Detection of a new emerging rabbit hemorrhagic disease type 2 virus
(GI.2) in China
Abstract
In May 2020, the first outbreak of rabbit viral hemorrhagic disease
(RHD) caused by rabbit hemorrhagic disease virus type 2 (GI.2) occurred
in Sichuan, China. The acute onset and short disease course resulted in
rabbit mortalities as high as 42.86%. Currently, basic research on the
etiology and genetic characteristics of GI.2 is lacking in China.
Pathological changes in various tissues from infected rabbits were
investigated, and the viral genome was characterized. This study used
RT-PCR, histopathology, scanning electron microscopy, and whole genome
sequencing analysis to identify the pathogen in samples from infected
rabbits that had died. RT-PCR identified the presence of GI.2. The
histopathology revealed liver cell necrosis and hemorrhaging into lung
alveoli. Electron microscopy demonstrated spherical GI.2 particles that
were 40 nm in diameter with an isometric interior. The gene sequence
length of the isolate was 7,464 bp and termed GI.2/CN/SC-04. The
phylogenetic analysis of the GI.2 genotype showed that the strain from
GI.2/CN/SC-04 clustered into a separate group compared to the isolate
from China (MT586027.1). Phylogenetic analysis based on whole sequences
and showed that GI.2/CN/SC-04 strains were identical and clustered with
other strains of GI.2 circulating globally. The results of recombination
analysis showed that GI.2/CN/SC-04 was recombined from MT586027.1 strain
(main parent strain) and MN90145.1(secondary parent strain), and both
the two recombination breakpoints 2858-5137nt. This was the study to
report that GI.2 had been isolated in China, to characterise the full
genome sequence and provide phylogenetic insights into the origin of
this exotic incursion. development.