Identification and partial characterisation of a new lagovirus in Australian wild rabbits

Rabbit Haemorrhagic Disease Virus (RHDV) is widely used in Australia to control feral rabbit populations. Before RHDV was released on the Australian continent in 1996, antibodies cross-reacting in RHDV specific ELISAs were found in Australian wild rabbits, leading to the hypothesis that a non-pathogenic calicivirus had been circulating in rabbit populations in Australia, potentially providing some level of cross-immunoprotection to RHDV infection. For the detection of this putative virus, a universal lagovirus PCR test was developed to screen a variety of different tissues of wild caught rabbits. We identified a new lagovirus in the intestinal tissues of three apparently healthy young wild rabbits. Quantitative Real Time PCR analysis revealed high concentrations of viral RNA in intestinal tissues and suggests a faecal-oral mode of transmission. Genome organisation and phylogenetic analysis following the sequencing of the entire viral genome revealed a new member of the genus Lagovirus within the family Caliciviridae.