The new French 2010 Rabbit Hemorrhagic Disease Virus causes an RHD-like disease in the Sardinian Cape hare (Lepus capensis mediterraneus)

Abstract

Lagovirus is an emerging genus of Caliciviridae, which includes the Rabbit Hemorrhagic Disease Virus (RHDV) of rabbits and the European brown hare syndrome virus (EBHSV) of hares that cause lethal hepatitis. In 2010, a new RHDV related virus (RHDV2) with a unique genetic and antigenic profile and lower virulence was identified in France in rabbits. Here we report the identification of RHDV2 as the cause in Sardinia of several outbreaks of acute hepatitis in rabbits and Cape hare (Lepus capensis mediterraneus). This is the first account of a lagovirus that causes fatal hepatitis in both rabbits and hares.

Figure 1

Geographic range of rabbit hemorrhagic disease (RHD) outbreaks in rabbits and Cape hares (Lepus capensis mediterraneus ) in Sardinia from 2008 to 2012. Green = rabbits infected by RHDV during 2008–2010; yellow: rabbits infected by RHDV in 2011; red: rabbits infected by RHDV2 during 2011–2012; blue: Cape hares infected by RHDV2 in the autumn of 2011.

Figure 2

Antigenic characterization using specific MAb panels of the rabbit hemorrhagic disease viruses (RHDVs) identified in Sardinia since 2008. MAb reactivity is proportional to the depth of blue. Dark blue: > 80%; medium blue: 40-80%; light blue: 10-40%; white: no reactivity. Im: RHDV used as immunogen in MAb production; R1: RHDVBs89 – RHDV used as reference; R1a: RHDVPv96 – RHDVa subtype used as reference; R2: RHDV2_10-32. Reference viruses used in the ELISAs. R1: RHDVBs89; R1a: RHDVPv96; R2u: RHDV2Ud11; E: EBHSVBs91 – EBHSV used as reference. Groups of RHDV collected in Sardinia. Rg1: RHDV identified in rabbits from 2008 to May 2011; Rg2: RHDV identified in rabbits after October 2011; Hg: Cape hares affected by a RHD-like disease collected in December 2011.

Figure 3

Phylogenetic analysis of rabbit hemorrhagic disease virus (RHDV) isolates and RHDV2 isolates identified in Italian hares and rabbits. For the phylogenetic analysis of the VP60 sequences, the neighbor-joining method was applied based on the Kimura 2-parameters using the software package MEGA5 [20]. The European brown hare syndrome virus (EBHSV) strain BS89 (GenBank accession number: X98002) was used as an outgroup to root the tree. Bootstrap probability values above 70% for 1000 replicate runs are indicated at the nodes. Twenty selected sequences representing previously described RHDV genogroups (G1-G6, [18]), four sequences of RCV-like isolates, and the sequences of the RHDV2 isolates identified in France in 2010 (strain 10–32) and in Italy (strains Ud11 and Tn12-1) were included. The GenBank accession numbers of these strains are indicated. The RHDV sequences from rabbits isolated before spring 2011 (accession numbers: KC595270 and KC345614) belong to genogroup 5, whereas those from rabbits and hares collected after this period (accession numbers: KC345611, KC345612, KC345613, and JX106023) belong to the genogroup RHDV2.