Figure 1.
Matrices of cross-reactive antibody binding correlations.
Pearson’s correlation (r) was calculated between all OspC pairs using antibody binding reactivity values for all 55 sera from patients with LD to populate the matrices shown as heat maps. The matrices computed for log10-transformed data (MD-log), rank transform (MD-rank) and binary transform (MD-binary) are shown in the left, middle and right panels, respectively.
Figure 2.
Distribution of Pearson’s r values from OspC cross-reactivity matrices.
The frequency histogram shows the distribution of r values obtained from the OspC cross-reactivity matrices calculated using either the observed (blue bars) or randomized (orange bars) antibody binding profiles and their 3 transform metrics, log10, rank and binary.
Table 1.
Twenty most cross-reactive OspC types for sera from patients with Lyme disease.
Figure 3.
Correlation between local sequence identity of terminal regions and cross-reactivity.
The x-axis values correspond to residue positions in the MSA index. The y-axis presents the correlation between local sequence identities of terminal regions and the average of three cross-reactivity matrices, i.e. r(MS-Cterm or Nterm, MD-avg3). The terminal regions used for local sequence identity calculations use all positions before (N-terminal: blue line) or after (C-terminal: red line) the corresponding MSA index position. The horizontal black line at y = 0.11 corresponds to the correlation between global sequence identity and the average of three cross-reactivity matrices, i.e. r(MS-Global, MD-avg3). The dashed vertical line is the breakpoint between the N-terminal and the C-terminal regions at MSA index 127.
Figure 4.
Heat maps of correlation between local sequence identity using subsets of sequentially consecutive polymorphic positions and antibody cross-reactivity.
Local sequence regions were systematically defined and correlations were calculated as described in Methods for Sequence Scanning. Each panel shows results from the calculation performed using the 3 transforms: log-transformed, rank and binary, on the left, middle and right panels, respectively. Each row in a heat map corresponds to the center of a sequence window and the columns encompass the results calculated using window sizes varying from 3 to 116 residues (only polymorphic positions are considered in the size). The individual alpha helical structures are indicated α1 through α5 [50]. The green to red gradient bar indicates the range of r values observed in the results (min: −0.33; max: 0.39).
Figure 5.
Maximum cross-reactivity regions for individual OspC types.
Solvent-accessible surface area representation of the 3D structure model constructed from the MSA using UCSF Chimera from the structure of OspC-A (pdb 1GGQ). The chains of OspC dimer are colored light and dark grey. The location of residues of highest correlation (r value) with antibody cross-reactivity (MD-avg3) are colored as follows: highest r value in one OspC protein (green); in two OspC proteins (yellow); in five OspC proteins (red).
Figure 6.
Comparison of conserved and variable residues between OspC pairs A, I3 and F, I3.
Panel A Partial amino acid sequence alignment of OspC types F (top row), A (bottom row) and the chimeric OspC I3 (middle). Only helices α2 through α5 are shown. Black bars indicate regions of sequence identity between the chimeric OspC I3 to the parental OspC types. Colored blocks represent individual amino acids. Panel B Top row: frontal view of the OspC dimer structure; bottom row, view from the top of the structure. The cartoon representation of the OspC dimer is colored from N- to C- terminus in blue to red, respectively. The surface representations show the combined amino acid sequences of pairs OspC A and I3 (left) and OspC F and I3 (center), where polymorphic positions identical within each pair are shown in green and mismatches appear in red. Residues strictly conserved in all 23 OspC proteins appear in light and dark gray.
Figure 7.
Multivariate analysis of antibody response to OspC types A, F and the chimera I3.
Log10-transformed intensity of antibody binding to OspC A, F and I3 by sera from 55 human patients with LD (blue dots) and 23 experimental infections of P. leucopus rodents (red dots). Correlation coefficient R2 is shown for each comparison.