Profound CD8+ T cell immunity elicited by sequential daily immunization with exogenous antigen plus the TLR3 agonist poly(I:C)

• Published in: Vaccine Vol. 29; no. 5; pp. 984 - 993
• Main Authors: Wick, Darin A., Martin, Spencer D., Nelson, Brad H., Webb, John R.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 29.01.2011; Elsevier; Elsevier Limited
• Subjects: Adjuvants, Immunologic - administration & dosage; agonists; Allergy and Immunology; Animals; Applied microbiology; Biological and medical sciences; CD8+ T cells; CD8-positive T-lymphocytes; CD8-Positive T-Lymphocytes - immunology; Cytokines - secretion; Enzyme-Linked Immunospot Assay; epitopes; Female; Fundamental and applied biological sciences. Psychology; Human papillomavirus 16; immunity; Immunization; Immunization - methods; Infections; Injections, Subcutaneous; Medical research; Mice; Mice, Inbred C57BL; Microbiology; neoplasms; Ovalbumin - administration & dosage; Ovalbumin - immunology; Papillomavirus E7 Proteins - administration & dosage; Papillomavirus E7 Proteins - immunology; Peptides; Poly I-C - administration & dosage; splenocytes; synthetic peptides; T cell receptors; TLR3; Toll-Like Receptor 3 - agonists; vaccination; Vaccine; vaccine development; Vaccines; Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies (general aspects); Viral infections; CD8+ T cells; Vaccine; TLR3; CD8 + T cells; Antigen; Immunization; CD8; T cells; CD8 T lymphocyte
• ISSN: 0264-410X; 1873-2518; 1873-2518
• DOI: 10.1016/j.vaccine.2010.11.036

The development of vaccines that elicit robust CD8+ T cell immunity has long been a subject of intense investigation. Although whole exogenous protein has not historically been considered as useful for eliciting CD8+ T cell immunity, we report herein that whole, protein antigen is capable of eliciting profound levels of CD8+ T cell immunity if it is administered via repeated, daily subcutaneous immunization in combination with the TLR3 agonist poly(I:C). Mice immunized for four consecutive days with 100μg of either whole exogenous OVA or whole HPV16 E7 protein combined with 10μg of poly(I:C) mounted remarkable antigen-specific CD8+ T cell responses as measured by tetramer staining and ELISPOT analysis of splenocytes and peripheral blood, with up to 30% of peripheral CD8+ T cells being antigen specific within 7–8 days of vaccination. CD8+ T cell immunity elicited using this vaccination approach was critically dependent upon cross presentation, as either whole protein or long synthetic peptides were highly effective immunogens whereas minimal peptide epitopes were not. Vaccine-induced CD8+ T cells were also able to regress large, established tumors in vivo. Together these data suggest that ‘cluster’ vaccination with exogenous antigen combined with TLR3 agonist may constitute a profoundly important advancement in therapeutic vaccine design.