Long-term studies on maternal immunity for Aujeszky's disease and classical swine fever in wild boar piglets.

The aim of the studies was to fathom the duration and the role of maternal immunity for Aujeszky's disease (AD) and classical swine fever (CSF) in wild boar offspring. In one experiment, two wild boar sows were infected with a low pathogenic pseudorabies virus (PRV) in 1999. A total of 51 offspring was born between 1999 and 2002 and was monitored for PRV maternal antibodies. In a second experiment, the maternal immunity for CSF was analysed. Therefore, a sow was orally vaccinated against CSF using vaccine baits containing the live-attenuated C-strain vaccine. The vaccination took place in January 1999. The sow gave birth to four piglets in 2001 and to two piglets in 2002. With respect to maternal immunity for AD, some piglets reacted positive in the ELISA up to 27-week post-partum while in the neutralization test antibodies were detected up to 15-week post-partum. The calculated half-life of neutralizing antibodies was 21 days. Regarding CSF, the neutralization titres of maternal antibodies dropped continuously reaching values of < or =10 ND50 20-week post-partum. After the 12th week post-partum, most of the sera reacted negative in the ELISA. However, after the third month, low levels of neutralization titres were still detectable. The results are discussed with respect to the epidemiology and control of both diseases in wild boar populations.