Post-licensing evaluation of Porvac® subunit vaccine against classical swine fever in two pig genetic development farms in Cuba.

Classical swine fever (CSF) is one of the most important diseases affecting pigs. For years, the main strategy to control CSF outbreaks in endemic regions has been a combination of stamping out of pigs in the affected area and the application of modified live vaccines (MLV) to limit the spread of the disease. However, the implementation of non-optimal vaccination has been associated with emergence of low virulence classical swine fever virus (CSFV) strains that are difficult to detect and eliminate. Porvac® is a second-generation subunit vaccine containing chimeric E2-CD154 fusion protein. This vaccine is safe, provides a very rapid onset of protection and prevents vertical transmission. Because of these advantages, Porvac® has been proposed to replace MLV as part of the effort to eliminate CSFV from Cuba. Pig Genetic Development Farms (GDF) are an important part of pig production in Cuba. They maintain, develop improved hybrid lines and supply superior boars and gilts to intermediate farms. Here we present data from a six-year post-marketing follow-up of the use of Porvac® in two pig GDFs in the province of Pinar del Río. After Porvac® intervention, the herd immunity in these GDFs increased from 50% to 100%, with all the breeding stock showing protective neutralizing antibody titres, and this coverage was maintained over the six years evaluated. In addition, the number of pigs testing positive for anti-Erns was progressively reduced after vaccination until it disappeared. This, together with the absence of CSFV RNA in the 10% of the breeding stock, indicates that the two GDFs were free of CSF circulation during these years. To the best of our knowledge these results represent the most extensive follow-up of the field application of a subunit vaccine against CSF and confirm the potential of Porvac® to provide high quality and sustained herd immunity against CSF.