Study on hybridized yeast-based HIV vaccine

Objective To perform pre-clinical study on a yeast-based HIV vaccine.Methods Plas- mids expressing Gag and IL-2 was respectively constructed and then transformed into yeast; yeast hybridization was performed to obtain yeast hybrid concurrently expressing Gag and IL-2; culture of yeast hybrid in large scale was performed.The final vaccine product was obtained through series of process including inactivation,lyophilization and filling.The efficacy and safety of the vaccine was analyzed in mouse and macaque models.Results Expres- sion of Gag and IL-2 in yeast hybrid is stable.Upon subcutaneous injection,HIV vaccine derived from the yeast hybrid could elicit strong Gag-specific cellular immune responses in mice and in macaque models,respectively.In addition,vaccine could also elicit strong protection from tumor challenge in mice.Study on safety indicated that, except for slight tenderness and swelling at the site of injection,there was no obvious acute as well as chronic tox- icity.Conclusion Yeast hybrid can be used as a vehicle for vaccine; yeast hybrid-based vaccine is capable of in- ducing strong antigen-specific cellular immune responses.Our studies imply that yeast hybrid is a promising vector and delivery system for the development of novel therapeutic vaccine candidates against infections and tumors.