[Biological characters of a coxsackievirus B3 variant strain isolated from a hand-foot-mouth disease patient with severe clinical symptoms].

Objective: To analyze the genetic and biological characters of a new isolate of coxsackievirus B3 (CoxB3), i.e. FY-19 strain, and investigate its mechanistic role in causing different clinical symptoms of hand-foot-mouth disease (HFMD).

Methods: FY-19 strain, isolated from a patient with severe clinical symptoms from Fuyang, China in 2008, was identified by the serological parameters via the Lim Benyesh-Melnick (LBM) antiserum pools. Its genotype was further characterized by sequencing the whole genome. And its biological characters were also examined by proliferation kinetic and pathogenetic analysis.

Results: FY-19 strain was identified as CoxB3 showing 23.0%, 16.5% and 32.1% difference with Nancy strain in 3'-, 5'-noncoding and coding regions respectively. FY-19 also showed a high homology with other HFMD-related CoxB3 isolates in China. But its homology with non-HFMD-related CoxB3 isolates was lower (13.5% and 25.0% difference in 3'-NCR and coding region respectively). The viral replication kinetic analysis suggested that the FY-19 proliferation increased rapidly and peaked at 14 hours post-infection. In pathological analysis, FY-19 strain induced mortal pathology in sucking mice.

Conclusion: Differences in genetic and biological characters exist between FY-19 and Nancy strains. Further analysis on the pathogenesis of this variant may aid in elucidating the mechanisms of HFMD.