ABSTRACT
The sensitivity of an enzyme-linked immunosorbent assay (ELISA) to detect low levels of antibody to respiratory syncytial (RS) virus was compared with a tube dilution neutralization test (NEUT) on sera obtained from children who received a parenteral live RS virus vaccine. Among the children who developed antibody in response to live RS virus vaccine. ELISA was as sensitive as NEUT at detecting antibody increases. Some children who did not have detectable prevaccine ELISA antibody possessed NEUT antibody; these children were generally less than 12 months old, suggesting that they had low levels of maternal antibody. Low levels of NEUT or ELISA antibody were associated with the absence of antibody increases after injection of live RS virus vaccine. The quantity of antibody stimulated by this live RS virus vaccine was small compared with that which was stimulated by naturally acquired RS virus infection. We concluded that ELISA is a satisfactory test for determining antibody to RS virus in vaccine field trials, given the understanding that low levels of preexisting antibody are not detected in some instances.
