Variability in a commercially available enzyme-linked immunosorbent assay system. II. Laboratory variability

Area of Science:

• Veterinary Immunology
• Diagnostic Assays
• Laboratory Science

Background:

• Enzyme-linked immunosorbent assays (ELISA) are widely used for antibody titer determination.
• Inter-laboratory and intra-laboratory variability can impact the reliability of ELISA results.
• Standardization is crucial for accurate and reproducible diagnostic testing in poultry health.

Purpose of the Study:

• To quantify the variability in ELISA results across multiple laboratories and days.
• To assess the reliability of single serum sample determinations for antibody titer.
• To determine the necessity of standardized reference pools in poultry diagnostic assays.

Main Methods:

• Serum pools of varying antibody titers (low, medium, high) were distributed to five cooperating poultry industry laboratories.
• Assays were conducted over three consecutive days at each laboratory.
• Data on antibody titers were collected and analyzed for inter-laboratory and intra-laboratory variations.

Main Results:

• Significant variations in ELISA results were observed among different laboratories.
• Substantial variability was also found among different testing days within the same laboratory.
• The greatest source of variability was identified as differences among laboratories.
• Correlations between daily mean titer and laboratory temperature were not significant.

Conclusions:

• Single determinations on individual serum samples are not reliable for estimating antibody titers due to high variability.
• The significant variability within and among laboratories highlights the critical need for standard reference pools.
• Implementing standard reference pools is essential to substantiate ELISA assay results and improve diagnostic accuracy.