2.5. Animals

Female 6–8-week-old C57BL/6NCrl mice were purchased from Charles Rivers (Calco, LC, Italy) and subjected to a quarantine and adaptation period of 1 week. Mice were housed under specific pathogen-free conditions at a temperature of 20–24 °C, relative humidity 55 ± 10%, and a 12 h light–dark cycle. Food and water were provided ad libitum. All procedures were performed in compliance with the guidelines for animal experiments of the EU directive (2010/63/EU) and permission from the Veterinary Administration of the Ministry of Agriculture and the Environment of the Republic of Slovenia (permission no. 822-0001/2021-1). The mice were monitored for weight loss and possible side effects for two weeks after the boost vaccination when the experiment was terminated, and blood, transfected skin and muscle tissue, and spleens were collected from vaccinated mice.