The degree of polymerization and sulfation patterns in heparan sulfate are critical determinants of cytomegalovirus entry into host cells

Herpesviruses attach to host cells by interacting with cell surface heparan sulfate (HS) proteoglycans prior to specific coreceptor engagement which culminates in virus-host membrane fusion and virus entry. Interfering with HS-herpesvirus interactions results in significant reduction in virus infectivity indicating that HS play important roles in initiating virus entry. In this study, we provide convincing evidence that specific sulfations as well as the degree of polymerization (dp) of HS govern human cytomegalovirus (CMV) infection and binding by following line of evidences. First, purified CMV extracellular virions preferentially bound to the sulfated longer chain of HS on a glycoarray compared to unsulfated glycosaminoglycans and shorter chain unsulfated HS. Second, the fraction of glycosaminoglycans (GAG) displaying higher dp and sulfation had a major impact on CMV infectivity and titers. Finally, cell lines knocked out for specific sulfotransferases Glucosaminyl 3-O-sulfotransferase (3-O-ST-1 and -4 and double -1/4) produced significantly reduced CMV titers compared to wild-type cells. Similarly, a peptide generated against sulfated-HS significantly reduced virus titers compared to the control peptide. Taken together, the above results highlight the significance of the chain length and sulfation patterns of HS in CMV binding and infectivity.