EB virus-positive tumors are inhibited by rBCG expressing hGM-CSF and LMP2A

Construction of rBCG carrying the IL-2-BZLF1 fusion gene and its immunological function

In this research, a recombinant Bacillus Calmette Guerin (rBCG) vector vaccine carrying a human IL-2 and EBV BZLF1 fusion gene (IL-2-BZLF1-rBCG) was constructed. The IL-2-BZLF1-rBCG construct was successfully generated and stably expressed the IL-2 and BZLF1 proteins. IL-2-BZLF1-rBCG activated the immune system and promoted the secretion of IFN-γ and TNF-α by CD4+ and CD8+ T cells. IL-2-BZLF1-rBCG activated lymphocytes to effectively kill EBV-positive NPC cells in vitro. Additionally, IL-2-BZLF1-rBCG stimulated the proliferation of NK cells and lymphocytes in vivo, activated related immune responses, and effectively treated EBV-positive NPC. The immune response to and pharmacological effect of IL-2-BZLF1-rBCG were explored in vitro and in vivo to provide a theoretical and experimental basis for the prevention and treatment of EBV-positive tumors with an rBCG vector vaccine. KEY POINTS: • rBCG with human IL-2 and BZLF1 of EB virus was constructed • The IL-2-BZLF1 fusion gene was stably expressed with rBCG • rBCG with IL-2-BZLF1 has an obvious immune response in vitro and in vivo.

Recombinant BCG to Enhance Its Immunomodulatory Activities

The bacillus Calmette-Guérin (BCG) is an attenuated Mycobacterium bovis derivative that has been widely used as a live vaccine against tuberculosis for a century. In addition to its use as a tuberculosis vaccine, BCG has also been found to have utility in the prevention or treatment of unrelated diseases, including cancer. However, the protective and therapeutic efficacy of BCG against tuberculosis and other diseases is not perfect. For three decades, it has been possible to genetically modify BCG in an attempt to improve its efficacy. Various immune-modulatory molecules have been produced in recombinant BCG strains and tested for protection against tuberculosis or treatment of several cancers or inflammatory diseases. These molecules include cytokines, bacterial toxins or toxin fragments, as well as other protein and non-protein immune-modulatory molecules. The deletion of genes responsible for the immune-suppressive properties of BCG has also been explored for their effect on BCG-induced innate and adaptive immune responses. Most studies limited their investigations to the description of T cell immune responses that were modified by the genetic modifications of BCG. Some studies also reported improved protection by recombinant BCG against tuberculosis or enhanced therapeutic efficacy against various cancer forms or allergies. However, so far, these investigations have been limited to mouse models, and the prophylactic or therapeutic potential of recombinant BCG strains has not yet been illustrated in other species, including humans, with the exception of a genetically modified BCG strain that is now in late-stage clinical development as a vaccine against tuberculosis. In this review, we provide an overview of the different molecular engineering strategies adopted over the last three decades in order to enhance the immune-modulatory potential of BCG.