Hand, foot and mouth disease is mainly caused by enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16), but EV-A71 is also associated with severe neurological complications. Host factors may contribute to the different clinical outcomes of EV-A71 and CV-A16 infections. A neurovirulent EV-A71 strain (EV-A71/UH1) from a fatal case, a non-neurovirulent EV-A71 strain (EV-A71/Sha66) and a CV-A16 strain (CV-A16/22159) from cases of uncomplicated HFMD were used. Replication of the viruses in SK-N-MC (neuronal) and HT-29 (intestinal) cell lines correlated with the severity of clinical disease associated with each virus. EV-A71/UH1 showed the greatest replication in neuronal cells. In HT-29 cells, both EV-A71 strains replicated well, but CV-A16/22159 showed no effective replication. The proteomes of mock and infected SK-N-MC and HT-29 cell lines were compared by 2D-SDS-PAGE. The differentially expressed proteins were identified by MALDI-TOF/TOF analysis. There were 46 and 44 differentially expressed proteins identified from SK-N-MC and HT-29 cells, respectively, categorized under apoptosis, stress, cytoskeletal, energy metabolism proteins and others. Western blot validation showed that EV-A71/UH1 and CV-A16 also differentially induced proteins involved in viral RNA translation and host cell stress responses in neuronal and intestinal cell lines.
Enterovirus A71 (EV-A71) belongs to the species group A in the Enterovirus genus within the Picornaviridae family. EV-A71 usually causes self-limiting hand, foot and mouth disease or herpangina but rarely causes severe neurological complications such as acute flaccid paralysis and encephalomyelitis. The pathology and neuropathogenesis of these neurological syndromes is beginning to be understood. EV-A71 neurotropism for motor neurons in the spinal cord and brainstem, and other neurons, is mainly responsible for central nervous system damage. This review on the general aspects, recent developments and advances of EV-A71 infection will focus on neuropathogenesis and its implications on other neurotropic enteroviruses, such as poliovirus and the newly emergent Enterovirus D68. With the imminent eradication of poliovirus, EV-A71 is likely to replace it as an important neurotropic enterovirus of worldwide importance.