Abstract
In mid-2020, using next-generation sequencing (NGS) technology, we
identified a divergent cluster 2 avian orthoreovirus (ARV) variant named
PHC-2020-0545, isolated from tendons of 33-day-old broilers with leg
swelling in China. Sequence comparison and phylogenetic analysis of
results revealed that the isolate strain was genetically distinct from
all known ARV strains in M1 and M3 genes, and the σC coding gene was
quite different from the identified ARV strains grouped into other
genotyping cluster. The recombination analysis revealed that multiple
segmental recombination, intra-segmental recombination and accumulation
of point mutations might contribute to the emergence of this isolate.
The broilers infected with the PHC-2020-0545 strain showed typical
clinical symptoms of tarsal joint swelling, and the isolate mainly
affected the movement, digestion and metabolism of broilers. Although
the mortality of broilers caused by the isolate was very low, the
results of viral load detection revealed that it had strong replication
ability in vivo. In addition, the infection route of the isolate is
related to its pathogenicity to broilers. Therefore, we determined that
the PHC-2020-0545 field strain is a unique novel recombinant ARV strain,
which might become prevalent in Chinese broiler flocks.