Bacteria and viruses in gene therapy: An evidence-based review

Gene therapy means introducing genetic information into a cell to treat or prevent disease. It can replace defective genes, suppress harmful genes, or enhance cellular functions; therefore, it is considered promising for various diseases such as genetic disorders, cancer, and viral infections. This review assembled evidence related to bacterial (Salmonella typhi, Escherichia coli, Listeria monocytogenes, and Lactococcus lactis) and viral (Retroviruses, Herpes simplex viruses, Lentiviruses, and Adenoviruses) vector-mediated gene therapeutics along with their efficacy, safety, and possible uses in gene therapy. The results demonstrated bacterial vectors can transfer their genes, especially in cancer treatment. Research has shown that live Salmonella strains can preferentially home into tumors and suppress their growth. E. coli has been modified to enhance the ability to transfer genetic material and minimize toxic impacts. Listeria monocytogenes bacterium has been considered for cancer treatment through immunotherapy, while Lactococcus lactis has the potential for use in inflammatory diseases because of its probiotic qualities. Surprisingly, viral vectors continue to dominate the field of gene therapy because they are effective in transferring genes. Both retroviruses and lentiviruses have been employed due to their capacity to integrate ad hoc within the host cell genome and maintain gene expression over long periods. Human herpes simplex viruses exhibit significant packaging capacity and neurotropism, while adenoviruses are utilized effectively in various cancer treatment applications.