A VACCINE CONJUGATE OF ISCAR IMMUNOCARRIER AND PEPTIDE EPITOPES OF THE E7 CERVICAL CANCER-ASSOCIATED PROTEIN OF HUMAN PAPILLOMAVIRUS TYPE-16 ELICITS SPECIFIC TH1-TYPE AND TH2-TYPE RESPONSES IN IMMUNIZED MICE IN THE ABSENCE OF OIL-BASED ADJUVANTS

TraT protein, known as ISCAR (=Immunostimulatory Carrier), is one of a family of integral membrane proteins (Imps) of Escherichia coli repre senting powerful carrier molecules which when injected into experiment al animals generate substantial antibody and T proliferative responses to molecules conjugated to it. We extend these findings to show that ISCAR functions to stimulate Th1- and Th2-type responses, including sp ecific cytotoxic T cells and tumour protection. We report here that by conjugating to ISCAR a 19mer peptide containing linear B epitopes, a T helper (Th) epitope, and a H-2(b)-restricted T cytotoxic (CTL) epito pe of E7 protein of human papillomavirus type 16 (HPV16), and immunizi ng C57B1/6 (H-2(b)) mice, we elicited (i) specific IgG2a and IgG1 anti bodies; (ii) IL-2 and IL-4 production by specifically recalled lymph n ode cells in vitro; (iii) cytotoxic T lymphocytes which specifically k illed both E7 peptide-pulsed, and whole E7 gene-transfected tumour tar get cells; and (iv) in vivo protection against an E7 gene-transfected tumour cell inoculum. These findings have implications for the design of vaccines to stimulate immune responses to endogenously processed ta rget antigens (e.g. tumour-associated antigens) without the unwanted s ide effects of oil-based adjuvants. In addition they support the case for a E7-targeted therapeutic vaccine for HPV-associated human cervica l cancer.