RESPIRATORY SYNCYTIAL VIRUS NEUTRALIZING ANTIBODIES IN PERSONS RESIDING IN CHICAGO, ILLINOIS

Abstract

The R.S. virus neutralization test was examined in terms of several factors bearing on the consistency and specificity of antibody response to a single strain (Randall) of this virus. It was found that this virus detected significant rises in antibody titer in 90% of 30 patients over 6 months of age who were infected with wild strains of R.S. virus between the years 1958 and 1962. Heterologous neutralizing antibodies to R.S. virus did not occur following human infections with various myxoviruses, adenoviruses, enteroviruses and herpesvirus. Indirect evidence was presented indicating that tile neutralizing activity of human serums is due to specific antibody and not due to non-specific, heat stable neutralizing substance. The titer of R.S. neutralizing antibodies was determined in the serums of 26 parturient mothers, and their 27 newborn babies, and 186 other individuals between the ages of 6 months and 69 years. Longitudinal observations of antibody titer were also conducted on 12 other infants. Neutralizing antibodies to R.S. virus were found to reach the term fetus at undiminished titer. In the longitudinal observations, serum neutralizing antibody titers were found to fall during the first months of life, decreasing by half in an average time of 43 days. Neutralizing antibodies, actively formed in response to R.S. virus infection, were observed to occur with rapidly increasing frequency in relation to age in subjects older than 6 months. These serologic findings indicated that among individuals residing in the metropolitan Chicago area, R.S. virus infection has been experienced by many during the first 2 years of life, most by school age, and all by 7 years of age. Geometric mean antibody titers were found to show a small, but probably significant, increase with age. The restriction of low titer reactors to pre-school children was noted. These serologic findings were interpreted as evidence that re-infections with R.S. virus occur, perhaps quite commonly.