**5. Conclusions**

We here demonstrate that priming with BCG.HTI2auxo.int significantly increased HTI-specific T-cell responses. Although priming with BCGwt led to a similar enhancement of the magnitude of the response, fewer peptide pools were recognized in BCGwt primed animals. The ability of the BCG.HTI2auxo.int priming immunization to increase T-cell immune responses when combined with ChAdOx1.HTI, while maintaining the breadth of the response, strengthens its applicability as a priming vaccine for the development of an efficacious HIV-1 vaccine. Finally, we demonstrate that in some mice, priming with BCG.HTI2auxo.int can alter the immunodominance profile of the vaccine-induced T-cell response. Further assessments and characterization of the T-cell response by intracellular cytokine staining would provide a more thorough overview of the vaccine-induced immune response and of potential functional differences, depending on the different vaccination regimen.

**Author Contributions:** Conceptualization, J.J., A.K., and C.B.; methodology, A.K. and N.G.; software, A.K.; validation, A.K., N.S. and A.O.; formal analysis, A.K.; investigation, A.K. and N.S.; resources, J.J., T.H.; data curation, A.K., N.G. and N.S.; writing—original draft preparation, A.K.; writing—review and editing, N.S., J.J. A.O. and C.B.; visualization, A.K.; supervision, N.S. and J.J.; project administration, J.J.; funding acquisition, J.J.", please turn to the CRediT taxonomy for the term explanation. Authorship must be limited to those who have contributed substantially to the work reported.

**Funding:** This research was funded by the European Union's Horizon 2020 research and innovation program under grant agreement No. 681137 and supported by Instituto de Salud Carlos III FIS PI14/00494. EAVI2020. In addition, it has been supported by the ISCIII, RETIC-RIS RD12/0017, and the HIVACAT Research Program.

**Conflicts of Interest:** The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. C. Brander is CSO at AELIX Therapeutics, Barcelona. The remaining authors declare no conflict of interest.
