Abstract:
Disease monitoring in free-ranging wildlife is a challenge and often relies on
passive surveillance. Alternatively, proactive surveillance that relies on the
detection of specific antibodies could give more reliable and timely insight into
disease presence and prevalence in a population, especially if the evidence of
disease occurs below detection thresholds for passive surveillance. Primary
binding assays, like the indirect ELISA for antibody detection in wildlife, are
hampered by a lack of species-specific conjugates. In this study, we developed
anti-kudu (Tragelaphus strepsiceros) and anti-impala (Aepyceros melampus)
immunoglobulin-specific conjugates in chickens and compared them to the
binding of commercially available protein-G and protein-AG conjugates, using
an ELISA-based avidity index. The conjugates were evaluated for cross-reaction
with sera from other wild herbivores to assess future use in ELISAs. The
developed conjugates had a high avidity of >70% against kudu and impala sera.
The commercial conjugates (protein-G and protein-AG) had significantly low
relative avidity (<20%) against these species. Eighteen other wildlife species
demonstrated cross-reactivity with a mean relative avidity of >50% with the
impala and kudu conjugates and <40% with the commercial conjugates. These
results demonstrate that species-specific conjugates are important tools for the
development and validation of immunoassays in wildlife and for the surveillance
of zoonotic agents along the livestock-wildlife-human interface.