Abstract
This study was performed to develop an improved enzyme-linked immunosorbent assay (ELISA) for the detection of measles antibodies.
A highly purified virus antigen was prepared from Vero cells infected with measles virus by density gradient ultracentrifugation. The control antigen was prepared from uninfected Vero cells as well. Since antibodies to Vero cells, non-Forssman antibodies, were found in some sera of young age group, it was essential to absorb the test sera with Vero-cell antigen before the ELISA test. A cut-off level (0.18) was estimated after absorption of 157 sera with Vero-cell antigen. By making use of this cut-off level, a highly sensitive and specific ELISA test was established. A conversion table was prepared for the calculation of measles ELISA antibody titer defined as reciprocal of the highest serum dilution which showed a positive score from the measured absorbance of a single serum dilution of 1: 200. By this method, ELISA antibody titers of many samples can be recorded at once. After a measles AIK-C vaccine virus infection, infants developed ELISA antibodies earlier than HI and neutralizing (NT) antibodies. Measles ELISA antibodies persisted for as long as NT antibodies after natural measles infection.
