Validation of an indirect ELISA employing a chimeric recombinant gag and env peptide for the serological diagnosis of equine infectious anemia.

ABSTRACT

The National Reference Center for equine infectious anemia (EIA) validated a commercial ELISA (Eradikit® EIAV Indirect ELISA, In3diagnostic®, Turin, Italy) employing a chimeric recombinant gag and env peptide for the detection of EIA virus antibodies, following the guidelines of the World Organization for Animal Health. The validation parameters evaluated were analytical sensitivity (Se) and specificity (Sp); diagnostic Se and Sp; precision, based on repeatability and reproducibility through the estimation of the standard deviation (SD) and the coefficient of variation (CV); accuracy, estimated from a multiple K and relative Sp and Se with respect to those of the agar gel immunodiffusion test (AGIDT). Positive and negative predictive values were also defined. The assay showed a high specificity and a limit of detection of 1.43 log10 major than AGIDT. Diagnostic Se was 100% and Sp was 99.3%, while SD values ranged from 1.58 to 5.01 with a CV between 2.8% and 28.8%. Multiple K was 0.98 and relative Se and Sp were respectively 99.1% and 100%. The assay proved to be robust and to possess a high sensitivity in detecting first antibodies produced at onset of infection as well as high analytic and diagnostic Se and Sp values, confirming it as a serological assay fit for purpose within EIA surveillance programs.