Differences in the appearance of antibodies to structural components of measles virus after immunization with inactivated and live virus.

Children immunized with inactivated (Tween 80 and diethyl ether, TE) measles vaccine, attenuated live vaccine, or a combination of the two types were studied with regard to the production of hemagglutination-inhibiting (HAI), hemolysis-inhibiting (HLI), and nucleocapsid complement-fixing (CF) antibodies. For identification of antibodies to envelope components distinct from hemagglutinin. HLI tests were done both before and after removal of HAI antibodies with TE-treated virus antigen. Immunization with three or four doses of TE vaccine led to the production of HAI antibodies and, in some cases, of nucleocapsid CF antibodies. Non-HAI HLI antibodies were not detected. In contrast, live vaccine caused the appearance of non-HAI HLI antibodies and, in the majority of cases, nucleocapsid CF antibodies. After combined immunization with TE vaccine and attenuated vaccine, non-HAI HLI antibodies were absent from 25 of 29 children. Most children exposed to wild measles virus after immunization with TE vaccine alone developed a poorer non-HAI HLI antibody response than children who had had normal measles. The latter infections resulted in a more pronounced non-HAI HLI and nucleocapsid CF antibody response than that observed after infections with vaccine virus. An even more accentuated response involving these antibodies was seen in patients with subacute sclerosing panencephalitis. Thus the failure of inactivated measles vaccines to prevent infection may be due to the absence of an envelope component responsible for the production of non-HAI HLI antibodies.