Classical swine fever virus (C strain) distribution in organ samples of inoculated piglets

Jemeršić, Lorena; Barlič–Maganja, Darja; Lojkić, Mirko; Madić, Josip; Grom, Jože; Čač, Željko; Roić, Besi; Terzić, Svjetlana; Lojkić, Ivana; Polančec, Denis; Čajavec, Stanislav

doi:10.1016/s0378-1135(01)00321-2

Cited by 26 publications

(15 citation statements)

References 14 publications

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“…The C-strain was not isolated from pigs for longer than 1 to 24 weeks (Terpstra, 1978;Lorena et al, 2001, Kaden et al,2004. However, recent real-time PCR data demonstrated the presence of C-strain RNA in the tonsils for at least 42 days post intramuscular vaccination, but no infectious vaccine virus could be isolated (Koenig et al, 2007a).…”

Section: Live Attenuated/modified Live (Mlv)mentioning

confidence: 99%

Control and eradication of Classic Swine Fever in wild boar

2009

EFSA Journal

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SummaryClassical swine fever (CSF) is a disease that has been causing major socio-economic damages in the EU during the last decades. Although considerable progress has been made in the eradication and prevention of the disease, the threat for an epidemic still exists.The virus is endemic in the wild boar population of several member states (MS). Wild boar cannot be managed as domestic pigs. Hunting and vaccination have been tentatively used in order to stop transmission by reducing the number of susceptibles. Oral vaccination of wild boar with modified live vaccine based on the C-strain (the only suitable) is used; this vaccine does not allow serological differentiation between vaccinated and infected animals.The aim of the control measures for CSF in wild boar is to reduce the risk of transmission to domestic pigs, to prevent an "endemic phase evolution" or to reduce the endemic phase duration.In order to support and to improve the control and eradication measures as regards CSF in wild boar, EFSA was requested by the Commission to provide scientific advice on the efficacy of the available surveillance, hunting and vaccination measures to control and eradicate CSF in feral pig populations (wild boar), considering the possible use of new diagnostic tests and vaccines.In order to reply to the mandate data were collected from MS through two questionnaires (CSF vaccines, hunting practices and CSF vaccination in wild boar). Data were also extracted from the EU CSF wild boar data base, after requesting permission from the participating MS.Considering that the data received were rather limited and not comparable, the WG decided to use a model in order to fill the gaps in the available knowledge. For the evaluation of the efficacy of CSF control in wild boar a continuous metapopulation compartmental model developed in an EU research project (FP6-5015599-CSFVACCINE&WILDBOAR) was applied.Although the disease manifests in the same manner in both domestic pig and wild boar it is more difficult to identify in wild boar because clinical monitoring of these is hardly possible. Wild boar found dead constitutes the main alert sign of CSF. Hunters and gamekeepers should be instructed to report the finding of each dead wild boar to the competent authority at all times. In case of high-risk situations, a passive surveillance should be complemented by an active serological surveillance. The active sampling of wild boar is not as efficient as in domestic pigs considering that hunting is the sole practical system to obtain samples and that the aim of hunting is quite different.Consequently, the sample size is not controlled by authorities and fits rarely the aim of the survey in terms of detecting the presence of disease at a certain level. In addition, the interpretation of serological results is confounded by maternal derived antibodies (until the 6th month of age), vaccination and the sampling quality.There is no definition at EU level of spatial and temporal units for surveillance, neither for criteria defining a disease free wi...

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Section: Live Attenuated/modified Live (Mlv)mentioning

confidence: 99%

Control and eradication of Classic Swine Fever in wild boar

2009

EFSA Journal

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“…Numerous evidences have proven this vaccine is of high efficacy, providing immunized animals with broad-spectrum, sometimes lifelong, protection, which is contributed by both cell-mediated immunity and humoral immunity of vaccinated pigs, effectively against all genotypes or subgenotypes of the viruses (Qiu, 2006). However, the vaccine viruses can persist in pigs for a relatively long period of time after vaccination (Lorena et al, 2001). Data from National Classical Swine Fever Reference Laboratory (China) indicated that the C-strain vaccine can still be detected in pig tonsils 42 days after vaccination using a real time RT-PCR assay and RT-nestPCR assay established in this study (not shown, unpublished).…”

Section: Discussionmentioning

confidence: 99%

“…Currently, the major procedure for control and prevention of CSF in mainland China is through massive mandatory vaccination of C-Strain vaccine (Qiu, 2006). However, the vaccine viruses can persist in pigs for a relatively long period of time after vaccination (Lorena et al, 2001). Therefore, the major problem faced by the breeding swine farms in the process of CSF eradication is the differentiation of pigs vaccinated with CSFV vaccines or infected with wild-type viruses.…”

Section: Introductionmentioning

confidence: 99%

Development and Application of a RT-NestPCR Assay for Differential Detection of C-Strain and Wild-Type Viruses of Classical Swine Fever Virus

Wang¹,

Yi-bao²,

Cong³

et al. 2013

SAR

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Due to the urgent need of differentiation of infected from vaccinated animals in control and eradication of classical swine fever (CSF) and the shortcomings of current differential diagnostic tools, this study is aiming to establish a RT-nestPCR assay for differential detection of wild-type viruses and lapinized Chinese vaccine strain (C-strain) of classical swine fever virus (CSFV) of high sensitivity. Two pairs of CSFV-specific primers were designed in the conservative regions of NS5B (a non-structural protein encoded by the CSFV genome, which performs the RNA dependent RNA polymerase activity) and 3′ un-translated regions (3′-UTR) to encompass the T-rich insertion uniquely existing in the 3′-UTR of C-strain genome. Thus the amplification fragment of C-strain is longer than that of the wild-type viruses for it contains the T-rich insertion region. Two pairs of primers were used in combination and the wild-type viruses and C-strain of CSFV could be detected and accurately distinguished with a high sensitivity through super fine resolution (SFR) argarose gel electrophoresis that displays the different lengths of the amplicons. The detection limit of the C-strain and Shimen strain were respectively 4.5×10 -2 pg and 3.2×10 -2 pg of viral RNA. The results of the specificity test showed that this method can detect different strains of CSFV without amplifying other non-CSFV pathogens. The results of the detection of 400 clinical samples indicated that 16 samples were CSFV positive in total; in which 4 samples were C-Strain positive and 12 were wild-type CSFV positive. The total CSFV positive rate was 4%. The detection results of the 14 batches of C-Strain vaccines showed that all samples displayed bands of C-Strain amplicons in the SFR argarose gel electrophoresis and all vaccines were free of wild-type virus contamination. In conclusion, the RT-nestPCR assay established in the present study could supply a sensitive and specific test method for distinguishing wild-type CSFV infected animals from those vaccinated with C-strain vaccines in the field.

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“…In piglets inoculated with the Chinese strain (C strain) vaccine virus, the virus can be detected in either tonsils or blood 2 to 16 days after vaccination (DPV). 13 The C strain can be detected in organs 8 DPV in domestic pigs and 9 DPV in wild boars. 6 The PAV-250 vaccine virus, a strain used in South America, persisted in the tonsils of vaccinated pigs until 28 28,2008).…”

Section: Introductionmentioning

confidence: 98%

Rapid Detection and Differentiation of Wild-Type and Three Attenuated Lapinized Vaccine Strains of Classical Swine Fever Virus by Reverse Transcription Polymerase Chain Reaction

et al. 2008

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Abstract. A simple one-step reverse transcription polymerase chain reaction (RT-PCR) method was developed based on T-rich insertions in the viral genome for simultaneous detection and differentiation of wild type and vaccine strains of Classical swine fever virus (CSFV). The CSFV-specific primers were designed to contain the sequences of the T-rich insertion sites that exist uniquely in the 39 nontranslated regions (39 NTR) of the genome of lapinized CSFV vaccine strains. By using a one-step RT-PCR or a nested PCR followed by an agarose gel electrophoresis or a multicapillary electrophoresis, the wild-type and lapinized vaccine strains of CSFV in clinical samples could be detected and accurately distinguished. These assays can be applied to at least 3 attenuated lapinized vaccine strains, lapinized Philippines Coronel (LPC), hog cholera lapinized virus (HCLV), and Chinese strain (C strain). The detection limit of the wild-type virus was 6.3 TCID 50 (50% tissue culture infective dose)/ml for RT-PCR and 0.63 TCID 50 /ml for nested PCR. In previous studies, notable Trich insertions of 12-13 nucleotides (nt) were found in the 39 NTR of the genome of lapinized vaccine strains of CSFV. However, this study discovered that 2 T-rich insertions, 42 and 36 nt in length, are present in the viral genome of lapinized vaccine strains LPC/PRK (primary rabbit kidney) and LPC/TS (Tam-Sui), respectively. These T-rich insertions of 12, 36, and 42 nt length increases the size of PCR fragments, which are favorable genetic markers for rapid detection of and differentiation between wild-type and different lapinized vaccine strains of CSFV.

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Classical swine fever virus (C strain) distribution in organ samples of inoculated piglets

Cited by 26 publications

References 14 publications

Control and eradication of Classic Swine Fever in wild boar

Control and eradication of Classic Swine Fever in wild boar

Development and Application of a RT-NestPCR Assay for Differential Detection of C-Strain and Wild-Type Viruses of Classical Swine Fever Virus

Rapid Detection and Differentiation of Wild-Type and Three Attenuated Lapinized Vaccine Strains of Classical Swine Fever Virus by Reverse Transcription Polymerase Chain Reaction

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