The use of nanotechnological approaches, including genetically engineered bacteriophages, opens up new possibilities for the development of anti-tumour vaccines against malignant melanoma. The aim of the doctoral research was to prepare a bacteriophage vaccine and to test its antitumour efficacy in a mouse model of malignant melanoma. We also wanted to evaluate the contribution of the combination of a bacteriophage vaccine and a gene electrotransfer (GET) of plasmids encoding interleukin-12 (IL-12) to the therapeutic potential. Using bacteriophage display technology, we produced genetically engineered M13 bacteriophages expressing the tumour peptides MAGE-A1, gp100 or MART-1/MELAN-A on the surface of the capsid. Expression of the fusion proteins was verified by Western transfer or LC-MS/MS analysis. The therapeutic potential of bacteriophage vaccination alone or in combination with GET IL-12 was tested in vivo in C57BL mice with B16F10 malignant melanoma. Response to therapy was further evaluated by histological and immunohistological analysis. After validation of the recombinant phagemid vectors by Sanger sequencing and amplification of the filamentous helper bacteriophage VCSM13, we successfully optimised the production process for amplification and purification of genetically engineered bacteriophages M13. No negative side effects were observed during in vivo experiments in mice. We have shown that genetically engineered bacteriophages activate cellular and humoral immunity and that bacteriophage therapy successfully slows tumour growth. GET IL-12 contributes to the therapeutic effect of genetically engineered bacteriophages and increases tumour growth delay. Genetically engineered bacteriophage and GET IL-12 therapies have a synergistic effect and lead to complete responses in 30% of cases. Histological and immunohistochemical analyses have shown that both bacteriophage monotherapy and especially in combination with GET IL-12 increase the proportion of necrosis and the infiltration of macrophages, CD4+ and CD8+ T lymphocytes in tumours. The results of the doctoral thesis showed that bacteriophage vaccines in combination with GET IL-12 have a potential that should be further investigated.
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