Foot-and-Mouth Disease Virus Receptors: Comparison of Bovine α _V Integrin Utilization by Type A and O Viruses

Abstract

Three members of the ␣ V integrin family of cellular receptors, ␣ V ␤ 1 , ␣ V ␤ 3 , and ␣ V ␤ 6 , have been identified as receptors for foot-and-mouth disease virus (FMDV) in vitro. The virus interacts with these receptors via a highly conserved arginine-glycine-aspartic acid (RGD) amino acid sequence motif located within the ␤G-␤H (G-H) loop of VP1. Other ␣ V integrins, as well as several other integrins, recognize and bind to RGD motifs on their natural ligands and also may be candidate receptors for FMDV. To analyze the roles of the ␣ V integrins from a susceptible species as viral receptors, we molecularly cloned the bovine ␤ 1 , ␤ 5 , and ␤ 6 integrin subunits. Using these subunits, along with previously cloned bovine ␣ V and ␤ 3 subunits, in a transient expression assay system, we compared the efficiencies of infection mediated by ␣ V ␤ 1 , ␣ V ␤ 3 , ␣ V ␤ 5 , and ␣ V ␤ 6 among three strains of FMDV serotype A and two strains of serotype O. While all the viruses could infect cells expressing these integrins, they exhibited different efficiencies of integrin utilization. All the type A viruses used ␣ V ␤ 3 and ␣ V ␤ 6 with relatively high efficiency, while only one virus utilized ␣ V ␤ 1 with moderate efficiency. In contrast, both type O viruses utilized ␣ V ␤ 6 and ␣ V ␤ 1 with higher efficiency than ␣ V ␤ 3 . Only low levels of viral replication were detected in ␣ V ␤ 5 -expressing cells infected with either serotype. Experiments in which the ligand-binding domains among the ␤ subunits were exchanged indicated that this region of the integrin subunit appears to contribute to the differences in integrin utilizations among strains. In contrast, the G-H loops of the different viruses do not appear to be involved in this phenomenon. Thus, the ability of the virus to utilize multiple integrins in vitro may be a reflection of the use of multiple receptors during the course of infection within the susceptible host.Foot-and-mouth disease virus (FMDV) is one of the most feared viral pathogens of livestock. Outbreaks can result in high morbidity and loss of production in infected animals, but the most devastating economic consequence to affected countries results from mass livestock culling and international trade restrictions imposed on animals and animal products. FMDV is the type species of the Aphthovirus genus of the Picornaviridae family and exists as many subtypes and variants within seven different serotypes.Limited trypsin digestion of FMDV results in the generation of noninfectious virions that are unable to adsorb to susceptible cells (5) due to the cleavage of VP1 at the Arg (R) residue of a highly conserved Arg-Gly-Asp (RGD) motif (62) located within a flexible external loop between the ␤G and ␤H strands (G-H loop) (1, 36, 41). In addition, peptides containing the RGD sequence inhibited the adsorption of the virus to tissue culture cells (6, 21), and genetically engineered virions containing either mutations or deletions of the RGD sequence were unable to bind to cells or cause disease in susceptible a...

A Peptide Selected by Biopanning Identifies the Integrin αvβ6 as a Prognostic Biomarker for Nonsmall Cell Lung Cancer

“…Integrin-binding specificity is determined by the sequence flanking the RGD domain, especially the sequence to the carboxy terminal side of the RGD (7,24,25). This is supported by the observation that strains of FMDV that have the sequence RGDLXXL use the a v h 6 integrin with the highest efficiency (26). Binding peptides have been isolated by panning a linear 12-mer-peptide library on recombinant truncated a v h 6 (27).…”

Use of Confocal Immunofluorescence Microscopy To Localize Viral Nonstructural Proteins and Potential Sites of Replication in Pigs Experimentally Infected with Foot-and-Mouth Disease Virus

“…Lesions first appear in animals which have been infected by contact with infected animals within 1 to 5 days of contact, depending on the intensity of contact, the virulence of the virus, and the dose used to inoculate the pigs. Inoculated animals have viremia from around 1 day after inoculation, and it is assumed that the spread of the virus within such infected animals is by the general circulation.The precise nature of the virus-cell interactions that give cell type specificity in vivo is not certain, although host cell integrins have been proposed as receptors for FMDV (11)(12)(13)(14)(15)(16)(19)(20)(21). Both ␣v␤3 and ␣v␤6 integrins have been proposed as cell membrane receptors for FMDV in vivo, and we have recently demonstrated, with bovine epithelium, that ␣v␤6 is expressed at considerably higher levels than ␣v␤3 on epithelial cells.…”

“…The precise nature of the virus-cell interactions that give cell type specificity in vivo is not certain, although host cell integrins have been proposed as receptors for FMDV (11)(12)(13)(14)(15)(16)(19)(20)(21). Both ␣v␤3 and ␣v␤6 integrins have been proposed as cell membrane receptors for FMDV in vivo, and we have recently demonstrated, with bovine epithelium, that ␣v␤6 is expressed at considerably higher levels than ␣v␤3 on epithelial cells.…”

Recovery of Infectious Foot-and-Mouth Disease Virus from Suckling Mice after Direct Inoculation with In Vitro-Transcribed RNA

“…The RGD triplet is highly conserved among natural isolates of FMDV (11,27), probably reflecting constraints imposed by the interaction with integrin receptors in vivo (13,31). However, RGD can become dispensable upon large-population passages of FMDV in cell culture, which are associated with amino acid substitutions at the capsid surface and the use of alternative receptors for cell entry (3,4,16,24,38,50).…”