Analysis of a Foot-and-Mouth Disease Virus Type A ₂₄ Isolate Containing an SGD Receptor Recognition Site In Vitro and Its Pathogenesis in Cattle

Abstract

Foot-and-mouth disease virus (FMDV) initiates infection by binding to integrin receptors via anFoot-and-mouth disease virus (FMDV) is the causative agent of foot-and-mouth disease (FMD), a highly contagious disease of cloven-hoofed animals, including cattle, swine, goats, sheep, and other species of wild ruminants. The virus exhibits a remarkable adaptation and serological diversity exemplified by the existence of a large number of subtypes within each serotype and the fact that infected animals can also become persistent carriers (2,3,27,49). In infected animals the virus replicates very rapidly and spreads among in-contact susceptible animals by aerosol or direct contact. Clinical signs of FMD, including vesicles on the feet and the mouth, can appear as early as 2 days after virus exposure (reference 20 and references therein).FMDV is the type species of the Aphthovirus genus of the family Picornaviridae. The viral genome, consisting of a single open reading frame, is flanked by a long 5Ј-nontranslated region (NTR) linked to a small viral peptide, VPg, and a short 3ЈNTR followed by a poly(A) tail (Fig. 1a). Four structural proteins (VP1 to VP4) constitute the viral capsid, and a number of essential nonstructural proteins, including the RNAdependent RNA polymerase (3D pol ), are involved in the replication of viral RNA (reviewed in references 7 and 45).The first step in FMDV infection involves the recognition of a cell surface receptor. An Arg-Gly-Asp (RGD) amino acid sequence located within the ␤G-␤H (G-H) loop of the capsid protein VP1 (1, 28, 30) is known to bind to several integrins of the ␣ V subgroup, including ␣ V ␤ 1 , ␣ V ␤ 3 , ␣ V ␤ 6 , and ␣ V ␤ 8 , and is involved in virus attachment to cells and interaction with neutralizing antibodies (8, 18, 21, 24-26, 34, 36, 39, 40, 52). The generation of genetically engineered virions carrying deletions or mutations of the RGD motif leads to virus which is unable to bind to cultured cells or cause disease in susceptible animals (29,34,37,43).In cell culture, FMDV binds preferentially to one or more of the above-mentioned integrins with different specificities, and integrin utilization varies between serotypes (7, 17, 18). The reason for this specificity is not clearly understood; however, it is known that sequences surrounding the RGD motif, or located in other regions of the viral capsid, could induce structural changes in the G-H loop of VP1 and modulate binding specificity (14,42). These changes may occur with the replacement of only one or a few amino acids at the surface of the virus (reviewed in reference 7). Viruses propagated in vitro can exploit alternative mechanisms to bind and enter the host cell independent of integrin binding. Among them, the use of heparan sulfate has been correlated with the acquisition of positively charged amino acids on the virus capsid surface (19,

Positively Charged Residues at the Five-Fold Symmetry Axis of Cell Culture-Adapted Foot-and-Mouth Disease Virus Permit Novel Receptor Interactions

“…The integrin-binding loop of FMDV A/Turkey/2/2006 includes the sequence RGDLGPL, and therefore the KGD viruses could use ␣v␤6 due to the presence of the DLGPL sequence. Other viable FMDVs have been described with mutations in the RGD (28,52,53), and some of these retain the D of the RGD motif and the conserved residues normally found after the RGD (see the introduction). For most of these viruses, integrin binding has not been investigated; however, a type A virus described by Rieder et al (52) with SGD was shown to preferentially infect cells transfected to express ␣v␤6, implying that this integrin may be used as a receptor.…”

“…Other viable FMDVs have been described with mutations in the RGD (28,52,53), and some of these retain the D of the RGD motif and the conserved residues normally found after the RGD (see the introduction). For most of these viruses, integrin binding has not been investigated; however, a type A virus described by Rieder et al (52) with SGD was shown to preferentially infect cells transfected to express ␣v␤6, implying that this integrin may be used as a receptor. The SGD virus used in these studies had an M (and not L) immediately after the RGD, which suggests that the DMXXL motif may also bind ␣v␤6.…”

A Safe Foot-and-Mouth Disease Vaccine Platform with Two Negative Markers for Differentiating Infected from Vaccinated Animals

“…FMDV type A 24 Cruzeiro was derived from the infectious cDNA clone, pA 24 Cru (referred to here as A 24 WT for simplicity [39]). A plasmid containing the BRV-2 (pBRV2, accession number EU236594) sequence from poly(C) to poly(A) described previously (20) was used as a source of bovine rhinitis virus 2 genetic material.…”

Nuclear Protein Sam68 Interacts with the Enterovirus 71 Internal Ribosome Entry Site and Positively Regulates Viral Protein Translation

“…The virus-infected cells were harvested after incubation for 24 h at 37°C. Virus proteins in infected cells were detected by Western blotting using mouse EV71 VP1 monoclonal antibodies, and virus titers were determined by plaque assay as previously described (36). The 50% tissue culture infective dose (TCID 50 ) per milliliter was obtained by plotting the plaque assay results in a logarithmic scale using Microsoft Excel (Microsoft).…”