The tuberculosis (TB) vaccine MTBVAC is the only live-attenuated
Mycobacterium tuberculosis
(
Mtb
)-based vaccine in clinical development, and it confers superior protection in different animal models compared to the current vaccine, BCG (
Mycobacterium bovis
bacillus Calmette-Guérin). With the aim of using MTBVAC as a vector for a dual TB-HIV vaccine, we constructed the recombinant MTBVAC.HIVA
2auxo
strain. First, we generated a lysine auxotroph of MTBVAC (MTBVACΔ
lys
) by deleting the
lysA
gene. Then the auxotrophic MTBVACΔ
lys
was transformed with the
E. coli
-mycobacterial vector p2auxo.HIVA, harboring the
lysA
-complementing gene and the HIV-1 clade A immunogen HIVA. This TB-HIV vaccine conferred similar efficacy to the parental strain MTBVAC against
Mtb
challenge in mice. MTBVAC.HIVA
2auxo
was safer than BCG and MTBVAC in severe combined immunodeficiency (SCID) mice, and it was shown to be maintained up to 42 bacterial generations
in vitro
and up to 100 days after inoculation
in vivo
. The MTBVAC.HIVA
2auxo
vaccine, boosted with modified vaccinia virus Ankara (MVA).HIVA, induced HIV-1 and
Mtb
-specific interferon-γ-producing T cell responses and polyfunctional HIV-1-specific CD8+ T cells producing interferon-γ (IFN-γ), tumor necrosis factor alpha (TNF-α), and CD107a in BALB/c mice. Here we describe new tools to develop combined vaccines against TB and HIV with the potential of expansion for other infectious diseases.