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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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Olesen ML, Jørgensen LL, Blixenkrone-Møller M, Sandberg E, Frandsen PL, Østergaard E, Bækdahl ER, Fridholm H, Fomsgaard A, Rosenstierne MW. Screening for viral extraneous agents in live-attenuated avian vaccines by using a microbial microarray and sequencing. Biologicals 2018; 51:37-45. [DOI: 10.1016/j.biologicals.2017.10.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 06/30/2017] [Accepted: 10/17/2017] [Indexed: 11/28/2022] Open
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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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Ochi A, Ochiai K, Kobara A, Nakamura S, Hatai H, Handharyani E, Tiemann I, Tanaka IB, Toyoda T, Abe A, Seok SH, Sunden Y, Torralba NC, Park JH, Hafez HM, Umemura T. Epidemiological study of fowl glioma-inducing virus in chickens in Asia and Germany. Avian Pathol 2012; 41:299-309. [PMID: 22702458 DOI: 10.1080/03079457.2012.684373] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Fowl glioma-inducing virus (FGV), which belongs to avian leukosis virus (ALV) subgroup A, induces fowl glioma. This disease is characterized by multiple nodular gliomatous growths of astrocytes and has been previously reported in Europe, South Africa, Australia, the United States and Japan. FGV and FGV variants have spread to ornamental Japanese fowl, including Japanese bantams (Gallus gallus domesticus), in Japan. However, it is unclear how and where FGV emerged and whether FGV is related to the past fowl glioma in European countries. In this study, the prevalence of FGV in European, Asian and Japanese native chickens was examined. FGV could not be isolated from any chickens in Germany and Asian countries other than Japan. Eighty (26%) out of 307 chickens reared in Japan were positive by FGV-screening nested polymerase chain reaction and 11 FGV variants with an FGV-specific sequence in their 3' untranslated region were isolated. In addition, four other ALVs lacking the FGV-specific sequence were isolated from Japanese bantams with fowl glioma and/or cerebellar hypoplasia. These isolates were considered to be distinct recombinant viruses between FGV variants and endogenous/exogenous avian retroviruses. These results suggest that the variants as well as distinct recombinant ALVs are prevalent among Japanese native chickens in Japan and that FGV may have emerged by recombination among avian retroviruses in the chickens of this country.
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Affiliation(s)
- Akihiro Ochi
- Laboratory of Comparative Pathology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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Liu C, Zheng S, Wang Y, Jing L, Gao H, Gao Y, Qi X, Qin L, Pan W, Wang X. Detection and molecular characterization of recombinant avian leukosis viruses in commercial egg-type chickens in China. Avian Pathol 2012; 40:269-75. [PMID: 21711186 DOI: 10.1080/03079457.2011.560932] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Two natural recombinant avian leukosis viruses (ALVs) were isolated from Chinese commercial egg-type chickens in 2009, which suffered from haemangiomas and myelocytomas. Sequence analysis of the complete proviral genomes revealed several unique genetic characteristics of the present two isolates, demonstrating that the two viruses were derived from recombination between earlier Chinese ALV-J and endogenous virus sequences. The two recombinant viruses presented typical genetic organization of replication-competent genus Alpharetrovirus, and the gag and pol genes were well conserved with those of ALVs. The env genes of the two viruses were composed of the internal identical sequences (about 240 bp) of endogenous viruses, and the rest of the sequence belonged to subgroup J ALVs. The long terminal repeats of the two viruses were more closely related to HPRS-103 and earlier Chinese ALV-J than other subgroup ALVs, and multiple transcription regulatory elements of ALV-J were highly conserved. In addition, the two viruses shared an almost identical 3'-untranslated region (UTR) sequence with earlier Chinese ALV-J strains and the US strain 4817, containing a ~127 bp deletion in the E element region. However, further comparison with endogenous ALV indicated that the 3'-UTR sequences with ~127 bp deletion of ALV-J were most probably derived from endogenous viruses by recombination. These results suggested that the two isolates can be characterized as recombinant ALV-J with the internal env gene and 3'-UTR sequence of endogenous ALV.
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Affiliation(s)
- Chaonan Liu
- Division of Avian infectious Diseases, National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, Heilongjiang, 150001, P.R. China
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Zhang H, Bacon LD, Fadly AM. Development of an Endogenous Virus–Free Line of Chickens Susceptible to All Subgroups of Avian Leukosis Virus. Avian Dis 2008; 52:412-8. [DOI: 10.1637/8180-112707-reg] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Kim YJ, Park SI, Park SJ, Kim HH, Jung YW, Kwon JT, Jang BG, Kim HK, Cho KO. Molecular analysis of endogenous avian leukosis/sarcoma virus genomes in Korean chicken embryos. J Vet Med Sci 2008; 70:17-23. [PMID: 18250567 DOI: 10.1292/jvms.70.17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Since the status of endogenous avian leucosis/sarcoma virus (ALSV) infections in Korean broiler chickens is unclear, this study examined embryonated eggs obtained from broiler farms and Korean native chicken breeds in Korea using PCR with the primer sets specific for endogenous ALSVs. The PCR assays detected the genomes of EAV, ev, ev/J and ART-CH belonging to the endogenous ALSV from all embryos tested. Phylogenetically, the Korean EAV genomes were more closely related to the prototype EAV-0 than to the other prototype, E51. The Korean ART-CH elements clustered together but were distinct from the prototype ART-CH clones, 5 and 14. Although there was comparatively little divergence in the nucleotide and amino acid sequences of the Korean ev and ev/J genomes compared with the other known ev and ev/J genomes, the Korean genomes had phylogenetically distinct branches. From these results, endogenous genomes are quite prevalent in Korean broiler chickens. In addition, the endogenous genomes circulating in Korean broiler chickens are genetically different from the other known endogenous genomes. These results are expected to provide useful information for the control and establishment of a surveillance system for endogenous ALSVs in Korea.
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Affiliation(s)
- You-Jung Kim
- Bio-Therapy Human Resources Center, College of Veterinary Medicine, Chonnam National University, Gwangju, Japan
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Grunder AA, Benkel BF, Chambers JR, Sabour MP, Gavora JS, Dickie JW. Characterization of four endogenous viral genes in semi-congenic lines of meat chickens. Poult Sci 1999; 78:873-7. [PMID: 10438132 DOI: 10.1093/ps/78.6.873] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Restriction fragment length polymorphism analyses were used to examine endogenous viral genes (ev genes or ALVE genes) of the avian leukosis viral (ALV) family in semi-congenic lines of meat chickens. The Generation 6 lines examined in this study were semi-congenic in that each contained birds with either zero or with one ALVE gene in hemizygous state plus some solitary long terminal repeat (LTR) elements. Using four restriction enzymes on chicken genomic DNA and two probes, one representing the entire ALV retroviral genome and one with only a small part plus the LTR, four ALVE genes were characterized. Each seemed to be complete with no detectable deletions. None appeared to be similar to known ALVE genes of White Leghorns, whereas two of the four may be the same as ALVE genes reported by others in White Plymouth Rock chickens.
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Affiliation(s)
- A A Grunder
- Centre for Food and Animal Research, Agriculture and Agri-Food Canada, Ottawa, Ontario.
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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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