277. Equine chorionic gonadotrophin isoform composition in commercial products compared with isoform composition in pregnant mare plasma
Authors: Ciller U. A., Ciller I. M., McFarlane J. R.
Journal: Reproduction, Fertility and Development
Summary
Equine chorionic gonadotrophin (eCG) harvested from pregnant mare plasma is widely used in assisted reproductive programmes across the livestock industry, yet commercial preparations exhibit considerable batch-to-batch variation in bioactivity that complicates clinical outcomes. Ciller and colleagues compared the isoform composition of 15 commercial eCG products against 23 pregnant mare plasma samples using iso-electric focusing to fractionate the hormone across acidic, intermediate, and basic pH ranges. Commercial preparations were found to be heavily skewed towards acidic isoforms (pH 3.0–5.1), accounting for 92% of detected immunoactivity, whilst native plasma showed a substantially more diverse distribution across all three pH categories; furthermore, measured immunoactivity in commercial products ranged from 44% to 362% of their stated bioactivity. This selective enrichment of acidic isoforms during commercial processing is likely to significantly alter the biological activity profile compared with endogenous hormone, and the wide variation in actual versus declared potency suggests that current manufacturing and quality control procedures merit urgent standardisation. For practitioners using eCG in reproductive protocols, these findings underscore the importance of treating batch variation as a genuine biological variable rather than a minor manufacturing inconsistency, and support the case for bioassay-based potency verification prior to clinical use.
Read the full abstract on the publisher's site
Practical Takeaways
- •Commercial eCG products are highly inconsistent in actual bioactivity despite manufacturer labelling — expect variable results between batches and products in breeding programs
- •The altered isoform composition in manufactured eCG may not mimic natural pregnancy physiology, potentially affecting reproductive outcomes compared to native plasma composition
- •When using commercial eCG for assisted reproduction, batch testing or alternative sourcing strategies should be considered to improve consistency and predictability of treatment response
Key Findings
- •Commercial eCG products showed 44-362% variation in immunoactivity compared to stated bioactivity
- •92% of immunoactivity in commercial preparations concentrated in acidic isoforms (pH 3.0-5.1), compared to broad distribution across all pH ranges in pregnant mare plasma
- •Isolation and manufacturing processes selectively enrich acidic eCG isoforms, creating products that do not reflect the natural isoform composition found in pregnant mare plasma