Gag Protein ◽  
Protein Levels ◽  
Prostate Epithelial Cells ◽  
Prostate Cancers

Heightened expression of human endogenous retrovirus (HERV) sequences has been associated with a range of malignancies, including prostate cancer, suggesting that they may serve as useful diagnostic or prognostic cancer biomarkers. We analysed the expression of HERV-K (Gag and Env/Np9 regions), HERV-E 4.1 (Pol and Env regions), HERV-H (Pol) and HERV-W (Gag) sequences in prostate cancer cells lines and normal prostate epithelial cells using qRT-PCR. HERV expression was also analysed in matched malignant and benign prostate tissue samples from men with prostate cancer (n = 27, median age 65.2 years (range 47–70)) and compared to prostate cancer-free male controls (n = 11). Prostate cancer epithelial cell lines exhibited a signature of HERV RNA overexpression, with all HERVs analysed, except HERV-E Pol, showing heightened expression in at least two, but more commonly all, cell lines analysed. Analysis of primary prostate material indicated increased expression of HERV-E Pol but decreased expression of HERV-E Env in both malignant and benign regions of the prostate in men with prostate cancer as compared to those without. Expression of HERV-K Gag was significantly higher in malignant regions of the prostate in men with prostate cancer as compared to matched benign regions and prostate cancer-free men (p < 0.001 for both), with 85.2% of prostate cancers donors showing malignancy-associated upregulation of HERV-K Gag RNA. HERV-K Gag protein was detected in 12/18 (66.7%) malignant tissues using immunohistochemistry, but only 1/18 (5.6%) benign tissue sections. Heightened expression of HERV-K Gag RNA and protein appears to be a sensitive and specific biomarker of prostate malignancy in this cohort of men with prostate carcinoma, supporting its potential utility as a non-invasive, adjunct clinical biomarker.

scholarly journals Human Endogenous Retrovirus Reactivation: Implications for Cancer Immunotherapy

Cancers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1999
Author(s):  
Annacarmen Petrizzo ◽  
Concetta Ragone ◽  
Beatrice Cavalluzzo ◽  
Angela Mauriello ◽  
Carmen Manolio ◽  
...  
Keyword(s):  
Cancer Immunotherapy ◽  
Genetic Material ◽  
Endogenous Retrovirus ◽  
Endogenous Retroviruses ◽  
Human Endogenous Retrovirus ◽  
Danger Signal ◽  
Human Endogenous Retroviruses ◽  
Double Stranded Rna ◽  
Specific Antigens ◽  
Viral Mimicry

Human endogenous retroviruses (HERVs) derive from ancestral exogenous retroviruses whose genetic material has been integrated in our germline DNA. Several lines of evidence indicate that cancer immunotherapy may benefit from HERV reactivation, which can be induced either by drugs or by cellular changes occurring in tumor cells. Indeed, several studies indicate that HERV proviral DNA can be transcribed either to double-stranded RNA (dsRNA) that is sensed as a “danger signal” by pattern recognition receptors (PRRs), leading to a viral mimicry state, or to mRNA that is translated into proteins that may contribute to the landscape of tumor-specific antigens (TSAs). Alternatively, HERV reactivation is associated with the expression of long noncoding RNAs (lncRNAs). In this review, we will highlight recent findings on HERV reactivation in cancer and its implications for cancer immunotherapy.

scholarly journals Identification and Characterization of Novel Human Endogenous Retrovirus Families by Phylogenetic Screening of the Human Genome Mapping Project Database

2000 ◽  
Vol 74 (8) ◽  
pp. 3715-3730 ◽  
Author(s):  
Michael Tristem
Keyword(s):  
Human Genome ◽  
Genome Mapping ◽  
Sequence Data ◽  
Endogenous Retrovirus ◽  
Endogenous Retroviruses ◽  
Human Endogenous Retrovirus ◽  
Sequence Information ◽  
Class Iii ◽  
Genome Mapping Project ◽  
Human Genome Mapping Project

ABSTRACT Human endogenous retroviruses (HERVs) were first identified almost 20 years ago, and since then numerous families have been described. It has, however, been difficult to obtain a good estimate of both the total number of independently derived families and their relationship to each other as well as to other members of the familyRetroviridae. In this study, I used sequence data derived from over 150 novel HERVs, obtained from the Human Genome Mapping Project database, and a variety of recently identified nonhuman retroviruses to classify the HERVs into 22 independently acquired families. Of these, 17 families were loosely assigned to the class I HERVs, 3 to the class II HERVs and 2 to the class III HERVs. Many of these families have been identified previously, but six are described here for the first time and another four, for which only partial sequence information was previously available, were further characterized. Members of each of the 10 families are defective, and calculation of their integration dates suggested that most of them are likely to have been present within the human lineage since it diverged from the Old World monkeys more than 25 million years ago.

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