Andes virus recognition of human beta3 integrin is determined by residue 33 within the beta3 integrin PSI domain

Andes virus (ANDV) causes a fatal hantavirus pulmonary syndrome (HPS) in humans and Syrian hamsters. Human avbeta3 integrins are receptors for several pathogenic hantaviruses, and the function of avbeta3 integrins on endothelial cells suggests a role for avbeta3 in hantavirus directed vascular permeability. Here we determined that ANDV infection of human endothelial cells or Syrian hamster derived BHK-21 cells was selectively inhibited by vitronectin, a high affinity avbeta3 integrin ligand, and by antibodies to avbeta3 integrins. Further, antibodies to the beta3 integrin PSI domain as well as PSI domain polypeptides derived from human and Syrian hamster beta3 subunits, but not murine or bovine beta3, inhibited ANDV infection of both BHK-21 and human endothelial cells. These findings suggest that ANDV interacts with beta3 subunits through PSI domain residues conserved in both Syrian hamster and human beta3 integrins. Sequencing the Syrian hamster beta3 integrin PSI domain revealed 8 differences between Syrian hamster and human beta3 integrins. Analysis of residues within the PSI domains of human, Syrian hamster, murine and bovine beta3 integrins identified unique proline substitutions at residues 32-33 of murine and bovine PSI domains that could determine ANDV recognition. Mutagenizing the human beta3 PSI domain to contain the L33P substitution present in bovine beta3 integrin abolished the ability of the PSI domain to inhibit ANDV infectivity. Conversely, mutagenizing either the bovine PSI domain, P33L, or the murine PSI domain, S32P, to the residue present human beta3 permitted PSI mutants to inhibit ANDV infection. Similarly, CHO cells transfected with the full length bovine beta3 integrin containing the P33L mutation, permitted infection by ANDV. These findings indicate that human and Syrian hamster avbeta3 integrins are key receptors for ANDV and that specific residues within the beta3 integrin PSI domain are required for ANDV infection. Since L33P is a naturally occuring human beta3 polymorphism these findings further suggest the importance of specific beta3 integrin residues in hantavirus infection. These findings also rationalize determining the role of beta3 integrins in hantavirus pathogenesis in the Syrian hamster model.