24 patients who meet all eligibility criteria will be enrolled, first 10 individuals will be assigned in the 0-24 week prime/boost regimen (ARM A). The next 10 volunteers will be assigned in the 0-8 week prime/boost regimen (ARM B).Four additional volunteers will be included as 'back-up' and assigned 2 in ARM A and 2 in ARM B to cover a possible 10% of patients who drop-off during the follow-up. Purpose of staging of 2 study arms is just to shorten overall study duration (from screening of first volunteer to 6 months after last immunisation of last volunteer).