A generic real-time TaqMan assay for specific detection of lapinized Chinese vaccines against classical swine fever

Xia, Haijian; Everett, Helen; Sosan, Olubukola; Crooke, Helen; Meindl-Böhmer, Alexandra; Qiu, Hua‐Ji; Moennig, V.; Belák, Sándór; Widén, Frederik

doi:10.1016/j.jviromet.2011.05.003

Cited by 23 publications

(19 citation statements)

References 18 publications

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“…With a limited number of sequences available for designing primers and probes specific for the two types of astroviruses, it was hard to ensure that the assay initially developed would be able to detect "specifically" the target virus in an expanding range of new samples. Lack of type-specific virus isolates would make it even harder, which is opposite to the development of a real-time RT-PCR assay for detection of CSFV where reference pestiviral RNA panel and virus isolates of different genotype are available for validation (Liu et al, 2011b). It is likely that the PAstV1 primers and/or probe shared high sequence similarity with other astroviruses, resulting in a low specificity, which was only revealed by a metagenomic approach.…”

Section: Discussionmentioning

confidence: 99%

Molecular investigations on the prevalence and viral load of enteric viruses in pigs from five European countries

Zhou

Ullman

Chowdry

et al. 2016

Veterinary Microbiology

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Enteric viral infections in pigs may cause diarrhea resulting in ill-thrift and substantial economic losses. This study reports the enteric infections with porcine astrovirus type 4 (PAstV4), porcine group A rotavirus (GARV), porcine group C rotavirus (GCRV), porcine circovirus type 2 (PCV2) and porcine kobuvirus (PKoV) in 419 pigs, comprising both healthy and diarrheic animals, from 49 farms in five European countries (Austria, Germany, Hungary, Spain and Sweden). Real-time RT-PCR assays were developed to test fecal samples and to compare the prevalence and viral load in relation to health status, farms of origin and age groups. The results showed that PAstV4 (70.4%) was the dominant virus species, followed by PKoV (56.7%), PCV2 (42.2%), GCRV (3%) and GARV (0.9%). Diarrheic pigs had a higher viral load of PAstV4 in the nursery and growing-finishing groups. Rotaviruses were mainly detected in diarrheic pigs, whereas PCV2 was more often detected in clinically healthy than in diarrheic pigs, suggesting that most PCV2 infections were subclinical. PAstV4, PCV2 and PKoV were considered ubiquitous in the European pig livestock and co-infections among them were frequent, independently of the disease status, in contrast to a low prevalence of classical rotavirus infections.

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Section: Discussionmentioning

confidence: 99%

Molecular investigations on the prevalence and viral load of enteric viruses in pigs from five European countries

Zhou

Ullman

Chowdry

et al. 2016

Veterinary Microbiology

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“…The HCLV vaccine (C-strain) belongs to CSFV 1.1 genogroup and was used in Spain in the 1980s for CSF control. This vaccine has 100% homology with the Z46258 strain into the N pro region [ 7 ]. Finally, the Thiverval vaccine strain (provided by Pasteur Institute, Romania) was used as the stimulus in the Elispot assay for detecting CSFV-specific interferon-gamma (IFN-γ) producing cells.…”

Section: Methodsmentioning

confidence: 99%

“…The HCLV vaccine was developed in China, by passage in rabbits. Because of its high efficacy and safety, the HCLV vaccine was introduced into many other countries and became known as the Chinese vaccine strain (C-strain) [ 7 ]. Immune responses elicited by these vaccines do not allow differentiating infected from vaccinated animals (DIVA).…”

Section: Introductionmentioning

confidence: 99%

Efficacy of a live attenuated vaccine in classical swine fever virus postnatally persistently infected pigs

Muñoz-González

Pérez‐Simó

Muñoz

et al. 2015

Vet Res

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Classical swine fever (CSF) causes major losses in pig farming, with various degrees of disease severity. Efficient live attenuated vaccines against classical swine fever virus (CSFV) are used routinely in endemic countries. However, despite intensive vaccination programs in these areas for more than 20 years, CSF has not been eradicated. Molecular epidemiology studies in these regions suggests that the virus circulating in the field has evolved under the positive selection pressure exerted by the immune response to the vaccine, leading to new attenuated viral variants. Recent work by our group demonstrated that a high proportion of persistently infected piglets can be generated by early postnatal infection with low and moderately virulent CSFV strains. Here, we studied the immune response to a hog cholera lapinised virus vaccine (HCLV), C-strain, in six-week-old persistently infected pigs following post-natal infection. CSFV-negative pigs were vaccinated as controls. The humoral and interferon gamma responses as well as the CSFV RNA loads were monitored for 21 days post-vaccination. No vaccine viral RNA was detected in the serum samples and tonsils from CSFV postnatally persistently infected pigs for 21 days post-vaccination. Furthermore, no E2-specific antibody response or neutralising antibody titres were shown in CSFV persistently infected vaccinated animals. Likewise, no of IFN-gamma producing cell response against CSFV or PHA was observed. To our knowledge, this is the first report demonstrating the absence of a response to vaccination in CSFV persistently infected pigs.

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“…Field-strain specific RT-PCR assays have been developed [22,23], however they rely upon pre-existing sequence information about circulating field strains and are susceptible to viral genome changes as such assays often rely on one or two nucleotide differences between the field strain and vaccine. An alternative approach is to test samples for the presence of all CSFV strains and then apply a vaccine-specific test [17,18,20]. This strategy assumes that an animal is not infected if vaccine-specific RNA is detected in tonsil tissue.…”

Section: Discussionmentioning

confidence: 99%

“…For example, following a campaign to vaccinate wild boar in Germany using oral baits, C-strain vaccine could be distinguished from the genotype 2.3 field virus in CSFV RNA positive samples obtained from hunted wild boar [19]. Another differential assay has been developed that can distinguish the genetically similar Riemser C-strain, HCLV and LPC vaccine strains from most field strain genotypes except some of the genotype 3 strains [20,21]. Other differential real-time RT-PCR tests have been developed to specifically detect diverse CSFV vaccine strains [22-24].…”

Section: Introductionmentioning

confidence: 99%

Differential detection of classical swine fever virus challenge strains in C-strain vaccinated pigs

Everett¹,

Crudgington²,

Sosan-Soulé³

et al. 2014

BMC Vet Res

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BackgroundControl of classical swine fever (CSF) by vaccination ideally requires that field strain infection can be detected irrespective of the vaccination status of the herd. To inform on the usefulness of molecular tests compatible with genetic Differentiation of Infected from Vaccinated Animals (DIVA) principles when using live-attenuated vaccines, tonsil homogenates from a vaccination-challenge experiment were analyzed using a differential real-time qRT-PCR for the C-strain vaccine or real-time qRT-PCR assays developed to specifically detect the challenge strains used.ResultsIn animals with high or moderate levels of blood viraemia, which were not, or not fully, protected by vaccination, challenge virus RNA was readily detected in tonsil homogenates. In three out of the seven vaccinated animals that had high or moderate viraemia, the vaccine strain RNA also could be detected but at lower levels. Lower but varying levels of challenge and/or vaccine virus RNA were detected in tonsil homogenate samples from animals with no or low-level viraemia, and in groups solely consisting of such animals, no transmission of infection to naïve in-contact animals occurred. In one group of animals that were vaccinated 3 days prior to challenge, viraemia levels varied from high to absent and transmission of challenge virus to naïve in-contact animals occurred. The DIVA assay revealed challenge virus in all tonsil homogenates from this group, even in those animals that did not have viraemia and were protected from clinical disease by vaccination. Such animals, particularly in a low biosecurity/informal farm setting, could constitute a risk for disease control in the field.ConclusionsGenetic DIVA testing is useful for detecting the presence of field virus infection especially in non-viraemic animals without overt clinical signs but which are incompletely protected by vaccination. Such tests could particularly be useful to inform decisions prior to and during cessation of a control strategy that employs vaccination.

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A generic real-time TaqMan assay for specific detection of lapinized Chinese vaccines against classical swine fever

Cited by 23 publications

References 18 publications

Molecular investigations on the prevalence and viral load of enteric viruses in pigs from five European countries

Molecular investigations on the prevalence and viral load of enteric viruses in pigs from five European countries

Efficacy of a live attenuated vaccine in classical swine fever virus postnatally persistently infected pigs

Differential detection of classical swine fever virus challenge strains in C-strain vaccinated pigs

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