Measles serodiagnosis: production and evaluation of the IgM-measles ELISA(IAL) reagent

RESUMO

Recent measles outbreaks in different countries led to an increase of laboratory measles diagnosis. Thus, we developed the IgM-Measles ELISAIAL, using measles virus antigens obtained from cell cultured in microcarriers in order to supply reagent kits to Brazilian public health laboratories. A batch of antigenic reagent was produced and evaluated in the enzyme immunoassay in comparison with clinical diagnosis and with as reference assay (IgM Capture ELISA(CDC)) data. This study was performed in a positive panel with 70 serum samples from patients with measles, and a negative panel with 132 samples from patients with unrelated diseases and without recent measles or vaccination history. In relation to other diagnostic methods, the IgM ELISAIAL presented sensitivity higher than 97.1 per cente, specificity and precision of 97 per cente, and agreement kappa (k) index higher than 0.94 (P < 0.05). Moreover, the IgM antibody profile from measles acute phase revealed by the assay was similar to the reference assay. A practical analysis system for checking the quality of new reagent batches was proposed based on the diagnostic features and agreement kappa index. Our findings suggest that measles antigenic reagents can be produced with reliable quality control system, and supplied to public health laboratories for routine serodiagnosis or population surveys.