Inclusion of an Arg-Gly-Asp Receptor-recognition Motif into the Capsid Protein of Rabbit Hemorrhagic Disease Virus Enables Culture of the Virus In Vitro [Immunology]

Rabbit hemorrhagic disease virus (RHDV), an important member of the caliciviridae family, cannot be propagated in vitro, which has greatly impeded the progress of investigations into the mechanisms of pathogenesis, translation, and replication of this and related viruses. In this study, we have successfully bypassed this obstacle by constructing a mutant RHDV (mRHDV) by using a reverse genetics-technique. By changing two amino acids (305S→R, 307N→D), we produced a specific receptor recognition motif (Arg-Gly-Asp, called RGD) on the surface of the RHDV capsid protein. mRHDV was recognized by the intrinsic membrane receptor (integrin) of the RK-13 cells, which then gained entry and proliferated, as well as imparted apparent cytopathic effects. After twenty passages, the titers of RHDV reached 1 x 104.3 TCID50 per mL at 72 h. Furthermore, mRHDV-infected rabbits showed typical rabbit plague symptoms and died within 48-72 hours. After immunization with inactivated mRHDV, the rabbits survived from wild-type RHDV infection, indicating that mRHDV could be a candidate virus strain for producing a vaccine against RHDV infection. In summary, this study offers a novel strategy for overcoming the challenges of proliferating RHDV in vitro. Because virus uptake via specific membrane receptors, several of which specifically bind to the RGD peptide motif, is a common feature of host cells, we believe that this the strategy could also be applied to other RNA viruses that currently lack suitable cell lines for propagation, such as hepatitis E virus and norovirus.

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