Helicobacter pyloriis a gram-negative bacterium that colonizes the human gastric mucosa causing gastritis and peptic ulcer and increasing the risk of gastric cancer. The efficacy of current antibiotic-based therapies can be limited by problems of patient compliance and increasing antibiotic resistance; the vaccine approach can overcome these limits. The present study describes the therapeutic vaccination of experimentallyH. pylori-infected beagle dogs, an animal model that reproduces several aspects of the human infection withH. pylori. The vaccine consisted of three recombinantH. pyloriantigens, CagA, VacA, and NAP, formulated at different doses (10, 25, or 50 μg each) with alum and administered intramuscularly either weekly or monthly. No adverse effects were observed after vaccination and a good immunoglobulin G response was generated against each of the three antigens. Bacterial colonization and gastritis were decreased after the completion of the vaccination cycle, especially in the case of the monthly immunization schedule. In conclusion, therapeutic vaccination in the beagle dog model was safe and immunogenic and was able to limitH. pyloricolonization and the related gastric pathology.

The aim of this study was to assess the role of TLR2, TLR4 and MyD88 accessory molecule in the effector and secretory response of macrophages to viable microbial agents. Using TLR-deleted macrophage cell lines generated from the bone marrow of genetically engineered mice (TLR4 gene-deficient, MyD88- and TLR2-knockout mice) and wild-type control mice, we found that TLR2-deleted macrophages exhibit increased ability to contain Candida albicans infection compared to TLR2+/+ counterpart. In contrast, both MyD88-/- and TLR4-/- macrophages retain levels of functional activity comparable to that of the respective wild-type MyD88+/+ and TLR4+/+ controls. The difference in anticandidal effector functions observed between TLR2-/- and TLR2+/+ macrophages is abrogated upon opsonization of the fungal target and interestingly is not observed when using other microbial targets, such as Streptococcus pneumoniae and Helicobacter pylori. When tested for secretory response to C. albicans, TLR2-deleted macrophages show a pattern of cytokine production similar to that of TLR2+/+ controls. Finally, flow cytometry analysis reveals that TLR2-deleted macrophages express only TLR4, while, as expected, TLR2+/+ macrophages are both TLR2 and TLR4 positive; in no cases, modulation of such markers occurs in macrophages exposed to C. albicans infection. In conclusion, these data indicate that TLR2 and TLR4 have different biological relevance, in which TLR2 but not TLR4, is involved in the accomplishment of macrophage-mediated anticandidal activity, while the secretory response to C. albicans appears to be TLR4 but not TLR2-dependent.

PT-9K/129G, a nontoxic mutant of pertussis toxin (PT) obtained by genetic manipulation, has been shown in animal models to be a promising candidate for new vaccines against whooping cough. To assess the safety and the immunogenicity of PT-9K/129G in humans, a pilot study has been performed in adult volunteers. The protein was found to be safe, capable of inducing high titers of toxin-neutralizing antibodies, and capable of generating immunological memory. In fact, vaccination caused an increase of cell-mediated response to PT, PT-9K/129G, S1 subunit, and B oligomer, indicating that memory T cells are induced by the vaccine. Since PT-9K/129G is mitogenic for T lymphocytes in vitro, it was investigated whether this activity is also present in vivo. No variation was observed in the proportion of T cells (CD3+), T helper cells (CD4+), and cytotoxic T cells (CD8+), as well as in that of other lymphoid populations, by FACS analysis. Interestingly, no thorough correlation was found between humoral and cellular responses. In one case, a very high cellular response was present in absence of detectable antibodies, suggesting that the antibody response, which is the only parameter measured in most clinical trials, may not give a complete picture of the response induced by a vaccine.