 The approach taken in this clinical study aims to overcome the antigenic variation of HIV-1 by focusing induced T cell responses on the functionally conserved regions of HIV-1 proteins, which HIV-1 cannot change without a significant cost to its fitness. Thus, the HIVconsv immunogen is a chimaeric protein assembled from the 14 most conserved regions of the HIV-1 proteome alternating among the four most common HIV-1 clades: A, B, C and D. The gene coding for HIVconsv was made synthetically and was inserted into three safe non-replicating vaccine vectors: plasmid DNA to construct pSG2.HIVconsv, attenuated chimpanzee adenovirus ChAdV63 to construct ChAdV63.HIVconsv and recombinant modified vaccinia virus Ankara MVA to construct MVA.HIVconsv. These three vectors facilitate delivery of the immunogen gene into host cells, which then express the HIVconsv protein and initiate a series of processes leading to the presentation of HIVconsv-derived peptides to the cells of the host immune system and induction of the HIVconsv-specific host T cell responses. 