Occurrence of Aujeszky’s disease virus single-reactor pigs in Poland

The aim of the study was to analyse the prevalence of single-reactor (SR) pigs in Poland, to attempt an explanation for this phenomenon, and to assess whether the occurrence of SR pigs could create problems for a successful Aujeszky’s disease virus (ADV) eradication programme in Poland. A total of 6494 ADV gE antibody positive/doubtful sera were retested by gB ELISA and subsequently by virus neutralisation test (VNT) to confirm the results of the glycoprotein E (gE) ELISA. Amongst the serum samples tested, 5.9% could be classified as being taken from SR pigs, as was shown by gE ELISA positive/doubtful results, which were not confirmed by negative findings in gB ELISA and VNT. It means that the observed SR phenomenon was due to a false positive/doubtful reaction in gE ELISA. This finding was strongly supported by the fact that the serum samples were taken from the animals from herds without any previous or subsequent history of Aujeszky’s disease. The low percentage of SR pigs does not seem to create a big obstacle to a successful ADV eradication programme in Poland.