Analysis of factor H/FHL-1 binding by the B. burgdorferi B31MI OspE, OspF, and Elp proteins. Recombinant S-tagged fusion proteins (the TIGR-assigned ORF designations are indicated above each lane) were generated, purified, separated by SDS-PAGE (15% Criterion precast gels), and immunoblotted. To assess expression and integrity of the recombinant proteins, a blot was screened with HRP-conjugated S protein (A). The proteins were then tested for factor H/FHL-1 binding by use of the ALBI assay (B), as described in the text. Molecular mass standards are indicated.