Evaluation of dried blood spot testing for serological monitoring of epizootic and zoonotic pathogens in domestic pigs

Dried blood spots (DBS) constitute a stable, cost-efficient sampling matrix that can be collected in a minimally invasive manner. Although widely adopted in human medicine, their use in veterinary diagnostics remains limited. This study aimed to establish and validate DBS elution protocols for use in commercial ELISAs to detect antibodies against Hepatitis E virus (HEV), African swine fever virus (ASFV) and Aujeszky's disease virus (ADV) in domestic pigs. DBS were prepared from EDTA blood, dried serum spots (DSS) from serum. Additional DBS samples were prepared after spiking blood from healthy pigs with antibodies. Various parameters were evaluated to establish the final elution protocols, i.e. number of disks, type and volume of elution buffer, incubation time of the disks in elution buffer, and volume of eluate used for detection. Once the final protocols were in place, for each pathogen 52 DBS were tested in three independent runs. The diagnostic performance was evaluated by comparing the ELISA results of DBS eluates with the corresponding serum or plasma samples. For HEV, only one out of 52 DBS samples qualitatively did not match the plasma result in any of the three runs. For ASFV, all 52 DBS samples matched the qualitative results of the corresponding liquid samples. For ADV, two samples yielded false negative results in all three runs. The results suggest that DBS represent a practical and reliable alternative to liquid blood samples for antibody detection in pigs. Further validation with field samples and large-scale testing is needed.