Infection competition against grouper nervous necrosis virus by virus-like particles produced in Escherichia coli

Dragon grouper (Epinephelus lanceolatus) nervous necrosis virus (DGNNV) comprises 180 copies of capsid protein that encapsulate a bipartite genome of single-stranded (+)-RNAs. This study reports that virus-like particles (VLPs) are formed in Escherichia coli expressing the full-length ORF encoding the DGNNV capsid protein. Two sizes of VLPs are observed. The heavier particles resemble the native piscine nodavirus in size and stain permeability, while the lighter ones are approximately two-thirds of the full size. The recombinant VLPs block attachment of native virus to the surface of cultured fish nerve cells, blocking infection by the native virus.