Neutralization assays were performed with pseudoviruses harboring the S proteins of B.1.1, BA.1, BA.2, BA.2.75, BA.5 and BQ.1.1. The BA.5 S-based derivatives are included in ( a , b , e – g ). The following sera were used. d Principal component (PC) analysis representing the antigenicity of the S proteins. The analysis is based on the results of neutralization assays using hamster sera ( c ). Assays for each serum sample were performed in triplicate to determine the 50% neutralization titer (NT 50 ). Each dot represents one NT 50 value, and the geometric mean and 95% confidential interval (CI) are shown. Statistically significant differences were determined by two-sided Wilcoxon signed-rank tests. The P values versus BA.2 ( a , c , left), BA.2.75 ( c , middle), BA.5 ( b , c , right) or B.1.1 ( e – g ) are indicated in the panels. The horizontal dashed line indicates the detection limit (120-fold). Information on the convalescent donors is summarized in Supplementary Table 3 .
