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Existence of Two Distinct Infectious Endogenous Retroviruses in Domestic Cats and Their Different Strategies for Adaptation to Transcriptional Regulation. J Virol 2016; 90:9029-45. [PMID: 27466428 DOI: 10.1128/jvi.00716-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 07/22/2016] [Indexed: 01/17/2023] Open
Abstract
UNLABELLED Endogenous retroviruses (ERVs) are the remnants of ancient retroviral infections of germ cells. Previous work identified one of the youngest feline ERV groups, ERV-DC, and reported that two ERV-DC loci, ERV-DC10 and ERV-DC18 (ERV-DC10/DC18), can replicate in cultured cells. Here, we identified another replication-competent provirus, ERV-DC14, on chromosome C1q32. ERV-DC14 differs from ERV-DC10/DC18 in its phylogeny, receptor usage, and, most notably, transcriptional activities; although ERV-DC14 can replicate in cultured cells, it cannot establish a persistent infection owing to its low transcriptional activity. Furthermore, we examined ERV-DC transcription and its regulation in feline tissues. Quantitative reverse transcription-PCR (RT-PCR) detected extremely low ERV-DC10 expression levels in feline tissues, and bisulfite sequencing showed that 5' long terminal repeats (LTRs) of ERV-DC10/DC18 are significantly hypermethylated in feline blood cells. Reporter assays found that the 5'-LTR promoter activities of ERV-DC10/DC18 are high, whereas that of ERV-DC14 is low. This difference in promoter activity is due to a single substitution from A to T in the LTR, and reverse mutation at this nucleotide in ERV-DC14 enhanced its replication and enabled it to persistently infect cultured cells. Therefore, ERV-DC LTRs can be divided into two types based on this nucleotide, the A type or T type, which have strong or attenuated promoter activity, respectively. Notably, ERV-DCs with T-type LTRs, such as ERV-DC14, have expanded in the cat genome significantly more than A-type ERV-DCs, despite their low promoter activities. Our results provide insights into how the host controls potentially infectious ERVs and, conversely, how ERVs adapt to and invade the host genome. IMPORTANCE The domestic cat genome contains many endogenous retroviruses, including ERV-DCs. These ERV-DCs have been acquired through germ cell infections with exogenous retroviruses. Some of these ERV-DCs are still capable of producing infectious virions. Hosts must tightly control these ERVs because replication-competent viruses in the genome pose a risk to the host. Here, we investigated how ERV-DCs are adapted by their hosts. Replication-competent viruses with strong promoter activity, such as ERV-DC10 and ERV-DC18, were suppressed by promoter methylation in LTRs. On the other hand, replication-competent viruses with weak promoter activity, such as ERV-DC14, seemed to escape strict control via promoter methylation by the host. Interestingly, ERV-DCs with weak promoter activity, such as ERV-DC14, have expanded in the cat genome significantly more than ERV-DCs with strong promoter activity. Our results improve the understanding of the host-virus conflict and how ERVs adapt in their hosts over time.
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Nitta T, Ha D, Galvez F, Miyazawa T, Fan H. Human and murine APOBEC3s restrict replication of koala retrovirus by different mechanisms. Retrovirology 2015; 12:68. [PMID: 26253512 PMCID: PMC4528783 DOI: 10.1186/s12977-015-0193-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 07/23/2015] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Koala retrovirus (KoRV) is an endogenous and exogenous retrovirus of koalas that may cause lymphoma. As for many other gammaretroviruses, the KoRV genome can potentially encode an alternate form of Gag protein, glyco-gag. RESULTS In this study, a convenient assay for assessing KoRV infectivity in vitro was employed: the use of DERSE cells (initially developed to search for infectious xenotropic murine leukemia-like viruses). Using infection of DERSE and other human cell lines (HEK293T), no evidence for expression of glyco-gag by KoRV was found, either in expression of glyco-gag protein or changes in infectivity when the putative glyco-gag reading frame was mutated. Since glyco-gag mediates resistance of Moloney murine leukemia virus to the restriction factor APOBEC3, the sensitivity of KoRV (wt or putatively mutant for glyco-gag) to restriction by murine (mA3) or human APOBEC3s was investigated. Both mA3 and hA3G potently inhibited KoRV infectivity. Interestingly, hA3G restriction was accompanied by extensive G → A hypermutation during reverse transcription while mA3 restriction was not. Glyco-gag status did not affect the results. CONCLUSIONS These results indicate that the mechanisms of APOBEC3 restriction of KoRV by hA3G and mA3 differ (deamination dependent vs. independent) and glyco-gag does not play a role in the restriction.
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Affiliation(s)
- Takayuki Nitta
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, 92697-3905, USA.
- Cancer Research Institute, University of California, Irvine, Irvine, CA, 92697-3905, USA.
- Department of Biology, Savannah State University, 3219 College St, Savannah, GA, 31404-5254, USA.
| | - Dat Ha
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, 92697-3905, USA.
- Cancer Research Institute, University of California, Irvine, Irvine, CA, 92697-3905, USA.
| | - Felipe Galvez
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, 92697-3905, USA.
- Cancer Research Institute, University of California, Irvine, Irvine, CA, 92697-3905, USA.
| | - Takayuki Miyazawa
- Laboratory of Signal Transduction, Department of Cell Biology, Institute for Virus Research, Kyoto University, 53 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan.
| | - Hung Fan
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, 92697-3905, USA.
- Cancer Research Institute, University of California, Irvine, Irvine, CA, 92697-3905, USA.
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Glynn SA, Busch MP, Dodd RY, Katz LM, Stramer SL, Klein HG, Simmons G, Kleinman SH, Shurin SB. Emerging infectious agents and the nation's blood supply: responding to potential threats in the 21st century. Transfusion 2013; 53:438-54. [PMID: 22690676 PMCID: PMC3644861 DOI: 10.1111/j.1537-2995.2012.03742.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 04/23/2012] [Indexed: 12/01/2022]
Affiliation(s)
- Simone A Glynn
- Transfusion Medicine and Cellular Therapeutics Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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A multicenter blinded analysis indicates no association between chronic fatigue syndrome/myalgic encephalomyelitis and either xenotropic murine leukemia virus-related virus or polytropic murine leukemia virus. mBio 2012; 3:mBio.00266-12. [PMID: 22991430 PMCID: PMC3448165 DOI: 10.1128/mbio.00266-12] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The disabling disorder known as chronic fatigue syndrome or myalgic encephalomyelitis (CFS/ME) has been linked in two independent studies to infection with xenotropic murine leukemia virus-related virus (XMRV) and polytropic murine leukemia virus (pMLV). Although the associations were not confirmed in subsequent studies by other investigators, patients continue to question the consensus of the scientific community in rejecting the validity of the association. Here we report blinded analysis of peripheral blood from a rigorously characterized, geographically diverse population of 147 patients with CFS/ME and 146 healthy subjects by the investigators describing the original association. This analysis reveals no evidence of either XMRV or pMLV infection. Chronic fatigue syndrome/myalgic encephalomyelitis has an estimated prevalence of 42/10,000 in the United States, with annual direct medical costs of $7 billion. Here, the original investigators who found XMRV and pMLV (polytropic murine leukemia virus) in blood of subjects with this disorder report that this association is not confirmed in a blinded analysis of samples from rigorously characterized subjects. The increasing frequency with which molecular methods are used for pathogen discovery poses new challenges to public health and support of science. It is imperative that strategies be developed to rapidly and coherently address discoveries so that they can be carried forward for translation to clinical medicine or abandoned to focus resource investment more productively. Our study provides a paradigm for pathogen dediscovery that may be helpful to others working in this field.
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Delviks-Frankenberry K, Cingoz O, Coffin JM, Pathak VK. Recombinant origin, contamination, and de-discovery of XMRV. Curr Opin Virol 2012; 2:499-507. [PMID: 22818188 PMCID: PMC3426297 DOI: 10.1016/j.coviro.2012.06.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 06/28/2012] [Indexed: 01/20/2023]
Abstract
The discovery and de-discovery of the xenotropic murine leukemia virus-related virus (XMRV) has been a tumultuous roller-coaster ride for scientists and patients. The initial associations of XMRV with chronic fatigue syndrome and prostate cancer, while providing much hope and optimism, have now been discredited and/or retracted following overwhelming evidence that (1) numerous patient cohorts from around the world are XMRV-negative, (2) the initial reports of XMRV-positive patients were due to contamination with mouse DNA, XMRV plasmid DNA, or virus from the 22Rv1 cell line and (3) XMRV is a laboratory-derived virus generated in the mid 1990s through recombination during passage of a prostate tumor xenograft in immuno-compromised mice. While these developments are disappointing to scientists and patients, they provide a valuable road map of potential pitfalls to the would-be microbe hunters.
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Affiliation(s)
| | - Oya Cingoz
- Program in Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston MA
| | - John M. Coffin
- Program in Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston MA
| | - Vinay K. Pathak
- Viral Mutation Section, NCI, HIV DRP, Frederick National Laboratory for Cancer Research, Frederick, MD
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Zhou Y, Steffen I, Montalvo L, Lee TH, Zemel R, Switzer WM, Tang S, Jia H, Heneine W, Winkelman V, Tailor CS, Ikeda Y, Simmons G. Development and application of a high-throughput microneutralization assay: lack of xenotropic murine leukemia virus-related virus and/or murine leukemia virus detection in blood donors. Transfusion 2012; 52:332-42. [PMID: 22239212 DOI: 10.1111/j.1537-2995.2011.03519.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Xenotropic murine leukemia virus (MLV)-related virus (XMRV) and other related MLVs have been described with chronic fatigue syndrome and certain types of prostate cancer. In addition, prevalence rates as high as 7% have been reported in blood donors, raising the risk of transfusion-related transmission. Several laboratories have utilized microneutralization assays as a surrogate marker for detection of anti-MLV serologic responses--with up to 25% of prostate cancer patients reported to harbor neutralizing antibody responses. STUDY DESIGN AND METHODS We developed a high-throughput microneutralization assay for research studies on blood donors using retroviral vectors pseudotyped with XMRV-specific envelopes. Infection with these pseudotypes was neutralized by sera from both macaques and mice challenged with XMRV, but not preimmune serum. A total of 354 plasma samples from blood donors in the Reno/Tahoe area were screened for neutralization. RESULTS A total of 6.5% of donor samples gave moderate neutralization of XMRV, but not control pseudotypes. However, further testing by Western blot revealed no evidence of antibodies against MLVs in any of these samples. Furthermore, no evidence of infectious virus or viral nucleic acid was observed. CONCLUSION A microneutralization assay was developed for detection of XMRV and can be applied in a high-throughput format for large-scale studies. Although a proportion of blood donors demonstrated the ability to block XMRV envelope-mediated infection, we found no evidence that this inhibition was mediated by specific antibodies elicited by exposure to XMRV or MLV. It is likely that this moderate neutralization is mediated through another, nonspecific mechanism.
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Affiliation(s)
- Yanchen Zhou
- Blood Systems Research Institute, Department of Laboratory Medicine, University of California at San Francisco, San Francisco, California 94118, USA
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Del Prete GQ, Kearney MF, Spindler J, Wiegand A, Chertova E, Roser JD, Estes JD, Hao XP, Trubey CM, Lara A, Lee K, Chaipan C, Bess JW, Nagashima K, Keele BF, Macallister R, Smedley J, Pathak VK, KewalRamani VN, Coffin JM, Lifson JD. Restricted replication of xenotropic murine leukemia virus-related virus in pigtailed macaques. J Virol 2012; 86:3152-66. [PMID: 22238316 PMCID: PMC3302341 DOI: 10.1128/jvi.06886-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 12/21/2011] [Indexed: 11/20/2022] Open
Abstract
Although xenotropic murine leukemia virus-related virus (XMRV) has been previously linked to prostate cancer and myalgic encephalomyelitis/chronic fatigue syndrome, recent data indicate that results interpreted as evidence of human XMRV infection reflect laboratory contamination rather than authentic in vivo infection. Nevertheless, XMRV is a retrovirus of undefined pathogenic potential that is able to replicate in human cells. Here we describe a comprehensive analysis of two male pigtailed macaques (Macaca nemestrina) experimentally infected with XMRV. Following intravenous inoculation with >10(10) RNA copy equivalents of XMRV, viral replication was limited and transient, peaking at ≤2,200 viral RNA (vRNA) copies/ml plasma and becoming undetectable by 4 weeks postinfection, though viral DNA (vDNA) in peripheral blood mononuclear cells remained detectable through 119 days of follow-up. Similarly, vRNA was not detectable in lymph nodes by in situ hybridization despite detectable vDNA. Sequencing of cell-associated vDNA revealed extensive G-to-A hypermutation, suggestive of APOBEC-mediated viral restriction. Consistent with limited viral replication, we found transient upregulation of type I interferon responses that returned to baseline by 2 weeks postinfection, no detectable cellular immune responses, and limited or no spread to prostate tissue. Antibody responses, including neutralizing antibodies, however, were detectable by 2 weeks postinfection and maintained throughout the study. Both animals were healthy for the duration of follow-up. These findings indicate that XMRV replication and spread were limited in pigtailed macaques, predominantly by APOBEC-mediated hypermutation. Given that human APOBEC proteins restrict XMRV infection in vitro, human XMRV infection, if it occurred, would be expected to be characterized by similarly limited viral replication and spread.
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Affiliation(s)
| | - Mary F. Kearney
- HIV Drug Resistance Program, National Cancer Institute, Frederick, Maryland, USA
| | - Jon Spindler
- HIV Drug Resistance Program, National Cancer Institute, Frederick, Maryland, USA
| | - Ann Wiegand
- HIV Drug Resistance Program, National Cancer Institute, Frederick, Maryland, USA
| | | | | | | | | | | | | | - KyeongEun Lee
- HIV Drug Resistance Program, National Cancer Institute, Frederick, Maryland, USA
| | - Chawaree Chaipan
- HIV Drug Resistance Program, National Cancer Institute, Frederick, Maryland, USA
| | | | | | | | - Rhonda Macallister
- Laboratory Animal Science Program, SAIC—Frederick, Inc., National Cancer Institute, Frederick, Maryland, USA
| | - Jeremy Smedley
- Laboratory Animal Science Program, SAIC—Frederick, Inc., National Cancer Institute, Frederick, Maryland, USA
| | - Vinay K. Pathak
- HIV Drug Resistance Program, National Cancer Institute, Frederick, Maryland, USA
| | | | - John M. Coffin
- HIV Drug Resistance Program, National Cancer Institute, Frederick, Maryland, USA
- Department of Molecular Biology and Microbiology, Tufts University, Boston, Massachusetts, USA
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Multiple sources of contamination in samples from patients reported to have XMRV infection. PLoS One 2012; 7:e30889. [PMID: 22363509 PMCID: PMC3282701 DOI: 10.1371/journal.pone.0030889] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 12/22/2011] [Indexed: 11/22/2022] Open
Abstract
Xenotropic murine leukemia virus (MLV)-related retrovirus (XMRV) was reported to be associated with prostate cancer by Urisman, et al. in 2006 and chronic fatigue syndrome (CFS) by Lombardi, et al. in 2009. To investigate this association, we independently evaluated plasma samples from 4 patients with CFS reported by Lombardi, et al. to have XMRV infection and from 5 healthy controls reported to be XMRV uninfected. We also analyzed viral sequences obtained from supernatants of cell cultures found to contain XMRV after coculture with 9 clinical samples from 8 patients. A qPCR assay capable of distinguishing XMRV from endogenous MLVs showed that the viral sequences detected in the CFS patient plasma behaved like endogenous MLVs and not XMRV. Single-genome sequences (N = 89) from CFS patient plasma were indistinguishable from endogenous MLVs found in the mouse genome that are distinct from XMRV. By contrast, XMRV sequences were detected by qPCR in 2 of the 5 plasma samples from healthy controls (sequencing of the qPCR product confirmed XMRV not MLV). Single-genome sequences (N = 234) from the 9 culture supernatants reportedly positive for XMRV were indistinguishable from XMRV sequences obtained from 22Rv1 and XMRV-contaminated 293T cell-lines. These results indicate that MLV DNA detected in the plasma samples from CFS patients evaluated in this study was from contaminating mouse genomic DNA and that XMRV detected in plasma samples from healthy controls and in cultures of patient samples was due to cross-contamination with XMRV (virus or nucleic acid).
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Abstract
Xenotropic murine leukemia virus-related virus (XMRV) was previously reported to be associated with human prostate cancer and chronic fatigue syndrome. Our groups recently showed that XMRV was created through recombination between two endogenous murine retroviruses, PreXMRV-1 and PreXMRV-2, during the passaging of a prostate tumor xenograft in nude mice. Here, multiple approaches that led to the identification of PreXMRV-2, as well as the distribution of both parental proviruses among different mouse species, are described. The chromosomal loci of both proviruses were determined in the mouse genome, and integration site information was used to analyze the distribution of both proviruses in 48 laboratory mouse strains and 46 wild-derived strains. The strain distributions of PreXMRV-1 and PreXMRV-2 are quite different, the former being found predominantly in Asian mice and the latter in European mice, making it unlikely that the two XMRV ancestors could have recombined independently in the wild to generate an infectious virus. XMRV was not present in any of the mouse strains tested, and among the wild-derived mouse strains analyzed, not a single mouse carried both parental proviruses. Interestingly, PreXMRV-1 and PreXMRV-2 were found together in three laboratory strains, Hsd nude, NU/NU, and C57BR/cd, consistent with previous data that the recombination event that led to the generation of XMRV could have occurred only in the laboratory. The three laboratory strains carried the Xpr1(n) receptor variant nonpermissive to XMRV and xenotropic murine leukemia virus (X-MLV) infection, suggesting that the xenografted human tumor cells were required for the resulting XMRV recombinant to infect and propagate.
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