Is human immunodeficiency virus RNA load composed of neutralized immune complexes?

During acute human immunodeficiency virus (HIV) infection, both virus load (HIV RNA) and infectivity are high (10³-10⁷ RNA copies/mL or TCID₅₀/mL) until antibody is produced, which may reduce the HIV infectivity. In HIV carriers, the HIV RNA load is elevated (10³-10⁵ copies/mL), but infectivity is low (10⁰-10² TCID₅₀/mL). The low infectivity in carriers could be due to neutralization by antibody in serum, resulting in immune complexes (ICs). We demonstrated that ICs in plasma, prepared with protein A beads, contained HIV RNA (80%-100%) in association with immunoglobulin G (IgG). In comparison, ICs from patients with acute HIV infection and little or no antibody contained virtually no HIV RNA. Moreover, ICs prepared by ultrafiltration contained IgG and specifically and irreversibly neutralized HIV, which indicates that the ICs contained neutralizing antibody. These findings indicate that the HIV RNA in the plasma of carriers is frequently composed of antibody-neutralized HIV as ICs.