Development of HPV16 mouse and dog models for more accurate prediction of human vaccine efficacy.

BACKGROUND: Animal models are essential to understand the physiopathology of human diseases but also to evaluate new therapies. However, for several diseases there is no appropriate animal model, which complicates the development of effective therapies. HPV infections, responsible for carcinoma cancers, are among these. So far, the lack of relevant animal models has hampered the development of therapeutic vaccines. In this study, we used a candidate therapeutic vaccine named C216, similar to the ProCervix candidate therapeutic vaccine, to validate new mouse and dog HPV preclinical models. ProCervix has shown promising results with classical subcutaneous murine TC-1 cell tumor isografts but has failed in a phase II study. RESULTS: We first generated E7/HPV16 syngeneic transgenic mice in which the expression of the E7 antigen could be switched on through the use of Cre-lox recombination. Non-integrative LentiFlash® viral particles were used to locally deliver Cre mRNA, resulting in E7/HPV16 expression and GFP reporter fluorescence. The expression of E7/HPV16 was monitored by in vivo fluorescence using Cellvizio imaging and by local mRNA expression quantification. In the experimental conditions used, we observed no differences in E7 expression between C216 vaccinated and control groups. To mimic the MHC diversity of humans, E7/HPV16 transgenes were locally delivered by injection of lentiviral particles in the muscle of dogs. Vaccination with C216, tested with two different adjuvants, induced a strong immune response in dogs. However, we detected no relationship between the level of cellular response against E7/HPV16 and the elimination of E7-expressing cells, either by fluorescence or by RT-ddPCR analysis. CONCLUSIONS: In this study, we have developed two animal models, with a genetic design that is easily transposable to different antigens, to validate the efficacy of candidate vaccines. Our results indicate that, despite being immunogenic, the C216 candidate vaccine did not induce a sufficiently strong immune response to eliminate infected cells. Our results are in line with the failure of the ProCervix vaccine that was observed at the end of the phase II clinical trial, reinforcing the relevance of appropriate animal models.

Vero/CHOK1, a novel mixture of cell lines that is optimal for the rescue of influenza A vaccine seeds.

Seasonal and pandemic influenza vaccine manufacturing is challenged with a tight production schedule. Reverse genetics constitutes a rapid method for creating viruses. Vero and CHOK1 cells were found to be an appropriate cell mixture for the generation of influenza reassortants by reverse genetics under the constraints of vaccine production, such as the use of regulatory-compliant cells and culture media devoid of components of animal origin. In addition, no further amplification in cell or egg substrates was required, thus reducing the time needed to obtain reassortant seed virus. In parallel, the cloning step was shown to be dramatically improved, permitting the rapid vRNA expression of influenza viruses. In addition, nucleoporation of the cells was conducted to more efficiently target the nucleus and avoid the use of chemical reagents containing proteins of animal origin. In conclusion, the reverse genetics system for influenza A viruses reported in this study was shown to be rapid, simple to perform and totally animal component-free to best comply with the requirements of health authorities for the production of a vaccine seed.