Abstract 96 – Species-specific validation of commercial immunoassays for accurate hormone quantification in polar bear serum

Erin Curry, Emily Virgin, Adrianna Tompros, Jessye Wojtusik

Although steroid and thyroid hormones are frequently studied in polar bears, there is growing
interest in evaluating less commonly investigated protein hormones and their roles in
reproduction, health, and metabolism. Due to limited availability of antibodies specific to polar
bear analytes, commercial assays designed to quantify hormones in domestic species may be
considered; however, it is crucial to validate these assays using polar bear samples to ensure
cross-species accuracy and reliability. Utilizing sera (n=435) collected from zoo polar bears
(n=91) of both sexes, a range of ages (0-31y), and across seasons, antibodies (n=80) from
commercial single-plex and multiplex enzyme-linked immunoassays targeted to canine (n=25),
feline (n=15), human (n=22), mouse (n=13), or rat (n=5) analytes were evaluated. Validation
steps included parallelism of serially diluted pooled samples to the assay standard curve,
dilution linearity, and recovery of spiked analyte. Of the 80 antibodies analyzed, only 27 (34%)
met validation criteria in polar bear serum; these included hormones involved in reproduction
(AMH, FSH, LH, oxytocin, prolactin), immunity/inflammation (IFN gamma, IL-2, IL-10, IP-10) and
metabolism (growth hormone, leptin, ghrelin), among others. Assays targeting canine analytes
resulted in 80% successful validation, followed by mouse (31%), rat (20%), human (9%), and
feline (0%). Preliminary data from individual samples revealed expected differences in hormone
trends between sexes, by age, and across seasons, indicating biological validation. Additionally,
several inflammatory markers were higher in individuals with known pathology compared to
healthy individuals, suggesting they may serve as biomarkers of health. These findings
underscore the critical importance of performing species-specific assay validations and have
resulted in a suite of tools that may be incorporated into polar bear monitoring surveys, both ex
situ and in situ.