Dirofilaria immitis: performance and standardization of specific antibody immunoassays for filariasis.
The factors associated with the development, optimization, and validation of immunoassays for the detection of parasite-specific antibody in filariasis infections were investigated using the dog heartworm, Dirofilaria immitis as a model. We examined two assays, the Protein A solid-phase radioimmunoassay (SPRIA) and enzyme-linked immunosorbent assay (ELISA), for quantitation of specific antibody to the parasite in canine serum. Precision, reproducibility, and parallelism were examined using response-error relationships and precision profile analyses. A staphylococcal Protein A saturation analysis was applied to the standardization of IgG anti-parasite antibody reference sera in weight per volume units (microgram/ml). Using the mean minimal detectable dose + 3 SD and an intraassay precision profile less than 10% coefficient of variation (CV) as criteria for assay sensitivity, the SPRIA and ELISA displayed comparable positive thresholds of 1 microgram/ml IgG anti-parasite antibody/ml of serum. Both assays demonstrated good reproducibility (less than 15% interassay CV) and parallelism (less than 20% interdilutional CV) over their working ranges (SPRIA: 1-40 micrograms/ml; ELISA: 1-5 micrograms/ml). Specificity of each assay was enhanced by preadsorption of cross-reacting antibodies in canine serum (i.e., specific for Toxocara canis antigens) with solid-phase antigen prior to assay. Methods for comparing different immunoassay designs are considered in relation to the variables that influence the assays' performance characteristics.
D000327:Adsorption; D000818:Animals; D000918:Antibody Specificity; D004183:Dirofilaria immitis / Q000276:immunology*; D004184:Dirofilariasis / Q000175:diagnosis* / Q000276:immunology; D004285:Dogs; D004306:Dose-Response Relationship, Immunologic; D004797:Enzyme-Linked Immunosorbent Assay; D005069:Evaluation Studies as Topic; D005370:Filarioidea / Q000276:immunology*; D007124:Immunoenzyme Techniques; D007074:Immunoglobulin G / Q000032:analysis*; D011863:Radioimmunoassay; D012015:Reference Standards; D013205:Staphylococcal Protein A; D014119:Toxocara / Q000276:immunology
D007074:Immunoglobulin G; D013205:Staphylococcal Protein A