Analysis of the steps involved in dengue virus entry into host cells

The initial steps of dengue viral entry have been divided into adsorption a nd penetration using acid glycine treatment to inactivate extracellular vir us after attachment to baby hamster kidney (BHK) cells but prior to penetra tion. First, we showed that virus infection was accomplished within 2 h aft er adsorption. Second, the assay was used to examine the properties of deng ue envelope E protein-specific monoclonal antibodies (MAbs), lectins, and h eparin. We found that three MAbs, 17-2, 46-9, and 51-3, may neutralize deng ue 2 virus (DEN-2) through inhibition of not only viral attachment but also of penetration. However, one MAb, 56-3.1, interfered specifically with att achment. Therefore, the functional domains of E protein involved in attachm ent and penetration may be different. Moreover, studies with lectins indica ted that carbohydrates, especially cr-mannose residues, present on the viri on glycoproteins may contribute to binding and penetration of the virus int o BHK and mosquito C6/36 cells. Finally, virus infectivity was inhibited by heparin through its blocking effects at both virus attachment and penetrat ion. This suggests that cell surface heparan sulfate functions in both vira l attachment and penetration of DEN-2 virus. In conclusion, our results fur ther elucidated some aspects of the dengue virus entry process. (C) 1999 Ac ademic Press.