Characterization of serological responses in Gamma-infected individuals. (A) Surface representation of structure of SARS-CoV-2 RBD. The positions of key Gamma mutations are highlighted in orange, and the ACE-2 epitope is indicated by purple dashed lines; inset shows the ACE-2 (shown as a ribbon diagram) and RBD interaction. (B) Binding to Wuhan-Hu-1 and variant RBDs by plasma IgG from Gamma-infected (black) and prepandemic (red) cohorts, summarized as area under the curve (AUC). (C) Neutralization activity against Wuhan-Hu-1 and variant pseudoviruses by plasma IgG from Gamma-infected (black) and Wuhan-Hu-1–infected (gray) cohorts, summarized as NT₅₀ values. B and C show averaged results from duplicate experiments. Numbers in red are mean geometric values; statistical differences determined by two-sided Kruskal-Wallis test with subsequent Dunn’s multiple comparisons.