Molecular characterization and pathogenicity of infectious bronchitis coronaviruses: complicated evolution and epidemiology in china caused by cocirculation of multiple types of infectious bronchitis coronaviruses.
OBJECTIVE
To monitor and study the molecular epidemiology, evolution and pathogenicity of infectious bronchitis viruses (IBVs) in China in recent years and further our knowledge of the evolution of IBVs.


METHODS
Thirty-seven IBV isolates were isolated from commercial chickens in China. The isolates were characterized by RT-PCR, sequencing, typing and analyzing the entire S1 gene. In addition, 4 selected IBV isolates were used to experimentally infect the specific pathogen-free chickens to study their pathogenicity.


RESULTS
Three types of IBV have been cocirculating in chicken flocks in China in recent years. Unique insertions and deletions in S1 protein regions were identified among different types of IBV. Moreover, a new IBV strain was isolated and identified in a layer hen. S1 gene analysis showed that a recombination event had occurred in the virus's evolutionary process. In addition, experimental infection has shown that IBV isolates have been nephropathogenic in China in recent years.


CONCLUSIONS
Mutations, insertions, deletions and recombination of the S1 protein gene contribute to the genetic diversity of IBV in China. Cocirculation of multiple types of IBV in field conditions in China renders its epidemiology and evolution very complicated, indicating the necessity for development of new vaccines or vaccine strategies.
Liu
Shengwang
S
Division of Avian Infectious Diseases, National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, PR China.
Zhang
Xiaonan
X
Wang
Yu
Y
Li
Chengren
C
Han
Zongxi
Z
Shao
Yuhao
Y
Li
Huixin
H
Kong
Xiangang
X
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D018352:Coronavirus Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D019143:Evolution, Molecular; D005838:Genotype; D054643:INDEL Mutation; D001351:Infectious bronchitis virus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D008562:Membrane Glycoproteins / Q000235:genetics; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D017354:Point Mutation; D011201:Poultry Diseases / Q000453:epidemiology* / Q000821:virology*; D012367:RNA, Viral / Q000235:genetics; D011995:Recombination, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins / Q000235:genetics
D008562:Membrane Glycoproteins; D012367:RNA, Viral; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins