<i>P. gingivalis</i> antiserum cross-reacts strongly with OMVs, but not with LPS.

<p>(A) ELISA plates were coated with LPS and OMVs of <i>P. gingivalis</i>. <i>P. gingivalis</i>, antiserum-2 and pre-immune serum were used at dilutions of 1∶1,000. Sera reactivity was determined as the absorbance at 405 nm (mean ± SD) for triplicate assays after a 30-min incubation with alkaline phosphatase substrate. (B) To test whether antiserum-2 cross-reacts with OMVs or LPS, we absorbed the serum against LPS and OMVs and removed bound antibodies. ELISA results are expressed as absorbance at 405 nm (mean ± SD) after a 30-min incubation with alkaline phosphatase substrate.