Disease severity-related antigenic differences in dengue 2 strains detected by dengue 4 monoclonal antibodies.

Low-passage epidemic Thai isolates of dengue 2 (DEN-2) were distinguished on the basis of associated disease severity by detection of virus determinants involved in enhanced macrophage infection when incubated with a panel of monoclonal antibodies derived from a DEN-4 strain associated with grade II dengue hemorrhagic fever (DHF). DEN-2 strains associated with DHF typically had multiple determinants that were involved in antibody-dependent enhancement of infection, whereas those associated with uncomplicated disease had few. These data provide further evidence that in epidemic areas where DHF is associated with prior circulation of low-level monotypic antibody, severe dengue disease could represent antibody-enhanced infection of human monocytes/macrophages.