title: Characterization of field strains of infectious laryngotracheitis virus in China by restriction fragment length polymorphism and sequence analysis.
abstract: Nineteen strains of infectious laryngotracheitis virus (ILTV; Gallid herpesvirus 1) were isolated from dead or diseased birds in chicken flocks from different areas of China between 2010 and 2014 and used to investigate ILTV epidemiology. These strains were characterized using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) patterns and sequence analysis of the thymidine kinase (TK) gene. PCR-RFLP analysis showed that the TK gene generated 2 patterns when digested with restriction endonuclease enzymes. Pattern A corresponded to 2 virulent field strains, while pattern B was characteristic of 2 virulent field strains, 15 low pathogenicity field strains, and all vaccine strains. Sequence analysis of the TK gene indicated that the messenger RNA polyadenylation signals could be identified in some isolates where amino acid 252 was threonine, and in those with methionine at that position. The present study has demonstrated that most of the outbreaks of ILT in China were caused either by low virulence strains or by vaccine-related strains, and also emphasizes the importance of reinforcing ILTV surveillance in both vaccinated and nonvaccinated flocks.
authors.affiliation: College of Animal Science, South China Agricultural University, Guangzhou, China (Yan, Li, Xie, Chen, Bi)Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China (Xie, Chen).
authors.forename: Zhuanqiang
authors.initials: Z
authors.lastname: Yan
authors.affiliation: College of Animal Science, South China Agricultural University, Guangzhou, China (Yan, Li, Xie, Chen, Bi)Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China (Xie, Chen).
authors.forename: Shengpeng
authors.initials: S
authors.lastname: Li
authors.affiliation: College of Animal Science, South China Agricultural University, Guangzhou, China (Yan, Li, Xie, Chen, Bi)Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China (Xie, Chen).
authors.forename: Qingmei
authors.initials: Q
authors.lastname: Xie
authors.affiliation: College of Animal Science, South China Agricultural University, Guangzhou, China (Yan, Li, Xie, Chen, Bi)Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China (Xie, Chen) fengch@scau.edu.cn.
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
authors.affiliation: College of Animal Science, South China Agricultural University, Guangzhou, China (Yan, Li, Xie, Chen, Bi)Key Laboratory of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, Guangzhou, China (Xie, Chen).
authors.forename: Yingzuo
authors.initials: Y
authors.lastname: Bi
mesh_terms: D000818:Animals; D001715:Bird Diseases / Q000453:epidemiology / Q000821:virology*; D001717:Birds; D002645:Chickens; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks / Q000662:veterinary; D006566:Herpesviridae Infections / Q000662:veterinary* / Q000821:virology; D001352:Herpesvirus 1, Gallid / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012150:Polymorphism, Restriction Fragment Length; D011201:Poultry Diseases / Q000453:epidemiology / Q000821:virology
keywords: China; epidemiology; infectious laryngotracheitis virus; isolation; sequence analysis