Expression of the α6 integrin confers papillomavirus binding upon receptor-negative B-cells

Abstract

Papillomaviruses (PV) bind to a wide range of cell lines in a specific and saturable manner. We have recently identified a candidate receptor for papillomavirus as the α6 integrin (Evander et al, J. Virol. 71, 2449-2456, 1997). We have further investigated the role the α6 integrin plays in PV binding. Here we show that the cells expressing the α6 integrin, partnered with either the β4 integrin or the β1 integrin, are equally able to bind PV HPV6b L1 virus-like particles, indicating that the beta partner does not play a major role in virus binding. In order to provide definitive evidence that the α6 integrin is required for PV binding we undertook to genetically complement the receptor-negative B-cell line DG75 by expressing the human α6A gene. The transduction of the α6 integrin gene into DG75 cells results in the cell sur[ace expression of the α6 protein and this expression confers upon DG75 cells the ability to bind laminin, a normal ligand for α6 integrin. Furthermore, the ↑ protein is partnered with the β1 integrin in DG75 cells. Finally, we show that the DG75-α6 cells were able to bind papillomavirus VLPs and this binding was inhibited by a functionally blocking anti-α6 antibody. Together these data indicate that the α6 integrin is a primary cell receptor for papillomaviruses and is both necessary and sufficient for PV binding.