Figure 3

IgG and IgM binding to the outbreak strain with sera from UAT negative LD cases. The immunoblots show IgG and IgM antibody binding, respectively, with sera from 25 UAT-negative cases to whole cells of the L. pneumophila serogroup 1 outbreak strain. Individual cases are identified by numbers above the nitrocellulose strips, and the upper and lower arrows to the right show the positions of proteins of molecular masses of approx. 80 kDa and 25 kDa, respectively. Strip a: binding of a monoclonal antibody to serogroup 1 L. pneumophila (Lp 1 from the Dresden panel [26]); strip b: IgM antibody reactions of serum from case no. 25 from another experiment with proteinase K treated cells, showing the ladder-like LPS antibody responses. IgG and IgM binding intensities of each serum to LPS are rated below the strips as + (strong), (+) (weak), and – none. Each 12% acrylamide gel was loaded with whole cells from the outbreak strain, corresponding to 2 μg protein/strip, and the strips were incubated with 1:200 serum dilutions. UAT: urine antigen test.