Physicochemical and immunological characterization of recombinant host-protective antigen (VP2) of infectious bursal disease virus

Small fusions to the N-terminal end of the host-protective antigen (VP2) of infections bursal disease virus lead to stable expression of VP2 in Escherichia coli and yeast, and reduce the levels of inclusion body formation in E. coli in comparison to VP2 constructs with larger N-terminal fusions. VP2 produced with small N-terminal fusions, like native viral VP2, can be fractionated into a high molecular weight ‘multimeric’ form and a monomeric form. A virus-neutralizing monoclonal antibody that only recognizes undenatured VP2 preferentially reacts with multimeric forms of recombinant VP2. Both native and recombinant monomeric forms of VP2 are non-immunogenic. The multimeric forms of viral and yeast-derived VP2 are highly immunogenic, while those produced in E. coli are not.