Recent progress in vaccines against foot-and-mouth disease

Abstract

Foot-and-mouth disease (FMD) is the most highly contagious disease affecting livestock resulting in significant adverse economic impact worldwide (16). The disease is caused by infection with the foot-and-mouth disease virus (FMDV), the prototypic member of the Aphthovirus genus within the family Picornaviridae. FMDV exists in seven distinct serotypes comprising O, A, C, Asia-1 and SAT 1-3 and multiple subtypes due to the high mutational rate of the virus. The virion compromises a single strand positive sense RNA genome encapsidated in a non-enveloped icosaherdal particle of about 25-30 nm (1). FMDV is translated as a single polyprotein that is posttranslationally cleaved to produce partial and full cleavage products resulting in four structural proteins (VP1 to VP4) and ten nonstructural proteins (NSP), which play different key roles during the viral replication cycle (12). FMD is endemic in large areas of the continents of Africa and Asia. In South America, recent outbreaks of FMD occurred in July 2017 in Colombia (http://www. oie.int/wahis_2/public/wahid.php/Diseaseinformation/ WI). Viruses circulating in endemic regions are classified into seven separate endemic pools based on their antigenic and epidemiological properties (Fig. 1). Strict control on the importation of animals and agricultural products allows Europe, North America and Australia to maintain free status without vaccination. The main legislative act of the EU regulating the control of footand-mouth disease is Council Directive 2003/85/EC of 29 September 2003 on Community measures for the control of foot-and-mouth disease. According to this document FMD outbreaks in previously FMDfree countries are initially controlled by the culling of infected and in-contact animals, restriction of the movement of susceptible animals, disinfection of infected premises, and occasionally emergency vaccination with an inactivated whole-virus antigen preparation, as it was the case in 2001 FMD epizootic in the Netherlands (41). However, currently available FMD vaccines confer protection against clinical FMD although they do Recent progress in vaccines against foot-and-mouth disease