A 70 kDa MHC class I associated protein (MAP-70) identified as a receptor molecule for Coxsackievirus A9 cell attachment

One of the major categories of disease-causing micro-organisms are viruses. New studies on many different viruses have shown that virus attachment and cell entry is often a multistep process, requiring many interactions betwe en the virus and cell surface molecules. In this study, we have attempted t o identify the cell surface molecules involved in Coxsackievirus A9 (CAV-9) , a common human pathogen and a member of the Picornavirus family, infectio us process. GMK cells susceptible to virus infection were surfaced labeled with biotin and then solubilized in non-ionic and zwiterionic detergents. F ree CAV-9 virions were used as an affinity surface, allowing the virus to b ind to the solubilized receptors. The virus-receptor complexes were then im munoprecipitated by an anti CAV-9 serum and protein-A sepharose beads. SDS- PAGE and two-dimensional electrophoresis revealed the presence of integrin alphav beta3 molecules and a 70 kDa protein with apparent isoelectric point (pI) 5.5. The identity of the integrin alphav beta3 molecules was confirme d by immunoprecipitation and Western blotting; whereas the 70 kDa protein w as also found ro co-immunoprecipitate with MHC class I molecules in non-str ingent conditions. Sequential immunoprecipitation experiments confirmed tha t the MHC class I associated protein (MAP-70) and the 70 kDa protein utiliz ed by CAV-9 were identical. The role of MAP-70 in CAV-9 infectious process is discussed. Human Immunology 61, 867-878 (2000). (C) American Society for Histocompatibility and Immunogenetics, 2000. Published by Elsevier Science Inc.