B-cell evolution in shape space — affinity maturation via somatic hypermutation
Shape space (Perelson & Oster 1979): antibodies and antigens live in an abstract N-dimensional space. Binding affinity = Gaussian function of distance.
Germinal center reaction: B-cells with high affinity are selected to proliferate and undergo somatic hypermutation — random walks in shape space guided by selection.
Memory: Long-lived memory B-cells (gold dots) persist after clearance. Second exposure triggers rapid recall response.
Colors: Pink=naive, Red=activated, Gold=memory, White=antigen