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Borodin AM, Emanuilova ZV, Smolov SV, Ogneva OA, Konovalova NV, Terentyeva EV, Serova NY, Efimov DN, Fisinin VI, Greenberg AJ, Alekseev YI. Eradication of avian leukosis virus subgroups J and K in broiler cross chickens by selection against infected birds using multilocus PCR. PLoS One 2022; 17:e0269525. [PMID: 35749432 PMCID: PMC9231750 DOI: 10.1371/journal.pone.0269525] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 05/23/2022] [Indexed: 12/04/2022] Open
Abstract
The avian leukosis virus (ALV) is a serious threat to sustainable and economically viable commercial poultry management world-wide. Active infections can result in more than 20% flock loss, resulting in significant economic damage. ALV detection and elimination from flocks and breeding programs is complicated by high sequence variability and the presence of endogenous virus copies which show up as false positives in assays. Previously-developed approaches to virus detection are either too labor-intensive to implement on an industrial scale or suffer from high false negative or positive rates. We developed a novel multi-locus multiplex quantitative real-time PCR system to detect viruses belonging to the J and K genetic subgroups that are particularly prevalent in our region. We used this system to eradicate ALV from our broiler breeding program comprising thousands of individuals. Our approach can be generalized to other ALV subgroups and other highly genetically diverse pathogens.
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Affiliation(s)
- Alexander M. Borodin
- Breeding and Genetic Center Smena, Ministry of Science and Higher Education of the Russian Federation, Bereznyaki, Russia
- Institute of Medical and Biological Research, Nizhnii Novgorod, Russia
| | - Zhanna V. Emanuilova
- Breeding and Genetic Center Smena, Ministry of Science and Higher Education of the Russian Federation, Bereznyaki, Russia
| | - Sergei V. Smolov
- Breeding and Genetic Center Smena, Ministry of Science and Higher Education of the Russian Federation, Bereznyaki, Russia
| | - Olga A. Ogneva
- Breeding and Genetic Center Smena, Ministry of Science and Higher Education of the Russian Federation, Bereznyaki, Russia
| | | | | | - Natalia Y. Serova
- All-Russian Research Veterinary Institute of Poultry Science Branch of the Federal Scientific Center All-Russian Research and Technological Poultry Institute Russian Academy of Science, St. Petersburg, Russia
| | - D. N. Efimov
- Federal Scientific Center All-Russian Research and Technological Poultry Institute Russian Academy of Science, Sergiev Posad, Russia
| | - V. I. Fisinin
- Federal Scientific Center All-Russian Research and Technological Poultry Institute Russian Academy of Science, Sergiev Posad, Russia
| | | | - Yakov I. Alekseev
- Syntol LLC, Moscow, Russia
- Institute for Analytical Instrumentation Russian Academy of Science, St. Petersburg, Russia
- * E-mail: (AJG); (YIA)
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Dai M, Xie T, Feng M, Zhang X. Endogenous retroviruses transcriptomes in response to four avian pathogenic microorganisms infection in chicken. Genomics 2022; 114:110371. [PMID: 35462029 DOI: 10.1016/j.ygeno.2022.110371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 02/20/2022] [Accepted: 04/17/2022] [Indexed: 01/14/2023]
Abstract
The impact of Endogenous retroviruses (ERVs) on chicken disease is not well understood. Here, we systematically identified 436 relatively complete ChERVs from the chicken genome. Subsequently, ChERV transcriptomes were analyzed in chicken after subgroup J avian leukosis virus (ALV-J), avian influenza virus (AIV), Marek's disease virus (MDV) and avian pathogenic Escherichia coli (APEC) infection. We found that about 50%-68% of ChERVs were transcriptionally active in infected and uninfected-samples, although the abundance of most ChERVs is relatively low. Moreover, compared to uninfected-samples, 49, 18, 66 and 17 ChERVs were significantly differentially expressed in ALV-J, AIV, MDV and APEC infected-samples, respectively. These findings may be of significance for understanding the role and function of ChERVs to response the pathogenic microorganism infection.
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Affiliation(s)
- Manman Dai
- National and Regional Joint Engineering Laboratory for Medicament of Zoonosis Prevention and Control, Guangdong Provincial Key Laboratory of Zoonosis Prevention and Control, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
| | - Tingting Xie
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Min Feng
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
| | - Xiquan Zhang
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
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Fulton JE, Mason AS, Wolc A, Arango J, Settar P, Lund AR, Burt DW. The impact of endogenous Avian Leukosis Viruses (ALVE) on production traits in elite layer lines. Poult Sci 2021; 100:101121. [PMID: 33975038 PMCID: PMC8131724 DOI: 10.1016/j.psj.2021.101121] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/26/2021] [Accepted: 02/26/2021] [Indexed: 11/28/2022] Open
Abstract
Avian Leukosis Virus subgroup E (ALVE) integrations are endogenous retroviral elements found in the chicken genome. The presence of ALVE has been reported to have negative impacts on multiple traits, including egg production and body weight. The recent development of rapid, inexpensive and specific ALVE detection methods has facilitated their characterization in elite commercial egg production lines across multiple generations. The presence of 20 ALVE was examined in 8 elite lines, from 3 different breeds. Seventeen of these ALVE (85%) were informative and found to be segregating in at least one of the lines. To test for an association between specific ALVE inserts and traits, a large genotype by phenotype study was undertaken. Genotypes were obtained for 500 to 1500 males per line, and the phenotypes used were sire-daughter averages. Phenotype data were analyzed by line with a linear model that included the effects of generation, ALVE genotype and their interaction. If genotype effect was significant, the number of ALVE copies was fitted as a regression to estimate additive ALVE gene substitution effect. Significant associations between the presence of specific ALVE inserts and 18 commercially relevant performance and egg quality traits, including egg production, egg weight and albumen height, were observed. When an ALVE was segregating in more than one line, these associations did not always have the same impact (negative, positive or none) in each line. It is hypothesized that the presence of ALVE in the chicken genome may influence production traits by 3 mechanisms: viral protein production may modulate the immune system and impact overall production performance (virus effect); insertional mutagenesis caused by viral integration may cause direct gene alterations or affect gene regulation (gene effect); or the integration site may be within or adjacent to a quantitative trait region which impacts a performance trait (linkage disequilibrium, marker effect).
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Affiliation(s)
- Janet E Fulton
- Department of Research and Development, Hy-Line International, Dallas Center, IA 50063, USA.
| | - Andrew S Mason
- Jack Birch Unit for Molecular Carcinogenesis, Department of Biology and The York Biomedical Research Institute, The University of York, York, YO10 5DD, United Kingdom
| | - Anna Wolc
- Department of Research and Development, Hy-Line International, Dallas Center, IA 50063, USA; Department of Animal Science, Iowa State University, Ames, IA 50011, USA
| | - Jesus Arango
- Department of Research and Development, Hy-Line International, Dallas Center, IA 50063, USA
| | - Petek Settar
- Department of Research and Development, Hy-Line International, Dallas Center, IA 50063, USA
| | - Ashlee R Lund
- Department of Research and Development, Hy-Line International, Dallas Center, IA 50063, USA
| | - David W Burt
- The University of Queensland, Brisbane, Queensland, 4072, Australia
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Chiu ES, VandeWoude S. Endogenous Retroviruses Drive Resistance and Promotion of Exogenous Retroviral Homologs. Annu Rev Anim Biosci 2020; 9:225-248. [PMID: 33290087 DOI: 10.1146/annurev-animal-050620-101416] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Endogenous retroviruses (ERVs) serve as markers of ancient viral infections and provide invaluable insight into host and viral evolution. ERVs have been exapted to assist in performing basic biological functions, including placentation, immune modulation, and oncogenesis. A subset of ERVs share high nucleotide similarity to circulating horizontally transmitted exogenous retrovirus (XRV) progenitors. In these cases, ERV-XRV interactions have been documented and include (a) recombination to result in ERV-XRV chimeras, (b) ERV induction of immune self-tolerance to XRV antigens, (c) ERV antigen interference with XRV receptor binding, and (d) interactions resulting in both enhancement and restriction of XRV infections. Whereas the mechanisms governing recombination and immune self-tolerance have been partially determined, enhancement and restriction of XRV infection are virus specific and only partially understood. This review summarizes interactions between six unique ERV-XRV pairs, highlighting important ERV biological functions and potential evolutionary histories in vertebrate hosts.
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Affiliation(s)
- Elliott S Chiu
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado 80523, USA; ,
| | - Sue VandeWoude
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado 80523, USA; ,
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Mason AS, Miedzinska K, Kebede A, Bamidele O, Al-Jumaili AS, Dessie T, Hanotte O, Smith J. Diversity of endogenous avian leukosis virus subgroup E (ALVE) insertions in indigenous chickens. Genet Sel Evol 2020; 52:29. [PMID: 32487054 PMCID: PMC7268647 DOI: 10.1186/s12711-020-00548-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 05/26/2020] [Indexed: 12/05/2022] Open
Abstract
Background Avian leukosis virus subgroup E (ALVE) insertions are endogenous retroviruses (ERV) that are restricted to the domestic chicken and its wild progenitor. In commercial chickens, ALVE are known to have a detrimental effect on productivity and provide a source for recombination with exogenous retroviruses. The wider diversity of ALVE in non-commercial chickens and the role of these elements in ERV-derived immunity (EDI) are yet to be investigated. Results In total, 974 different ALVE were identified from 407 chickens sampled from village populations in Ethiopia, Iraq, and Nigeria, using the recently developed obsERVer bioinformatics identification pipeline. Eighty-eight percent of all identified ALVE were novel, bringing the known number of ALVE integrations to more than 1300 across all analysed chickens. ALVE content was highly lineage-specific and populations generally exhibited a large diversity of ALVE at low frequencies, which is typical for ERV involved in EDI. A significantly larger number of ALVE was found within or near coding regions than expected by chance, although a relative depletion of ALVE was observed within coding regions, which likely reflects selection against deleterious integrations. These effects were less pronounced than in previous analyses of chickens from commercial lines. Conclusions Identification of more than 850 novel ALVE has trebled the known diversity of these retroviral elements. This work provides the basis for future studies to fully quantify the role of ALVE in immunity against exogenous ALV, and development of programmes to improve the productivity and welfare of chickens in developing economies.
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Affiliation(s)
- Andrew S Mason
- The University of York, York, YO10 5DD, UK. .,The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK.
| | - Katarzyna Miedzinska
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Adebabay Kebede
- LiveGene-CTLGH, International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia.,Addis Ababa University, Addis Ababa, Ethiopia
| | - Oladeji Bamidele
- African Chicken Genetic Gains, Department of Animal Sciences, Obafemi Awolowo, Ile Ife, Osun, Nigeria
| | - Ahmed S Al-Jumaili
- School of Life Sciences, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK.,University of Anbar, Ramadi, Anbar, Iraq
| | - Tadelle Dessie
- LiveGene-CTLGH, International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia
| | - Olivier Hanotte
- LiveGene-CTLGH, International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia.,School of Life Sciences, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK.,University of Anbar, Ramadi, Anbar, Iraq
| | - Jacqueline Smith
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
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Mason AS, Fulton JE, Smith J. Endogenous avian leukosis virus subgroup E elements of the chicken reference genome. Poult Sci 2020; 99:2911-2915. [PMID: 32475424 PMCID: PMC7597685 DOI: 10.1016/j.psj.2019.12.074] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 11/08/2019] [Accepted: 12/31/2019] [Indexed: 11/29/2022] Open
Abstract
The chicken reference genome contains 2 endogenous avian leukosis virus subgroup E (ALVE) insertions, but gaps and unresolved repetitive sequences in previous assemblies have hindered their precise characterization. Detailed analysis of the most recent reference genome (GRCg6a) now shows both ALVEs within contiguous chromosome assemblies for the first time. ALVE6 (ALVE-JFevA) and ALVE-JFevB are both located on chromosome 1, with ALVE6 close to the p-arm telomere. ALVE-JFevB is a structurally intact element containing the ALVE gag, pol, and env genes and is capable of forming replication competent viruses. In contrast, ALVE6 contains a 3,352 bp 5′ truncation and lacks the entire 5′ long terminal repeat and gag gene. Despite this, ALVE6 remains able to produce intact envelope protein, likely due to a mutation in the recognition site for a known inhibitory miRNA (miR-155). Whole genome resequencing data sets from layers, broilers, and 3 independent sources of wild-caught red junglefowl were surveyed for the presence of each of these reference genome ALVEs. ALVE-JFevB was found in no other chicken or red junglefowl genomes, whereas ALVE6 was identified in some layers, broilers, and native breeds but not within any other red junglefowl genome. Improved assembly contiguity has facilitated better characterization of the 2 ALVEs of the chicken reference genome. However, both the limited ALVE content and unique presence of ALVE-JFevB suggests that the reference individual is unrepresentative of ancestral Gallus gallus ALVE diversity.
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Affiliation(s)
- Andrew S Mason
- Department of Biology, The University of York, York YO10 5DD, UK; The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian EH25 9RG, UK.
| | | | - Jacqueline Smith
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian EH25 9RG, UK
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Rutherford K, Meehan CJ, Langille MGI, Tyack SG, McKay JC, McLean NL, Benkel K, Beiko RG, Benkel B. Discovery of an expanded set of avian leukosis subgroup E proviruses in chickens using Vermillion, a novel sequence capture and analysis pipeline [corrected]. Poult Sci 2016; 95:2250-8. [PMID: 27354549 DOI: 10.3382/ps/pew194] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 04/08/2016] [Indexed: 01/26/2023] Open
Abstract
Transposable elements (TEs), such as endogenous retroviruses (ERVs), are common in the genomes of vertebrates. ERVs result from retroviral infections of germ-line cells, and once integrated into host DNA they become part of the host's heritable genetic material. ERVs have been ascribed positive effects on host physiology such as the generation of novel, adaptive genetic variation and resistance to infection, as well as negative effects as agents of tumorigenesis and disease. The avian leukosis virus subgroup E family (ALVE) of endogenous viruses of chickens has been used as a model system for studying the effects of ERVs on host physiology, and approximately 30 distinct ALVE proviruses have been described in the Gallus gallus genome. In this report we describe the development of a software tool, which we call Vermillion, and the use of this tool in combination with targeted next-generation sequencing (NGS) to increase the number of known proviruses belonging to the ALVE family of ERVs in the chicken genome by 4-fold, including expanding the number of known ALVE elements on chromosome 1 (Gga1) from the current 9 to a total of 40. Although we focused on the discovery of ALVE elements in chickens, with appropriate selection of target sequences Vermillion can be used to develop profiles of other families of ERVs and TEs in chickens as well as in species other than the chicken.
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Affiliation(s)
- K Rutherford
- Dalhousie University, Faculty of Computer Science, 6050 University Avenue, Halifax, NS, Canada, B3H 4R2
| | - C J Meehan
- Dalhousie University, Faculty of Computer Science, 6050 University Avenue, Halifax, NS, Canada, B3H 4R2 Institute of Tropical Medicine, Department of Biomedical Sciences, Antwerp 2000, Belgium
| | - M G I Langille
- Dalhousie University, Faculty of Computer Science, 6050 University Avenue, Halifax, NS, Canada, B3H 4R2 Dalhousie University, Faculty of Medicine, Department of Pharmacology, 5850 College St, Halifax, NS, Canada, B3H 4R2
| | - S G Tyack
- EW GROUP, 1 Hogenboegen, Visbek, Germany
| | - J C McKay
- EW GROUP, 1 Hogenboegen, Visbek, Germany
| | - N L McLean
- Dalhousie University, Faculty of Agriculture, Department of Plant and Animal Sciences, Box 550, Truro, NS, B2N 5E3
| | - K Benkel
- Dalhousie University, Faculty of Agriculture, Department of Plant and Animal Sciences, Box 550, Truro, NS, B2N 5E3
| | - R G Beiko
- Dalhousie University, Faculty of Computer Science, 6050 University Avenue, Halifax, NS, Canada, B3H 4R2
| | - B Benkel
- Dalhousie University, Faculty of Agriculture, Department of Plant and Animal Sciences, Box 550, Truro, NS, B2N 5E3
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Elamurugan A, Karthik K, Badasara SK, Hajam IA, Saravanan M. Novel insights into identification of shedders and transmitters of avian leukosis virus. ASIAN PACIFIC JOURNAL OF TROPICAL DISEASE 2015. [DOI: 10.1016/s2222-1808(15)60889-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Rutherford K, McLean N, Benkel BF. A rapid profiling assay for avian leukosis virus subgroup E proviruses in chickens. Avian Dis 2014; 58:34-8. [PMID: 24758110 DOI: 10.1637/10595-061813-reg.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Endogenous retroviral elements (ERVs) are prolific components of the genomes of complex species, typically occupying more sequence space than do essential, protein-encoding genes. Much of what we know today about the structure and function, as well as the evolution and pathogenic potential, of ERVs was fleshed out over several decades during the last century using the avian leukosis virus subgroup E-related (ALVE) family of endogenous retroviruses of chickens as a model system. A critical enabling factor in the elucidation of ALVE structure and function is the ability to detect and unambiguously identify specific ALVE proviral elements and to develop accurate element profiles for individual chickens under study. Currently, the most common approach for ALVE locus detection involves element-specific PCR assays carried out using primers that target host DNA near the insertion site of the provirus (i.e., the upstream and downstream flanks of the unoccupied site). Here we describe a new approach for proviral detection that exploits restriction enzyme sites in flanking DNA to develop ALVE element profiles more rapidly than with assays currently in use. Moreover, unlike element-specific PCR tests, the "profiling" assay detects novel ALVEs for which insertion sites have not yet been identified as well as previously characterized elements.
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Rutherford K, Benkel BF. Characterization of insertion sites and development of locus-specific assays for three broiler-derived subgroup E avian leukosis virus proviruses. Avian Pathol 2013; 42:373-8. [PMID: 23796057 DOI: 10.1080/03079457.2013.809694] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
This report deals with the identification of novel elements belonging to a family of endogenous retroviruses, designated endogenous avian leukosis virus-type proviral elements (ALVE), that reside in the genome of the chicken and are closely related to exogenous avian leukosis viruses. The study of ALVE elements in the chicken genome serves as a model system for understanding the interplay between endogenous viruses and their vertebrate hosts in general, including humans. In this report, we characterize the insertion sites and describe locus-specific, diagnostic polymerase chain reaction-based assays for three previously discovered, but as yet not localized, ALVE elements. In addition, we assess the proviral integrity, provide the complete element sequence and examine the genomic environs of the three broiler-derived elements.
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Affiliation(s)
- Katherine Rutherford
- Department of Plant and Animal Sciences, Faculty of Agriculture, Dalhousie University, Truro, Nova Scotia, Canada
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Smith A, Benkel BF. Novel avian leukosis virus-related endogenous proviruses from layer chickens: characterization and development of locus-specific assays. Poult Sci 2009; 88:1580-5. [PMID: 19590071 DOI: 10.3382/ps.2009-00148] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During the course of evolution, vertebrate genomes have been invaded and colonized by retroviruses. In humans, for example, endogenous retroviruses (long terminal repeat elements) occupy roughly twice as much sequence space as essential genes. There are numerous reports in the literature implicating endogenous proviruses in the modulation of host physiology. The fact that many of these host-virus interactions take place in a proviral locus-specific manner speaks to the need for rapid assays for element profiling. This report deals with the identification of novel elements belonging to a family of endogenous retroviruses, designated ALVE, that reside in the genome of the chicken and that are closely related to exogenous avian leukosis viruses. The study of ALVE elements in the chicken genome serves as a model system for understanding the interplay between endogenous viruses and their vertebrate hosts in general, including humans. In this report, we present locus-specific, diagnostic PCR-based assays for 2 novel ALVE elements. In addition, we characterize the proviral structures and examine the genomic environments of both novel elements along with a previously described element known as ALVE-NSAC-3.
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Affiliation(s)
- A Smith
- Nova Scotia Agricultural College, Department of Plant and Animal Sciences, Truro, Nova Scotia, B2N 5E3, Canada
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12
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Benkel BF. Locus-specific diagnostic tests for endogenous avian leukosis-type viral loci in chickens. Poult Sci 1998; 77:1027-35. [PMID: 9657616 DOI: 10.1093/ps/77.7.1027] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The genome of the chicken, Gallus gallus, contains endogenous proviral elements (ALVE elements or ev genes) that display a high degree of similarity to the Avian Leukosis class of retroviruses. The ALVE proviruses are known to modulate physiological processes of the host birds. Different ALVE elements retain variable portions of the complete, prototype viral genome, and each provirus resides in its own specific location within the host genome. Thus, each ALVE element has its own particular potential to modulate host physiology depending on the nature of its integration site, the completeness of the proviral genome, and the level of expression of the locus. It is important, therefore, to be able to establish the ALVE element profiles of chickens quickly and accurately, both in the laboratory and in a commercial setting. The current method of choice for simple, quick, and accurate typing is the polymerase chain reaction (PCR). This paper reviews the present status of PCR typing of ALVE proviruses and lists the assay protocols for 19 different elements. In addition, it compares the insertion sites of these elements in an effort to identify common motifs at ALVE integration sites.
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Affiliation(s)
- B F Benkel
- Agriculture and Agri-Food Canada, Centre for Food and Animal Research, Ottawa, Ontario.
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13
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Fadly AM, Smith EJ. Role of contact and genetic transmission of endogenous virus-21 in the susceptibility of chickens to avian leukosis virus infection and tumors. Poult Sci 1997; 76:968-73. [PMID: 9200232 DOI: 10.1093/ps/76.7.968] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The role of contact and genetic transmission of endogenous virus-21 (EV21) on response of chickens to avian leukosis virus (ALV) infection and tumors was studied. F1 progeny of a cross between RPRL late-feathering (LF) line EV21+ males and RPRL early feathering (EF) line 15B1 females harboring or lacking EV21 were used. The EF chicks lacking EV21 were inoculated with a field strain of subgroup A ALV at hatch and contact exposed to LF, EV21+ hatchmates for various time intervals. In a second experiment, EV21 contact-exposed and unexposed EF chicks as well as LF, EV21+ hatchmates were inoculated with ALV at various ages. Chickens were tested for ALV-induced viremia and antibody and were observed for tumors until 24 wk of age. Antibody to EV21 in EF chickens contact-exposed to LF, EV21+ hatchmates varied from 10 to 65%, and was detected by 10 wk of age. By 24 wk of age, ALV-induced viremia and tumors in EF chickens varied from 5 to 30%, and from 15 to 32%, respectively, regardless of exposure to EV21. The incidence of ALV-induced tumors was significantly higher in LF chickens genetically infected with EV21 than in EV21 contact-exposed or unexposed EF chickens, but only in chickens inoculated with ALV at hatch. The data suggest that contact infection with EV21 has no influence on ALV infection and tumors. The data also suggest that genetic transmission of EV21 may increase susceptibility of chickens to ALV infection and tumors following infection with ALV at hatch, but not at 4 wk of age or older.
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Affiliation(s)
- A M Fadly
- USDA, Agricultural Research Service, Avian Disease and Oncology Laboratory, East Lansing, Michigan 48823, USA
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