Recombinant Mycobacterium smegmatis transfected with a pMyong2 vector expressing Human Immunodeficiency Virus Type I Gag can induce enhanced virus-specific immune responses in mice

Abstract

Recently, number of patient co-infected HIV-1 and TB is increased. The circumstance has pushed novel medicine for treating both HIV-1 and TB at one go. In the situation, a novel Mycobacterium-Escherichia coli shuttle vector system was developed using pMyong2, a linear plasmid from Mycobacterium yongonense. The novel vector system provides an enhanced expression of heterologous genes in recombinant Mycobacterium smegmatis (rSmeg), compared to the pAL5000 derived vector system. To investigate the usefulness of rSmeg using pMyong2 in vaccine application, I transformed M. smegmatis with pMyong2 system expressing Human Immunodeficiency Virus Type I (HIV-1) Gag p24 antigen (rSmeg-pMyong2-p24) and examined its cellular and humoral immune responses against HIV-1 gag protein. I found that rSmeg-pMyong2-p24 expressed higher levels of Gag protein in infected macrophage cell line (J774A.1) and mouse bone marrow derived dendritic cells (BMDCs) compared to rSmeg strains using two other vector systems, pAL5000 derived vector (rSmeg-pAL5000-p24) and the integrative plasmid, pMV306 (rSmeg-pMV306-p24). Immunization of mice with rSmeg-pMyong2-p24 elicited more effective immunity, compared to the other two rSmeg strains, as evidenced by higher levels of HIV-1 Gag-specific CD4 and CD8 T lymphocyte proliferation, interferon gamma ELISPOT cell induction, and antibody production. Furthermore, rSmeg-pMyong2-p24 showed a higher level of cytotoxic T cell response against target cells expressing Gag p24 proteins. My data suggest that Mycobacterium-Escherichia coli shuttle vector system with pMyong2 may provide an advantage in vaccine application of rSmeg over other vector systems.