ogen in CM while did not affect the capacity of the sap mutant strain to replicate, increased the growth rate of the wild type strain. In order to confirm that the capacity of GBS to hydrolyze aglucans is associated to an a increased expression of SAP, we compared a total protein extract derived from COH1 wild type and COH1Dsap strains grown in the presence of different carbohydrates, for the ability to degrade pullulan. As shown in the Fig. 7, pullulanase 11179435 activity was only T0070907 site observed in the protein extracts of COH1 wild type grown in the presence of sugars inducing SAP 4 GBS Pullulanase Activity using the purified recombinant SAP protein as an inhibiting antigen. The addition of an unrelated recombinant GBS surface protein did not inhibit antibody binding to the SAP protein in this assay. These findings other than indicating the specificity of the antibody response towards SAP, suggest that the CBMs might be important for the immunogenicity of the protein. Anti-SAP antibodies block SAP and PulA enzymatic activity In order to test whether the immunoglobulin-mediated response towards SAP impaired bacterial metabolic activity versus aglucans, we tested by DNS acid assay the capacity of mouse and rabbit anti-SAP sera to prevent GBS pullulanase activity. We performed dose-dependent experiments incubating SAP-expressing bacteria with different sera dilutions in a range between 0.1 2%. As shown in Fig. 9, we observed that a SAP mouse antiserum was able to block in a dose dependent fashion the ability of GBS COH1 strain to degrade pullulan up to 80% of the initial activity. As expected, the addition in the assay of two unrelated sera did not inhibit GBS SAP activity. Similar results were obtained performing the experiments using glycogen as a substrate. Depletion of specific anti-SAP antibodies by absorbing the anti-SAP serum to a CNBR resin coated with recombinant SAP, resulted in no inhibition of GBS capacity to catabolize pullulan. As a control, the absorbed anti-SAP serum lost the capacity to recognize the recombinant form of SAP in immunoblotting assay. These data clearly postulate that anti-SAP antibodies mediate in vivo prevention of GBS pullunase activity. The attempt to reduce SAP enzymatic activity by adding to bacteria human sera containing anti-SAP antibodies or anti-SAP antibodies purified from human sera was unsuccessful. We hypothesize that the quantity and quality of anti-SAP antibodies derived from adult healthy volunteers that 
have been in contact with GBS, is not sufficient for our in vitro assay. Unfortunately, no sera from convalescent patients or with GBS invasive disease are at the moment available in our laboratory. Since SAP CBM appears to be a very immunogenic domain and that it is highly homologous among streptococcal 14530216 pullulanases, we decided to test whether anti-SAP specific sera were able to reduce the capacity of GAS to catabolize pullulan. For these experiments we used GAS SF370 strain, which in the presence of pullulan expresses PulA, as demonstrated by both Western Blotting and FACS analysis. As shown in Fig. 9B, we observed that a SAP antiserum was able to reduce the activity of GAS to catabolize pullulan, up to 50% of the initial activity. These data confirm our hypothesis that the activity of anti-pullulanase antibodies may be cross-species. expression, such as pullulan and glycogen. These findings suggest that GBS utilize a-glucans as a carbon energy source and that pullulanase is indispensable to this activi