Prevalence of neutralizing antibodies against a candidate rotavirus vaccine in adults.
Because of the morbidity and mortality from infection with rotaviruses in children under 2 years, in many parts of the world but especially in developing countries, an urgent need for a vaccine has been recognized. At present, a vaccine candidate of bovine origin, the RIT 4237 strain vaccine developed from a strain received from Mebus et al., is available. This strain has been shown to induce cross protection by challenge of colostrum deprived piglets with human rotavirus strains. Before testing its protective effect in children, preliminary studies in adult volunteers are required to evaluate its degree attenuation and immunogenicity. With regard to the latter we have studied the antibody profile of 87 healthy adults, ages 25 to 40 years, from whom blood samples were taken between January and June 1982. Antibodies versus RIT 4237 were measured both by neutralization and ELISA techniques. Analysis of the results revealed a significant difference in antibody levels according to sex, since high neutralizing antibody titers (greater than 1:320) were observed about 7 times more frequently in women than in men. Furthermore, no seasonal variation in the level and the distribution of serum antibody titers was found when comparing blood specimens taken from male volunteers in winter and spring. As far as antibody levels obtained by neutralization and ELISA assays is concerned, a good correlations was noted in 75% of cases. However, in 22 out of 87 sera high levels of neutralizing antibodies were found in association with low ELISA antibody titers or vice versa. These results suggest that screening of adult volunteers should be performed by means of a neutralization assay prior to administration of a candidate vaccine. However, in the absence of such preliminary testing, male volunteers should be chosen since there is a higher probability of low pre-existing antibody levels among such subjects.