A novel, broad spectrum therapeutic HPV vaccine targeting the E7 proteins of HPV16, 18, 31, 45 and 52 that elicits potent E7-specific CD8T cell immunity and regression of large, established, E7-expressing TC-1 tumors

Persistent infection by high risk genotypes of human papillomavirus (HPV) is the cause of cervical cancer, which remains one of the most common cancers among women worldwide. In addition, there is a growing appreciation that high risk HPVs are associated with a number of other cancers including anogenital cancers as well as a subset of head and neck cancers. Recently, prophylactic HPV vaccines targeting the two most prevalent high risk HPVs (HPV16 and HPV18) have been deployed in large-scale vaccination campaigns. However, the extent to which these prophylactic vaccines confer protection against other high risk HPV genotypes is largely unknown and prophylactic vaccines have been shown to be ineffective against pre-existing infection. Thus there continues to be an urgent need for effective therapeutic vaccines against HPV. The E7 protein of HPV16 has been widely studied as a target for therapeutic vaccines in HPV-associated cancer settings because HPV16 is the most prevalent of the high risk HPV genotypes. However, HPV16 accounts for only about 50% of cervical cancers and there are at least 15 other high risk HPVs that are known to be oncogenic. We have developed a novel, broad-spectrum, therapeutic vaccine (Pentarix) directed at the E7 proteins from five of the most prevalent high-risk genotypes of HPV worldwide (HPV16, 18, 31, 45 and 52) that together account for more than 80% of all HPV-associated cancers. Pentarix is a recombinant protein-based vaccine that elicits strong, multi-genotype specific CD8 T cell immunity when administered to mice in combination with adjuvants comprised of agonists of the TLR3 or TLR9 family of innate immune receptors. Furthermore, large, established E7-expressing TC-1 tumors undergo rapid and complete regression after therapeutic vaccination of mice with Pentarix. Together, these data suggest that Pentarix may be of clinical value for patients with E7-positive, HPV-associated precancerous lesions or malignant disease.

Immunogenicity in mice and rhesus monkeys vaccinated with recombinant vaccinia virus expressing bivalent E7E6 fusion proteins from human papillomavirus types 16 and 18

BACKGROUND

Persistent infection with high-risk human papillomavirus (HPV) is a predominant cause of cervical cancer, and HPV16 and HPV18 occur in 50% and 20% of cervical cancer cases, respectively. The viral oncogenes E6 and E7 are constitutively expressed by HPV-associated tumour cells and can therefore be used as target antigens for immunotherapy. In this study, we constructed a recombinant vaccinia virus co-expressing the HPV16/18 E7E6 fusion proteins (rVVJ16/18E7E6) for use as a therapeutic vaccine for the treatment of HPV16⁺ and HPV18⁺ cancers.

METHODS

We constructed a bivalent recombinant vaccinia virus expressing modified E7E6 fusion proteins of HPV type 16 and 18 (rVVJ16/18E7E6) based on the vaccinia virus Tiantan strain. We then defined the cellular immune responses to the virus in mice and rhesus monkeys and assessed antitumour efficacy of these responses in mice using the TC-1 tumour challenge model.

RESULTS

Our data demonstrated that rVVJ16/18E7E6 was able to elicit varying levels of CD8⁺ T cell immune responses and lysis of target cells in mice in response to peptides HPV16E7₄₉₋₅₇ and HPV18E6₆₇₋₇₅. Furthermore, the virus was also able to induce anti-tumour responses in the HPV16⁺ TC-1 tumour challenge model, including partial protection (30-40%) and delayed tumour appearance. In addition, the virus was able to induce immune responses in rhesus monkeys.

CONCLUSIONS

The recombinant vaccinia virus rVVJ16/18E7E6 can generate clear and significant cellular immunity in both mice and rhesus monkeys. These data provide a basis for the use of this recombinant virus as a potential vaccine candidate for further study.

Expression of Human papillomavirus 16 E7ggg oncoprotein on N- and C-terminus of Potato virus X coat protein in bacterial and plant cells

The E7 oncoprotein from Human papillomavirus type 16 (HPV16) is an attractive candidate for anti-cancer therapeutical vaccine development. In this study, we engineered different fusions of mutagenized coding sequence of E7 oncoprotein (E7ggg) with coat protein of Potato virus X (PVX CP) both on 5'- and 3'-terminus of PVX CP and evaluated the influence of the length of linker (no linker, 4, 15aa) connecting PVX CP and E7ggg on their production. At first the expression in Escherichia coli was conducted to assess the characteristics of the recombinant protein prior to be further produced in plants, that is, resultant proteins were used for screening of their immunological reactivity with antibodies against PVX CP and E7. Fusion proteins successfully expressed in bacteria and plants were partially purified and their reactivity and ability to form virus-like particles were evaluated with anti-E7 antibodies.

Computer-aided analysis of structural properties and epitopes of Iranian HPV-16 E7 oncoprotein

Infection by human papillomavirus type 16 (HPV-16) is the cause of 50% or more of cervical cancers in women. The E7 oncoprotein of HPV-16 has long been known as a potent immortalizing and transforming agent. We used different servers like PseAAC, MHC_binding, MHC_II_binding and Expasy for the present computational prediction. The results for T cell epitopes showed that B1501, A0203, A0201, A0202, A6801 and DRB0405 alleles had lower IC50 than other alleles. We also predicted several peptides with the best binding affinities for alleles of the most frequent MHC class I and II alleles of the various ethnic groups living in the different region of Iran. Two peptides (26-35) and (44-52) were predicted as B-cell epitopes. According to this analysis 1 N-glycosylation site, 2 PKC sites, 4 CK2 sites and 3 disulfide sites were predicted. Our computational study predicted that B cell epitope 1 was Casein kinase II phosphorylated (site No. 31) and glycosylated (site No. 29). Putative MHC-I epitopes 3 and 5 and MHC-II epitopes 19, 21 and 26 were predicted to be casein kinase II phosphorylated. MHC-II epitopes 19 and 21 was predicted to be glycosylated. T cell epitopes 1, 13, 16 and 24 were demonstrated to be kinase C phosphorylated. The result of this analysis for Iranian HPV-16 E7 also indicated that 21.43%, 18.37% and 60.20% of the protein were in the α-helix, extended strand and random coil respectively.

A novel fusion protein-based vaccine comprising a cell penetrating and immunostimulatory peptide linked to human papillomavirus (HPV) type 16 E7 antigen generates potent immunologic and anti-tumor responses in mice

The ultimate success of cancer vaccination is dependent upon the generation of tumor-specific CTLs. In this study, we designed and evaluated a novel fusion protein comprising a cell penetrating and immunostimulatory peptide corresponding to residues 32-51 of the Limulus polyphemus protein (LALF(32-51)) linked to human papillomavirus (HPV) 16 E7 antigen (LALF(32-51)-E7). We demonstrated that LALF(32-51) penetrates the cell membrane and delivers E7 into cells. In a preclinical model of HPV16-induced cervical carcinoma we showed that vaccination with adjuvant-free LALF(32-51)-E7 fusion protein significantly improves the presentation of E7-derived peptides to T-cells in vitro and induces suppression of tumor growth.

A conserved E7-derived cytotoxic T lymphocyte epitope expressed on human papillomavirus 16-transformed HLA-A2+ epithelial cancers

Human Papillomavirus 16 (HPV-16) has been identified as the causative agent of 50% of cervical cancers and many other HPV-associated tumors. The transforming potential/tumor maintenance capacity of this high risk HPV is mediated by two viral oncoproteins, E6 and E7, making them attractive targets for therapeutic vaccines. Of 21 E6 and E7 peptides computed to bind HLA-A*0201, 10 were confirmed through TAP-deficient T2 cell HLA stabilization assay. Those scoring positive were investigated to ascertain which were naturally processed and presented by surface HLA molecules for CTL recognition. Because IFNγ ELISpot frequencies from healthy HPV-exposed blood donors against HLA-A*0201-binding peptides were unable to identify specificities for tumor targeting, their physical presence among peptides eluted from HPV-16-transformed epithelial tumor HLA-A*0201 immunoprecipitates was analyzed by MS(3) Poisson detection mass spectrometry. Only one epitope (E7(11-19)) highly conserved among HPV-16 strains was detected. This 9-mer serves to direct cytolysis by T cell lines, whereas a related 10-mer (E7(11-20)), previously used as a vaccine candidate, was neither detected by MS(3) on HPV-transformed tumor cells nor effectively recognized by 9-mer specific CTL. These data underscore the importance of precisely defining CTL epitopes on tumor cells and offer a paradigm for T cell-based vaccine design.

Treatment with imiquimod enhances antitumor immunity induced by therapeutic HPV DNA vaccination

BACKGROUND

There is an urgent need to develop new innovative therapies for the control of advanced cancer. The combination of antigen-specific immunotherapy with the employment of immunomodulatory agents has emerged as a potentially plausible approach for the control of advanced cancer.

METHODS

In the current study, we explored the combination of the DNA vaccine encoding calreticulin (CRT) linked to human papillomavirus type 16 (HPV-16) E7 antigen (CRT/E7) with the TLR7 agonist imiquimod for their ability to generate E7-specific immune responses and antitumor effects in tumor-bearing mice.

RESULTS

We observed that treatment with CRT/E7 DNA in combination with imiquimod leads to an enhancement in the E7-specific CD8+ T cell immune responses and a decrease in the number of myeloid-derived suppressor cells in the tumor microenvironment of tumor-bearing mice. Furthermore, treatment with CRT/E7 DNA in combination with imiquimod leads to significantly improved antitumor effects and prolonged survival in treated mice. In addition, treatment with imiquimod led to increased number of NK1.1+ cells and F4/80+ cells in the tumor microenvironment. Macrophages and NK1.1+ cells were found to play an important role in the antitumor effects mediated by treatment with CRT/E7 DNA in combination with imiquimod.

CONCLUSIONS

Thus, our data suggests that the combination of therapeutic HPV DNA vaccination with topical treatment with the TLR7 agonist imiquimod enhances the antitumor immunity induced by DNA vaccination. The current study has significant implications for future clinical translation.

Antibody detection against HPV16 E7 & GP96 fragments as biomarkers in cervical cancer patients

BACKGROUND & OBJECTIVE

Cervical cancer is the second most frequent cancer among females worldwide, especially human papilloma viruses (HPV) types 16 and 18. In viral systems the identification of serological markers would facilitate the diagnosis of HPV infections and virus-related disease. The aim of the present investigation was to determine and search for serologic markers in cervical cancer patients associated with HPV.

METHODS

A total of 58 Iranian women with invasive cervical carcinoma including adenocarcinoma and squamous cell carcinoma (SCC) were included. Serum antibody response to HPV infections in patients was detected by Western blot and ELISA techniques based on recombinant HPV16E7 and the N-terminal and C-terminal fragments of gp96 (NT-gp96 and CT-gp96) proteins. These recombinant proteins were expressed in Escherichia coli as a His-tag protein and purified using affinity chromatography.

RESULTS

The ELISA results indicated that patients with high antibody response to HPV16E7 had significant seroreactivity to CT-gp96 fragment. In Western blot analysis, a strong association between anti-E7, anti-NT-gp96 and anti-CT-gp96 reactivity and cervical cancer was obtained using purified recombinant proteins. In adenocarcinoma cases, no significant difference was observed in seroreactivities between normal and patients.

INTERPRETATION & CONCLUSION

The evaluation of cervical cancer patients' seroreactivities against three recombinant proteins (rE7, rNT-gp96 and rCT-gp96) showed significantly higher levels of these markers in SCC only, but not in adenocarcinoma and control groups. Also, the usage of both techniques (ELISA and Western blotting) can provide more reliable tools for diagnosis of cervical cancer.

The biological properties of E6 and E7 oncoproteins from human papillomaviruses

More than 100 different human papillomavirus (HPV) types have been isolated so far, and they can be sub-grouped in cutaneous or mucosal according to their ability to infect the skin or the mucosa of the genital or upper-respiratory tracts. A sub-group of human mucosal HPVs, referred to as high-risk HPV types, is responsible for approximately 5% of all human cancers, which represents one-third of all the tumours induced by viruses. Epidemiological and biological studies have shown that HPV16 is the most oncogenic type within the high-risk group. Emerging lines of evidence suggest that, in addition to the high-risk mucosal HPV types, certain cutaneous HPVs are involved in skin cancer. HPV-associated cancers are intimately linked to HPV persistence and the accumulation of chromosomal rearrangements. The products of the early genes, E6 and E7, of the high-risk mucosal HPV types play a key role in both events. Indeed, these proteins have developed a number of strategies to evade host immuno-surveillance allowing viral persistence, and to alter cell cycle and apoptosis control, facilitating the accumulation of DNA damage/mutations. Often, the two oncoproteins target the same cellular pathways with different mechanisms, showing a strong synergism in promoting cellular transformation and neutralizing the immune response. Here, we review most of the findings on the biological properties and molecular mechanisms of the oncoproteins E6 and E7 from mucosal and cutaneous HPV types.

Analysis of antibody response to HPV 16 and HPV 18 antigens in Tunisian patients

OBJECTIVE

The aim of this present study was to use Luminex technology to detect antibodies against the late antigen L1 as well as those directed against the early antigens E6 and E7.

BACKGROUND DATA

Human papillomavirus (HPV) serology is complex because infection and disease lead to distinct type-specific antibody responses.

MATERIALS AND METHODS

Viral antigens were expressed with pGEX vectors in Escherichia coli and then used in Luminex as coating antigens for antibody detection in 205 human sera samples: 71 cervical cancer cases, 64 cases of cervical inflammation, and 70 controls.

RESULTS

The data showed that 90.14% of sera among the cervical cancer patients had seropositivity toward at least one of the HPV 16 or HPV 18 antigens. Moreover, the percentages of positivity toward E6 and E7 HPV 16 antigens were 44% and 61%, respectively, versus only 21% for the L1 antigen. Among cervical cancer patients, the data showed different distributions in women of different ages. In addition, the intensity of the antibody response was also different for the six antigens analyzed.

CONCLUSIONS

Antibody detection depends on the type of antigen, and is well correlated with international scientific findings. The differences in antibody response between patients with inflammation and patients with cervical cancer were significant.

Expression of IL-15RA or an IL-15/IL-15RA fusion on CD8+ T cells modifies adoptively transferred T-cell function in cis

IL-15 and IL-15 receptor alpha (IL-15RA) play a significant role in multiple aspects of T-cell biology. However, given the evidence that IL-15RA can present IL-15 in trans, the functional capacity of IL-15RA expressed on CD8(+) T cells to modify IL-15 functions in cis is currently unclear. In the current study, we explore the functional consequences of IL-15RA, expression on T cells using a novel method to transfect naive CD8(+) T cells. We observed that RNA nucleofection led to highly efficient, non-toxic, and rapid manipulation of protein expression levels in unstimulated CD8(+) T cells. We found that transfection of unstimulated CD8(+) T cells with IL-15RA RNA led to enhanced viability of CD8(+) T cells in response to IL-15. Transfection with IL-15RA enhanced IL-15-mediated phosphorylation of STAT5 and also promoted IL-15-mediated proliferation in vivo of adoptively transferred naïve CD8(+) T cells. We demonstrated that IL-15RA can present IL-15 via cis-presentation on CD8(+) T cells. Finally, we showed that transfection with a chimeric construct linking IL-15 to IL-15RA cell autonomously enhances the viability and proliferation of primary CD8(+) T cells and cytotoxic potential of antigen-specific CD8(+) T cells. The clinical implications of the current study are discussed.

Monitoring the trafficking of adoptively transferred antigen- specific CD8-positive T cells in vivo, using noninvasive luminescence imaging

Understanding of the trafficking of antigen-specific CD8(+) T cells in vivo will provide insight about how our immune system controls infectious diseases and cancers. In the current study we used a luciferase-expressing human papillomavirus type 16 (HPV-16) E7-specific CD8(+) T cell for adoptive transfer to control E7-expressing TC-1 tumor cells. We used noninvasive luminescence imaging to monitor the trafficking of E7-specific CD8(+) T cells over time. We also boosted the luciferase-expressing E7-specific CD8(+) T cells in vivo, using E7-expressing vaccinia. We found that injected E7-specific T cells preferentially migrated to the E7-expressing tumor site but not to the E7-negative control tumor site, and increased in number at the tumor site over time. In addition, vaccination with E7-expressing vaccinia led to a significant increase in the number of E7-specific CD8(+) T cells at the tumor site, resulting in a significant antitumor effect compared with vaccination with wild-type vaccinia. Thus, our data suggest that the antitumor effects generated by adoptive transfer of E7-specific CD8(+) T cells can be significantly enhanced by vaccination with E7-expressing vaccinia and that our system represents a plausible approach to investigate the trafficking and biology of antigen-specific T cells in vivo.

[Linkage of modified human papillomavirus type 16 E7 to CD40 ligand enhances specific CD8+ T-lymphocyte induction and anti-tumour activity of DNA vaccine]

OBJECTIVE

To develop human papillomavirus (HPV) 16 DNA vaccine for the treatment of HPV16 infection and its related tumors.

METHODS

HPV16 oncogene E7 was modified by combined approaches including insertion and replication of specific region of E7 gene, murine codon optimization, and point-mutation at transforming regions of the E7 protein. The resulting artificial gene, named as mE7, was obtained by gene synthesis. The mE7 gene was then genetically fused to murine CD40 ligand (CD40L) by overlapping PCR to form the mE7/CD40L fusion gene. The mE7/CD40L gene was inserted into pVR1012 plasmid and then immunized C57/BL6 mice intramuscularly. The E7-specific IFN-gamma-secreting CD8+ T cells were analyzed with EIISPOT, and E7-specific antibody was measured by indirect ELISA. FACS assays were performed to analyze the activation of E7-specific Th cells. Mice were vaccinated, followed by tumor challenged or challenged before immunization. Tumor growth was observed.

RESULTS

The mE7 DNA vaccine elicited an increased E7-specific antibody level (P < 0.01), E7-specific IFN-gamma-secreting CD8+ T (P < 0.01), and CD4+ T cells number (P < 0.05), compared with those of mice immunized with wE7 gene. Furthermore, the mE7/CD40L DNA vaccine elicited an increased number of E7-specific IFN-gamma secreting CD8+ T cell compared with that of mice immunized with mE7 gene (P < 0.01); however, no significant differences were found between mice immunized with the mE7 gene and mE7/CD40L fusion gene in the E7-specific antibody production and Th cell activation. In the preventive experiment, all mice received the mE7 or mE7/CD40L remained tumor-free 7 weeks after challenges with TC-1 tumor cells, while the wE7 group exhibited tumor growth within 2 weeks. In the therapeutic experiment, all the mice in the wE7 group exhibited tumor growth within 8 days, while among mice receiving the mE7 and mE7/CD40L, 30% and 45% of mice remained tumor-free after TC-1 challenge, respectively. HE staining of tumor tissues showed copious lymphocytes infiltration around tumor cells in mE7 and mE7/CD40L mice with regression of tumor growth.

CONCLUSIONS

The mE7 DNA vaccine increases the E7-specific humoral and cellular immune responses, and the fusion of CD40L to mE7 gene enhances the specific immune responses and anti-tumor effects against HPV16 E7-expressing murine tumors. mE7/CD40L may therefore be a suitable and promising target for HPV16 therapeutic vaccine.

Prediction of class I T-cell epitopes: evidence of presence of immunological hot spots inside antigens

Motivation: Processing and presentation of major histocompatibility complex class I antigens to cytotoxic T-lymphocytes is crucial for immune surveillance against intracellular bacteria, parasites, viruses and tumors. Identification of antigenic regions on pathogen proteins will play a pivotal role in designer vaccine immunotherapy. We have developed a system that not only identifies high binding T-cell antigenic epitopes, but also class I T-cell antigenic clusters termed immunological hot spots.

Methods: MULTIPRED, a computational system for promiscuous prediction of HLA class I binders, uses artificial neural networks (ANN) and hidden Markov models (HMM) as predictive engines. The models were rigorously trained, tested and validated using experimentally identified HLA class I T-cell epitopes from human melanoma related proteins and human papillomavirus proteins E6 and E7. We have developed a scoring scheme for identification of immunological hot spots for HLA class I molecules, which is the sum of the highest four predictions within a window of 30 amino acids.

Results: Our predictions against experimental data from four melanoma-related proteins showed that MULTIPRED ANN and HMM models could predict T-cell epitopes with high accuracy. The analysis of proteins E6 and E7 showed that ANN models appear to be more accurate for prediction of HLA-A3 hot spots and HMM models for HLA-A2 predictions. For illustration of its utility we applied MULTIPRED for prediction of promiscuous T-cell epitopes in all four SARS coronavirus structural proteins. MULTIPRED predicted HLA-A2 and HLA-A3 hot spots in each of these proteins.

Intrabody strategies for the treatment of human papillomavirus-associated disease

Human papillomaviruses (HPVs) are associated with a variety of epithelial lesions, including benign genital warts and cervical intraepithelial neoplasia. Both cause significant morbidity in the general population, with cervical intraepithelial neoplasia progressing to cervical cancer in a subset of women who cannot resolve their infection. At present, there are no antiviral agents for the treatment of genital HPV infections, with many lesions requiring surgical intervention. Although other approaches are available for the treatment of genital warts, HPV infection cannot usually be cured and lesion recurrence is often a problem. A growing understanding of the molecular biology of HPV infection has identified several viral protein functions that may serve as drug targets. Among these are the HPV E1 and E2 proteins, which are necessary for viral genome replication and partitioning, and the E6 and E7 proteins, which are necessary for cell proliferation and apoptotic inhibition. With the exception of E1, these proteins lack enzymatic activity and achieve their effects by interacting with cellular proteins. Protein-protein interactions are in general quite difficult to inhibit using conventional small molecule drugs, but are amenable to inhibition using intracellular antibodies or intrabodies, which bind the viral proteins and sterically inhibit their association with cellular partners. The lack of homology between viral and cellular proteins, and the fact that HPV infections can be treated topically, makes them particularly well suited to the intrabody approach. This review covers the various strategies that are being considered for the treatment of HPV infections and the different intrabody formats that have been used to inhibit HPV function in model systems. The clinical utility of the approach is considered alongside the general difficulties of using protein molecules as intracellular therapeutics.

Secondary immunisation with high-dose heterologous peptide leads to CD8 T cell populations with reduced functional avidity

Expansion of high- or low-avidity CD8 T cells in vitro inversely correlates with the concentration of peptide ligand present during culture. In contrast, the selective enrichment of high- or low-avidity T cell populations in vivo using peptide immunisation is not well documented. In our study, a single immunisation with different doses of wild-type peptide or a variant peptide able to stimulate CTL responses cross-reactive with wild-type peptide failed to shift the average avidity of the responding CD8 T cell population specific to either peptide. However, in contrast to homologous prime-boost immunisation, heterologous prime-boost immunisation incorporating high doses of the second immunogen resulted in peptide-specific CD8 T cell populations polarized toward a low average functional avidity. These data suggest that sequential exposure to structurally related viral peptides could impair rather than promote anti-viral immunity by lowering the avidity of the responding CD8 T cell population. This study has implications for improving vaccine strategies against viruses and tumours and enhances our understanding of heterologous immunity during sequential viral infection.

Listeria-based vaccines can overcome tolerance by expanding low avidity CD8+ T cells capable of eradicating a solid tumor in a transgenic mouse model of cancer

We have created a transgenic mouse with tissue-specific expression of the human papilloma virus (HPV) 16 E6 and E7 oncoproteins in the thyroid as a model of HPV transformed cancer. The expression of the transgenes results in the formation of palpable thyroid tumors. E7 is not expressed in other tissues but is expressed in medullary thymic epithelial cells, which have been implicated in the control of negative selection. We show that Listeria-based vaccines against E7 can induce the regression of solid implanted tumors in the transgenic mice, although at a lower frequency than in wild type (WT) mice. E7-specific CD8+ T cells induced in transgenic mice are of both lower avidity and lower frequency when compared to the WT mice. In this model, Listeria-based vaccines against E7 appear to be overcoming central tolerance by expanding low avidity CD8+ T cells specific for E7 that are not deleted during thymopoesis and can eliminate solid tumors.

Prediction of supertype-specific HLA class I binding peptides using support vector machines

Experimental approaches for identifying T-cell epitopes are time-consuming, costly and not applicable to the large scale screening. Computer modeling methods can help to minimize the number of experiments required, enable a systematic scanning for candidate major histocompatibility complex (MHC) binding peptides and thus speed up vaccine development. We developed a prediction system based on a novel data representation of peptide/MHC interaction and support vector machines (SVM) for prediction of peptides that promiscuously bind to multiple Human Leukocyte Antigen (HLA, human MHC) alleles belonging to a HLA supertype. Ten-fold cross-validation results showed that the overall performance of SVM models is improved in comparison to our previously published methods based on hidden Markov models (HMM) and artificial neural networks (ANN), also confirmed by blind testing. At specificity 0.90, sensitivity values of SVM models were 0.90 and 0.92 for HLA-A2 and -A3 dataset respectively. Average area under the receiver operating curve (A(ROC)) of SVM models in blind testing are 0.89 and 0.92 for HLA-A2 and -A3 datasets. A(ROC) of HLA-A2 and -A3 SVM models were 0.94 and 0.95, validated using a full overlapping study of 9-mer peptides from human papillomavirus type 16 E6 and E7 proteins. In addition, a large-scale experimental dataset has been used to validate HLA-A2 and -A3 SVM models. The SVM prediction models were integrated into a web-based computational system MULTIPRED1, accessible at antigen.i2r.a-star.edu.sg/multipred1/.

Adjuvant properties of listeriolysin O protein in a DNA vaccination strategy

The use of infectious agents as vaccine adjuvants has shown utility in both prophylactic and therapeutic vaccinations. Listeria monocytogenes has been used extensively as a vaccine vehicle due to its ability to initiate both CD4(+) and CD8(+) immune responses. Previous work from this laboratory has used transgenic Listeria to deliver vaccine constructs. A chimeric protein composed of tumor antigen and a non-hemolytic variant of the Listeria protein, listeriolysin O (LLO), has demonstrated effective tumor protection beyond that of antigen alone expressed in the same system. To address the question of how fusion with LLO improves vaccine efficacy, we constructed a number of DNA plasmid vaccines to isolate this effect in the absence of other endogenous Listeria effects. Here we have analyzed the ability of these vaccines to induce the regression of previously established tumors. A vaccine strategy using DNA vaccines bearing the tumor antigen either alone or in combination with LLO in addition to plasmids encoding MIP-1alpha and GM-CSF was examined. Further, LLO was used either as a chimera or in a bicistronic construct to address the importance of fusion between these elements. Notably, the strategies employing both chimeric and bicistronic vaccines were effective in reducing tumor burden suggesting that LLO can act as an adjuvant that does not require fusion with the tumor antigen to mediate its effect.

Deficiencies in myeloid antigen-presenting cells in women with cervical squamous intraepithelial lesions

BACKGROUND

There is little information on the function of dendritic cells in women with human papillomavirus (HPV)-related cervical squamous intraepithelial lesions (SILs). In the current study the functions of dendritic cells in the development of T-cell immunity in women with cervical SILs were assessed.

METHODS

The percentage of myeloid dendritic cells (MDCs) and plasmacytoid dendritic cells (PDCs) in peripheral blood were enumerated of 44 patients with SIL (low-grade, 19; high-grade, 25), 19 patients with atypical squamous cells of undetermined significance (ASCUS), and 18 controls. The expression of costimulatory receptors was assessed and the ability of monocyte-derived dendritic cells (MDDC) to present HPV16-E6 and HPV16-E7 antigens to autologous T cells.

RESULTS

Patients with either low (L)-grade or high (H)-grade SIL had significantly lower median plasma levels of interferon-gamma than did the controls (P = .038 and .031, respectively). Compared with the controls, patients with ASCUS or LSILs had significantly lower median percentages of MDCs (P = .002 and P < .001, respectively), and significantly lower median percentages of MDDCs that expressed CD86 (P < .001 and P = .003, respectively) and major histocompatability complex class-II antigen human leukocyte antigen DR (HLA-DR) (P = .012 and P < .001, respectively). T cells of patients with ASCUS or LSILs proliferated less than those of the controls in response to HPV16-E7 (P = .002 and .046, respectively).

CONCLUSIONS

Low levels of peripheral blood MDCs and of MDDCs expressing CD86 and HLA-DR suggest that deficiencies in the ability of MDDC to present antigen to autologous T cells may lead to persistent infection with HPV and the development of cervical SILs in HPV-infected women.

Toll-like receptor adaptor molecules enhance DNA-raised adaptive immune responses against influenza and tumors through activation of innate immunity

Toll-like receptors (TLRs) recognize microbial components and trigger the signaling cascade that activates the innate and adaptive immunity. TLR adaptor molecules play a central role in this cascade; thus, we hypothesized that overexpression of TLR adaptor molecules could mimic infection without any microbial components. Dual-promoter plasmids that carry an antigen and a TLR adaptor molecule such as the Toll-interleukin-1 receptor domain-containing adaptor-inducing beta interferon (TRIF) or myeloid differentiation factor 88 (MyD88) were constructed and administered to mice to determine if these molecules can act as an adjuvant. A DNA vaccine incorporated with the MyD88 genetic adjuvant enhanced antigen-specific humoral immune responses, whereas that with the TRIF genetic adjuvant enhanced cellular immune responses. Incorporating the TRIF genetic adjuvant in a DNA vaccine targeting the influenza HA antigen or the tumor-associated antigen E7 conferred superior protection. These results indicate that TLR adaptor molecules can bridge innate and adaptive immunity and potentiate the effects of DNA vaccines against virus infection and tumors.

E6/E7 expression of human papillomavirus types in cutaneous squamous cell dysplasia and carcinoma in immunosuppressed organ transplant recipients

BACKGROUND

DNA of cutaneous human papillomavirus (HPV) types is frequently found in nonmelanoma skin cancer, and their E6 and E7 proteins can have transforming properties.

OBJECTIVES

To assess the biological activity of HPV types found in tumour tissues we examined HPV E6/E7 RNA expression and the antibody response to E6, E7 and L1 proteins.

METHODS

Thirty-one snap-frozen biopsies from six immunosuppressed organ transplant recipients representing seven squamous cell carcinomas (SCCs), one basal cell carcinoma, four actinic keratoses (AKs), seven normal skin and 12 verrucae vulgaris (Vv) were analysed for 24 cutaneous HPV types by an L1 DNA polymerase chain reaction (PCR)-based method. The presence of E6/E7 transcripts of HPV 5, 8, 9, 15 and 20 was investigated by real-time reverse transcription-PCR. HPV DNA load was determined for HPV 8, 9 and 15 in 11 biopsies. Antibody response was measured by enzyme-linked immunosorbent assay using affinity-purified, bacterially expressed complete viral proteins fused to glutathione S-transferase as antigens.

RESULTS

HPV DNA was detected in 25 of 31 tissue samples, indicating eight single and 17 multiple HPV infections. E6/E7 transcripts of HPV 8, 9 and 15 were found in low copy numbers in one SCC and three AKs, but not in normal skin or Vv. All four patients examined showed antibodies to cutaneous HPV antigens, but the antibody response did not correlate with E6/E7 expression detected in the tumour.

CONCLUSIONS

Transcriptional activity of the E6/E7 oncogenes in AK and SCC suggests an active role of HPV in the lesion.

A trial of SGN-00101 (HspE7) to treat high-grade anal intraepithelial neoplasia in HIV-positive individuals

OBJECTIVES

To test a therapeutic vaccine consisting of a fusion of the human papillomavirus (HPV) 16 E7 protein and the Mycobacterium bovis heat shock protein 65 (SGN-00101) to treat high-grade anal intraepithelial neoplasia (HG-AIN) in HIV-positive individuals.

DESIGN

A phase I/II trial with three cohorts of five participants each, sequentially assigned to receive 100, 500 or 1000 microg SGN-00101, injected three times subcutaneously in alternating thighs at 4-week intervals. Anal disease was assessed at baseline, 8, 12, 24 and 48 weeks and was classified as the more severe of anal cytology and anal biopsy. Anal HPV DNA was detected using L1 consensus primer-based PCR followed by type-specific probing and dot-blot hybridization (DBH). HPV16, 18 and 31 DNA copy numbers were measured using quantitative real-time PCR.

SETTING

University-based research clinic.

PARTICIPANTS

Thirteen HIV-positive men and two HIV-positive women with HG-AIN.

RESULTS

There were no drug-related serious adverse events or significant changes in HIV viral load and CD4/CD8 ratio. At 48 weeks, two of five participants in both the 100 and 500 microg cohorts regressed to AIN 1 and one of five participants in the 1000 microg cohort regressed to atypical squamous cells of undetermined significance (ASC-US). All participants had at least one oncogenic HPV type at baseline. Three of five (60%) participants who regressed to AIN 1 or ASC-US became HPV-negative using DBH and real-time PCR, compared with none of 10 participants with no clinical response (P = 0.02).

CONCLUSIONS

SGN-00101 was well tolerated in HIV-positive individuals, with preliminary evidence for clinical activity.

Oral administration of human papillomavirus type 16 E7 displayed onLactobacillus casei induces E7-specific antitumor effects in C57/BL6 mice

The mounting of a specific immune response against the human papillomavirus type 16 E7 protein (HPV16 E7) is important for eradication of HPV16 E7-expressing cancer cells from the cervical mucosa. To induce a mucosal immune response by oral delivery of the E7 antigen, we expressed the HPV16 E7 antigen on the surface of Lactobacillus casei by employing a novel display system in which the poly-gamma-glutamic acid (gamma-PGA) synthetase complex A (PgsA) from Bacillus subtilis (chungkookjang) was used as an anchoring motif. After surface expression of the HPV16 E7 protein was confirmed by Western blot, flow cytometry and immunofluorescence microscopy, mice were orally inoculated with L. casei-PgsA-E7. E7-specific serum IgG and mucosal IgA productions were enhanced after oral administration and significantly enhanced after boosting. Systemic and local cellular immunities were significantly increased after boosting, as shown by increased counts of lymphocytes (SI = 9.7 +/- 1.8) and IFN-gamma secreting cells [510 +/- 86 spot-forming cells/10(6)cells] among splenocytes and increased IFN-gamma in supernatants of vaginal lymphocytes. Furthermore, in an E7-based mouse tumor model, animals receiving orally administered L. casei-PgsA-E7 showed reduced tumor size and increased survival rate versus mice receiving control (L. casei-PgsA) immunization. These results collectively indicate that the oral administration of E7 displayed on lactobacillus induces cellular immunity and antitumor effects in mice.