Antibody avidity following secondary dengue virus type 2 infection across a range of disease severity.

Abstract Background The four dengue virus serotypes (DENV1-4) are responsible for the most prevalent mosquito-borne viral illness in humans. DENV causes a spectrum of disease from self-limiting dengue fever (DF) to severe, life-threatening dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). Antibodies from one infection can contribute to either protection or increased disease severity in a subsequent infection with a distinct DENV serotype. The effectiveness of the antibody response is modulated by both the affinity and avidity of the antibody/antigen interaction. Objectives We investigated how antibody avidity developed over time following secondary DENV2 infection across different disease severities. Study design We analyzed sera from 42 secondary DENV2-infected subjects (DF, n  = 15; DHF, n  = 16; DSS, n  = 11) from a pediatric hospital-based dengue study in Nicaragua. IgG avidity against DENV2 virions was measured in samples collected during acute and convalescent phases as well as 3, 6, and 18 months post-illness using a urea enzyme-linked immunosorbent assay. Results The data show a significant increase in avidity from acute to convalescent phase followed by a decrease from convalescent phase to 3 months post-symptom onset, then a plateau. Linear regression analysis comparing antibody avidity between disease severity groups over time indicate that individuals with more severe disease (DHF/DSS) experienced greater decay in antibody avidity over time compared to less severe disease (DF), and ROC curve analysis showed that at 18 months post-illness, lower avidity was associated with previously having experienced more severe disease. Conclusions These data suggest that increased dengue disease severity is associated with lower antibody avidity at later time-points post-illness.