The trial is a randomised, open, dose-selection, single centre trial. One adjuvant will be assessed, aluminum hydroxide (alum). Three different dosages - 10µg, 30µg, and 100µg - of GMZ2 will be evaluated with the aluminum hydroxide adjuvant. A total of 30 volunteers will be enrolled and randomized into three groups of 10. As this is a dose escalation study, volunteers in Group 1 will receive the initial dose of 10µg on the first vaccination day. After a satisfactory safety profile at this dose (see sections 6.2.2 and 6.2.3), we will proceed to vaccinate volunteers in Group 2 with the higher dose of 30µg after a 2-week interval. The same procedure will also be followed for volunteers in Group 3, who will be administered their initial dose of 100µg GMZ2 if the review of the safety profile of Group 2 is satisfactory. The aim will be to recruit all volunteers before the intended start of the study. The randomization procedure will be performed in the following way: when participants are found to be eligible and have signed their informed consent they will be numbered sequentially (in order of enrollment). The numbers will be randomly assigned to 3 groups of 10 numbers through a specific randomization computer program. These groups will be the treatment groups.