Serologic response of infected mice to homologous and heterologous <i>B</i>. <i>burgdorferi</i> strains.

<p><b>A.)</b> Representative immunoblots with sera of mice infected with <i>B</i>. <i>afzelii</i> strain PKo (lanes 1–5) or <i>B</i>. <i>burgdorferi</i> strain B31 (lanes 6–10) against whole cell lysates of strains PKo (top panels) and B31 (bottom panels) <b>B.)</b> Whole cell lysates of strains B31 (lanes 1–2) and PKo (lanes 3–4), with or without OspC (lanes 1 & 3 versus 2 & 4, respectively), stained with coomassie brilliant blue (CBB) to visualize all proteins (left-most panel), or transferred to membranes and incubated with infected mouse sera (panels on the right side of the figure). A blot containing the same lysates was also incubated with polyclonal rabbit antiserum raised against recombinant OspC from strain B31 (second panel from the left). The mobility of OspC is indicated at the right side of the figure. Molecular weight markers (MW) are visible at the left side of the figures, with mass indicated (kD). <b>C.)</b> ELISA titers of pooled sera from 5 mice infected with either strain B31 or PKo and tested against lysates of homologous and heterologous strains, as identified beneath the graphs. Each bar represents the average of three technical replicates, with the standard deviation shown. Baseline absorbances were determined for the same dilutions of pooled pre-immune sera, in triplicate, against B31-S9 and PKo lysates. The threshold for positive sero-reactivity was set at 3 standard deviations above the mean absorbance of pre-immune sera at each dilution, indicated by a dark line. The ELISA titer represents the highest dilution of immune sera at which absorbance above this baseline cut-off was achieved, as indicated by asterisks.