CHARACTERIZATION OF FUNCTIONAL DOMAINS IN THE HUMAN CORONAVIRUS HCV 229E RECEPTOR

Human aminopeptidase N (hAPN or CD13) and porcine aminopeptidase N (pA PN) are functional receptors for human coronavirus (HCV) 229E and porc ine transmissible gastroenteritis virus (TGEV), respectively, However, hAPN cannot function as a receptor for TGEV and pAPN cannot function as a receptor for HCV 229E, In this study, we constructed a series of chimeric hAPN/pAPN genes and expressed the corresponding proteins in t ransfected cells, Subsequently, we identified the chimeric proteins th at can function as a receptor for HCV 229E, The results show that repl acement of a small region of pAPN sequence (pAPN amino acids 255-348) with the corresponding hAPN sequence (hAPN amino acids 260-353) conver ts pAPN into a functional receptor for HCV 229E. The region of hAPN th at we have defined in this way does not correspond to the region of pA PN that has been identified as essential for the TGEV-receptor interac tion, We conclude that although both viruses use a homologous receptor protein, different regions of the protein are required to mediate sus ceptibility to infection with HCV 229E and TGEV.