OBJECTIVE: The spike (S) protein of porcine hemagglutinating encephalomyelitis virus (PHEV) may mediate infection by binding to a cellular neural cell adhesion molecule (NCAM). This study aimed to identify the crucial domain of the S1 subunit of the S protein that interacts with NCAM. METHODS: Three truncated segments (S(1-291), S(277-794) and S(548-868)) of the S gene of PHEV and the NCAM gene were cloned individually into the Escherichia coli expression vectors and yeast two-hybrid expression vectors. The interaction between S(1-291), S(277-794), S(548-868) and NCAM were detected by a GST pull-down experiment and yeast two-hybrid assay. RESULTS: Three fusion proteins (S(1-291), S(277-794) and S(548-868)) were screened for their interactions with NCAM by protein-protein interaction assays. The results of these assays clarified that S(277-794) interacted with NCAM, while S(1-291) and S(548-868) did not. CONCLUSIONS: A small fragment (258-amino-acid fragment, residues 291-548) on the PHEV S protein was posited to be the minimum number of amino acids necessary to interact with NCAM. This fragment may be the receptor-binding domain that mediates PHEV binding to NCAM.
A Small Region of Porcine Hemagglutinating Encephalomyelitis Virus Spike Protein Interacts with the Neural Cell Adhesion Molecule