Surface display of an internal His-tag on virus-like particles of Nudaurelia capensis ω virus (NωV) produced in a baculovirus expression system

Nudaurelia capensis ω virus (NωV) is a member of the Tetraviridae, a family of small, icosahedral, non-enveloped, (+) sense single-stranded RNA insect viruses with T = 4 symmetry. NωV virus-like particles (VLPs), which are morphologically indistinguishable from native virions and capable of packaging heterologous RNA, may be produced in the baculovirus expression system. As a first step towards manipulating the tropism of tetraviral nanoparticles (Capsivectors™), a (His)6-tag was inserted into the GH loop (between Ala 378 and Gly 379) of the surface-exposed Ig-like domain of NωV capsid protein (p70). His-tagged p70 produced in a baculovirus expression system self-assembled into ωHis VLPs that exhibited similar morphological and RNA encapsidation properties as wild-type NωV VLPs produced in the same system. Two assays using paramagnetic pre-charged nickel beads confirmed that multiple affinity tags were present on the surface of ωHis VLPs and were capable of binding. These results indicate that the GH loop is a suitable site for the retargeting of NωV particles for potential biotechnological applications.