Pulmonary dry powders containing a vaccine against Human papillomavirus 

Irene Rossi¹, Francesca Buttini¹, Fabio Sonvico¹, Gloria Spagnoli², Davide Cavazzini², Angelo Bolchi², Fabio Stellari³, Simone Ottonello², Ruggero Bettini¹

¹Food and Drug Department, University of Parma, Parma, Parco Area delle Scienze 27/A, 43123, Italy

²Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Parco Area delle Scienze 11/A, 43123, Italy

³Chiesi Farmaceutici S.p.A., Parma, Largo Belloli 11/A, 43122, Italy

Summary

Pulmonary immunization is an attractive and alternative way of vaccine administration offering many advantages over injection-requiring and other needle-free immunizations. The aim of this work was to develop dry powders, obtained by spray drying, containing a novel thermostable antigen against Human papillomavirus (HPV). Several powder formulations were prepared, with an increasing content of HPV vaccine, ranging from 0.33 up to 2.00% w/w. Each powder was characterized in terms of aerodynamic performance and protein structure preservation. The best performing powder was the one containing 2.00% w/w HPV vaccine, which presented an Emitted Fraction (EF) > 75% and a Fine Particle Fraction (FPF) of 92.96% ± 2.52. This study also allowed to evaluate the influence of the buffer volume in which the protein was dissolved (with respect to the whole sprayed solution) on the yield of the production process and on the respirability of the final product. Indeed, the best performing powder was the one produced starting from the most concentrated buffer solution.

Various biochemical tests, including Sodium Dodecyl Sulphate-PolyAcrilamide Gel Electrophoresis (SDS-PAGE) and enzyme-linked immunosorbent assay (ELISA), confirmed the preservation of a native conformation of the antigen after drying. Pulmonary delivery of the dry powder vaccine was assessed by in vivo imaging in mice (IVIS^® Spectrum, In Vivo Imaging System) using a fluorescently labelled (Alexa Fluor 750) derivative of the HPV antigen. This study revealed a preferential central (trachea and lung parenchyma) localization of the antigen, indicating significant vaccine deposition within the conductive airways.