AUTHOR=Wang Linguo , Zhang Pantao , Huang Baicheng , Wang Mengyue , Tian Hui , Liu Peng , Liu Wujie , Tian Kegong 

TITLE=Fiber Protein Produced in Escherichia coli as a Subunit Vaccine Candidate Against Egg-Drop Syndrome 76

JOURNAL=Frontiers in Veterinary Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.819217

DOI=10.3389/fvets.2022.819217

ISSN=2297-1769

ABSTRACT=The Egg-drop syndrome 76 (EDS 76) caused by duck atadenovirus A (DAdV-1) infection in laying hens leads to the decrease of egg production, causing heavy economic losses in the poultry industry, thus, vaccines with high safety and immunogenicity are needed. In this study, the DAdV-1 fiber protein expressed in Escherichia coli (E. coli) with codon optimization showed the hemagglutination (HA) titer of 13 log2 after purification (0.6 mg/mL). Compared with inactivated EDS 76 vaccine, the specific-pathogen-free (SPF) chickens immunized with 0.4 mL fiber protein (HA titer of 11 log2) induced an equal level of hemagglutination inhibition (HI) titer and neutralizing antibodies. Meanwhile, after immunization with fiber protein, the lowest HI titer that could provide the effect to reduce egg production rate in laying hens after the challenge was 7 log2. Moreover, fiber protein with a HA titer of 7 log2 could induce a HI titer no less than 7 log2 in laying hens, which was equal to or higher than the lowest HI titer (7 log2) that could reduce egg production against DAdV-1 infection significantly, indicating that it is economically feasible for vaccine development. Importantly, the HI antibodies maintained at a high level up to 180 days post-immunization contribute to the clinical application of the vaccine candidate. Overall, the fiber protein produced in E. coli is an effective subunit vaccine candidate in EDS 76 control for its high immunogenicity and protection in chickens.