Novel cell adhesive glycosaminoglycan-binding proteins of Japanese encephalitis virus

Glycosaminoglycans (GAGs) are present in the extracellular matrix and/or tissue cell surface and, by binding to specified GAG-binding proteins, control many important cellular functions. Some animal viruses had evolved to use GAGs as part of their strategy to invade host cells. In this study, two putative GAG-binding proteins were identified from the E protein sequence of the live-attenuated strain CH2195LA of Japanese encephalitis virus (JEV): (i) the first GAG-binding region at residues from E-279 to E-297 (279KLTSGHLKCRLKMDKLALK297) and (ii) the second GAG-binding region at residues from E-397 to E-416 (397KAGSTLGKAFFSTTLKGAQR416). Four recombinant proteins with or without these two GAG-binding regions were expressed in Escherichia coli and purified to examine their GAG-binding properties. The first GAG binding region was demonstrated to exhibit a higher affinity in heparin-Sepharase column. Dose-dependent increases of BHK-21 cell binding were also demonstrated by cell binding enzyme-linked immunosorbent assay (ELISA). Immobilized on glass coverslips, the GAG-binding recombinant protein of JEV promoted BHK-21 cell adhesion and proliferation. The present studies demonstrate the recombinant GAG-binding proteins of JEV stimulate cell adhesive and proliferation with a potential for applications in tissue engineering.