Rekombinante Parapockenvakzine gegen die klassische Schweinepest

Recombinant parapoxvirus vaccine against classical swine fever:
comparative characterization of immune reactions in swine Despite
good efforts in eradication of classical swine fever (CSFV) within
the EU massive disease outbreaks cannot be excluded. Therefore an
“intervention vaccination strategy” is one option in legal EU
combat strategies against CSF. At the moment an E2 subunit vaccine
is licensed in the EU but possibly can be replaced by an improved
vaccine to achieve optimal stimulation of the humoral as well as
the cellular immune responses. The aim of the present work was the
generation of a new Parapoxvirus ovis vector expressing the E2
glycoprotein of CSFV which was named ORFV D1701VrVE2. It could be
successfully demonstrated that his vector vaccine efficiently
expresses the foreign gene even in cells of swine as a non
permissive host. It was shown to be completely avirulent for pigs.
The vector is a potent stimulator of IFN-α and VSV antiviral
activity in porcine PBMC supernatants. In several animal
immunisation experiments with swine ORFV D1701VrVE2 induced
CSFV-neutralizing serum antibodies already after a single
application. Immunized piglets were protected against lethal CSFV
challenge and did not develop fever. Vaccinated and challenged
animals recovered from the characteristic CSFV-induced B-cell
reduction. The distribution of the vaccine dose over four
intra-muscular injection sites (multi-site application) led to a
rapid induction of neutralizing antibodies and to solid protection
from CSF after a single vaccination. In contrast to single site
vaccinated animals, multi-site vaccinated piglets did not transmit
the challenge virus to a naive sentinel. Two successive vector
virus applications in a homologous prime-boost regimen did not
provoke IFN-γ producing cells among PBMC. However, a heterologous
prime-boost regimen as a combination of prime with baculovirus
expressed glycoprotein E2 followed by boost with the parapoxvirus
vector induced high numbers of IFN-γ producing cells. A similar
beneficial effect became evident when the challenge infection
mimicked the booster vaccination after a single vector prime. In
contrast when the challenge CSFV was applied after a homologous
prime with modified live CSFV vaccine the immunised piglets
responded with lower numbers of IFN-γ producing cells as well as
lower titres of CSFV-neutralizing serum antibodies. In additional
experiments the adjuvant effect of lipoprotein L-OprI of
Pseudomonas aeruginosa was tested in combined administration with
baculovirus expressed E2 in piglets using sub-optimal doses of the
E2 protein. The adjuvant showed a beneficial effect on the
formation of CSFV neutralizing serum antibodies but had no
influence on the number of IFN-γ producing cells in piglets before
challenge. As another important CSFV subunit the immunogenic
properties of the E. coli produced non structural protein NS3 have
been tested. Although NS3 induced high amounts of IFN-γ producing
cells in PBMC of vaccinated piglets their serum antibodies did not
neutralize CSFV and even after two booster vaccinations the animals
were not protected against lethal CSFV challenge.