Vaccine potential of two previously uncharacterized African swine fever virus isolates from southern Africa and heterologous cross protection of an avirulent European isolate

摘要

African swine fever (ASF) is a mostly fatal viral infection of domestic pigs forwhich there is no vaccine available. The disease is endemic to most of sub-SaharanAfrica, causes severe losses and threatens food security in large parts of the continent.Naturally occurring attenuated ASF viruses have been tested as vaccine candidates,but protection was variable depending on the challenge virus. In thisstudy, the virulence of two African isolates, one from a tick vector and the otherfrom an indigenous pig, was determined in domestic pigs to identify a potentialvaccine strain for southern Africa. Neither isolate was suitable as the tick isolatewas moderately virulent and the indigenous pig virus was highly virulent. The latterwas subsequently used as heterologous challenge in pigs first vaccinated with anaturally attenuated isolate previously isolated in Portugal. Although a statisticallysignificant reduction in death rate and virus load was observed compared withunvaccinated pigs post-challenge, all pigs succumbed to infection and died.