Decorin binding protein A (DbpA; BBA24) is a highly immunoreactive B. burgdorferi protein, as evidenced by the appearance of high titer anti-DbpA serum IgG antibodies in the early stages of experimentally infected mice (10, 11), nonhuman primates (12), and human Lyme disease patients (13). This evidence concerns the gene YBX3 and Lyme disease.