Expression of caspid protein VP1 for use as antigen for the diagnosis of enterovirus 71 infection

To produce enterovirus 71 antigen for diagnostic purposes, the gene encodin g the entire capsid protein VP1 was amplified by reverse transcription-poly merase chain reaction (RT-PCR), cloned and expressed in Escherichia coli as a poly-histidine fusion protein. Western blotting experiments with sera fr om patients with enterovirus 71 infection indicated that immunoglobulin G ( IgG) and IgM antibodies bound to a single polypeptide VP1. According to the se results, IgM anti-VP1 appeared in sera of patients with a symptomatic en terovirus 71 acute infection, whereas IgG anti-VP1 was present in sera of p ast infection. This finding suggests that detecting IgG and IgM immune resp onses against linear epitopes of recombinant VP1 is an effective means of d etermining the different phases of enterovirus 71 infection. In addition, s era containing coxsackie virus 16 (CA16) antibodies did not cross-react wit h the recombinant VP1 of enterovirus 71, despite the homology between VP1 p roteins of both viruses. Comparison with reference PCR and neutralization a ssays showed these antibody tests to be appropriate for the serodiagnosis o f enterovirus 71 infection. (C) 2000 Wiley-Liss, Inc.