Southern analysis of the L. pneumophila tra1 (A), lvh (B), enhC (C), and rtxA (D) loci in strains AA100, JR32, and Lp01. Total bacterial DNA was digested with either EcoRI (A; B, bottom; C, lane 2; and D, lanes 1 and 2) or PstI (B, top; C, lane 1; and D, lane 3) and hybridized with probes against tra1 (P5 [A1], P6 [A2], and P7 [A3]), lvh (P1 [B1], P2 [B2], P3 [B3], and P4 [B4]), enhC (P8 [C]), and rtxA (P9 [D1] and P10 [D2 and D3]). The positions of probes within each locus are shown in Fig. 1. In panel A2 irrelevant lanes were removed and the gap between strains AA100 and Lp01 was closed.