FIG 9.

Leu⁵⁹³ in L4 is essential for binding of antibodies in the sera of secondary syphilis patients. (A) Multiple-sequence alignment of the L4 regions of BamAs from geographically diverse T. pallidum subsp. pallidum strains, sequences amplified from skin biopsy specimens from two secondary syphilis patients (Cali-77 and Cali-84) enrolled at our Cali, Colombia, study site (43, 44), and the Gauthier strain of the T. pallidum subsp. pertenue. All strains of T. pallidum subsp. pertenue in the database have same the L4 sequence. The arrow indicates residue 593. Immunoblotting and ELISA reactivities of pooled IRS from rabbits infected with the T. pallidum Nichols strain (B) and sera from Cali-84 (C) and Cali-77 (D) against L4^Nichols and L4^{Mexico A}. The ELISA results are means ± SEMs from three independent experiments. Statistical significance was assigned according to the following scheme: **, P < 0.005; ***, P < 0.0001.