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

BMC Veterinary Research

Helen R Crooke¹  Olubukola Sosan-Soulé¹  Bentley S Crudgington¹  Helen E Everett¹ 

[1] Virology Department, APHA, New Haw, Addlestone KT15 3NB, UK

关键词: C-strain;    Vaccination;    Infection;    DIVA PCR test;    Classical swine fever virus;   

Others  :  1091871
DOI  :  10.1186/s12917-014-0281-9

 received in 2014-07-24, accepted in 2014-11-14,  发布年份 2014

【 摘 要 】

Background

Control 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.

Results

In 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.

Conclusions

Genetic 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.

【 授权许可】

   
2014 Crown copyright; licensee BioMed Central.

【 图 表 】

Figure 1.

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