Five Amino Acid Substitutions in the S1 Unit of Infectious Bronchitis Virus Are Critical Determinants Enhancing Its Adaptation to Vero Cells

The S1 subunit of the spike protein of avian infectious bronchitis virus (IBV) plays a crucial role in determining its host range and cell and tissue tropism. Following the continuous passage of IBV-EP3 through Vero cells over up to 65 generations, a total of 19 amino acid mutations accumulated in t...

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Main Authors: Zhichao Cai, Mingjing Zhang, Shouguo Fang
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Veterinary Sciences
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Online Access:https://www.mdpi.com/2306-7381/12/5/394
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author Zhichao Cai
Mingjing Zhang
Shouguo Fang
author_facet Zhichao Cai
Mingjing Zhang
Shouguo Fang
author_sort Zhichao Cai
collection DOAJ
description The S1 subunit of the spike protein of avian infectious bronchitis virus (IBV) plays a crucial role in determining its host range and cell and tissue tropism. Following the continuous passage of IBV-EP3 through Vero cells over up to 65 generations, a total of 19 amino acid mutations accumulated in the S1 region of IBV-P65. To investigate the impact of these mutations on the adaptability of IBV to Vero cells, six recombinant viruses carrying either a subset or all of the identified mutations were constructed and obtained via a reverse genetics system. Analyses on the growth characteristics of these recombinant viruses and Western blot detection of the expression levels of their spike proteins indicated that the IBV mutant obtained by replacing the amino acid sequence from positions 179 to 323 in the S1 region of IBV-P65 with the corresponding segment from IBV-EP3 S1 significantly impaired viral growth and exhibited a lower replication efficiency in Vero cells, suggesting that five amino acid substitutions (T181I, I246T, F267C, T273I, Q296K) within this region could enhance the adaptation of IBV to Vero cells.
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spelling doaj-art-1c583a450eb34e7c8d9807b4961cfd482025-08-20T01:56:45ZengMDPI AGVeterinary Sciences2306-73812025-04-0112539410.3390/vetsci12050394Five Amino Acid Substitutions in the S1 Unit of Infectious Bronchitis Virus Are Critical Determinants Enhancing Its Adaptation to Vero CellsZhichao Cai0Mingjing Zhang1Shouguo Fang2College of Agriculture, Yangtze University, Jingzhou 434025, ChinaCollege of Agriculture, Yangtze University, Jingzhou 434025, ChinaCollege of Agriculture, Yangtze University, Jingzhou 434025, ChinaThe S1 subunit of the spike protein of avian infectious bronchitis virus (IBV) plays a crucial role in determining its host range and cell and tissue tropism. Following the continuous passage of IBV-EP3 through Vero cells over up to 65 generations, a total of 19 amino acid mutations accumulated in the S1 region of IBV-P65. To investigate the impact of these mutations on the adaptability of IBV to Vero cells, six recombinant viruses carrying either a subset or all of the identified mutations were constructed and obtained via a reverse genetics system. Analyses on the growth characteristics of these recombinant viruses and Western blot detection of the expression levels of their spike proteins indicated that the IBV mutant obtained by replacing the amino acid sequence from positions 179 to 323 in the S1 region of IBV-P65 with the corresponding segment from IBV-EP3 S1 significantly impaired viral growth and exhibited a lower replication efficiency in Vero cells, suggesting that five amino acid substitutions (T181I, I246T, F267C, T273I, Q296K) within this region could enhance the adaptation of IBV to Vero cells.https://www.mdpi.com/2306-7381/12/5/394infectious bronchitis viruscell tropismadaptation
spellingShingle Zhichao Cai
Mingjing Zhang
Shouguo Fang
Five Amino Acid Substitutions in the S1 Unit of Infectious Bronchitis Virus Are Critical Determinants Enhancing Its Adaptation to Vero Cells
Veterinary Sciences
infectious bronchitis virus
cell tropism
adaptation
title Five Amino Acid Substitutions in the S1 Unit of Infectious Bronchitis Virus Are Critical Determinants Enhancing Its Adaptation to Vero Cells
title_full Five Amino Acid Substitutions in the S1 Unit of Infectious Bronchitis Virus Are Critical Determinants Enhancing Its Adaptation to Vero Cells
title_fullStr Five Amino Acid Substitutions in the S1 Unit of Infectious Bronchitis Virus Are Critical Determinants Enhancing Its Adaptation to Vero Cells
title_full_unstemmed Five Amino Acid Substitutions in the S1 Unit of Infectious Bronchitis Virus Are Critical Determinants Enhancing Its Adaptation to Vero Cells
title_short Five Amino Acid Substitutions in the S1 Unit of Infectious Bronchitis Virus Are Critical Determinants Enhancing Its Adaptation to Vero Cells
title_sort five amino acid substitutions in the s1 unit of infectious bronchitis virus are critical determinants enhancing its adaptation to vero cells
topic infectious bronchitis virus
cell tropism
adaptation
url https://www.mdpi.com/2306-7381/12/5/394
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