Foot-and-Mouth Disease Virus Virulent for Cattle Utilizes the Integrin α v β 3 as Its Receptor

Abstract

ABSTRACT Adsorption and plaque formation of foot-and-mouth disease virus (FMDV) serotype A 12 are inhibited by antibodies to the integrin α v β 3 (A. Berinstein et al., J. Virol. 69:2664–2666, 1995). A human cell line, K562, which does not normally express α v β 3 cannot replicate this serotype unless cells are transfected with cDNAs encoding this integrin (K562-α v β 3 cells). In contrast, we found that a tissue culture-propagated FMDV, type O 1 BFS, was able to replicate in nontransfected K562 cells, and replication was not inhibited by antibodies to the endogenously expressed integrin α 5 β 1 . A recent report indicating that cell surface heparan sulfate (HS) was required for efficient infection of type O 1 (T. Jackson et al., J. Virol. 70:5282–5287, 1996) led us to examine the role of HS and α v β 3 in FMDV infection. We transfected normal CHO cells, which express HS but not α v β 3 , and two HS-deficient CHO cell lines with cDNAs encoding human α v β 3 , producing a panel of cells that expressed one or both receptors. In these cells, type A 12 replication was dependent on expression of α v β 3 , whereas type O 1 BFS replicated to high titer in normal CHO cells but could not replicate in HS-deficient cells even when they expressed α v β 3 . We have also analyzed two genetically engineered variants of type O 1 Campos, vCRM4, which has greatly reduced virulence in cattle and can bind to heparin-Sepharose columns, and vCRM8, which is highly virulent in cattle and cannot bind to heparin-Sepharose. vCRM4 replicated in wild-type K562 cells and normal, nontransfected CHO (HS + α v β 3 − ) cells, whereas vCRM8 replicated only in K562 and CHO cells transfected with α v β 3 cDNAs. A similar result was also obtained in assays using a vCRM4 virus with an engineered RGD→KGE mutation. These results indicate that virulent FMDV utilizes the α v β 3 integrin as a primary receptor for infection and that adaptation of type O 1 virus to cell culture results in the ability of the virus to utilize HS as a receptor and a concomitant loss of virulence.