Recombinant Leishmania Tarentolae Encoding the HPV Type 16 E7 gene in Tumor Mice Model

Abstract

Background: Cervical cancer, the third most prevalent cause of cancer in women worldwide, is associated with HPVs. The critical role of E7 protein in HPV-related malignancies has designated it as a strong contender for generating vaccines against HPV. Materials & methods: In this study, we developed a novel live vaccine using recombinant Leishmania tarentolae expressing E7-green fluorescent protein (GFP) fusion protein for the protection of mice against HPV-associated tumors. In order to transfect L. tarentolae with E7-GFP fusion construct, pLEXSY-neo2 system was applied. Followed by PCR, fluorescence imaging and fluorescence-activated cell sorting analysis, integration of E7-GFP gene into parasites genome was confirmed. A comparative study of six groups of C57BL/6 mice was performed to analyze antigen-specific humoral and cellular immune responses against E7 encoding live and DNA vaccines. Furthermore, the anti-tumor protective effect of L. tarentolae-E7-GFP was compared to other vaccination strategies, namely pcDNA-E7 as the DNA vaccine and pcDNA-E7/L. tarentolae-E7-GFP as the prime-boost regimen. Results: We found that E7-GFP expressing recombinant L. tarentolae induces significant levels of IgG2a and IFN-γ, while there is no significant IL-5 production compared with that of other strategies and control groups before and after challenge with TC-1 tumor cells. It is noteworthy that the designed live vaccine showed the best protection and minimum tumor size among all groups against TC-1-induced tumors. Conclusion: Overall, the results obtained revealed that the E7-GFP recombinant L. tarentolae could be a potential live vaccine for induction of immune responses in vivo.

KEYWORDS::

• E7
• HPV
• Leishmania tarentolae
• live vaccine
• TC-1
• tumor

Acknowledgements

The authors wish to thank A Javadi (Pasteur Institute of Iran, Department of Immunology) and Sh. Alizadeh (Pasteur institute of Iran, Molecular Immunology and Vaccine Research Laboratory) for their technical assistance.

Financial & competing interests disclosure

The authors acknowledge the financial support from the Iran National Science Foundation (ID 89000588) for experimental works. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

All mouse experiments including maintenance, animals‘ handling program and blood sample collection were approved by Institutional Animal Care and Research Advisory Committee of Pasteur Institute of Iran (Education Office dated January, 2010), based on the Specific National Ethical Guidelines for Biomedical Research issued by the Research and Technology Deputy of Ministry of Health and Medicinal Education (MOHME) of Iran that was issued in 2005.

Additional information

Funding

The authors acknowledge the financial support from the Iran National Science Foundation (ID 89000588) for experimental works. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.