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Li X, Lin W, Chang S, Zhao P, Zhang X, Liu Y, Chen W, Li B, Shu D, Zhang H, Chen F, Xie Q. Isolation, identification and evolution analysis of a novel subgroup of avian leukosis virus isolated from a local Chinese yellow broiler in South China. Arch Virol 2016; 161:2717-25. [PMID: 27422398 DOI: 10.1007/s00705-016-2965-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 07/01/2016] [Indexed: 10/21/2022]
Abstract
Avian leukosis virus (ALV) causes high mortality associated with tumor formation and decreased fertility, and results in major economic losses in the poultry industry worldwide. Recently, a putative novel ALV subgroup virus named ALV-K was observed in Chinese local chickens. In this study, a novel ALV strain named GD14LZ was isolated from a Chinese local yellow broiler in 2014. The proviral genome was sequenced and phylogenetically analyzed. The replication ability and pathogenicity of this virus were also evaluated. The complete proviral genome sequence of GD14LZ was 7482 nt in length, with a genetic organization typical of replication-competent type C retroviruses lacking viral oncogenes. Sequence analysis showed that the gag, pol and gp37 genes of GD14LZ have high sequence similarity to those of other ALV strains (A-E subgroups), especially to those of ALV-E. The gp85 gene of the GD14LZ isolate showed a low sequence similarity to those other ALV strains (A-E subgroups) but showed high similarity to strains previously described as ALV-K. Phylogenetic analysis of gp85 also suggested that the GD14LZ isolate was related to ALV-K strains. Further study showed that this isolate replicated more slowly and was less pathogenic than other ALV strains. These results indicate that the GD14LZ isolate belongs to the novel subgroup ALV-K and probably arose by recombination of ALV-K with endogenous viruses with low replication and pathogenicity. This virus might have existed in local Chinese chickens for a long time.
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Affiliation(s)
- Xinjian Li
- College of Animal Science, South China Agricultural University, No. 483 Wushan Road, Tianhe District, Guangzhou, Guangdong, People's Republic of China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, 510642, People's Republic of China
| | - Wencheng Lin
- College of Animal Science, South China Agricultural University, No. 483 Wushan Road, Tianhe District, Guangzhou, Guangdong, People's Republic of China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, 510642, People's Republic of China.,Key Laboratory of Animal Health Aquaculture and Environmental Control, Guangzhou, 510642, Guangdong, People's Republic of China.,South China Collaborative Innovation Center for Poultry Disease Control and Product Safety, Guangzhou, 510642, People's Republic of China
| | - Shuang Chang
- College of Veterinary Medicine, Shandong Agricultural University, Taian, 271018, People's Republic of China
| | - Peng Zhao
- College of Veterinary Medicine, Shandong Agricultural University, Taian, 271018, People's Republic of China
| | - Xinheng Zhang
- College of Animal Science, South China Agricultural University, No. 483 Wushan Road, Tianhe District, Guangzhou, Guangdong, People's Republic of China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, 510642, People's Republic of China
| | - Yang Liu
- College of Animal Science, South China Agricultural University, No. 483 Wushan Road, Tianhe District, Guangzhou, Guangdong, People's Republic of China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, 510642, People's Republic of China
| | - Weiguo Chen
- College of Animal Science, South China Agricultural University, No. 483 Wushan Road, Tianhe District, Guangzhou, Guangdong, People's Republic of China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, 510642, People's Republic of China
| | - Baohong Li
- Institute of Animal Science, Guangdong Academy of Agriculture Sciences, Guangzhou, 510640, People's Republic of China
| | - Dingming Shu
- Institute of Animal Science, Guangdong Academy of Agriculture Sciences, Guangzhou, 510640, People's Republic of China
| | - Huanmin Zhang
- USDA, Agriculture Research Service, Avian Disease and Oncology Laboratory, East Lansing, MI, 48823, USA
| | - Feng Chen
- College of Animal Science, South China Agricultural University, No. 483 Wushan Road, Tianhe District, Guangzhou, Guangdong, People's Republic of China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, 510642, People's Republic of China.,Key Laboratory of Animal Health Aquaculture and Environmental Control, Guangzhou, 510642, Guangdong, People's Republic of China
| | - Qingmei Xie
- College of Animal Science, South China Agricultural University, No. 483 Wushan Road, Tianhe District, Guangzhou, Guangdong, People's Republic of China. .,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, 510642, People's Republic of China. .,Key Laboratory of Animal Health Aquaculture and Environmental Control, Guangzhou, 510642, Guangdong, People's Republic of China. .,South China Collaborative Innovation Center for Poultry Disease Control and Product Safety, Guangzhou, 510642, People's Republic of China.
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Zavala G, Cheng S, Barbosa T. Natural infection and transmission of a retrovirus closely related to myeloblastosis-associated virus type 1 in egg-type chickens. Avian Dis 2012; 56:7-14. [PMID: 22545523 DOI: 10.1637/9755-040811-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
Myeloblastosis-associated virus type 1 (MAV-1) is an exogenous avian retrovirus with oncogenic potential. MAV-1 was detected in young chicks hatching from eggs produced by an experimental genetic line of egg-type chickens. Transmissibility of MAV-1 had not been documented previously. This investigation was intended to partially characterize the virus involved and to study its transmissibility and oncogenicity in naturally and contact-infected chickens. Commercially produced white and brown layer pullets free of exogenous avian leukosis viruses were commingled at hatch with naturally MAV-1-infected chickens. The original MAV-1-infected chickens were discarded after approximately 8 wk, and the contact-exposed chickens were maintained in isolation for 36 wk. Young specific-pathogen-free (SPF) single comb white leghorn chickens were added to the group to study possible horizontal transmission of MAV-1 in young chickens. Upon weekly virus isolation attempts, MAV-1 was readily isolated from the contact-exposed white layers but not from the brown layers between 36 and 53 wk of age (18 wk in total). Three-week-old SPF chickens were readily infected with MAV-1 by contact as early as 1 wk postexposure. Throughout 22 hatches derived from the white and brown MAV-1-contact-exposed layers (between 36 and 53 wk of age), MAV-1 was frequently detected in the white layer progeny, whereas the virus was seldom isolated from the progeny produced by the brown layers during the same 18-wk period. MAV-1 induced a persistent infection in some of the SPF chickens that were exposed by contact at 3 wk of age. Gross tumors were not detected in any of the originally infected experimental chickens at 8 wk of age, in the contact-exposed brown or white layers at the termination of the study at 53 wks of age, or in the contact-exposed SPF chickens at the end of the study at 12 wk of age. Exogenous avian leukosis-related viruses may still be detected in egg-type chickens, emphasizing the importance of thorough screening before incorporation of experimental genetic material into commercial genetic lines of egg-type chickens.
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Affiliation(s)
- Guillermo Zavala
- Department of Population Health, Poultry Diagnostic and Research Center, The University of Georgia, 953 College Station Road, Athens, GA 30602-4875, USA.
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Feng SZ, Jiao PR, Qi WB, Fan HY, Liao M. Development and strategies of cell-culture technology for influenza vaccine. Appl Microbiol Biotechnol 2010; 89:893-902. [PMID: 21063703 DOI: 10.1007/s00253-010-2973-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2010] [Revised: 10/16/2010] [Accepted: 10/17/2010] [Indexed: 01/20/2023]
Abstract
Influenza is a pandemic contagious disease and causes human deaths and huge economic destruction of poultry in the world. In order to control and prevent influenza, mainly type A, influenza vaccine for human and poultry were available since the 1940s and 1920s, respectively. In the development of vaccine production, influenza viruses were cultured originally from chicken embryos to anchorage-dependent cell lines, such as MDCK and Vero. The anchorage-independent lines have also been used to produce influenza virus, such as PER.C6 and engineering modified MDCK and Vero. During the process of influenza vaccine production, the common problem faced by all producers is how to improve the titer of influenza virus. This paper focuses on the developments of cell culture for influenza virus vaccine production, limitations of cell culture, and relative strategies for improvement virus yields in cell-culture systems.
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Affiliation(s)
- Shao-Zhen Feng
- Laboratory of Avian Medicine, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
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Barbosa T, Zavala G, Cheng S. Molecular characterization of three recombinant isolates of avian leukosis virus obtained from contaminated Marek's disease vaccines. Avian Dis 2008; 52:245-52. [PMID: 18646453 DOI: 10.1637/8100-083107-reg.1] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Three natural recombinant avian leukosis viruses (ALV; PDRC-1039, PDRC-3246, and PDRC-3249) expressing a subgroup A gp85 envelope protein and containing long terminal repeats (LTR) of endogenous ALV-E viruses were isolated from contaminated commercial Marek's disease vaccines, cloned, and completely sequenced. Their full genomes were analyzed and compared with representative strains of ALV. The proviral DNA of all three isolates displayed 99.3% identity to each other, suggesting a possible common ancestor, even though the contaminating viruses were obtained from three separate vaccine serials produced by two different vaccine manufacturing companies. The contaminating viruses have a genetic organization typical of replication-competent alpharetroviruses. The proviral genomes of PDRC-1039 and PDRC-3246 are 7497 bp long, and the PDRC-3249 is three base pairs shorter because of a deletion of a threonine residue within the gp85 coding region. The LTR, gag, pol, and the transmembrane (TM) region (gp37) of the env gene of all three viruses displayed high identity to endogenous counterpart sequences (>98%). Only the surface (SU) region (gp85) of the env gene displayed high identity with exogenous ALV-A (98.7%). Locus-specific polymerase chain reaction (PCR) analysis for ALV endogenous sequences (ev loci) in the chicken embryo fibroblasts used to produce the original vaccine vials identified the presence of ev-1, ev-2, ev-3, ev-4, and ev-6 in all three vaccines. Homologous recombination most likely took place to involve the SU region of the env gene because the recombinant viruses only differ in this particular region from the consensus ALV-E. These results suggest that the contaminating ALV isolates probably emerged by recombination of ALV-A with endogenous virus sequences before vaccine preparation.
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Affiliation(s)
- Taylor Barbosa
- Department of Population Health, College of Veterinary Medicine, University of Georgia, 953 College Station Rd., Athens, GA 30605, USA
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