FIGURE LEGENDS
Table 1Recombinant outcome detected using the Recombination Detection Program v4.56.
Table 2Detection of viral loads in tissues and body fluids of rabbits infected with RHDV2 (SC20-01 strain).
Fig. 1Details of the first case of RHD caused by RHDV2 in China.(A) The location of the first case of RHD caused by RHDV2 in China. (B) Clinical signs of infected rabbits. Dead rabbits show typical clinical signs of RHD, including anorexia, cachexia, opisthotonos, and bloody nasal discharge. (C) Pathological tissue changes in infected rabbits. The major pathological changes of tissues are haemorrhages and congestions in the lungs, as well as acute hepatitis.
Fig. 2TEM images of viral particles extracted from supernatants of homogenized livers of the infected rabbits. Supernatants of homogenized livers were clarified with 30% sucrose solution. Icosahedral symmetry viral particles were observed with a diameter ranging from 30 to 40 nm, which was consistent with those of RHDV.
Fig. 3Phylogenetic analysis of RHDV2 China isolation strain SC20-01. (A) Maximum likelihood tree for RHDV based on the VP60 protein using MEGA5.0 software. RHDV isolation strain SC20-01 belonged to the RHDV2 subtype and was most closely related with several isolation strains in Europe. (B) Nucleotide sequence divergence scans and Bootscanning of RHDV. Recombination events of the SC20-01 strain were examined using SimPlot with one apparent breakpoint that separated the SC20-01 genome into two regions being detected.
Maximum likelihood tree for RHDV based on the non-structural (10~5304 bp) (C) and structural protein-coding regions (5304~7378bp) (D) using MEGA5.0 software. The non-structural protein-coding region of SC20-01 was more closely related with that of classic RHDV than RHDV2. Further, the results indicated that SC20-01 was a classic RHDV/RHDV2 recombination strain.
Fig. 4Animal regress experiment of SPF rabbits infected with RHDV2 China isolation strain SC20-01. (A) SPF rabbits infected with SC20-01 strain showed typical clinical signs and pathological changes of RHD. SC20-01 strain was highly fatal and could cause the death of the SPF rabbits after 24 post-injection hours. (B) IHC analysis of tissues from rabbits in both groups. Images of IHC analysis showed that VP60 of RHDV2 was present in the tissues of the rabbits in the experiment group and was mainly located in the cellular cytoplasm.