Immunoradiometric assay for quantitation of Dirofilaria immitis antigen in dogs with heartworm infections

Journal Article · Mon Oct 01 04:00:00 EDT 1984 · Am. J. Vet. Res.; (United States)

OSTI ID:5982000

Hamilton, R G; Scott, A L

An immunoradiometric assay (IRMA) was developed, optimized, and validated for detection of parasite-specific antigen in sera from hosts with filarial infections, using Dirofilaria immitis in dogs as a model. The precision, reproducibility, and parallelism of the IRMA were examined, using precision profile analysis. The IRMA had acceptable precision and reproducibility (less than 15% intra-assay coefficient of variation (CV)) over a working range of 10 to 2000 ng of D immitis-antigen (AG)/ml. The IRMA parallelism (agreement between dilutions) was acceptable (less than 10% interdilutional CV) with laboratory-spiked D immitis AG sera containing no D immitis-antibody (AB). However, it was not acceptable (greater than 20% interdilutional CV) for analysis of sera from naturally infected dogs containing D immitis AB, probably due to dissociation of immune-complexed AG with increasing serum dilution. Nonparallelism limited the accuracy of binding data interpolation from the standard curve. Specificity of the IRMA was enhanced by preabsorption of the radiolabeled detection antibody with Toxocara canis AG before use. Varying amounts of D immitis AG (22 to 1000 ng/ml) were detected in 42% (20/48) of microfilaremic dogs. The presence of AG-specific AB at concentrations as low as 1 microgram/ml reduced the ability of the IRMA to detect D immitis AG. Factors that influence the accuracy and sensitivity of immunoassays for circulating filarial antigens are discussed.

• Research Organization: Johns Hopkins Univ. School of Medicine, Baltimore, MD
• OSTI ID: 5982000
• Journal Information: Am. J. Vet. Res.; (United States), Journal Name: Am. J. Vet. Res.; (United States) Vol. 45:10; ISSN AJVRA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ACCURACY
ANIMALS
ANTIBODIES
ANTIGENS
BIOLOGICAL MODELS
BODY
CARDIOVASCULAR SYSTEM
DISEASES
DOGS
HEART
INFECTIOUS DISEASES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
ORGANS
RADIOASSAY
RADIOIMMUNOASSAY
RADIOISOTOPES
TESTING
TRACER TECHNIQUES
VALIDATION
VERTEBRATES