Antibody response to oral administration of recombinant L. plantarum Lastly, to assess the systemic and mucosal antibody immune response induced by the oral administration of recombinant L. plantarum, we immunized mice and tested serum levels of OspAspecific total IgG, IgG1 and IgG2a antibodies (Fig. 8) , and the levels of mucosal OspA-specifc IgA in bronchoalveolar lavage (BAL) and stool suspensions (Stool) (Fig. 9) , by indirect ELISA. In contrast to the controls, mice orally administered with L. plantarum expressing lipidated OspA (LpA) or the unlipidated mutant developed high titers of IgG specific antibody 68 days after the first inoculation (Fig. 8A) . However, mice inoculated with LpA produced higher levels of OspA-specific IgG1 compared to mice inoculated with LpA D17 , as shown on day 68 after the first inoculation (**p,0.01) (Fig. 8B ). In contrast, mice inoculated with either LpA or LpA D17 developed equivalent levels of IgG2a (Fig. 8C) . Furthermore, the same mice inoculated with LpA and LpA D17 developed a high OspA-specific IgA antibody titer in BAL (Fig. 9A) and stool (Fig. 9B) , 68 days after the first inoculation. Differences between LpA and LpA D17 were not statistically significant.