The increased virulence of hypervirulent fowl adenovirus 4 is independent of fiber-1 and penton

• Published in: Research in veterinary science 2020-08, Vol.131, p.31-37
• Main Authors: Liu, Ruxin, Zhang, Yuhan, Guo, Huifang, Li, Ning, Wang, Baiyu, Tian, Kaiyue, Wang, Zeng, Yang, Xia, Li, Yongtao, Wang, Hailong, Zhang, Youming, Fu, Jun, Zhao, Jun
• Format: Article
• Language: English
• Subjects: Adenoviruses; Chickens; Cloning; E coli; Economic impact; Fiber-1; Genes; Genomes; Hepatitis; Hepatitis-hydropericardium syndrome; Hypervirulent FAdV-4; Infections; Mortality; Pathogenesis; Pathogenicity; Pathogens; Penton base; Plasmids; Poultry; Proteins; Structural proteins; Vaccines; Veterinary medicine; Virulence; Viruses
• ISSN: 0034-5288; 1532-2661
• DOI: 10.1016/j.rvsc.2020.04.005

Hepatitis-hydropericardium syndrome (HHS) caused by hypervirulent fowl adenovirus 4 (FAdV-4) have been causing great economic losses to Chinese poultry industry since 2015. Elucidation of the pathogenesis of FAdV-4 will lay solid foundation for developing attenuated FAdV-4 vaccine and vaccine vector. Our previous study has demonstrated that the increased virulence of hypervirulent FAdV-4 was associated with fiber-2 and hexon genes. However, the roles of fiber-1 and penton in virulence of FAdV-4 have never been elucidated. To further investigate the roles of the major structural proteins fiber-1 and penton in the virulence of hypervirulent FAdV-4, the fiber-1- and penton-replaced mutant viruses were constructed based on the FAdV-4 infectious clones of hypervirulent strain HNJZ using Redαβ recombineering techniques. The pathogenicity of the rescued viruses was evaluated in 3-week-old SPF chickens. Chickens infected with the rescued recombinant viruses carrying the fiber-1 or penton base gene from a nonpathogenic strain ON1 developed similar clinical signs to the natural hypervirulent FAdV-4 infection, including HHS-indicative gross lesions and histopathological changes in sick/dead chickens. Our results suggested that the increased virulence of hypervirulent FAdV-4 was independent of fiber-1 and penton. The detailed pathogenesis of FAdV-4 and the roles of fiber-1 and penton in the viral replication and infection process need to be further explored. •Fiber-1- and penton-replaced FAdV-4 mutants were rescued for the first time.•Roles of fiber-1 and penton in the virulence of FAdV-4 were first reported.•Virulence of hypervirulent FAdV-4 was independent of the fiber-1 and penton.