Classical and African swine fever in domestic pigs and European wild boar. Optimization of control strategies and laboratory diagnosis

Classical and African swine fever are highly contagious, notifiable viral diseases affecting different members of the Suidae family, both showing tremendous impact on animal health and pig production. Optimization of CSF control strategies comprised two different approaches. In a first step, the current strategy of oral immunization of wild boar using a conventional C-strain vaccine was supplemented with the implementation of genetic DIVA using a recently developed multiplex rRT-PCR assay. This approach facilitates a rapid and reliable differentiation of field virus infected from C-strain vaccinated wild boar, and thus presents a promising tool also for emergency vaccination scenarios in domestic pigs. However, the use of conventional modified live vaccines like the C-strain does not allow serological differentiation of infected from vaccinated animals which is a prerequisite for modern disease control. Therefore, the second part comprised the evaluation of the new generation marker vaccine CP7_E2alf to generate data for the authorization process. In the framework of the presented studies, innocuousness in calves, goats, lambs, and rabbits as well as safety in domestic pigs and wild boar was proven. Moreover, protection against lethal CSF challenge infection after oral and intramuscular vaccination of domestic pigs was investigated, and confirmed for a duration of at least 6 months. Furthermore, CP7_E2alf proved outstanding efficacy against challenge infection of domestic pigs and wild boar with a highly virulent CSFV strain of genotype 1.1 and an isolate of genotype 2.3 representing strains currently prevalent in Europe. Candidate CP7_E2alf showed all virtues of a safe and efficacious marker vaccine against CSF that would be suitable for intramuscular vaccination of domestic pigs and oral vaccination of wild boar. For this reason, licensing of CP7_E2alf will be beneficial for future CSF control. African swine fever, one of the most important differential diagnoses of CSF, is currently affecting domestic pigs and wild boar on the territory of the Russian Federation. So far, the outbreak situation could not be resolved and the disease constantly spreads towards the EU. Disease dynamics, especially regarding wild boar, are almost unknown. For this reason, circulating ASFV isolates were characterized for the first time in animal experiments in European wild boar of different age classes. As an exceptionally high virulence was observed in all age classes of animals, endemic situations driven by chronically infected animals or carriers seem unlikely.