Detection of a new emerging strain of rabbit haemorrhagic disease virus 2 (GI.2) in China

Abstract

Introduction In May 2020, an outbreak of rabbit haemorrhagic disease 2 (RHD2) caused by the rabbit haemorrhagic disease virus 2 (RHDV2, GI.2) occurred in Sichuan, China. The acute onset and short disease course resulted in rabbit mortality as high as 42.86%. Currently, basic research on the aetiology and genetic characteristics of GI.2 is lacking in China. Material and Methods Pathological changes in various tissues from infected rabbits were investigated and the viral genome was characterised. This study used RT-PCR, histopathology and scanning electron microscopy to identify the pathogen in samples from infected rabbits that had died. Phylogenetic trees were constructed based on whole genome sequence analysis, and recombination events were analysed. Results RT-PCR identified the presence of GI.2. Histopathology revealed liver cell necrosis and haemorrhaging into lung alveoli. Electron microscopy demonstrated spherical GI.2 particles that were 40 nm in size. The gene sequence length of the isolate was 7,445 bp (GenBank accession number MW178244). A phylogenetic analysis based on the genome of the isolated strain and 60 reference strains showed that the isolate was grouped together with GI.2 strain MT586027.1 in a relatively independent sub-branch. The results of the recombination analysis showed that the strain was recombined from the MT586027.1 (major parent) and MN90145.1 (minor parent) strains, and recombination breakpoints were at locations in the 2858–5137 nt range. Conclusion The results of this study extend our understanding of the molecular epidemiology of GI.2.

First report of GI.1aP-GI.2 recombinants of rabbit hemorrhagic disease virus in domestic rabbits in China

“…The NSP encoding genes of Lagoviruses determine the potential of virus replication and immune evasion (Urakova et al, 2015;Zhu et al, 2022), which is a complex process promoting virus evolution with frequent nucleotide variation (Silvério et al, 2018;Mahar et al, 2021). In this study, the recombination analysis reveals that the GI.1aP-GI.2 variants branches into a single clade, which possess similar molecular origins of the parental GI.1a and GI.2, indicating that this new recombination event may occur in China's RHDV strains after the outbreak of GI.2 in 2020 (Chen et al, 2022). Furthermore, the high nucleotide within these four variants also demonstrates that these novel recombinant strains have close geographical relationship.…”

The pathogenicity comparison of Lagovirus europaeus GI.1 and GI.2 strains in China by using relative quantitative assay

“…Rabbits were injected with GI.1, and Pasteurellosis multocida combined inactivated vaccine before and five days after the onset of rabbit farm, but the effect was not obvious 13 . In a previous study, we isolated a GI.2 strain SCCN04 from these dead rabbits at a rabbit farm in Jintang 14 .…”

“…In addition, with pathogenic (variants GI.1a and GI.1b) and benign (genotype GI.4) strains that served as donors for the non-structural part while GI.2 composed the structural part. In our previous study 14 , we performed genetic characterization of SCCN04, where the whole genome phylogenetic tree, the non-structural phylogenetic genes tree and the structural genes phylogenetic tree were constructed, and recombination events were analysed. The results showed that SCCN04 and Chinese isolate SC2020/0401(MT586027.1) formed a small branch and were the most closely related among all the genome phylogenetic trees, and SCCN04 was closely related to European GI.2 isolates on a large branch.…”

Neglected Spleen Transcriptional Profile Reveals Inflammatory Disorder Conferred by Rabbit Hemorrhagic Disease Virus 2 Infection

“…In April 2020, the first RHDV2 outbreak occurred in rabbit farms located in the southwest of China [ 13 , 16 , 30 ]. Before that, the prevention and control of RHD had been effective and stable in local areas.…”