Acquisition of human papillomavirus (HPV) results in an infection of variable duration which may or may not be associated with clinically apparent lesions. Lesions caused by skintropic HPV types generally manifest as cutaneous warts and most often resolve over a period of months to years. On the other hand, anogenital infections are more likely to remain clinically inapparent. The development of DNA amplificationbased tests has demonstrated that anogenital infections are quite common and generally self-limited. For example, we and others have shown by PCR testing of multiple samples collected at different points in time-that 70 to 90% of sexually active adolescents and young women who develop an incident cervical HPV infection will show clearance of infection within 12 to 30 months (47, 61, 94). The factors influencing the natural history of these infections are not well understood. Given that persistent anogenital infection with oncogenic HPV types is associated with increased risk of neoplasia and invasive cancers (22, 59, 70, 71, 94, 124) and that cervical carcinoma remains a leading cause of death among women in developing countries (129), understanding these factors is of considerable importance. Substantial effort has been directed recently at understanding the role of the host’s immune response in the natural history of HPV, and in particular, anti-viral, cell-mediated immunity. Empirical evidence for the importance of cell-mediated immunity in control of HPV infection comes from an extensive body of literature documenting the increased prevalence of HPV infection and associated disease among immunosuppressed populations, including those with iatrogenic immunosuppression such as renal transplant recipients and individuals with human immunodeficiency virus (HIV) infection. Sillman and coauthors (128) reported in 1984 on 20 immunosuppressed women with various causes of immunosuppression who had lower genital neoplasia, describing evidence of associated HPV infection in all 20. Penn, in 1986, reported a 100-fold increase in cancer of the vulva and anus in renal transplant recipients (111). In the 1990s, as molecular testing for HPV infection came into its own, several reports confirmed increased incidence of HPV infection (50) and associated morbidities, including warts (77) and cervical squamous intraepithelial lesions (SIL) (104), among immunosuppressed renal

https://cvi.asm.org/content/cdli/8/2/209.full.pdf

Cell-mediated immune response to human papillomavirus infection.

One half of a group of 20 patients with human papillomavirus type 16 (HPV16)-induced vulvar intraepithelial neoplasia grade 3 displayed a complete regression (CR) after therapeutic vaccination with HPV16 E6/E7 synthetic long peptides. Patients with relatively larger lesions generally did not display a CR. To investigate immune correlates of treatment failure, patients were grouped according to median lesion size at study entry, and HPV16-specific immunity was analyzed at different time points by complementary immunological assays. The group of patients with smaller lesions displayed stronger and broader vaccine-prompted HPV16-specific proliferative responses with higher IFNgamma (P = 0.0003) and IL-5 (P < 0.0001) levels than patients with large lesions. Characteristically, this response was accompanied by a distinct peak in cytokine levels after the first vaccination. In contrast, the patient group with larger lesions mounted higher frequencies of HPV16-specific CD4(+)CD25(+)Foxp3(+) T cells (P = 0.005) and displayed a lower HPV16-specific IFNgamma/IL-10 ratio after vaccination (P < 0.01). No disparity in T memory immunity to control antigens was found, indicating that the differences in HPV-specific immunity did not reflect general immune failure. We observed a strong correlation between a defined set of vaccine-prompted specific immune responses and the clinical efficacy of therapeutic vaccination. Notably, a high ratio of HPV16-specific vaccine-prompted effector T cells to HPV16-specific CD4(+)CD25(+)Foxp3(+) T cells was predictive of clinical success. Foxp3(+) T cells have been associated previously with impaired immunity in malignancies. Here we demonstrate that the vaccine-prompted level of this population is associated with early treatment failure.

https://www.pnas.org/content/pnas/107/26/11895.full.pdf

Success or failure of vaccination for HPV16-positive vulvar lesions correlates with kinetics and phenotype of induced T-cell responses

Papillomaviruses have evolved mechanisms that result in escape from host immune surveillance. The E5 protein is expressed early in papillomavirus infection in the deep layers of the infected epithelium. It is localized to the Golgi apparatus (GA) and endoplasmic reticulum. The E5 protein of bovine papillomavirus (BPV) impairs the synthesis and stability of major histocompatibility (MHC) class I complexes and prevents their transport to the cell surface due to retention in the GA. Here we show that human papillomavirus type 16 (HPV-16) E5 also causes the retention of MHC (HLA) class I complexes in the GA and impedes their transport to the cell surface, which is rescued by treatment with interferon. Unlike BPV E5, HPV-16 E5 does not affect the synthesis of HLA class I heavy chains or the expression of the transporter associated with antigen processing TAP. These results show that downregulation of surface MHC class I molecules is common to both BPV and HPV E5 proteins. Moreover, we determined that HPV-16 E5 downregulates surface expression of HLA-A and HLA-B, which present viral peptides to MHC class I-restricted cytotoxic T lymphocytes (CTLs), but not the natural killer (NK) cell inhibitory ligands HLA-C and HLA-E. Selective downregulation of cell surface HLA class I molecules may allow the virus to establish infection by avoiding immune clearance of virus-infected cells by both CTLs and NK cells.

/pdf/e5-protein-of-human-papillomavirus-type-16-selectively-2xe3ei70j3.pdf

E5 protein of human papillomavirus type 16 selectively downregulates surface HLA class I.

It has long been a matter of debate whether tumors are spontaneously immunogenic in patients. With the availability of sensitive methods, naturally occurring T cells directed against tumor-associated antigens (TAAs) can be frequently detected in cancer patients. In this review, we summarize the current data on T cell responses to TAAs in various malignancies, including melanoma, colorectal cancer, leukemia, and breast cancer. T cell responses against various antigens, including melanoma differentiation antigens, carcinoembryonic antigen, epithelial cell adhesion molecule, her-2/neu, Wilms' tumor protein, proteinase 3, NY-ESO-1, and surviving, have been reported in a substantial number of patients. In contrast, other TAAs, including most antigens of the MAGE family, do not usually elicit spontaneous T cell responses. A distinction between direct ex vivo T cell responses and in vitro-generated T cell responses is provided because in vitro stimulation results in quantitative and functional changes of T cell responses. The possible role of TAA-specific T cells in immunosurveillance and tumor escape and the implications for immunological treatment strategies are discussed. Naturally occurring T cells against TAAs are a common phenomenon in tumor patients. Understanding the mechanisms and behavior of natural TAA-specific T cells could provide crucial information for rational development of more efficient T cell-directed immunotherapy.

https://clincancerres.aacrjournals.org/content/clincanres/9/12/4296.full.pdf

Natural T cell immunity against cancer.

Human papillomavirus type 16 (HPV16) infection has been linked to the development of cervical and anal dysplasia and cancer. One hallmark of persistent infection is the synthesis of the viral E7 protein in cervical epithelial cells. The expression of E7 in dysplastic and transformed cells and its recognition by the immune system as a foreign antigen make it an ideal target for immunotherapy. Utilizing the E7-expressing murine tumour cell line, TC-1, as a model of cervical carcinoma, an immunotherapy based on the administration of an adjuvant-free fusion protein comprising Mycobacterium bovis BCG heat shock protein (hsp)65 linked to HPV16 E7 (hspE7) has been developed. The data show that prophylactic immunization with hspE7 protects mice against challenge with TC-1 cells and that these tumour-free animals are also protected against re-challenge with TC-1 cells. In addition, therapeutic immunization with hspE7 induces regression of palpable tumours, confers protection against tumour re-challenge and is associated with long-term survival (> 253 days). In vitro analyses indicated that immunization with hspE7 leads to the induction of a Th1-like cell-mediated immune response based on the pattern of secreted cytokines and the presence of cytolytic activity following antigenic recall. In vivo studies using mice with targeted mutations in CD8 or MHC class II or depleted of CD8 or CD4 lymphocyte subsets demonstrate that tumour regression following therapeutic hspE7 immunization is CD8-dependent and CD4-independent. These studies extend previous observations on the induction of cytotoxic T lymphocytes by hsp fusion proteins and are consistent with the clinical application of hspE7 as an immunotherapy for human cervical and anal dysplasia and cancer.

https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2249.2000.01293.x

Immunotherapy of a human papillomavirus (HPV) type 16 E7-expressing tumour by administration of fusion protein comprising Mycobacterium bovis bacille Calmette-Guérin (BCG) hsp65 and HPV16 E7.

Cervical cancer (CaCx) is the second most common female malignancy worldwide and remains a clinical problem despite improvements in early detection and therapy. CaCx and preinvasive cervical intraepithelial neoplasia (CIN3) are strongly associated with infection by human papillomavirus (HPV), particularly types 16 and 18. Two nonstructural viral proteins, E6 and E7, are constitutively expressed in cervical tumors and are crucial for the maintenance of the transformed phenotype. These proteins thus provide attractive targets for immunotherapy of CaCx mediated by CD8+ CTLs. However, reliable detection and generation of HPV-specific CTLs in humans has been difficult. Recently, soluble fluorogenic MHC-peptide complexes (tetramers) have greatly increased the sensitivity of antiviral and antitumor CTL detection. To examine the feasibility of this approach for detecting HPV-specific CTLs, we constructed a tetramer consisting of HLA-A*0201 and the best studied HPV CTL peptide epitope, HPV 16 E711-20. Between 2 and 12% of short-term HPV 16 E711-2 CTL lines derived from CaCx patients stained highly with the tetramer. Direct ex vivo staining of peripheral blood mononuclear cells revealed CD8+ tetramer+ high cells at low frequencies in both CIN3 patients (1 of 1,260 to 1 of 19,073) and normal controls (1 of 1,855 to 1 of 42,004). However, short-term in vitro stimulation with the HPV 16 E711-20 peptide expanded CD8+tetramer+ cells to a greater extent in the peripheral blood mononuclear cells from CIN3 patients. Furthermore, the tetramer provided a powerful tool to isolate polyclonal and clonal peptide-specific CTLs from an established HPV 16 E7,11-20-specific CTL line. These purified CTLs were able to lyse both peptide-pulsed targets and targets expressing endogenously processed HPV antigens. This tetramer may therefore be useful for selecting rare high-affinity HPV-specific CTLs for the immunotherapy of CaCx.

/pdf/use-of-fluorogenic-histocompatibility-leukocyte-antigen-a-2qvequo7b0.pdf

Use of Fluorogenic Histocompatibility Leukocyte Antigen-A*0201/HPV 16 E7 Peptide Complexes to Isolate Rare Human Cytotoxic T-Lymphocyte- recognizing Endogenous Human Papillomavirus Antigens

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Use of Fluorogenic Histocompatibility Leukocyte Antigen-A*0201/HPV 16 E7 Peptide Complexes to Isolate Rare Human Cytotoxic T-Lymphocyte- recognizing Endogenous Human Papillomavirus Antigens