Classical swine fever: Comparison of oronasal immunisation with CP7E2a1f marker and C-strain vaccines in domestic pigs

Veterinary and Agrochemical Research Centre (VAR), Department of Virology, Groeselenberg 99, B-1180 Brussels, Belgium.
Veterinary Microbiology (Impact Factor: 2.51). 09/2009; 142(1-2):59-68. DOI: 10.1016/j.vetmic.2009.09.044
Source: PubMed


Effective oronasal vaccination against classical swine fever (CSF) is essential to achieve protection in wild boar. However the currently available live CSF vaccines, e.g. C-strain, do not allow serological differentiation between infected and vaccinated animals (DIVA). A modified live marker vaccine candidate (CP7E2alf) has been recently developed (Reimann et al., 2004). This communication reports the comparison of CP7E2alf and C-strain virus vaccines during 98 days following oronasal immunisation in domestic pigs. C-strain vaccine virus was consistently detected in tonsils of all (n=30) animals from 3 to 77 days post vaccination (dpv) and in blood (n=36) between 3 and 13dpv by CSFV-specific rRT-PCR. CP7E2alf virus RNA was detected in 6 animals slaughtered between 4 and 63dpv by a BVDV-specific rRT-PCR. The chimeric virus was not detected in blood samples. As detected by CSFV E2-specific antibody ELISA and virus neutralisation tests, seroconversion first occurred at 11dpv in the C-strain vaccinated group and between 11 and 15dpv in the CP7E2alf vaccinated group. The serological response was still present at 98dpv. The CP7E2alf serological response remained negative using the CSFV E(rns) ELISA whereas seroconversion occurred in the C-strain vaccinated group. In conclusion, the primary replication site of CP7E2alf vaccine virus was found to be the tonsils as in the C-strain and virulent field strains. Persistence of CP7E2alf in the tonsils was also demonstrated up to 63dpv. Both vaccines showed immunogenicity after oronasal administration in domestic pigs. In contrast to the C-strain, CP7E2alf vaccine allowed the use of DIVA approaches in serological tests. This study confirms CP7E2alf as a promising marker vaccine candidate for oronasal vaccination programmes to control CSF in domestic pigs and wild boar.

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    • " Neither fever nor leukopenia was registered in the inoculated animals and virus could not be isolated from purified white blood cells or from nasal or fecal excretions . In another experiment it was shown that the vaccine was also innocuous for the target species : no clinical signs , transmission , or shedding of the vaccine virus was observed ( Tignon et al . , 2010 ; König et al . , 2011 ; Gabriel et al . , 2012 ) . This novel vaccine has been licensed by the European Medicines Agency in 2014 and has the potential to replace conventional MLV in oral immunization of wild boar . Other live DIVA vaccines based on porcine adenovirus as vector for the E2 glycoprotein of CSFV have been developed earlier"
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    ABSTRACT: Classical swine fever (CSF) is a viral disease with severe economic consequences for domestic pigs. Natural hosts for the CSF virus (CSFV) are members of the family Suidae, i.e., Eurasian wild boar (sus scrofa) are also susceptible. CSF in wild boar poses a serious threat to domestic pigs. CSFV is an enveloped RNA virus belonging to the pestivirus genus of the Flaviviridae family. Transmission of the infection is usually by direct contact or by feeding of contaminated meat products. In recent decades CSF has been successfully eradicated from Australia, North America, and the European Union. In areas with dense wild boar populations CSF tends to become endemic whereas it is often self-limiting in small, less dense populations. In recent decades eradication strategies of CSF in wild boar have been improved considerably. The reduction of the number of susceptible animals to a threshold level where the basic reproductive number is R0 < 1 is the major goal of all control efforts. Depending on the epidemiological situation, hunting measures combined with strict hygiene may be effective in areas with a relatively low density of wild boar. Oral immunization was shown to be highly effective in endemic situations in areas with a high density of wild boar.
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    • "The observation that one C-strain vaccinated pig did not seroconvert at all during the test period according to the PrioCHECK CSFV Ab 2.0 ELISA test, whereas pestivirus antibodies could be detected in serum samples from this pig at post vaccination day 28 when using the in-house pestivirus blocking ELISA (Table 1) demonstrated the importance of using several tests for serological diagnostics . Another study has shown seroconversion in all 18 Cstrain vaccinated animals tested at post vaccination day 18 using a different commercial ELISA for detection of E2- specific antibodies (HerdCheck CSFV, IDEXX) (Tignon et al., 2010). This may indicate, that the PrioCHECK CSFV Ab 2.0 ELISA that we have used is less sensitive, which has also been observed previously (Schroeder et al., 2012). "
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    ABSTRACT: Several studies have highlighted the important role of cytokines in disease development of classical swine fever virus (CSFV) infection. In the present study, we examined the kinetics of 7 porcine cytokines in serum from pigs infected with 3 different CSFV strains. Based on the clinical picture in 6-month-old Danish pigs, the strains used for inoculation were classified as being of low (Bergen), low to moderate (Eystrup) and moderate to high (Lithuania) virulence. The cytokines interferon-alpha (INF-α), interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-α) showed increased levels after CSFV infection with more or less comparable course in the 3 groups. However, the cytokine level peaked with a 2-3days delay in pigs infected with the low virulent strain compared to those infected with a moderately or highly virulent strain. These findings may indicate that INF-α, IL-8 and TNF-α are involved in the immune response during CSFV infection with strains of different virulence.
    No preview · Article · Oct 2013 · Research in Veterinary Science
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    • "It displays promising potency and induces similar effective protection against a CSFV challenge to the C-strain [6]. The CP7_E2alf vaccine behaves similarly to CSFV and uses the same primary replication site [7]. Moreover, the safety and efficiency of the CP7_E2alf vaccine in both intramuscular and oral application protocols has been demonstrated in pigs as well as wild boars, together with persistent immunity for 6 months post-vaccination [8-10]. "
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    ABSTRACT: The conventional C-strain vaccine induces early protection against classical swine fever (CSF), but infected animals cannot be distinguished from vaccinated animals. The CP7_E2alf marker vaccine, a pestivirus chimera, could be a suitable substitute for C-strain vaccine to control CSF outbreaks. In this study, single oral applications of CP7_E2alf and C-strain vaccines were compared for their efficacy to induce protection against a CSF virus (CSFV) challenge with the moderately virulent Bas-Rhin isolate, in pigs as early as two days post-immunization. This work emphasizes the powerful potential of CP7_E2alf vaccine administered orally by a rapid onset of partial protection similar to that induced by the C-strain vaccine. Furthermore, our results revealed that both vaccinations attenuated the effects induced by CSFV on production of the pig major acute phase protein (PigMAP), IFN-alpha, IL-12, IL-10, and TGF-beta1 cytokines. By this interference, several cytokines that may play a role in the pathogeny induced by moderately virulent CSFV strains were revealed. New hypotheses concerning the role of each of these cytokines in CSFV pathogeny are discussed. Our results also show that oral vaccination with either vaccine (CP7_E2alf or C-strain) enhanced CSFV--specific IgG2 production, compared to infection alone. Interestingly, despite the similar antibody profiles displayed by both vaccines post-challenge, the production of CSFV-specific IgG1 and neutralizing antibodies without challenge was lower with CP7_E2alf vaccination than with C-strain vaccination, suggesting a slight difference in the balance of adaptive immune responses between these vaccines.
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