 The study presents a new threefold multiplexed alzanafagocytic killing assay, MOPA, that can assess the immunogenicity of group B streptococcus, GBS, vaccines against serotypes IA-3 and V. The MOPA uses baby rabbit complement, BRC, to measure the alzonic index, OI, which is a measure of the ability of antibodies in serum to kill bacteria. The study optimizes the BRC concentration and shows that the MOPA has high specificity and accuracy, with R2 values greater than 0.950 for all three serotypes. The intersay precision of the GBS MOPA is 12.5% of the average coefficient of variation. This article was authored by Minit Jichoi, Ji Yun-no, He Jin Chong and others.