[Foot-and-mouth disease:: an old disease--new solutions]

The recent outbreak of foot-and-mouth disease in United Kingdom provoked a crisis in the European Union with deleterious consequences not only for livestock industry. Public opinion is more and more concerned about stamping out measures used to control the disease even with previously vaccinated animals. Presently the trend is to "vaccinate for life". This policy change requires to improve vaccines and diagnostic tools. It is not foreseen nevertheless to come back to a generalized vaccination of cattle as it was the case previously in continental Europe, despite its efficacy. According to the new policy, it will only be emergency vaccination to control outbreaks; it will compulsorily use inactivated vaccines. The vaccines will have to confer quickly a strong (sterile) protection against several serotypes during the same outbreak. Several serotypes could be involved in case of agroterrorism. Another feature of foot-and-mouth virus infection is the generation of asymptomatic carriers of wild virus after infection even in previously vaccinated animals. In order to get round this problem, so-called "marker vaccines" associated with a companion diagnostic test are developed: it aims to be able to differentiate simply vaccinated animals from infected ones, whether they were previously vaccinated or not. These vaccines are presently highly purified inactivated vaccines and the companion diagnostic test is based upon the detection of specific antibodies directed against virus-induced non-structural proteins. These antibodies should not be detected in simply vaccinated animals. This technology takes into account the fact that foot-and-mouth disease virus multiplication implies the synthesis of a polyprotein subsequently cleaved. It allows to certify the absence of infection at a herd level not yet at an individual level. Another research trend is to identify virus receptors in animals in order to better understand the pathogenesis of the infection and the reasons why some animals become asymptomatic carriers of wild virus after infection.