A Small Region of Porcine Hemagglutinating Encephalomyelitis Virus Spike Protein Interacts with the Neural Cell Adhesion Molecule

Objective: The spike (5) 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 Si subunit of the S protein that interacts with NCAM. Methods: Three truncated segments (S1-291, S277-794 and S548-868) of the 5 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 S1-291, S277-794 and S548-868 and NCAM were detected by a GST pull-down experiment and yeast two-hybrid assay. Results: Three fusion proteins (S1-291, S277-794 and S548-868) were screened for their interactions with NCAM by protein-protein interaction assays. The results of these assays clarified that S277-794 interacted with NCAM, while S1-291 and S548-868 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 receptorbinding domain that mediates PHEV binding to NCAM. (C) 2015 S. Karger AG, Basel