Abstract
Rabbit haemorrhagic disease virus (RHDV) is a calicivirus that causes acute infections in both domestic and wild European rabbits (Oryctolagus cuniculus). The virus causes significant economic losses in rabbit farming and reduces wild rabbit populations. The recent emergence of RHDV variants capable of overcoming immunity to other strains emphasises the need to develop universally effective antivirals to enable quick responses during outbreaks until new vaccines become available. The RNA-dependent RNA polymerase (RdRp) is a primary target for the development of such antiviral drugs. In this study, we used cell-free in vitro assays to examine the biochemical characteristics of two rabbit calicivirus RdRps and the effects of several antivirals that were previously identified as human norovirus RdRp inhibitors. The non-nucleoside inhibitor NIC02 was identified as a potential scaffold for further drug development against rabbit caliciviruses. Our experiments revealed an unusually high temperature optimum (between 40 and 45 °C) for RdRps derived from both a pathogenic and a non-pathogenic rabbit calicivirus, possibly demonstrating an adaptation to a host with a physiological body temperature of more than 38 °C. Interestingly, the in vitro polymerase activity of the non-pathogenic calicivirus RdRp was at least two times higher than that of the RdRp of the highly virulent RHDV.
Highlights
Rabbit haemorrhagic disease (RHD) is a highly infectious disease with high case fatality and morbidity rates in adult rabbits
To investigate the biochemical properties of rabbit calicivirus RNA-dependent RNA polymerase (RdRp) and to test potential inhibitors, the entire RdRp coding regions from a pathogenic Rabbit haemorrhagic disease virus (RHDV) strain (Czech V351) and that of a non-pathogenic rabbit caliciviruses (RCVs) strain (RCV-A1) were cloned into a bacterial expression vector, which allowed the production of recombinant proteins with a C-terminal leucine-glutamic acid followed by a hexahistidine tag to facilitate nickel affinity purification
Vitro polymerase activity of the enzyme was at least times higher than the RHDV
Summary
Rabbit haemorrhagic disease (RHD) is a highly infectious disease with high case fatality and morbidity rates in adult rabbits. The incubation period ranges between 1 and 3 days and rabbits usually die within 12–36 h after the onset of fever, which is not always observed [1,2,3]. The primary target organs for RHD are the liver, lungs and the spleen, with involvement of the resident macrophages [4]. Haemorrhages and congestions can be found in a variety of organs, in the lungs, heart and kidneys, as a result of massive disseminated intravascular coagulation [1,5]. Rabbit haemorrhagic disease virus (RHDV) infection in rabbits causes severe leukopenia, involving B and T lymphocytes [6,7], and Viruses 2016, 8, 100; doi:10.3390/v8040100 www.mdpi.com/journal/viruses
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call