Thin section immuno-electron microscopy has been successfully applied to investigate and identify the classical and mild form of HFRS viruses isolated in the People's Republic of China. The results showed that all the 8 strains studied (derived from different parts of China, adapted in different cell lines) share a common morphology and morphogenesis. Essentially, the viruses possess characteristics of members of the Bunyaviridae Family, however, differing by a larger size and size variation and formation of cytoplasmic viral inclusions.

Canine distemper (CD), caused by the CDV variant strain with H I542N/Y549H , has become an epidemic in fur-bearing animals in China since 2012. To well understand the genomic and replicated characteristics of the CDV variants, we determined the viral growth kinetics and completed the genome sequences of two CDV strains, namely SDZC(17)M2 and LNDL(17)M4, isolated from CDV-infected minks from Shandong and Liaoning province in China, in 2017. SDZC(17)M2 showed higher viral titers and extensive syncytia in BHK-minkSLAM (BMS) cells than LNDL(17)M4. Although both two strains belong to the Asia-1 genotype and clustered an independent clade in the phylogenetic tree, SDZC(17)M2, harboring I542N/Y549H substitutions in the H protein, shared high identity (99.3-99.6% nt) with the other variant strains, whereas LNDL(17)M4, with the only Y549H substitution, shared a lower identity (97.7%-97.9% nt) with the other variant strains. Furthermore, a novel R223K substitution was identified in the conserved cleavage site (RRQRR→ RRQKR) of the F protein in the SDZC(17)M2 strain. However, it which did not significantly affect the cell to cell fusion activity when combined with the CDV H/minkSLAM in BHK-21 cells. The key variations in the genome contributed to the virulence and the evolutionary trend need to be determined in the future.