Formulations of single or multiple H-pylori antigens with DC Chol adjuvantinduce protection by the systemic route in mice - Optimal prophylactic combinations are different from therapeutic ones

The ability to induce a protective response against Helicobacter pylori inf ection has been investigated by systemic immunization of mice with urease f ormulated with the cationic lipid DC Chol. This compound acts both as a for mulating agent and as an adjuvant and induces a balanced Th1/Th2 response s hown to be more effective for protection in our previous studies. Urease-DC Chol induced a significant protection in prophylaxis but not in therapeuti c immunization. The protection level was between 1.5 and 2 log reduction of bacterial density measured by quantitative culture compared to unimmunized -infected mice. In parallel, the protective efficacy of other H. pylori ant igens formulated in a similar way and administered with DC Chol was tested. These antigens were tested alone or in combination in prophylactic and the rapeutic regimens. Some combinations of antigens induced a better prophylac tic or therapeutic activity than urease alone (0.5-1.5 log further reductio n in prophylaxis and therapy respectively, P < 0.05). The combinations that induced the best protection were different in prophylaxis and therapy. In conclusion, DC Chol provides a convenient and efficient method to formulate different antigens even when they are present in non-compatible buffers in itially. Moreover, the results obtained in protection against H. pylori wit h such formulations should lead the way to future clinical trials. <(c)> 20 01 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.