Antiviral Immunity Evoked Post Foot-and-Mouth Disease Virus (FMDV) Infection and Vaccination

Abstract

sulphate (HS) proteoglycans [8]. The integrin binding is mediated by a highly conserved arginine-glycine aspartic acid (RGD) motif located in GH-loop of VP1. The principal receptor used by field strains of FMDV to initiate infection is αvβ6 integrin which is due to its epithelial cell restricted expression [9-12]. The other 3 integrins recognized as receptors for field strains of FMDV are αvβ 1, αvβ 3 and αvβ 8 [13-15]. The role of these 3 integrins in pathogenesis is not clear and αvβ3 has been found as a poor receptor for FMDV [16]. However, cell culture adapted viruses often use heparansulphate (HS) as receptors and can initiate infection via an integrin-independent process [8,17-19]. After binding to the receptor, virus is endocytosed by clathrin dependent endocytosis into endosomes and then acidic pH of endosomes dissociates the capsid to release viral RNA [20]. The hydrophobic regions of capsid fuse with the endosomal lipid bilayer leading to a pore formation and then subsequently release of viral RNA into cytoplasm [21]. The viral RNA is later on translated into viral structural and non-structural proteins [22]. After FMDV infection, primary replication occurs in the mucosa-associated lymphoid tissue (MALT) of the nasopharynx and thereafter in the pulmonary alveolar septa. As viraemia approaches in 24-48 hours [23], the replication increases in the lungs and decreases in the nasopharynx [9,10,23]. Then lesions appear in the mouth and feet of susceptible animals. The viraemic phase is defined by vesiculation and erosion of epithelia of mouth, feet, teats, prepuce and ruminal pillars [24,25]. It has been shown that