Immunoglobulin A Antibody Responses in Patients with Primary or Secondary Dengue Infections

Abstract

IgM serological diagnostic plays an important role in the dengue epidemiological surveillance. However, IgA has been identified as a possible diagnostic marker for early stage and recent infections. The aim of this study was to know the IgA response in dengue patients in relation to type of infection, serotype specificity and role as early and recent infection marker. IgA behavior in dengue patients, using a method defined as Indirect Sandwich ELISA-IgA (ELISA-IgA) and Capture IgM ELISA (MAC- ELISA) as reference assay was studied. The sensibility and specificity of the system were 91.06% and 83.73% respectively. In acute phase of illness, IgA was only detected in secondary cases with 32.3%. IgM appears later than IgA in secondary cases. No significant differences in IgA or IgM responses between primary and secondary cases were found in samples collected after day 5 of onset of symptoms. In days 41-54, the percentage of IgA was lower respect to IgM. IgA was detected until day47 inprimary and until day50 insecondary cases. An elevated cross-reactivity in IgA was observed between dengue serotypes contrary to IgM. The usefulness of IgA, as alternative early diagnostic tool, could be influenced by the absence or very low percentages of positives cases in the first four days of onset of symptoms. However, for definition of secondary infection could be important. IgA could be an alternative tool, better than IgM, as recent infection marker for dengue fever, but this requires more studies in future investigations.