Serological characterisation of Lagovirus virus-like particles originating from native and mutated VP60 of rabbit haemorrhagic disease virus 2 and European brown hare syndrome virus

Abstract

Introduction: Since lagoviruses cannot be cultivated in vitro, using expression systems is an alternative and promising way of producing viral antigens for diagnostic purposes. It offers the possibility of their use as active immunogens for vaccine production. Materials and methods: We have produced virus-like particles (VLPs) in the baculovirus expression system in Sf9 insect cells based on wild-type and mutated variants of VP60 protein from the Polish strain of European brown hare syndrome virus (EBHSV) and wild-type and mutated versions of VP60 protein of Polish strain of rabbit haemorrhagic disease virus 2 (RHDV2). VLPs were purified with the use of sucrose gradient ultracentrifugation. Results: Protein production was confirmed by Western blot analysis using rabbit or hare sera and ELISA tests with different types of monoclonal antibodies. Hemagglutination properties of some VLPs have been evaluated as well. Electron microscopy of EBHSV-WT, RHDV2-WT and four produced VP60 variants revealed the formation of characteristic VLP structures. Conclusions: For the first time, we have obtained a mutated version of VLPs of RHDV2 with RGD motif in the VP60 protein sequence, which could be potentially used as a vehicle to deliver cargo to eukaryotic cells. We have also described VLPs based on VP60 protein from EBHSV and RHDV with three lysines substitutions in S and P2 domain. In addition, VLPs of EBHSV and RHDV2 could be potentially used as vaccine candidates.