Development of a Multiplex Bead Serological Assay for Use in Global Laboratories to Assess Population Immunity to Measles and Rubella

Abstract

Abstract Serosurveys are an important tool for the evaluation of population immunity and guidance of immunization activities. The multiplex bead assay (MBA) offers multiple benefits over standard serological assays and this study sought to compare the use of MBA to measure humoral immunity to measles and rubella compared to the enzyme immunoassay (EIA) for both viruses and the plaque reduction neutralization (PRN) for measles. Multiplex beads coupled with laboratory-produced purified measles whole virus antigen (WVA) correlated better to EIA and PRN than baculovirus-expressed measles nucleoprotein (N); therefore, a commercial antigen source of measles WVA was evaluated. The commercial measles WVA demonstrated significant correlation using Pearson’s correlation coefficient to the laboratory-produced WVA MBA (R=0.995, p=<0.0001) and demonstrated a strong linear relationship between the two WVA MBA assays (R2= 0.926). The commercial measles WVA MBA correlated strongly to PRN (R=0.9530, p=<0.0001) with a linear relationship comparable to the laboratory-produced WVA and PRN (R2=0.716 and R2=0.768, respectively). Receiver operator curve (ROC) analysis resulted in a seroprotection cutoff of 153 mIU/ml, similar to the established correlate of protection of 120 mIU/ml, with a sensitivity of 98% and a specificity of 84%. Comparison of the rubella MBA to EIA demonstrated a strong linear correlation of the two assays (R=0.959 and R2=0.919). ROC analysis yielded a cutoff of 9.36 IU/ml, similar to the accepted cutoff of 10 IU/ml for seroprotection with a sensitivity of 99% and a specificity of 100%. The results presented here support the use of the MBA as a tool to conduct multiplexed serosurveys to assess population immunity to measles and rubella.