Molecular cloning of the hepatitis A virus receptor from a simian cell line

Using a eukaryotic expression system in combination with a monoclonal antibody (MAb) capable of blocking hepatitis A virus (HAV) adsorption, a cDNA clone was selected from a library of S.la/Ve-1 cells, a cell line that is highly susceptible to the virus. Sequence analysis of the cDNA revealed a single open reading frame that encoded a protein consisting of 460 amino acids. The deduced primary structure of the protein included a signal sequence, a transmembrane domain, four sites for N-linked glycosylation, cysteine residues attributable to an immunoglobulin domain and threonine clusters characteristic of mucin-like protein. By employing a vaccinia virus expression vector, the cDNA was expressed in HeLa cells where it induced marked HAV attachment which was specifically blocked by the MAb. The cDNA obtained was thus assumed to encode a functional receptor for HAV.