Discrepancy in Dengue Virus Neutralizing Antibody Titers between Plaque Reduction Neutralizing Tests with Fcγ Receptor (FcγR)-Negative and FcγR-Expressing BHK-21 Cells

摘要

Protective immunity against dengue virus (DENV) is best reflected by the presence of neutralizing antibodies. The conventional plaque reduction neutralizing test (PRNT) is performed using Fcγ receptor (FcγR)-negative cells. Because FcγR plays a key role in antibody-dependent enhancement, we examined neutralizing antibody titers of mouse monoclonal antibodies and human serum samples in PRNTs using FcγRIIA-negative and FcγRIIA-expressing BHK cells. There was a discrepancy in dengue virus neutralizing antibody titers between PRNTs using FcγRIIA-negative versus FcγRIIA-expressing BHK cells. Neutralizing antibody titers to DENV-1 and DENV-2 tested with monoclonal antibodies, and with most of the human serum samples, were higher in assays using BHK cells than those using FcγRIIA-expressing BHK cells. The results suggest that neutralizing antibody titers determined using FcγRIIA-expressing cells may better reflect the protective capacity of anti-DENV antibodies, as the major target cells of DENV infection are FcγR-positive cells.