Characterization of the highly immunogenic VP2 protrusion domain as a diagnostic antigen for members of Birnaviridae family

Abstract

Birnaviridae is a family of viruses (birnaviruses) which consists of four genera, members of which cause diseases in fish, birds, mollusks, and insects. The genome of birnaviruses encodes the highly immunogenic VP2 capsid protein. In order to demonstrate that the VP2 protein can be exploited as a diagnostic antigen for birnaviruses, we developed a lateral flow assay based on the surface-exposed VP2 protrusion domain of a representative birnavirus, infectious bursal disease virus (IBDV) of serotype 1 which causes the highly devastating infectious bursal disease in chickens. The biophysical characterization of the purified domain reveals that the domain predominantly consists of β-sheets, exists in a trimeric form, and remains folded at high temperatures, making it suitable for diagnostic purposes. Owing to its highly immunogenic nature and excellent biophysical properties, we employed the VP2 protrusion domain in a gold nanoparticle-based lateral flow assay for rapid detection of anti-IBDV antibodies in serum samples of infected chickens. Our results indicate that the domain binds anti-IBDV antibodies with high specificity during laboratory testing and on-site testing. The lateral flow assay reported here yields comparable results in a qualitative manner as obtained through a commercial enzyme-linked immunosorbent assay (ELISA). As VP2 is a common capsid protein of birnaviruses, the lateral flow assay can be generalized for other birnaviruses, and members of Tetraviridae and Nodaviridae families which contain homologous VP2 capsid proteins. Keywords Birnavirus . Circular dichroism . Gold nanoparticle-based lateral flow assay . Infectious bursal disease virus . Infrared spectroscopy . VP2 protrusion domain Electronic supplementary material The online version of this article (https://doi.

Oral Immunization with Recombinant Saccharomyces cerevisiae Expressing Viral Capsid Protein 2 of Infectious Bursal Disease Virus Induces Unique Specific Antibodies and Protective Immunity

“…VP2 is the major structural protein constituting the viral capsid, accounting for about 51% of the total viral proteins. As the major host-protective immunogen of IBDV, VP2 has more than three independent epitopes that can induce virus-neutralizing antibodies [ 9 , 10 ].…”