Article ID: JJID.2016.379
Dengue is the most important arboviral disease worldwide. We previously reported that most dengue-immune inhabitants in endemic countries have infection-enhancing antibodies whose in vitro activity does not decrease in the presence of complement: that is, complement-independent enhancing antibodies (CiEAb). Here, we compared levels of CiEAb and complement-dependent neutralizing antibodies (CdNAb) in dengue-immune humans. A typical antibody dose–response pattern obtained in our assay system to measure the neutralizing/enhancing antibody balance showed both neutralizing and enhancing activities depending on serum dilution factor. The inclusion of complement in the assay system increased the neutralizing antibody activities at lower dilutions, indicating the presence of CdNAb. In contrast, similar dose–response curves were obtained with and without complement at higher dilutions, indicating higher levels of CiEAb than CdNAb. For an experimental support, a cocktail of mouse monoclonal antibodies against dengue virus type 1 was prepared. The dose–response curves obtained in the assay, with or without complement, were similar to those of the human serum samples, when a high proportion of D1-V-3H12 (enhancing-only antibody and thus a model of CiEAb) was used in the cocktail. This study revealed higher level induction of CiEAb than CdNAb in humans naturally infected with dengue viruses.
