San Juan Laboratories, Dengue Branch, Division of Vector-Borne Viral Diseases, Center for Infectious Diseases, Centers for Disease Control, U.S. Public Health Service, GPO Box 4532, San Juan, Puerto Rico 00936
A variety of methods have been employed to detect viral immune complexes (IC) in clinical specimens. However, most techniques used were not antigen-specific. We developed a simple, specific double antibody sandwich technique to detect artificial anti-dengue (DEN) IgM immune complex (IgM-IC). Positive reactivity with IgM-ICs prepared with live DEN-1, -2, and -3 viruses was found to be related to IgM titers exceeding 1:20 and to the titer of the viruses. Most IgM-ICs prepared with live DEN-4 virus did not react. In contrast, IgM-ICs prepared with hemagglutination antigens, representing all 4 serotypes, reacted positively with amounts of antigens ranging from 2 to 8 units. These IgM-ICs were not type-specific.