MEASLES VIRUS-SPECIFIC FUNCTIONAL ANTIBODY-RESPONSES AND VIREMIA DURING ACUTE MEASLES

Antibody titers measured in functional and immunofluorescent assays we re compared with proportions of peripheral blood mononuclear cells inf ected with measles virus in 8 adults with measles. In addition, a sync ytium inhibition assay (SIA) for measuring neutralizing antibody using low-passage virus was compared with a standard plaque neutralization test (PNT). Antibody-dependent cellular cytotoxicity (ADCC) antibody r ose later but attained higher titer than neutralizing, antibody-depend ent complement-mediated lysis, IgM, or IgG antibodies. When titer chan ges between specimens from each patient obtained on different days wer e compared, only ADCC (r = .81, P = .026) and IgM (r = .81, P = .027) antibodies correlated with reductions in viremia. SIA and PNT correlat ed well (r = .93, P < .001). ADCC may be an important defense against measles. The delay in ADCC antibody relative to other antibodies is un ique among viruses studied. The SIA is a useful alternative to the PNT for measuring measles neutralizing antibody.