Identification of Echovirus 1 and Coxsackievirus A9 receptor molecules viaa novel flow cytometric quantification method

Background: Virus-receptor binding is an essential step in every virus infe ctious process. Many viruses employ more than one receptor molecule or even receptor complexes for attachment. In this study, we investigate time bind ing of Echovirus 1 (Echo1) and Coxsackievirus A9 (CAV-9) on cell surface mo lecules. CAV-9 has been reported to utilize integrin alphav beta (3) in bin ding to cells, whereas Echo1 has been known to utilize integrin alpha2 beta (1). Methods and Results: We directly test whether the presence of these molecul es alone was sufficient for virus binding. We devised a novel flow cytometr ic binding assay that enables us to quantify virus particles bound on host cells and to further determine the extent to which viruses utilize specific receptors. Conclusions: By quantifying virus particles and possible receptor molecules , we found that Echo1 utilizes mainly integrin alpha2 beta (1). CAV-9 utili zes integrin alphav beta (3) to a much lesser extent (40%), indicating that CAV-9 also utilizes other receptor(s). Cytometry 43:279-289, 2001. (C) 200 1 Wiley-Liss. Inc.