Biological characteristics of an Enterovirus 71 subgroup C4 strain isolated in China

Background Hand, foot, and mouth disease (HFMD) is a widespread infectious disease primarily affecting infants and young children. Enterovirus 71 (EV71) comprises seven genogroups, among which subgroup C4 is the dominant viral agent in China and is frequently associated with HFMD and central nervous system infections. We analyzed the genetic characteristics of an EV71 subgroup C4 strain through whole-genome sequencing and investigated its biological characteristics, including infectivity, replication, and cytotoxicity, in human rhabdomyosarcoma (RD) and African green monkey kidney (Vero) cells. Methods We examined the genetic and biological features of a clinical EV71 GD10 strain isolated in China. Its relationships with strains listed in GenBank were evaluated using phylogenetic analysis. Viral infectivity and replication were assessed in RD and Vero cells. Cytotoxicity was evaluated by measuring cell viability, lactate dehydrogenase (LDH) release, and ATP levels. Effects on blood–brain barrier (BBB) integrity were investigated in vitro by assessing transendothelial electrical resistance and viral load across the barrier. Results Sequence analysis confirmed that GD10 belonged to subgroup C4 and closely resembled strains from China. GD10 infection induced a pronounced cytopathic effect and elevated viral RNA levels in RD cells but not in Vero cells. The infection time-dependently increased LDH release and reduced ATP levels. GD10 compromised BBB integrity and crossed the cellular barrier in vitro . Conclusion The GD10 strain demonstrated strong adaptability to RD cells and impaired BBB function. Our results improve the understanding of virus–host interactions and may support efforts towards EV71 vaccine development.