Genomic Characteristics And Pathological Study On The Pathogenicity Of Novel Duck Reovirus In Duckings

In this study,we used cell culture technology,light microscopy,qRT-PCR technology,RT-PCR technology,gene amplification and sequencing,animal model of infection,histopathology,immunohistochemistry and other research methods to conduct a systematic study about the proliferation of five NDRV(JZ061214,HP080421,HP081122,HP09318,YM101120)in the baby hamster kidney(BHK-21)cell,the complete genomes sequencing and analysis of one NDRV(here we chose HP080421strain),the amplification,the sequencing and sequence analysis of S1 gene,the pathogenicity of three DRV with severe genetic difference among the five strains in cherry valley ducks.1.Complete genomes sequencing and analysis of HP080421 strainWe obtained the full length of the complete genome sequence(23419 bp)with ten segments.The homology analysis showed that each segment of HP080421 was closely related to NDRV-SD12 and DRV-091..2.The amplification,the sequencing and sequence analysis of S1 gene in five DRV strainsThe S1 gene of five DRVs was amplified and we got a fragment of about 1568 bp in length.The results showed that the S1 nucleotide sequences from the five DRV shared high identity with NDRV,they both shared above 90% identity with NDRV.The five DRVs shared low identity with MDRV and ARV,about 35.0%-37.4% with MDRV and43.2%-45.3% with ARV.The phylogenetic tree further showed that the five DRVs had the closest genetic relationship,among which JZ061214 strain had the closest genetic relationship to other reference strains,and there was a certain genetic distance between JZ061214 strain and the other four NDRV strains(HP09318 strain,HP081122 strain,HP080421 strain and YM101120strain).3.The pathogenicity of three NDRV strains in cherry valley ducksWe used the virus to infect 7-day-old Cherry Valley ducks and found that the ducklings in the three infected groups had transient lassitude and anorexia,some duckeyes had tears.the spleens were obviously enlarged and had yellow and white lesions;The group of JZ061214 was the most serious,and the YM101120 group yellow and white spots in spleen disappeared in 5 and 7 days post-infection.The spleen tissue showed different degree of necrosis in the infected groups.The pathologic changes in bursa of fabricius were lymphoid follicles decreased;while in the thymus showed that there was necrotic foci and large amount of erythrocyte around the thymic corpuscle tissues.And the result of IHC showed that the viral load of the spleen was the highest at3 dpi and 5dpi.The statistical results of IHC further showed that the strain with the highest virus content in the spleen of the three strains was JZ061214.The virus content of the remaining two viruses was similar,and there was significant statistical differences between JZ061214 group and the other two groups.