Rubella remains a social and economic burden due to the high incidence of congenital rubella syndrome (CRS) in some countries. For this reason, an accurate and efficient high-throughput measure of antibody response to vaccination is an important tool. In order to measure rubella-specific neutralizing antibodies in a large cohort of vaccinated individuals, a high-throughput immunocolorimetric system was developed. Statistical interpolation models were applied to the resulting titers to refine quantitative estimates of neutralizing antibody titers relative to the assayed neutralizing antibody dilutions. This assay, including the statistical methods developed, can be used to assess the neutralizing humoral immune response to rubella virus and may be adaptable for assessing the response to other viral vaccines and infectious agents.A cute infection with rubella virus usually results in a mild fever and rash. However, complications can arise when infection occurs during pregnancy. In this case, rubella virus is able to establish infection in the fetus, where there is up to a 90% risk of developing congenital rubella syndrome (CRS) if infection occurs during the first trimester (1, 2). Although vaccination programs have decreased the number of rubella cases and CRS in most countries, the burden of rubella and CRS is still high in many developing countries. Improved surveillance is needed to evaluate the progress of control programs (3).Traditional assays, like enzyme immunoassays (EIA), hemagglutination inhibition assays (HAI), and neutralization assays, have been successfully implemented for laboratory diagnostics and screening techniques. However, issues such as false positives, lack of sensitivity, standardization between platforms, and the time and resources needed to efficiently measure responses in a large number of samples still exist (4-10). Thus, a standard and efficient method that resolves some or all of these issues is needed. Our laboratories previously used a rubella virus-specific chemiluminescent immunoassay (Beckman Coulter Access, Brea, CA) and in-house colorimetry-and fluorescence-based immunoassays (Centers for Disease Control and Prevention [CDC]) to measure antibody titers to rubella virus. The chemiluminescent immunoassay produced highly sensitive and reproducible antibody titer data and revealed a large spectrum of antibody responses in individuals vaccinated against rubella virus (11,12). Although this quantifies rubella virus antibodies, the focus of our current study was to measure functional neutralizing antibodies against rubella virus.The first aim of this study was to adapt an immunocolorimetric system for the large-scale, high-throughput quantitation of rubella virus-neutralizing antibody in a cohort of 2,091 subjects and to test the level of precision between repeated results. Next, statistical approaches were used to interpolate these data into quantitative estimates of individual subject titer values that can be used as continuous measurements in subsequent analyses. Finally, correla...
