Abstract
Abstract We have developed a vaccine design that uses the unique ability of the endoplasmic reticulum (ER) chaperone, heat shock protein gp96, to bind antigenic peptides and deliver them to antigen-presenting cells. Secreted form of gp96, gp96-Ig, was generated by replacing the ER retention sequence KDEL with the IgG1-Fc domain. To generate a cellular SIV vaccine, HEK-293 cells were transfected with gp96-Ig and the cDNAs encoding the SIV antigens gag, env and retanef. Irradiated, transfected 293 cells that secrete 1, 5 or 50 micrograms gp96-Ig-SIV complexes in 24h, were injected intraperitoneally (IP) in Mamu-A*01+ Rhesus Macaques at 0, 4 and 25 weeks. To determine whether gp96-Ig vaccination induces mucosal immunity, we used the 3T3-OVA-gp96-Ig/OT-1 model. Our data indicate that the best route of vaccination for induction of mucosal CD8-CTL immunity is the IP route. Gp96-Ig immunization increases frequency of CD11chighMHC classIIhighCD103+ cells in peritoneal cavity and efficiently induces CCR9 on responding T cells. In nonhuman primate model, the frequency of SIV-specific cells in the rectal mucosa reached 30-50% after the third immunization. We conclude that gp96-Ig vaccination startegy induces antigen-specific effector memory CD8T cells migrating to the intestinal mucosa and thus could be extremely useful for improving protection against a range of mucosal pathogens.