Vaccination of weaner pigs against classical swine fever with the subunit vaccine "Porcilis® Pesti":: influence of different immunisation pattern on excretion and transmission of challenge virus

Excretion and transmission of CSFV after vaccination with the CSF subunit marker vaccine "Porcilis(R) Pesti" have been studied using the following different vaccination schedules: Group A - two vaccinations with an interval of 28 d, challenge 14 d after second vaccination (p.v(2).); group B - two vaccinations with an interval of 14 d, challenge 14 d later; group C - two vaccinations with an interval of 28 d, challenge at time of booster vaccination; group D - two vaccinations with an interval of 14 d, challenge 7 d p.v(2).; group E single vaccination and infection 14 d later. After infection one sentinel pig was added to the vaccinated and infected pigs of each group. A single vaccination did not induce protective immunity against a CSFV challenge. Double vaccination at a four-week interval protected piglets from clinical infection, and neither viraemia and leukopenia nor virus excretion were detected if infected 14 d p.v(2). Two vaccinations at a two-week interval followed by a challenge 7 d p.v(2). led to a short viraemia on day 5 p.i. but without excretion of CSFV. Though all other vaccination schedules induced a reduction in virus shedding and a decrease in CSFV replication, in all these cases in-contact controls became infected. The results of transmission of CSFV are discussed in relation to a potential use of subunit marker vaccines in CSF control.