Association of L. biflexa transformants with MDCK monolayers. Adhesion of MDCK epithelial cells with L. interrogans (L1-130), L. biflexa wild-type strain (wt), and ligA- (ligA), and ligB- (ligB) L. biflexa transformants. Results were determined after 30, 60, and 240 minutes exposure, followed by extensive washing of non-adherent bacteria. The bars show the mean number of bacteria associated per host cell ± standard deviation carried out in 10 random fields in two independent experiments. The numbers of adherent leptospires/cell between the L. biflexa wild-type strain and the ligA- and ligB- L. biflexa transformants were statiscally different at 240 minutes (P < 0.05).