Yu Zhang, Aijing Liu, Hongyu Cui, Xiaole Qi, Changjun Liu, Yanping Zhang, Kai Li, Li Gao, Xiaomei Wang, Qing Pan, Yulong Gao

Vet Microbiol.2021 Nov 17;264:109285.doi: 10.1016/j.vetmic.2021.109285. Online ahead of print.

Abstract

Hepatitis-hydropericardium syndrome (HHS) in birds is mainly caused by virulent fowl adenovirus 4 (FAdV-4). A novel genotype, hypervirulent FAdV-4, emerged in 2015 with a high mortality rate ranging from 30 % to 100 % in chickens. Vaccination is an economically feasible method to control HHS. Although there have been various reports of inactivated vaccines from virulent wild-type FAdV-4 against HHS, biosafety threats of inactivated vaccines from potential pathogenic components have been presented to the poultry industry, and safer vaccines are urgently needed. A non-pathogenic recombinant FAdV-4 strain, designated as rHN20, was generated based on the hypervirulent strain in our previous study. Here, we developed a novel inactivated oil-adjuvanted vaccine derived from rHN20 strain and evaluated its immunogenicity in specific-pathogen-free chickens. Chickens subcutaneously or intramuscularly immunized with the inactivated vaccine produced high titers of neutralizing antibodies and were protected from a lethal dose of virulent wild-type FAdV-4 challenge. Collectively, an inactivated vaccine was developed, which was capable of providing full protection for chickens against HHS, and significantly reduced the potential biosafety threats.

Keywords: Biosafety; Fowl adenovirus 4; Hepatitis-hydropericardium syndrome; Inactivated vaccine; Recombinant virus.

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