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

Levels 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.IgG 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.Swine dysentery (SD) is a mucohaemorrhagic colitis of pigs resulting from infection of the large intestine with the anaerobic spirochaete Brachyspira hyodysenteriae [1]. The disease has a worldwide distribution and causes significant economic loss. Successful control programs for SD rely on accurate, cost-effective and timely detection of infected herds and animals. Diagnosis is usually based on clinical signs and detection of the causative spirochaete by culture and/or PCR [2-4]. Although not widely used, serological tests measuring serum immunoglobulins specific to B. hyodysenteriae have potential to be used at the herd level for routine surveillance [5]. ELISA systems using whole spirochaete cells [6,7], lipopolysaccharide (LPS) [8], and the B. hyodysenteriae outer membrane lipoprotein Bhlp29.7 [9] as antigens all have been described for this purpose. Elevated antibody levels have been detected in pigs for up to 150 da