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Materniak-Kornas M, Kubiś P, Sell B, Pougialis G, Löchelt M, Kuźmak J. An Outbred Calf Model for Determining Innate Immune Sensing and Evolutionary Trajectories of a Cell Culture-Adapted Bovine Foamy Virus Variant. Viruses 2023; 15:1772. [PMID: 37632114 PMCID: PMC10458543 DOI: 10.3390/v15081772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/10/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023] Open
Abstract
Bovine foamy virus (BFVbta) displays a very high degree of cell-associated replication which is unprecedented even among the other known foamy viruses. Interestingly, recent studies have shown that it can in fact adapt in vitro to high-titer (HT) cell-free transmission due to genetic changes acquired during repeated rounds of cell-free BFVbta passages in immortalized bovine MDBK cells. Molecular clones obtained from the HT BFVbta Riems cell-free variant (HT BFVbta Riems) have been thoroughly characterized in MDBK cell cultures However, during recent years, it has become increasingly clear that the source of the host cells used for virus growth and functional studies of virus replication and virus-cell interactions plays a paramount role. Established cell lines, mostly derived from tumors, but occasionally experimentally immortalized and transformed, frequently display aberrant features relating, for example. to growth, metabolism, and genetics. Even state-of-the-art organoid cultures of primary cells cannot replicate the conditions in an authentic host, especially those concerning cell diversity and the role of innate and adaptive immunity. Therefore, to determine the overall replication characteristics of the cloned wt and HT BFVbta Riems variant, we conducted a small-scale animal pilot study. The replication of the original wt BFVbta Riems isolate, as well as that of its HT variant, were analyzed. Both BFVbta variants established infection in calves, with proviruses in peripheral blood mononuclear cells and induced Gag-specific antibodies. In addition, a related pattern in the host innate immune reaction was detected in the peripheral blood leukocytes of the BFV-infected calves. Surprisingly, an analysis of the Gag sequence two weeks post-inoculation revealed that the HT BFVbta variant showed a very high level of genetic reversion to the wild type (parental BFVbta genotype).
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Affiliation(s)
- Magdalena Materniak-Kornas
- Department of Biochemistry, National Veterinary Research Institute, 24-100 Pulawy, Poland; (P.K.); (J.K.)
| | - Piotr Kubiś
- Department of Biochemistry, National Veterinary Research Institute, 24-100 Pulawy, Poland; (P.K.); (J.K.)
| | - Bartosz Sell
- Department of Pharmacology and Toxicology, National Veterinary Research Institute, 24-100 Pulawy, Poland;
| | - Georgios Pougialis
- Division of Viral Transformation Mechanisms, Research Program Infection, Inflammation and Cancer, German Cancer Research Center, 69120 Heidelberg, Germany; (G.P.); (M.L.)
| | - Martin Löchelt
- Division of Viral Transformation Mechanisms, Research Program Infection, Inflammation and Cancer, German Cancer Research Center, 69120 Heidelberg, Germany; (G.P.); (M.L.)
- Division of Virus-Associated Carcinogenesis, Research Program Infection, Inflammation and Cancer, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Jacek Kuźmak
- Department of Biochemistry, National Veterinary Research Institute, 24-100 Pulawy, Poland; (P.K.); (J.K.)
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Occurrence of Equine Foamy Virus Infection in Horses from Poland. Viruses 2022; 14:v14091973. [PMID: 36146781 PMCID: PMC9504846 DOI: 10.3390/v14091973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 11/28/2022] Open
Abstract
Equine foamy virus (EFVeca) is a foamy virus of non-primate origin and among the least-studied members of this retroviral subfamily. By sequence comparison, EFVeca shows the highest similarity to bovine foamy virus. In contrast to simian, bovine or feline foamy viruses, knowledge about the epidemiology of EFVeca is still limited. Since preliminary studies suggested EFVeca infections among horses in Poland, we aimed to expand the diagnostics of EFVeca infections by developing specific diagnostic tools and apply them to investigate its prevalence. An ELISA test based on recombinant EFVeca Gag protein was developed for serological investigation, while semi-nested PCR for the detection of EFVeca DNA was established. 248 DNA and serum samples from purebred horses, livestock and saddle horses, Hucul horses and semi-feral Polish primitive horses were analyzed in this study. ELISA was standardized, and cut off value, sensitivity and specificity of the test were calculated using Receiver Operating Characteristic and Bayesian estimation. Based on the calculated cut off, 135 horses were seropositive to EFVeca Gag protein, while EFVeca proviral DNA was detected in 85 animals. The rate of infected individuals varied among the horse groups studied; this is the first report confirming the existence of EFVeca infections in horses from Poland using virus-specific tools.
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Seroprevalence of feline foamy virus in domestic cats in Poland. J Vet Res 2021; 65:407-413. [PMID: 35111993 PMCID: PMC8775732 DOI: 10.2478/jvetres-2021-0059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 10/25/2021] [Indexed: 11/20/2022] Open
Abstract
Abstract
Introduction
Feline foamy virus (FFVfca) is widespread and its prevalence in naturally infected domestic cats ranges between 30% and 80% worldwide. The infection is persistent, with a sustained antibody response in FFVfca-positive cats; however to date, no defined disease or clinical symptoms have been proved to be associated with it. The goal of the presented study was to determine the prevalence of FFVfca infection in domestic cats in Poland.
Material and Methods
A total of 223 serum samples collected from domestic cats were tested with a glutathione S-transferase capture ELISA test to detect antibodies specific to capsid (Gag), accessory (Bet) and envelope (Env) FFVfca antigens. A Western blot test was used to confirm the ELISA results.
Results
The cut-off value for the Gag antigen was established by calculation and evaluation with the immunoblotting assay. The cut-off values for Bet and Env were calculated from the reactivity of Gag-negative samples. The sera of 99 cats (44%) showed reactivity to Gag, those of 80 did so (35.9 %) to Bet, while only 56 samples (25%) were reactive to Env. Only 51 (22.9%) sera were positive for all antigens. The main diagnostic antigen was selected to be Gag. A statistically significant association was found between FFVfca status and the age of the cat.
Conclusions
This study proved the high seroprevalence of FFVfca in domestic cats in Poland for the first time and confirmed that adult cats are at higher FFVfca infection risk than preadult cats. Its results correspond to those reported from other countries.
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Jaguva Vasudevan AA, Becker D, Luedde T, Gohlke H, Münk C. Foamy Viruses, Bet, and APOBEC3 Restriction. Viruses 2021; 13:504. [PMID: 33803830 PMCID: PMC8003144 DOI: 10.3390/v13030504] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/10/2021] [Accepted: 03/16/2021] [Indexed: 01/24/2023] Open
Abstract
Non-human primates (NHP) are an important source of viruses that can spillover to humans and, after adaptation, spread through the host population. Whereas HIV-1 and HTLV-1 emerged as retroviral pathogens in humans, a unique class of retroviruses called foamy viruses (FV) with zoonotic potential are occasionally detected in bushmeat hunters or zookeepers. Various FVs are endemic in numerous mammalian natural hosts, such as primates, felines, bovines, and equines, and other animals, but not in humans. They are apathogenic, and significant differences exist between the viral life cycles of FV and other retroviruses. Importantly, FVs replicate in the presence of many well-defined retroviral restriction factors such as TRIM5α, BST2 (Tetherin), MX2, and APOBEC3 (A3). While the interaction of A3s with HIV-1 is well studied, the escape mechanisms of FVs from restriction by A3 is much less explored. Here we review the current knowledge of FV biology, host restriction factors, and FV-host interactions with an emphasis on the consequences of FV regulatory protein Bet binding to A3s and outline crucial open questions for future studies.
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Affiliation(s)
- Ananda Ayyappan Jaguva Vasudevan
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany;
| | - Daniel Becker
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; (D.B.); (H.G.)
| | - Tom Luedde
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany;
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany; (D.B.); (H.G.)
- John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre & Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Carsten Münk
- Clinic for Gastroenterology, Hepatology and Infectiology, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany;
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5
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Gessain A, Montange T, Betsem E, Bilounga Ndongo C, Njouom R, Buseyne F. Case-Control Study of the Immune Status of Humans Infected With Zoonotic Gorilla Simian Foamy Viruses. J Infect Dis 2021; 221:1724-1733. [PMID: 31822908 DOI: 10.1093/infdis/jiz660] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 12/10/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Zoonotic simian foamy viruses (SFVs) establish persistent infections in humans, for whom the long-term consequences for health are poorly described. In this study, we aimed to characterize blood-cell phenotypes and plasma biomarkers associated with gorilla SFV infection in humans. METHODS We used a case-control design to compare 15 Cameroonian hunters infected with gorilla SFV (cases) to 15 controls matched for age and ethnicity. A flow cytometry-based phenotypic study and quantification of plasma immune biomarkers were carried out on blood samples from all participants. Wilcoxon signed-rank tests were used to compare cases and controls. RESULTS Cases had a significantly higher percentage of CD8 T lymphocytes than controls (median, 17.6% vs 13.7%; P = .03) but similar levels of B, natural killer, and CD4 T lymphocytes. Cases also had a lower proportion of recent CD4 thymic emigrants (10.9% vs 18.6%, P = .05), a higher proportion of programmed death receptor 1 (PD-1) expressing memory CD4 T lymphocytes (31.7% vs 24.7%, P = .01), and higher plasma levels of the soluble CD163 scavenger receptor (0.84 vs .59 µg/mL, P = .003) than controls. CONCLUSIONS We show, for the first time, that chronic infection with SFV is associated with T lymphocyte differentiation and monocyte activation.
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Affiliation(s)
- Antoine Gessain
- Unité d'Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France.,Unité Mixte de Recherche du Centre National de la Recherche Scientifique 3569, Paris, France
| | - Thomas Montange
- Unité d'Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France.,Unité Mixte de Recherche du Centre National de la Recherche Scientifique 3569, Paris, France
| | | | | | | | - Florence Buseyne
- Unité d'Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France.,Unité Mixte de Recherche du Centre National de la Recherche Scientifique 3569, Paris, France
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6
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Functional Analyses of Bovine Foamy Virus-Encoded miRNAs Reveal the Importance of a Defined miRNA for Virus Replication and Host-Virus Interaction. Viruses 2020; 12:v12111250. [PMID: 33147813 PMCID: PMC7693620 DOI: 10.3390/v12111250] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/22/2020] [Accepted: 10/27/2020] [Indexed: 12/19/2022] Open
Abstract
In addition to regulatory or accessory proteins, some complex retroviruses gain a repertoire of micro-RNAs (miRNAs) to regulate and control virus–host interactions for efficient replication and spread. In particular, bovine and simian foamy viruses (BFV and SFV) have recently been shown to express a diverse set of RNA polymerase III-directed miRNAs, some with a unique primary miRNA double-hairpin, dumbbell-shaped structure not known in other viruses or organisms. While the mechanisms of expression and structural requirements have been studied, the functional importance of these miRNAs is still far from understood. Here, we describe the in silico identification of BFV miRNA targets and the subsequent experimental validation of bovine Ankyrin Repeat Domain 17 (ANKRD17) and Bax-interacting factor 1 (Bif1) target genes in vitro and, finally, the suppression of ANKRD17 downstream genes in the affected pathway. Deletion of the entire miRNA cassette in the non-coding part of the U3 region of the long terminal repeats attenuated replication of corresponding BFV mutants in bovine cells. This repression can be almost completely trans-complemented by the most abundant miRNA BF2-5p having the best scores for predicted and validated BFV miRNA target genes. Deletion of the miRNA cassette does not grossly affect particle release and overall particle composition.
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Iwasaki R, Nakagiri Y, Yaguchi Y, Oguma K, Ono M, Horikita T, Sentsui H. Survey of bovine foamy virus infection among cattle in Japan and comparison with bovine leukemia virus infection. J Vet Med Sci 2020; 82:615-618. [PMID: 32201403 PMCID: PMC7273609 DOI: 10.1292/jvms.19-0592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The prevalence of bovine foamy virus (BFV) infections in cattle on farms in the Kanto region of Japan was determined using agar gel immunodiffusion (AGID) test and polymerase chain reaction
(PCR). Six out of 20 farms contained BFV-positive cattle. Furthermore, 16.7% (91/545) of all cattle tested positive for BFV. This suggested that BFV-infected cattle are widely prevalent in
Japan. Positive results for BFV infection were consistent between AGID and PCR tests. Additionally, we tested for bovine leukemia virus (BLV) infections at nine farms, primarily those
containing BFV-infected cows. At each farm, the infection rate of BFV was lower than that of BLV. Further, cattle that were PCR-positive but antibody-negative, indicating immune tolerance to
BFV, were not detected.
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Affiliation(s)
- Ryoji Iwasaki
- Laboratory of Veterinary Epizootiology, Department of Veterinary Medicine, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-0880, Japan
| | - Yu Nakagiri
- Laboratory of Veterinary Epizootiology, Department of Veterinary Medicine, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-0880, Japan
| | - Yuji Yaguchi
- Ibaraki Kenhoku Animal Hygiene Service Station, Nakakawauchi 966-1, Mito, Ibaraki 310-0002, Japan
| | - Keisuke Oguma
- Laboratory of Veterinary Epizootiology, Department of Veterinary Medicine, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-0880, Japan
| | - Mamiko Ono
- Laboratory of Large Animal Clinical Sciences, Department of Veterinary Medicine, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-0880, Japan
| | - Tetsuya Horikita
- Laboratory of Large Animal Clinical Sciences, Department of Veterinary Medicine, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-0880, Japan
| | - Hiroshi Sentsui
- Laboratory of Veterinary Epizootiology, Department of Veterinary Medicine, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-0880, Japan
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8
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Infection with Foamy Virus in Wild Ruminants-Evidence for a New Virus Reservoir? Viruses 2020; 12:v12010058. [PMID: 31947727 PMCID: PMC7019589 DOI: 10.3390/v12010058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/29/2019] [Accepted: 12/31/2019] [Indexed: 12/14/2022] Open
Abstract
Foamy viruses (FVs) are widely distributed and infect many animal species including non-human primates, horses, cattle, and cats. Several reports also suggest that other species can be FV hosts. Since most of such studies involved livestock or companion animals, we aimed to test blood samples from wild ruminants for the presence of FV-specific antibodies and, subsequently, genetic material. Out of 269 serum samples tested by ELISA with the bovine foamy virus (BFV) Gag and Bet antigens, 23 sera showed increased reactivity to at least one of them. High reactive sera represented 30% of bison samples and 7.5% of deer specimens. Eleven of the ELISA-positives were also strongly positive in immunoblot analyses. The peripheral blood DNA of seroreactive animals was tested by semi-nested PCR. The specific 275 bp fragment of the pol gene was amplified only in one sample collected from a red deer and the analysis of its sequence showed the highest homology for European BFV isolates. Such results may suggest the existence of a new FV reservoir in bison as well as in deer populations. Whether the origin of such infections stems from a new FV or is the result of BFV inter-species transmission remains to be clarified.
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9
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Materniak-Kornas M, Tan J, Heit-Mondrzyk A, Hotz-Wagenblatt A, Löchelt M. Bovine Foamy Virus: Shared and Unique Molecular Features In Vitro and In Vivo. Viruses 2019; 11:E1084. [PMID: 31766538 PMCID: PMC6950176 DOI: 10.3390/v11121084] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 12/18/2022] Open
Abstract
The retroviral subfamily of Spumaretrovirinae consists of five genera of foamy (spuma) viruses (FVs) that are endemic in some mammalian hosts [1]. Closely related species may be susceptible to the same or highly related FVs. FVs are not known to induce overt disease and thus do not pose medical problems to humans and livestock or companion animals. A robust lab animal model is not available or is a lab animal a natural host of a FV. Due to this, research is limited and often focused on the simian FVs with their well-established zoonotic potential. The authors of this review and their groups have conducted several studies on bovine FV (BFV) in the past with the intention of (i) exploring the risk of zoonotic infection via beef and raw cattle products, (ii) studying a co-factorial role of BFV in different cattle diseases with unclear etiology, (iii) exploring unique features of FV molecular biology and replication strategies in non-simian FVs, and (iv) conducting animal studies and functional virology in BFV-infected calves as a model for corresponding studies in primates or small lab animals. These studies gained new insights into FV-host interactions, mechanisms of gene expression, and transcriptional regulation, including miRNA biology, host-directed restriction of FV replication, spread and distribution in the infected animal, and at the population level. The current review attempts to summarize these findings in BFV and tries to connect them to findings from other FVs.
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Affiliation(s)
| | - Juan Tan
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China;
| | - Anke Heit-Mondrzyk
- German Cancer Research Center DKFZ, Core Facility Omics IT and Data Management, 69120 Heidelberg, Germany; (A.H.-M.); (A.H.-W.)
| | - Agnes Hotz-Wagenblatt
- German Cancer Research Center DKFZ, Core Facility Omics IT and Data Management, 69120 Heidelberg, Germany; (A.H.-M.); (A.H.-W.)
| | - Martin Löchelt
- German Cancer Research Center DKFZ, Program Infection, Inflammation and Cancer, Div. Viral Transformation Mechanisms, 69120 Heidelberg, Germany
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Buseyne F, Betsem E, Montange T, Njouom R, Bilounga Ndongo C, Hermine O, Gessain A. Clinical Signs and Blood Test Results Among Humans Infected With Zoonotic Simian Foamy Virus: A Case-Control Study. J Infect Dis 2019; 218:144-151. [PMID: 29608711 DOI: 10.1093/infdis/jiy181] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 03/27/2018] [Indexed: 11/13/2022] Open
Abstract
Background A spillover of simian foamy virus (SFV) to humans, following bites from infected nonhuman primates (NHPs), is ongoing in exposed populations. These retroviruses establish persistent infections of unknown physiological consequences to the human host. Methods We performed a case-control study to compare 24 Cameroonian hunters infected with gorilla SFV and 24 controls matched for age and ethnicity. A complete physical examination and blood test were performed for all participants. Logistic regression and Wilcoxon signed rank tests were used to compare cases and controls. Results The cases had significantly lower levels of hemoglobin than the controls (median, 12.7 vs 14.4 g/dL; P = .01). Basophil levels were also significantly lower in cases than controls, with no differences for other leukocyte subsets. Cases had significantly higher urea, creatinine, protein, creatinine phosphokinase, and lactate dehydrogenase levels and lower bilirubin levels than controls. Cases and controls had similar frequencies of general, cutaneous, gastrointestinal, neurological, and cardiorespiratory signs. Conclusions The first case-control study of apparently healthy SFV-infected Cameroonian hunters showed the presence of hematological abnormalities. A thorough clinical and laboratory workup is now needed to establish the medical relevance of these observations because more than half of cases had mild or moderate anemia. Clinical Trials Registration NCT03225794.
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Affiliation(s)
- Florence Buseyne
- Unité d'épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France.,UMR CNRS 3569, Paris, France
| | - Edouard Betsem
- Unité d'épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France.,UMR CNRS 3569, Paris, France.,Université of Yaoundé I, Yaoundé, Cameroon
| | - Thomas Montange
- Unité d'épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France.,UMR CNRS 3569, Paris, France
| | | | | | - Olivier Hermine
- INSERM UMR 1163, CNRS ERL 8254, Paris, France.,Hôpital Necker, Université Paris Descartes, Sorbonne Paris Cité, Paris, France.,Laboratoire d'Excellence GR-Ex, Paris, France
| | - Antoine Gessain
- Unité d'épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France.,UMR CNRS 3569, Paris, France
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11
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Hachiya Y, Kimura K, Oguma K, Ono M, Horikita T, Sentsui H. Isolation of bovine foamy virus in Japan. J Vet Med Sci 2018; 80:1604-1609. [PMID: 30175751 PMCID: PMC6207520 DOI: 10.1292/jvms.18-0121] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Bovine foamy virus (BFV) is endemic in many countries, but has not been reported in
Japan. A syncytium-forming virus was isolated from peripheral blood leukocytes of
clinically healthy cattle on a farm in Kanagawa prefecture during a periodic
epidemiological survey of viral diseases. The isolate was propagated in primary fetal
bovine muscle cells and subsequently passaged in Madin–Darby bovine kidney cells. Since
the isolate appeared to be distinct from the viruses with syncytium-forming ability
previously isolated in Japan, we attempted to identify it using genomic analyses and
electron microscopy. A phylogenetic analysis revealed that the isolate belongs to the
bovine foamy virus cluster and is highly similar to a BFV strain isolated in China. A
sero-epidemiological survey was performed using agar gel immunodiffusion test with the
isolated virus as the antigen, and five of the 57 cattle tested were found to be
seropositive.
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Affiliation(s)
- Yuma Hachiya
- Department of Veterinary Medicine, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-0880, Japan
| | - Kumiko Kimura
- National Institute of Animal Health, National Agriculture and Food Research Organization (NARO) 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan
| | - Keisuke Oguma
- Department of Veterinary Medicine, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-0880, Japan
| | - Mamiko Ono
- Department of Veterinary Medicine, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-0880, Japan
| | - Tetsuya Horikita
- Department of Veterinary Medicine, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-0880, Japan
| | - Hiroshi Sentsui
- Department of Veterinary Medicine, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-0880, Japan
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12
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Materniak-Kornas M, Osiński Z, Rudzki M, Kuźmak J. Development of a Recombinant Protein-based ELISA for Detection of Antibodies Against Bovine Foamy Virus. J Vet Res 2017; 61:247-252. [PMID: 29978080 PMCID: PMC5894420 DOI: 10.1515/jvetres-2017-0034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 08/18/2017] [Indexed: 11/15/2022] Open
Abstract
Introduction Infections with bovine foamy virus (BFV) were found in many countries but there is a lack of large-scale surveys on the prevalence of BFV among dairy cattle. The aim of this study was to develop and validate the recombinant Gag protein-based ELISA and to estimate the prevalence of antibodies against BFV. Material and Methods Gag coding region from BFV was cloned into expression vector pT7Arg-STOP, which expressed a high level of recombinant Gag protein from E.coli. The ELISA was standardised, and the cut-off value and sensitivity and specificity of the test were calculated using a receiver operating characteristic and Bayesian estimation. Results A total of 3,051 serum samples were tested by ELISA and 939 (30.8%) sera were recognised as positive. When Bayesian approach was used, the overall true BFV prevalence was 29.7% (95% CI: 25.9–33.4%). Conclusion Expressed Gag protein of BFV has been used successfully as an antigen for ELISA. Eventually, this study provides basic information about the epidemiological status of infection with BFV in dairy cattle in Poland, which can be used for further studies on dissemination and transmission of BFV infection.
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Affiliation(s)
| | - Zbigniew Osiński
- Departament of Hygiene of Feeding Stuffs, National Veterinary Research Institute, 24-100 Pulawy, Poland
| | - Marcin Rudzki
- Chair and Department of Jaw Orthopaedics, Medical University, 20-081 Lublin, Poland
| | - Jacek Kuźmak
- Department of Biochemistry, National Veterinary Research Institute, 24-100 Pulawy, Poland
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13
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Muniz CP, Jia H, Shankar A, Troncoso LL, Augusto AM, Farias E, Pissinatti A, Fedullo LP, Santos AF, Soares MA, Switzer WM. An expanded search for simian foamy viruses (SFV) in Brazilian New World primates identifies novel SFV lineages and host age-related infections. Retrovirology 2015; 12:94. [PMID: 26576961 PMCID: PMC4650395 DOI: 10.1186/s12977-015-0217-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/20/2015] [Indexed: 11/19/2022] Open
Abstract
Background While simian foamy viruses have co-evolved with their primate hosts for millennia, most scientific studies have focused on understanding infection in Old World primates with little knowledge available on the epidemiology and natural history of SFV infection in New World primates (NWPs). To better understand the geographic and species distribution and evolutionary history of SFV in NWPs we extend our previous studies in Brazil by screening 15 genera consisting of 29 NWP species (140 monkeys total), including five genera (Brachyteles, Cacajao, Callimico, Mico, and Pithecia) not previously analyzed. Monkey blood specimens were tested using a combination of both serology and PCR to more accurately estimate prevalence and investigate transmission patterns. Sequences were phylogenetically analyzed to infer SFV and host evolutionary histories. Results The overall serologic and molecular prevalences were 42.8 and 33.6 %, respectively, with a combined assay prevalence of 55.8 %. Discordant serology and PCR results were observed for 28.5 % of the samples, indicating that both methods are currently necessary for estimating NWP SFV prevalence. SFV prevalence in sexually mature NWPs with a positive result in any of the WB or PCR assays was 51/107 (47.7 %) compared to 20/33 (61 %) for immature animals. Epidemiological analyses revealed an increase in SFV prevalence with age in captive Cebus monkeys. Phylogenetic analysis identified novel SFVs in Cacajao,Leontopithecus, and Chiropotes species that had 6–37 % nucleotide divergence to other NWP SFV. Comparison of host and SFV phylogenies showed an overall cospeciation evolutionary history with rare ancient and contemporaneous host-switching for Saimiri and Leontopithecus and Cebus xanthosternos, respectively. Conclusions We identified novel SFV in four neotropical monkey genera in Brazil and demonstrate that SFV prevalence increases with age in Cebus monkeys. Importantly, our test results suggest that both molecular and serological screening are currently required to accurately determine infection with NWP SFV. Our study significantly expands knowledge of the epidemiology and natural history of NWP SFVs. The tools and information provided in our study will facilitate further investigation of SFV in NWPs and the potential for zoonotic infection with these viruses.
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Affiliation(s)
- Cláudia P Muniz
- Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. .,Laboratory Branch, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, 1600 Clifton Rd., MS G45, Atlanta, 30329, USA.
| | - Hongwei Jia
- Laboratory Branch, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, 1600 Clifton Rd., MS G45, Atlanta, 30329, USA.
| | - Anupama Shankar
- Laboratory Branch, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, 1600 Clifton Rd., MS G45, Atlanta, 30329, USA.
| | - Lian L Troncoso
- Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
| | | | - Elisabete Farias
- Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
| | | | | | - André F Santos
- Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Marcelo A Soares
- Departamento de Genética, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. .,Programa de Genética, Instituto Nacional de Câncer, Rio de Janeiro, Brazil.
| | - William M Switzer
- Laboratory Branch, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, 1600 Clifton Rd., MS G45, Atlanta, 30329, USA.
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14
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Bao Q, Hipp M, Hugo A, Lei J, Liu Y, Kehl T, Hechler T, Löchelt M. In Vitro Evolution of Bovine Foamy Virus Variants with Enhanced Cell-Free Virus Titers and Transmission. Viruses 2015; 7:5855-74. [PMID: 26569290 PMCID: PMC4664980 DOI: 10.3390/v7112907] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 10/23/2015] [Accepted: 10/26/2015] [Indexed: 11/16/2022] Open
Abstract
Virus transmission is essential for spreading viral infections and is a highly coordinated process which occurs by cell-free transmission or cell-cell contact. The transmission of Bovine Foamy Virus (BFV) is highly cell-associated, with undetectable cell-free transmission. However, BFV particle budding can be induced by overexpression of wild-type (wt) BFV Gag and Env or artificial retargeting of Gag to the plasma membrane via myristoylation membrane targeting signals, closely resembling observations in other foamy viruses. Thus, the particle release machinery of wt BFV appears to be an excellent model system to study viral adaption to cell-free transmission by in vitro selection and evolution. Using selection for BFV variants with high cell-free infectivity in bovine and non-bovine cells, infectivity dramatically increased from almost no infectious units to about 105-106 FFU (fluorescent focus forming units)/mL in both cell types. Importantly, the selected BFV variants with high titer (HT) cell-free infectivity could still transmit via cell-cell contacts and were neutralized by serum from naturally infected cows. These selected HT-BFV variants will shed light into virus transmission and potential routes of intervention in the spread of viral infections. It will also allow the improvement or development of new promising approaches for antiretroviral therapies.
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Affiliation(s)
- Qiuying Bao
- Division of Molecuar Diagnostics of Oncogenic Infections, Research Focus Infection, Inflammation and Cancer, German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), Im Neuenheimer Feld 242, 69120, Germany.
| | - Michaela Hipp
- Division of Molecuar Diagnostics of Oncogenic Infections, Research Focus Infection, Inflammation and Cancer, German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), Im Neuenheimer Feld 242, 69120, Germany.
| | - Annette Hugo
- Division of Molecuar Diagnostics of Oncogenic Infections, Research Focus Infection, Inflammation and Cancer, German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), Im Neuenheimer Feld 242, 69120, Germany.
| | - Janet Lei
- Division of Molecuar Diagnostics of Oncogenic Infections, Research Focus Infection, Inflammation and Cancer, German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), Im Neuenheimer Feld 242, 69120, Germany.
- Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK.
| | - Yang Liu
- Division of Molecuar Diagnostics of Oncogenic Infections, Research Focus Infection, Inflammation and Cancer, German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), Im Neuenheimer Feld 242, 69120, Germany.
- Department Viral Recombination, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702-1201, USA.
| | - Timo Kehl
- Division of Molecuar Diagnostics of Oncogenic Infections, Research Focus Infection, Inflammation and Cancer, German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), Im Neuenheimer Feld 242, 69120, Germany.
| | - Torsten Hechler
- Division of Molecuar Diagnostics of Oncogenic Infections, Research Focus Infection, Inflammation and Cancer, German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), Im Neuenheimer Feld 242, 69120, Germany.
- Heidelberg Pharma GmbH, 68526 Ladenburg, Germany.
| | - Martin Löchelt
- Division of Molecuar Diagnostics of Oncogenic Infections, Research Focus Infection, Inflammation and Cancer, German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), Im Neuenheimer Feld 242, 69120, Germany.
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15
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Troncoso LL, Muniz CP, Siqueira JD, Curty G, Schrago CG, Augusto A, Fedullo L, Soares MA, Santos AF. Characterization and comparative analysis of a simian foamy virus complete genome isolated from Brazilian capuchin monkeys. Virus Res 2015; 208:1-6. [DOI: 10.1016/j.virusres.2015.05.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 05/25/2015] [Indexed: 12/28/2022]
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16
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Lei J, Osen W, Gardyan A, Hotz-Wagenblatt A, Wei G, Gissmann L, Eichmüller S, Löchelt M. Replication-Competent Foamy Virus Vaccine Vectors as Novel Epitope Scaffolds for Immunotherapy. PLoS One 2015; 10:e0138458. [PMID: 26397953 PMCID: PMC4580568 DOI: 10.1371/journal.pone.0138458] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 08/31/2015] [Indexed: 12/19/2022] Open
Abstract
The use of whole viruses as antigen scaffolds is a recent development in vaccination that improves immunogenicity without the need for additional adjuvants. Previous studies highlighted the potential of foamy viruses (FVs) in prophylactic vaccination and gene therapy. Replication-competent FVs can trigger immune signaling and integrate into the host genome, resulting in persistent antigen expression and a robust immune response. Here, we explored feline foamy virus (FFV) proteins as scaffolds for therapeutic B and T cell epitope delivery in vitro. Infection- and cancer-related B and T cell epitopes were grafted into FFV Gag, Env, or Bet by residue replacement, either at sites of high local sequence homology between the epitope and the host protein or in regions known to tolerate sequence alterations. Modified proviruses were evaluated in vitro for protein steady state levels, particle release, and virus titer in permissive cells. Modification of Gag and Env was mostly detrimental to their function. As anticipated, modification of Bet had no impact on virion release and affected virus titers of only some recombinants. Further evaluation of Bet as an epitope carrier was performed using T cell epitopes from the model antigen chicken ovalbumin (OVA), human tyrosinase-related protein 2 (TRP-2), and oncoprotein E7 of human papillomavirus type 16 (HPV16E7). Transfection of murine cells with constructs encoding Bet-epitope chimeric proteins led to efficient MHC-I-restricted epitope presentation as confirmed by interferon-gamma enzyme-linked immunospot assays using epitope-specific cytotoxic T lymphocyte (CTL) lines. FFV infection-mediated transduction of cells with epitope-carrying Bet also induced T-cell responses, albeit with reduced efficacy, in a process independent from the presence of free peptides. We show that primate FV Bet is also a promising T cell epitope carrier for clinical translation. The data demonstrate the utility of replication-competent and -attenuated FVs as antigen carriers in immunotherapy.
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Affiliation(s)
- Janet Lei
- Division of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Wolfram Osen
- Division of Translational Immunology, Research Program Tumor Immunology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Adriane Gardyan
- Division of Translational Immunology, Research Program Tumor Immunology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Agnes Hotz-Wagenblatt
- Bioinformatics Core Facility, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Guochao Wei
- Division of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Lutz Gissmann
- Division of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Stefan Eichmüller
- Division of Translational Immunology, Research Program Tumor Immunology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Martin Löchelt
- Division of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
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17
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Bing T, Wu K, Cui X, Shao P, Zhang Q, Bai X, Tan J, Qiao W. Identification and functional characterization of Bet protein as a negative regulator of BFV3026 replication. Virus Genes 2014; 48:464-73. [PMID: 24615636 DOI: 10.1007/s11262-014-1052-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Accepted: 02/23/2014] [Indexed: 11/26/2022]
Abstract
Foamy virus (FV) establishes persistent infection in the host without causing apparent disease. Besides the transactivator Tas protein, another auxiliary protein--Bet--has been reported in prototype foamy virus, equine foamy virus, and feline foamy virus. Here, we found the putative bbet gene in clone C74 from a cDNA library of bovine foamy virus strain 3026 (BFV3026) by comparison of gene localization, composition, and splicing features with other known bet genes. Subsequently, BBet protein was detected in BFV3026-infected cells by Western blot and immunofluorescence analyses. Analysis of the BBet mutant infectious clone (pBS-BFVdelBBet) revealed that BBet could inhibit BFV3026 replication. Consistent with this result, overexpression of BBet in Cf2Th cells reduced BFV replication by approximately threefold. Furthermore, virus replication levels similarly were reduced by approximately threefold in pBS-BFV-transfected and BFV3026-infected Cf2Th cells stably expressing BBet compared with control cells. After three passages, BFV3026 replicated more slowly in BBet-expressing cells. This study implicates BBet as a negative regulator of BFV replication and provides a resource for future studies on the function of this protein in the virus lifecycle.
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Affiliation(s)
- Tiejun Bing
- Key Laboratory of Molecular Microbiology and Biotechnology (Ministry of Education) and Key Laboratory of Microbial Functional Genomics (Tianjin), College of Life Sciences, Nankai University, Tianjin, 300071, China
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18
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Identification of novel, highly expressed retroviral microRNAs in cells infected by bovine foamy virus. J Virol 2014; 88:4679-86. [PMID: 24522910 DOI: 10.1128/jvi.03587-13] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED While numerous viral microRNAs (miRNAs) expressed by DNA viruses, especially herpesvirus family members, have been reported, there have been very few reports of miRNAs derived from RNA viruses. Here we describe three miRNAs expressed by bovine foamy virus (BFV), a member of the spumavirus subfamily of retroviruses, in both BFV-infected cultured cells and BFV-infected cattle. All three viral miRNAs are initially expressed in the form of an ∼ 122-nucleotide (nt) pri-miRNA, encoded within the BFV long terminal repeat U3 region, that is subsequently cleaved to generate two pre-miRNAs that are then processed to yield three distinct, biologically active miRNAs. The BFV pri-miRNA is transcribed by RNA polymerase III, and the three resultant mature miRNAs were found to contribute a remarkable ∼ 70% of all miRNAs expressed in BFV-infected cells. These data document the second example of a retrovirus that is able to express viral miRNAs by using embedded proviral RNA polymerase III promoters. IMPORTANCE Foamy viruses are a ubiquitous family of nonpathogenic retroviruses that have potential as gene therapy vectors in humans. Here we demonstrate that bovine foamy virus (BFV) expresses high levels of three viral microRNAs (miRNAs) in BFV-infected cells in culture and also in infected cattle. The BFV miRNAs are unusual in that they are initially transcribed by RNA polymerase III as a single, ∼ 122-nt pri-miRNA that is subsequently processed to release three fully functional miRNAs. The observation that BFV, a foamy virus, is able to express viral miRNAs in infected cells adds to emerging evidence that miRNA expression is a common, albeit clearly not universal, property of retroviruses and suggests that these miRNAs may exert a significant effect on viral replication in vivo.
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19
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Rola-Łuszczak M, Materniak M, Pluta A, Hulst M, Kuźmak J. Transcriptomic microarray analysis of BoMac cells after infection with bovine foamy virus. Arch Virol 2014; 159:1515-9. [PMID: 24380972 DOI: 10.1007/s00705-013-1959-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 11/18/2013] [Indexed: 12/22/2022]
Abstract
Bovine foamy virus (BFV) infections are highly prevalent among cattle worldwide. However, relatively little is known about the impact of this virus on the host immune system. In our study, we focused on a bovine macrophage cell line (BoMac) and examined changes in the BoMac transcriptome after in vitro infection with BFV using bovine BLOPlus oligo microarrays. One hundred twenty-four genes showed significant changes in expression level. The biological process categories found to be enriched include metabolic processes, cell communication, transport, immune system processes, and response to extracellular stimuli. RT-qPCR was applied to confirm the results obtained for representative genes.
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Affiliation(s)
- Marzena Rola-Łuszczak
- Department of Biochemistry, National Veterinary Research Institute, Partyzantów 57, 24-100, Pulawy, Poland,
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20
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Kehl T, Tan J, Materniak M. Non-simian foamy viruses: molecular virology, tropism and prevalence and zoonotic/interspecies transmission. Viruses 2013; 5:2169-209. [PMID: 24064793 PMCID: PMC3798896 DOI: 10.3390/v5092169] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 09/04/2013] [Accepted: 09/05/2013] [Indexed: 12/27/2022] Open
Abstract
Within the field of retrovirus, our knowledge of foamy viruses (FV) is still limited. Their unique replication strategy and mechanism of viral persistency needs further research to gain understanding of the virus-host interactions, especially in the light of the recent findings suggesting their ancient origin and long co-evolution with their nonhuman hosts. Unquestionably, the most studied member is the primate/prototype foamy virus (PFV) which was originally isolated from a human (designated as human foamy virus, HFV), but later identified as chimpanzee origin; phylogenetic analysis clearly places it among other Old World primates. Additionally, the study of non-simian animal FVs can contribute to a deeper understanding of FV-host interactions and development of other animal models. The review aims at highlighting areas of special interest regarding the structure, biology, virus-host interactions and interspecies transmission potential of primate as well as non-primate foamy viruses for gaining new insights into FV biology.
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Affiliation(s)
- Timo Kehl
- German Cancer Research Center, INF242, Heidelberg 69120, Germany
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +49-6221-42-4935; Fax: +49-6221-42-4932
| | - Juan Tan
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China; E-Mail:
| | - Magdalena Materniak
- Department of Biochemistry, National Veterinary Research Institute, Partyzantow Ave. 57, Pulawy 24-100, Poland; E-Mail:
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Lukic DS, Hotz-Wagenblatt A, Lei J, Räthe AM, Mühle M, Denner J, Münk C, Löchelt M. Identification of the feline foamy virus Bet domain essential for APOBEC3 counteraction. Retrovirology 2013; 10:76. [PMID: 23880220 PMCID: PMC3751544 DOI: 10.1186/1742-4690-10-76] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 07/19/2013] [Indexed: 11/10/2022] Open
Abstract
Background APOBEC3 (A3) proteins restrict viral replication by cytidine deamination of viral DNA genomes and impairing reverse transcription and integration. To escape this restriction, lentiviruses have evolved the viral infectivity factor (Vif), which binds A3 proteins and targets them for proteolytic degradation. In contrast, foamy viruses (FVs) encode Bet proteins that allow replication in the presence of A3, apparently by A3 binding and/or sequestration, thus preventing A3 packaging into virions and subsequent restriction. Due to a long-lasting FV-host coevolution, Bet proteins mainly counteract restriction by A3s from their cognate or highly related host species. Results Through bioinformatics, we identified conserved motifs in Bet, all localized in the bel2 exon. In line with the localization of these conserved motifs within bel2, this part of feline FV (FFV) Bet has been shown to be essential for feline A3 (feA3) inactivation and feA3 protein binding. To study the function of the Bet motifs in detail, we analyzed the ability of targeted deletion, substitution, and chimeric FFV-PFV (prototype FV) Bet mutants to physically bind and/or inactivate feA3. Binding of Bet to feA3Z2b is sensitive to mutations in the first three conserved motifs and N- and C-terminal deletions and substitutions across almost the complete bel2 coding sequence. In contrast, the Bel1 (also designated Tas) domain of Bet is dispensable for basal feA3Z2b inactivation and binding but mainly increases the steady state level of Bet. Studies with PFV Bel1 and full-length FFV Bel2 chimeras confirmed the importance of Bel2 for A3 inactivation indicating that Bel1 is dispensable for basal feA3Z2b inactivation and binding but increases Bet stability. Moreover, the bel1/tas exon may be required for expression of a fully functional Bet protein from a spliced transcript. Conclusions We show that the Bel2 domain of FV Bet is essential for the inactivation of APOBEC3 cytidine deaminase restriction factors. The Bel1/Tas domain increases protein stability and can be exchanged by related sequence. Since feA3 binding and inactivation by Bet are highly correlated, the data support the view that FV Bet prevents A3-mediated restriction of viral replication by creating strong complexes with these proteins.
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Affiliation(s)
- Dragana Slavkovic Lukic
- Research Program Infection and Cancer, Department Genome Modifications and Carcinogenesis, German Cancer Research Center-DKFZ, Heidelberg, Germany
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