A DNA vaccine constructed with human papillomavirus type 16 (HPV16) E7 and E6 genes induced specific immune responses

FLT3L and granulocyte macrophage colony-stimulating factor enhance the anti-tumor and immune effects of an HPV16 E6/E7 vaccine

HPV16 infections promote the development and progression of cervical cancer. We investigated Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor as new adjuvants to an HPV16 vaccine. C57BL/6 mice were immunized by intramuscular injections of HPV16 E6/E7 plasmids every two weeks, three times in all. An in vivo imaging system was used to observe tumor growth and metastasis. Pathological changes to the heart, liver, spleen, lungs, brain and kidneys were recorded, and the survival rate of the mice was determined. The constructed HPV16 E6/E7 vaccine had no notable side effects in terms of physiological or biochemical indexes. Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor increased the inhibitory effects of the HPV16 E6/E7 vaccine on tumor growth and metastasis in vivo. The HPV16 E6/E7 vaccine enhanced the survival of mice and increased their serum-specific antibody and interferon-γ levels. Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor augmented these effects. In a cytotoxic lymphocyte killing test, Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor improved the ability of splenic lymphocytes from HPV16 E6/E7-vaccinated mice to kill B16 cells. As Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor enhanced the anti-tumor and immune effects of the HPV16 vaccine, these adjuvants should be considered for the treatment of cervical cancer.

For t 2 DNA vaccine prevents Forcipomyia taiwana (biting midge) allergy in a mouse model

BACKGROUND

Forcipomyia taiwana (biting midge) is the most prevalent allergenic biting insect in Taiwan, and 60% of the exposed subjects develop allergic reactions. Subjects with insect allergy frequently limit their outdoor activities to avoid the annoyingly intense itchy allergic reactions, leading to significant worsening of their quality of life. Allergen-specific immunotherapy is the only known therapy that provides long-term host immune tolerance to the allergen, but is time-consuming and cumbersome. This study tested whether the For t 2 DNA vaccine can prevent allergic symptoms in For t 2-sensitized mice.

MATERIALS AND METHODS

Two consecutive shots of For t 2 DNA vaccine were given to mice with a 7-day interval before sensitization with recombinant For t 2 proteins, using the two-step sensitization protocol reported previously.

RESULTS

The For t 2 DNA vaccine at 50 μg prevented the production of For t 2-specific IgE (P < 0.05), as well as midge allergen-challenge-induced scratch bouts, midge allergen-induced IL-13 and IL-4 production from splenocytes, and inflammatory cell infiltrations in the lesions 48 h after intradermal challenge.

CONCLUSIONS

This study is the first to demonstrate that DNA vaccine encoding midge allergen is effective in preventing allergic skin inflammation induced by biting midge. Immunotherapy using For t 2 DNA vaccine can protect mice from being sensitized by midge allergen and may be a promising treatment for biting midge allergy in the future.

Chimeric infectious bursal disease virus-like particles as potent vaccines for eradication of established HPV-16 E7-dependent tumors

Cervical cancer is caused by persistent high-risk human papillomavirus (HR-HPV) infection and represents the second most frequent gynecological malignancy in the world. The HPV-16 type accounts for up to 55% of all cervical cancers. The HPV-16 oncoproteins E6 and E7 are necessary for induction and maintenance of malignant transformation and represent tumor-specific antigens for targeted cytotoxic T lymphocyte–mediated immunotherapy. Therapeutic cancer vaccines have become a challenging area of oncology research in recent decades. Among current cancer immunotherapy strategies, virus-like particle (VLP)–based vaccines have emerged as a potent and safe approach. We generated a vaccine (VLP-E7) incorporating a long C-terminal fragment of HPV-16 E7 protein into the infectious bursal disease virus VLP and tested its therapeutic potential in HLA-A2 humanized transgenic mice grafted with TC1/A2 tumor cells. We performed a series of tumor challenge experiments demonstrating a strong immune response against already-formed tumors (complete eradication). Remarkably, therapeutic efficacy was obtained with a single dose without adjuvant and against two injections of tumor cells, indicating a potent and long-lasting immune response.

The efficiency of a novel delivery system (PEI600-Tat) in development of potent DNA vaccine using HPV16 E7 as a model antigen

DNA vaccination is a promising approach for inducing both humoral and cellular immune responses. The mode of plasmid DNA delivery is critical to make progress in DNA vaccination. Using human papillomavirus type 16 E7 as a model antigen, this study evaluated the effect of peptide-polymer hybrid including PEI600-Tat conjugate as a novel gene delivery system on the potency of antigen-specific immunity in mice model. At ratio of 10:50 PEI-Tat/E7DNA (w/w), both humoral and cellular immune responses were significantly enhanced as compared with E7DNA construct and induced Th1 response. Therefore, this new delivery system could have promising applications in gene therapy.

Tumour antigen-targeted immunotherapy for chronic myeloid leukaemia: is it still viable?

In haematological cancers, malignant cells circulate in the blood and lymphatic system. This may make leukaemic cells easier to target by immunotherapy than in other types of cancer. Various immunotherapy strategies have been trialled in several leukaemias including chronic myeloid leukaemia (CML) and in general, these have been aimed at targeting tumour-associated antigens (TAA). There are numerous TAA expressed by CML patients including WT1, proteinase 3, BCR-ABL and HAGE amongst others. The immunogenicity of the CML-specific tumour antigen, BCR-ABL, has been the subject of much debate and its role in the development of the disease and its unique sequence spanning the breakpoint region make it an ideal target for immunotherapy. However, there are a limited number of immunogenic epitopes across the junctional region, which are restricted to only a few HLA types, namely A2, A3 and B7 (Clark et al. in Blood 98:2887-2893, 2001). The second CML-associated antigen is the helicase antigen HAGE, a cancer-testis antigen found to be over-expressed in more than 50% of myeloid leukaemias (Adams et al. in Leukaemia 16:2238-2242, 2002). Very little is known about the function of this antigen and its significance to CML. However, its membership of the DEAD-box family of ATP-dependent RNA helicases and the involvement of other members of this family in tumour cell proliferation (Eberle et al. in Br J Cancer 86:1957-1962, 2002; Yang et al. in Cell Signal 17:1495-504, 2005) suggest a crucial role in the RNA metabolism of tumour cells. For these reasons, HAGE also seems to be a good target for immunotherapy as it would be applicable for the majority of patients with CML. This review aims to discuss the potential of immunotherapy for the treatment of leukaemia, in particular CML, and the prospect of targeting three CML associated antigens: BCR, ABL and HAGE. During his career, Prof. Tony Dodi made a significant contribution in this area of leukaemia research, confirming the identity of immunogenic HLA-A3 and B7-restricted peptides as targets for CTL. Published, as a highlighted paper in Clark et al. (Blood 98:2887-2893, 2001), this study demonstrated the expression of MHC-peptide complexes on the surface of CML cells and the presence of tetramer-positive CTL activity in CML patients positive for these two HLA alleles. His drive and dedication for research excellence will be remembered by all who knew and worked with him.

Enhanced immunogenicity of HPV16E7 accompanied by Gp96 as an adjuvant in two vaccination strategies

Human papillomavirus, particularly type 16 (HPV16) is present in more than 99% of cervical cancers. E7 is the major oncogenic protein produced in cervical cancer-associated HPV16. An efficient vaccine against viral infection requires induction of strong humoral and cellular responses against viral proteins. Heat shock proteins (HSPs) like Gp96 have been described as potent tumor vaccines in animal models and are currently studied in human clinical trials. In this study, we investigated the utility of HPV16 E7 along with Gp96 as an adjuvant in C57BL/6 mice model. We compared the level of humoral and cellular immune responses by E7+Gp96 co-injection as DNA/DNA and prime-boost (DNA/protein) immunization strategies. In prime-boost immunization strategies, we first immunized C57BL/6 mice with the complete open-reading frame of E7 and Gp96 (pcDNA-E7 and pcDNA-Gp96) and then boosted with rE7, rNT-gp96 (N-terminal extension of Gp96) and rCT-gp96 (C-terminal extension of Gp96) mixed with Montanide 720 in different formulations. The humoral immune responses against rE7 and the different truncated forms of rGp96 suggested a mixed Th1/Th2 response with high intensity toward Th2. Assessment of lymphoproliferative and cytokine responses against rE7 and the different fragments of Gp96, showed that DNA vaccination including E7 and Gp96 induced Th1 response. We concluded that co-delivery of naked DNA E7+Gp96 plasmid was immunologically more effective than E7 alone. Our study demonstrated that co-delivery of E7+Gp96 as DNA/DNA and E7+CT-gp96 as DNA/protein could be an effective approach to induce E7-specific immune responses as a potential vaccine candidate for cervical cancer.

Vaccines to treat cancer--an old approach whose time has arrived

There are extensive DNA changes in tumor cells and the genes of tumor cells continuously mutate at a high rate. While this can provide therapeutic targets, it makes it unlikely that an agent that is selective for a single target will work against all cells in a tumor. However, it may be possible to use tumor epitopes as sentinels to engage adaptive and innate immunological mechanisms and create a tumor destructive environment effective also against variant cells that have lost a given antigen or their ability to present it. We hypothesize that therapeutic tumor vaccines, in combination with the targeting, to tumors, of costimulatory molecules such as anti-CD137scFv, or lymphokines such as GMCSF, will expand anti-tumor responses for therapeutic benefit when used as an adjunct to surgery and chemotherapy.