DNA vaccine encoding endosome‐targeted human papillomavirus type 16 E7 protein generates CD4⁺ T cell‐dependent protection

Abstract

Human papillomavirus type 16 is commonly implicated in cervical cancers. The viral genome encodes potential targets like the oncoprotein E7, expressed in transformed cells but thought to represent a poorly immunogenic antigen. We describe in this work a DNA-based vaccination protocol aimed at inducing an efficient anti-E7 immune response in vivo. Plasmids allowing the expression of the E7 protein in distinct cellular compartments were generated and assayed in an in vivo model of tumor growth. Our data demonstrate that mice vaccinated with a plasmid encoding for an E7 protein fused to a domain of the MHC class II-associated invariant chain (IiE7) were protected against tumor challenge. Mice immunized against an ubiquitinated form of E7 (Ub(Ala)E7) failed to control tumor growth. Protection induced by IiE7 was correlated with the development of CD8 + CTL and required the presence of CD4 + cells. In vitro studies confirmed that the IiE7 fusion protein was expressed at high levels in the endosomal compartment of transfected cells, while the natural and the ubiquitin-modified form of E7 were mainly nuclear. The present study suggests that an efficient anti-tumor response can be induced in vivo by DNA constructs encoding for E7 protein forms localizing at the endosomal compartment.

Vaccination against Lymphocytic Choriomeningitis Virus Infection in MHC Class II-Deficient Mice

“…As a first step to test this, we confirmed that tethering to Ii chain significantly improved MHC class I-associated Ag presentation, as expected. With this information available, it was logical to go on and test whether Ii linkage might also induce protective CD8 + T cell immune responses in MHC class II-deficient hosts, although a previous study on the anticancer effect of an Ii-linked DNA vaccine pointed to an MHC class II dependence of protection (33). Our finding in this study, that only the adenoviral Ii-linked vaccine induced a potent CD8 + T cell response and robust short-term protection in MHC class II-deficient hosts, could support the assumption that a high level of Ag presentation on the vaccine vector-transduced cells, as is achieved with Ii linkage, in combination with innate signals induced through recognition of molecular patterns of the adenoviral vector, might act in concert to activate CD8 + T cells in the absence of CD4 + T cell help.…”

Immunotherapy for head and neck cancer

“…Use of intracellular targeting strategies to the MHC class I and II processing pathways for enhanced antigen presentation by DCs [75][76][77][78][79] Codon optimization [80,81] Enhanced presentation of antigen through a MHC class I single chain trimer (SCT) composed of peptide, b2-microglobulin, and MHC class I heavy chain [82] Augmentation of DC and T cell interaction Inhibition of DC apoptosis [72,83] Promotion of in vivo DC expansion [84,85] Co-expression of cytokines and stimulatory molecules [76,86,87] Induction of helper T cell function [79] The DNA vaccine was well tolerated and a subset of the vaccinated patients who received the maximum dose of 4 mg of DNA/vaccination and a total of 4 vaccinations demonstrated detectable, systemic levels of E7-specific CD8+ T cell immune responses (Maura Gillison, personal communication).…”

Hepatitis B Surface Antigen-based Vaccines for Human Neoplastic Disease

“…A number of studies suggest that vaccine-induced protection against TC-1 tumour is CD4 + cell independent Cheng et al, 2003;Loeser et al, 2007), 165 which was also the case with an E7-expressing tumour . However in some studies, CD4 + cells appear to play a role in tumour protection (Brulet et al, 2007;Park et al, 2008). Although both DCs and Langerhans cells can be directly cytopathic to tumour cells (Le Poole et al, 2008), the specific CD4 + subtype/s involved in TC-1 tumour protection have not as yet been identified.…”

“…There is currently no vaccine which targets non-structural HPV antigens to provide protection against HPV-associated neoplasia, however animal models have demonstrated cell-mediated protection to be an efficacious strategy (Brulet et al, 2007;Daftarian et al, 2007;Haigh et al, 2007;Peng et al, 2008;Best et al, 2009;Chuang et al, 2009b;Yan et al, 2009). pE7HBE6 DNA vaccine shows great promise for use as a protective vaccine as well as a therapeutic agent, which would be cheap and stable and applicable to nations of all socio-economic status.…”

“…This chapter has demonstrated that the CD8 + T-cell response to pE7HBE6 DNA vaccine provided protection against TC-1 challenge (Figures 5.1, 5.2, 5.3, 5.4). Published studies demonstrated that E7 (RAH)-and E6 (EVY)-directed CTL responses can have a therapeutic effect on established HPV-associated tumours (Brulet et al, 2007;Daftarian et al, 2007;Haigh et al, 2007;Peng et al, 2008;Best et al, 2009;Chuang et al, 2009b;Yan et al, 2009). …”