Novel monoclonal antibodies against Fiber-1 of duck adenovirus 3 and their B cell epitopes

Abstract

Recently, the outbreak of the infection of Duck adenovirus 3 (DAdV-3) characterized by swelling and hemorrhagic liver and kidney has caused huge economic losses to duck industry since 2014 in China. To date, the B cell epitopes in the Fiber-1 protein and the underlying infection mechanism of DAdV-3 have not been investigated. In this study, the recombinant Fiber-1 protein was first expressed in E. coli and six novel monoclonal antibodies (mAbs) against Fiber-1 were generated, designated as 1D8, 1E6, 3G6, 4G1, 4G2, and 6F10, respectively. Moreover, mAbs 3G6 and 6F10 could efficiently immunoprecipitate the Fiber-1 in LMH cells infected with DAdV-3 or transfected with pcDNA3.1-Fiber-1. Notably, mAbs 3G6 and 4G2 also showed certain neutralizing activity against DAdV-3 infection in vitro. Epitopes mapping revealed that the B cell epitope recognized by 6F10, 3G6, 4G1, 1D8, 4G2, and 1E6 was located in 34-66aa, 67-99aa, 64-296aa, 297-329aa, 330-362aa, and 363-395aa, respectively. Sequence alignments further found that the six epitopes recognized by these mAbs were highly conserved among different DAdV-3 isolates. The generated mAbs specific to Fiber-1 and their defined epitopes provide powerful tools for establishing rapid and efficient diagnostics for the detection of DAdV-3 and pave the way for further studying on the critical role of Fiber-1 in mediating the infection of DAdV-3.

Isolation, characterization, evaluation of pathogenicity, and immunomodulation through interferon production of duck adenovirus type-3 (DAdV-3)

“…Like the serotype 4 fowl adenovirus ( FAdV-4 ), DAdV-3 also has 2 fiber proteins (fiber-1 and fiber-2). Previous studies have shown that the fiber proteins are related to virus neutralization, so they are ideal for the detection of viruses and vaccine development ( Yin et al, 2019 ; Shao et al, 2022 ; Lin et al, 2023 ) The amino acid sequences of hexon proteins are different in each strain which is important for virus classification ( Marek et al, 2010 ). Penton, as a bond between hexon and fiber, plays an important role in the stability of viral capsid and the attachment of invading virion ( Gao et al, 2019 ).…”

Tropism and infectivity of duck adenovirus type-3 virus in chickens

“…Similar to FAdV-4, DAdV-3 has two ber proteins, a short ber-1 and a longer ber-2. Fiber-1 can directly mediate the infection of DAdV-3, while ber-2 can induce neutralizing antibodies and be used as an effective protective immunogen to offer complete protection against DAdV-3 infection [6][7][8]. Hexon, as the principal ingredient of the capsid, is the basis for the classi cation of DAdVs.…”