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Variability in a commercially available enzyme-linked immunosorbent assay system. II. Laboratory variability
D L Kreider1, J K Skeeles, M Parsley
1Department of Animal and Poultry Sciences, University of Arkansas, Fayetteville 72701.
Insights
Variability in enzyme-linked immunosorbent assays (ELISA) is significant across different laboratories and days. Single serum sample tests are unreliable; standard reference pools are needed for accurate antibody titer estimation.
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.
Abstract:
An experiment was conducted to determine the amount of variability that occurred in enzyme-linked immunosorbent assays when samples from common serum pools were assayed in five different labs on three consecutive days. Low- (approximately 1:2000), medium- (approximately 1:4000), and high-titered (approximately 1:8000) serum pools were distributed to five poultry industry laboratories that cooperated in the study. Results varied significantly among different laboratories and among different days in the same lab. Variation among days within the same laboratory and among laboratories were large. The greatest variability occurred among labs. Correlations between mean daily titer and laboratory ambient temperature were small and not significant. The amount of variability within and among different laboratories that were observed indicate that single determinations on individual serum samples are not likely to give a reliable estimate of antibody titer. The large variability within labs further indicates the need for standard reference pools of positive serum to be included in assays in order to substantiate assay results.
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