Fig. 5

B cell lineage complexity change under malaria stimulation. a Diversity and size of B cell lineages for infants (N = 6) and toddlers (N = 9) from whom paired PBMC samples at pre-malaria (blue) and acute malaria (pink) were obtained. Each circle represents an individual lineage. The area of each circle is proportional to the SHM load. Labeled green arrows indicate representative lineages whose intra-lineage structures were shown in detail in (b) and (c). Each circle’s x and y coordinates were determined by its diversity (the number of unique RNA molecules in a lineage) and size (the number of total RNA molecules in a lineage), respectively. Blue and pink dashed lines represent the linear fit for pre-malaria and acute malaria lineages, respectively. Black dashed lines indicate y = x parity, such that lineages lying on the parity line are comprised entirely of unique RNA molecules with minimum clonal expansion, such as lineage in (c). On the other hand, lineages comprised of clonally expanded RNA molecules are close to the y axis, such as lineage (b). b, c Each node is a unique RNA molecule species. The height of the node corresponds to the number of RNA molecules of the same species, the color corresponds to number of nucleotide mutations, and the distance between nodes is proportional to the Levenshtein distance between the node sequences, as indicated in the legend above each lineage. All unlabeled nodes share the isotype with the root. d The non-singleton lineage percent (lineages comprises at least two RNA molecules) between infants and toddlers at pre-malaria (blue) and acute (pink) malaria. *P < 0.05 by two-tailed Wilcoxon signed-rank test (between time points, solid lines); N.S. indicates no significant difference by two-tailed Mann–Whitney U test (between age groups, dashed lines). e The difference of linear regression slopes (angles), or degree of diversity change, between pre-malaria and acute malaria for infants (black) and toddlers (red). N.S. indicates no significant difference by two-tailed Mann–Whitney U test. Bars indicate means. Differences in variance were not significant by squared ranks test