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A., S. immunoglobulin G (IgG) and IgA through colonization or contamination has been explained in several countries (3, 13, 15, 19, 29, 32, 39). It has been shown that PsaA has a significant role in protection against pneumococcal carriage, and it has been proposed for use as a component of a combined mucosal protein vaccine including PspA (7). More recently, we have explained an increase in both systemic and mucosal antibodies in saliva and nasal and bronchial wash samples after intranasal immunization of mice with a cholera toxin B subunit (CTB)-PsaA fusion protein (1). PsaA has been shown to be highly conserved by restriction fragment Levalbuterol tartrate length analysis of PCR-amplified of the 23 vaccine serotypes (30) and by analysis of the reactivity of monoclonal antibodies with samples from 90 serotypes (8). More recently, a PCR-based identification method based on was shown to amplify the gene from your 90 tested serotypes (26). The facts that some monoclonal antibodies raised against PsaA show immunoreactivity with homologous proteins in several viridans group streptococcal species generally isolated from human clinical specimens (8, 16) and that the gene shows elevated sequence identity with homologs (16) have raised issues about possible alterations in the normal microbiota caused by immunization with PsaA. In this work, we demonstrate that intranasal immunization with CTB-PsaA fusion protein does not significantly alter the natural oral or nasopharyngeal microbiota in mice but is able to protect mice against colonization with strain 0603 (serotype Levalbuterol tartrate 6B) (21). After 5 days, animals were sacrificed and nasal washes were performed as previously explained (38). Serial dilutions of the samples were plated on blood agar made up of 4 g ml?1 gentamicin. The total quantity of CFU in each sample was estimated while considering the volume recovered. For representation in the graphic and statistical analysis, results were expressed as log10 values and recovery of 0 CFU was considered 1 CFU. Only mice that had been immunized with CTB-PsaA showed a statistically significant decrease in terms of the number of CFU ( 0.01, Mann-Whitney U test) recovered from your nasopharynx, as well as in terms of the number of colonized mice ( 0.05, Fisher exact test) (Fig. ?(Fig.2).2). However, we could not detect a correlation in individual mice between the level of IgG and protection against colonization. Immunization with PsaA either alone or along with CTB did not confer protection against challenge (data not shown). For this reason, further investigation was restricted to mice that received the Rabbit polyclonal to PITPNM1 CTB-PsaA Levalbuterol tartrate fusion protein or the controls, saline and CTB, intranasally. These results are in contrast with data published by other groups showing significant antibody induction in both serum and saliva and protection through immunization with PsaA by using CTB as adjuvant (7). It is important to point out that there are important differences in the antigens used in these studies. Immunization in the work of Briles and collaborators (7) was performed with PsaA made up of a signal sequence from outer membrane surface protein OspA from (and treated for Levalbuterol tartrate endotoxin removal), CTB used in the previous work was purified from test, whereas those not normally distributed were analyzed by the Levalbuterol tartrate Mann-Whitney U test ( 0.05). As shown in Fig. ?Fig.3A,3A, no differences were detected between the groups in total counts of bacteria recovered from either nasal washes or saliva and grown on blood agar plates 3 weeks after the last immunization. When we evaluated streptococci (Fig. ?(Fig.3B),3B), lactobacilli (Fig. ?(Fig.3C),3C), and staphylococci (Fig. ?(Fig.3D)3D) individually, we could not detect any statistically significant differences in bacterial loads in animals from your CTB-PsaA group in relation to.