The use of ELISAs for monitoring exposure of pig herds to Brachyspira hyodysenteriae

Yong Song,David J Hampson,Barbara Frey

doi:10.1186/1746-6148-8-6

Yong Song, David J Hampson + Show 1 more

Open Access

https://doi.org/10.1186/1746-6148-8-6

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Abstract

BackgroundSwine dysentery (SD), a mucohaemorrhagic diarrhoeal disease of pigs, results from infection of the large intestine with the spirochaete Brachyspira hyodysenteriae. ELISA systems using whole spirochaete cells (WC) and the B. hyodysenteriae outer membrane lipoprotein Bhlp29.7 previously have been established as potential diagnostic tools for SD. However, their true value in identifying infected herds remains unclear. The present study aimed to compare the performance of whole-cell and Bhlp29.7 based ELISAs in detecting specific immunoglobulin class IgG and IgM to B. hyodysenteriae in growing pigs, and additionally evaluated whether meat juice could serve as a source of specific antibodies.ResultsLevels of circulating IgG and IgM reacting with WC spirochaete preparations and recombinant Bhlp29.7 peaked 4-6 weeks post-infection in the experimentally challenged pigs, and remained elevated in the present study. In a cohort of pigs on an infected farm levels of antibody directed against both antigens showed a progressive increase with time. However, other than for the level of IgG against WC antigen, a significant increase in antibody levels also was observed in a cohort of pigs on a non-infected farm. In addition, assays using meat juice had 100% specificity and equivalent sensitivity to those based on serum, and likewise the best performance was achieved using the WC IgG ELISA.ConclusionsIgG ELISAs using either WC or Bhlp29.7 as plate-coating antigens were shown to be useful for monitoring the dynamics of B. hyodysenteriae infection in grower pigs. Of the two antigens, the WC preparation tended to give better discrimination between pigs from infected and non-infected farms. Testing of meat juice was shown to have potential for identifying infected herds.

Highlights

Swine dysentery (SD), a mucohaemorrhagic diarrhoeal disease of pigs, results from infection of the large intestine with the spirochaete Brachyspira hyodysenteriae
IgG and IgM antibodies reacting with the whole spirochaete cells (WC) antigen increased to a maximum at 4-6 weeks post-infection (PI); they showed a slight decline, they were still elevated at 10 weeks PI (Figure 1, panel A)
In the case of the Bhlp29.7 antigen, antibody levels peaked at 4 weeks PI and the subsequent decline was more rapid than with the WC antigen, but the IgG level in one pig became elevated again after 8 weeks PI (Figure 1, panel B)

Summary

Introduction

Swine dysentery (SD), a mucohaemorrhagic diarrhoeal disease of pigs, results from infection of the large intestine with the spirochaete Brachyspira hyodysenteriae. ELISA systems using whole spirochaete cells (WC) and the B. hyodysenteriae outer membrane lipoprotein Bhlp29.7 previously have been established as potential diagnostic tools for SD. Their true value in identifying infected herds remains unclear. Elevated antibody levels have been detected in pigs for up to 150 days following experimental infection [10], and sera obtained from pigs at slaughter can be used to assess the likely SD status of the source herds [9]. This proposition was tested in the current study by following antibody levels in the experimental pigs for 10 weeks after experimental infection

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