Prevalence of IgG antibodies against Malawi polyomavirus in patients with autoimmune diseases and lymphoproliferative disorders subjected to bone marrow transplantation

Introduction

Human polyomaviruses (HPyVs) cause persistent/latent infections in a large fraction of the population. HPyV infections may cause severe diseases in immunocompromised patients. Malawi polyomavirus (MWPyV) is the 10th discovered human polyomavirus (HPyV 10). MWPyV was found in stool samples of healthy children. So far, the few investigations carried out on HPyV 10 did not find an association with human disease.

Methods

In this study, to verify the putative association between MWPyV and human diseases, MWPyV seroprevalence was investigated in patients affected by i) lymphoproliferative disorders (LPDs) and ii) immune system disorders, i.e., autoimmune diseases (ADs), and in iii) healthy subjects. An indirect ELISA, employing virus-like particles (VLPs) to detect serum IgG antibodies against MWPyV/HPyV 10, was carried out. The study also revealed the prevalence of another polyomavirus, Merkel cell polyomavirus (MCPyV).

Results

Sera from patients with distinct autoimmune diseases (n = 44; mean age 20 years) had a prevalence of MWPyV antibodies of 68%, while in patients with lymphoproliferative disorders (n = 15; mean age 14 years), subjected to bone marrow transplantation, the prevalence was 47%. In healthy subjects (n = 66; mean age 13 years), the prevalence of MWPyV antibodies was 67%. Our immunological investigation indicates that MWPyV/HPyV 10 seroconversion occurs early in life and MWPyV/HPyV 10 appears to be another polyomavirus ubiquitous in the human population. A significantly lower MWPyV antibody reactivity together with a lower immunological profile was detected in the sera of LPD patients compared with HS2 (*p < 0.05) (Fisher's exact test). LPD and AD patients have a similar MCPyV seroprevalence compared with healthy subjects.

Discussion

MWPyV seroprevalence indicates that this HPyV is not associated with lymphoproliferative and autoimmune diseases. However, the ability to produce high levels of antibodies against MWPyV appears to be impaired in patients with lymphoproliferative disorders. Immunological investigations indicate that MWPyV seroconversion occurs early in life. MCPyV appears to be a ubiquitous polyomavirus, like other HPyVs, in the human population.

Prophylactic cancer vaccines: development and challenges for HBV and HPV vaccines in Latin America

Vaccines against hepatitis B virus (HBV) and human papillomaviruses (HPV) are two safe and highly effective vaccines that were developed at the end of the 20th century and can prevent human cancer. HBV vaccine prevents liver cancer, and HPV prevents cervical and other HPV-related cancers. Starting with the immunogen identification, 15 years were necessary to reach the industrial production of HBV vaccine, and 20 years, for the HPV vaccines. However, while HBV vaccines have been commercially available for over 40 years and are used in most countries, there are still significant challenges to achieve universal childhood immunization against hepatitis B. Similarly, HPV vaccines have been commercially available for 17 years, and yet, countries with higher cervical cancer still have the lowest HPV vaccination rates. We describe the development of HBV and HPV vaccines and discuss the challenges to reaching equitable access to these vaccines in Latin America.

Prognostic value of antibodies to Merkel cell polyomavirus T antigens and VP1 protein in patients with Merkel cell carcinoma

BACKGROUND

Merkel cell polyomavirus (MCPyV) is the main aetiological agent of Merkel cell carcinoma (MCC). Serum antibodies against the major MCPyV capsid protein (VP1) are detected in the general population, whereas antibodies against MCPyV oncoproteins (T antigens) have been reported specifically in patients with MCC.

OBJECTIVES

The primary aim was to assess whether detection of serum antibodies against MCPyV proteins at baseline was associated with disease outcome in patients with MCC. The secondary aim was to establish whether evolution of these antibodies during follow-up was associated with the course of the disease.

METHODS

Serum T-antigen and VP1 antibodies were assessed by enzyme-linked immunosorbent assay using recombinant proteins in a cohort of 143 patients with MCC, including 84 patients with serum samples available at baseline.

RESULTS

Low titres of VP1 antibodies at baseline (< 10 000) were significantly and independently associated with increased risk of recurrence [hazard ratio (HR) 2·71, 95% confidence interval (CI) 1·13-6·53, P = 0·026] and death (HR 3·74, 95% CI 1·53-9·18, P = 0·004), whereas T-antigen antibodies were not found to be associated with outcome. VP1 antibodies did not differ between patients in remission and those with recurrence or progression during follow-up. However, T-antigen antibodies were more frequently detected in patients with recurrence or progression at 12 months (P = 0·020) and 24 months (P = 0·016) after diagnosis.

CONCLUSIONS

VP1 antibodies constitute a prognostic marker at baseline, whereas T-antigen antibodies constitute a marker of disease recurrence or progression if detected > 12 months after diagnosis.

Antibodies to VP1 of swine pasivirus in humans without evidence of transmission from a pig source

BACKGROUND

Swine pasivirus (SPaV1) is a recently described enteric virus close to human parechoviruses and highly prevalent in pigs. Antibodies to Escherichia coli-expressed VP1 of SpaV1 have been found in a majority of humans in China.

OBJECTIVES

The objectives were to estimate the antibody prevalence in a European country, to test if exposure to the virus was linked to pig products and if this exposure was a risk factor for the development of diabetes type 1.

STUDY DESIGN

An ELISA test was developed and used to screen 842 healthy subjects with known exposure to pig products, 39 patients with diabetes type 1 and 20 controls.

RESULTS

We identified a high seroprevalence (15.6%) reacting to VP1 of SPaV1 among healthy human subjects. Analysis of risk factors argues against cross-species transmission from pigs as the source of infection. Data also indicate that the presence of SPaV1 VP1-binding antibodies is not associated with diabetes type 1 in humans.

CONCLUSION

Our results suggest that the seroreactivity frequently found in humans against SpaV1 is due to cross-reactivity with related antigen, perhaps a picornavirus, and that SpaV1 is not a zoonotic virus.

Identification of the neutralizing epitopes of Merkel cell polyomavirus major capsid protein within the BC and EF surface loops

Merkel cell polyomavirus (MCPyV) is the first polyomavirus clearly associated with a human cancer, i.e. the Merkel cell carcinoma (MCC). Polyomaviruses are small naked DNA viruses that induce a robust polyclonal antibody response against the major capsid protein (VP1). However, the polyomavirus VP1 capsid protein epitopes have not been identified to date. The aim of this study was to identify the neutralizing epitopes of the MCPyV capsid. For this goal, four VP1 mutants were generated by insertional mutagenesis in the BC, DE, EF and HI loops between amino acids 88-89, 150-151, 189-190, and 296-297, respectively. The reactivity of these mutants and wild-type VLPs was then investigated with anti-VP1 monoclonal antibodies and anti-MCPyV positive human sera. The findings together suggest that immunodominant conformational neutralizing epitopes are present at the surface of the MCPyV VLPs and are clustered within BC and EF loops.

Somatostatin Receptors 2A and 5 Are Expressed in Merkel Cell Carcinoma with No Association with Disease Severity

BACKGROUND/AIMS

Merkel cell carcinoma (MCC) is a rare high-grade neuroendocrine tumour of the skin. It has been speculated that MCCs express somatostatin receptors (SSTRs), but this has never been assessed in a large series of MCCs. The main aim of this study was to assess the expression of SSTR2A and SSTR5 in MCC tumours. The secondary aims were to assess whether expression of SSTR was associated with the Ki67 proliferative index, Merkel cell polyomavirus (MCPyV) status, clinical characteristics and outcome.

METHODS

Clinical data and tumours were collected from an ongoing cohort of French patients with MCC. Immunohistochemistry was performed with anti-SSTR2A and anti-SSTR5 monoclonal antibodies, and tumours were classified into 3 groups: 'no expression', 'low expression' and 'moderate expression' using an SSTR staining score.

RESULTS

SSTR expression was assessed for 105 MCC tissue samples from 98 patients, and clinical characteristics were available for 87 of them. SSTR expression was consistent between the primary skin tumour and the corresponding metastases for SSTR2A and SSTR5 in 3/7 and 6/7 cases, respectively. SSTR2A and SSTR5 were expressed in 58 cases (59.2%) and in 44 cases (44.9%), respectively. Overall, at least one SSTR was expressed in 75 tumours (76.5%). SSTR expression was not associated with clinical characteristics, Ki67 proliferative index, recurrence-free survival or MCC-specific survival. Expression of SSTR2A was associated with MCPyV status in MCC tumours but not SSTR5.

CONCLUSION

SSTRs were expressed in a high proportion of MCCs, although expression was heterogeneous between tumours and was not associated with disease severity.

Merkel cell polyomavirus in merkel cell carcinoma: clinical and therapeutic perspectives

Merkel cell carcinoma (MCC) is a rare and often aggressive cutaneous cancer with a poor prognosis. The incidence of this cancer increases with age, immunodeficiency and sun exposure. Merkel cell polyomavirus (MCPyV), a new human polyomavirus identified in 2008, is detected in the majority of the MCCs and there is a growing body of evidence that healthy human skin harbors resident or transient MCPyV. A causal link between MCPyV and MCC has been evidenced and this is the first polyomavirus to be clearly implicated as a causal agent underlying a human cancer, and MCPyV was recently classified as a 2A carcinogen. MCC is thus a rare tumor caused by a very common viral skin infection. The aim of this review is to provide a basic overview of the epidemiological, clinical, and pathological characteristics of MCC, to present the current knowledge on MCPyV polyomavirus and its causal association with MCC development, and to describe the therapeutic implications of this causal link.

Natural killer and dendritic cells collaborate in the immune response induced by the vaccine against uterine cervical cancer

Virus-like particles (VLPs) of human papillomavirus (HPV) are used as a vaccine against HPV-induced cancer, and recently we have shown that these VLPs are able to activate natural killer (NK) cells. Since NK cells collaborate with dendritic cells (DCs) to induce an immune response against viral infections and tumors, we studied the impact of this crosstalk in the context of HPV vaccination. NK cells in the presence of HPV-VLPs enhanced DC-maturation as shown by an upregulation of CD86 and HLA-DR and an increased production of IL-12p70, but not of the immunosuppressive cytokine IL-10. This activation was bidirectional. Indeed, in the presence of HPV-VLPs, DCs further activated NK cells by inducing the upregulation of cell surface activation markers (CD69 and HLA-DR). The function of NK cells was also improved as shown by an increase in IFN-γ secretion and cytotoxic activity against an HPV(+) cell line. This crosstalk between NK cells and DCs needed CD40 interaction and IL-12p70 secretion, whereas NKG2D was not implicated. Our results provide insight into how VLPs interact with innate immune cells and how NK cells and DCs play a role in the immune response induced by this vaccine agent.

Screening of human papillomavirus infection in women with systemic sclerosis

OBJECTIVES

High risk human papilloma-viruses (HR HPV) are associated with risk of cervical dysplasia and carcinoma. The risk is increased in patients with immune deficiency or auto-immune disease as systemic lupus erythematosus. Currently, no data are available about the human papillomavirus status in women with systemic sclerosis (SSc).

METHODS

Thirty-one women with SSc were evaluated for cervical HPV infection and dysplasia, and compared to fifty age-matched control. Cervical swabs were tested by the INNO-LiPA assay®. Serum antibodies against HPV 16 and 18 were assessed using enzyme-linked immunosorbent assay in the SSc group.

RESULTS

The overall HPV frequency was comparable between SSc and controls (32% vs. 38%), as well as the HR HPV frequency (28% vs. 34%), but infection by ≥2 HPV was two times more frequent in the SSc group (50% vs. 26% of the HPV positive samples). The most prevalent genotype was 52 in the SSc group (12%), and 52/53 in the control group (8% for both). Pap smears were within the normal range. Seropositivity for HPV 16 and 18 was 13% and 6.5%, respectively. A diffuse systemic sclerosis and a younger age at first intercourse were more frequent in cases of overall HPV positivity. Current smoking and a higher number of sexual partners were only observed in cases of seropositivity.

CONCLUSIONS

This is the first study to evaluate HPV status in women with SSc. HR HPV52 was the most common genotype with a greater multi-HPV infection rate. This result needs to be confirmed in a larger study.

Serological cross-reactivity between Merkel cell polyomavirus and two closely related chimpanzee polyomaviruses

Phylogenetic analyses based on the major capsid protein sequence indicate that Merkel cell polyomavirus (MCPyV) and chimpanzee polyomaviruses (PtvPyV1, PtvPyV2), and similarly Trichodysplasia spinulosa-associated polyomavirus (TSPyV) and the orangutan polyomavirus (OraPyV1) are closely related. The existence of cross-reactivity between these polyomaviruses was therefore investigated. The findings indicated serological identity between the two chimpanzee polyomaviruses investigated and a high level of cross-reactivity with Merkel cell polyomavirus. In contrast, cross-reactivity was not observed between TSPyV and OraPyV1. Furthermore, specific antibodies to chimpanzee polyomaviruses were detected in chimpanzee sera by pre-incubation of sera with the different antigens, but not in human sera.

Hepatitis E virus seroprevalence and risk factors for individuals in working contact with animals

BACKGROUND

In industrial countries genotypes 3 and 4 of HEV are detected in swine, wild boar, deer and rabbits, and they are associated with autochthonous infections suggesting the existence of zoonotic HEV infections, compatible with the putative involvement of undercooked pork and big game products as a source of infection.

OBJECTIVES

To evaluate the prevalence of anti-HEV antibodies in different population groups in contact with animals and to investigate risk factors for HEV infection.

STUDY DESIGN

Serum samples were collected from 859 healthy French subjects, including pig farm workers, forestry workers and individuals without working contact with animals (control group). In addition, 58 swine veterinarians were included in the study. Subjects were interviewed using a structured questionnaire, and anti-HEV antibodies were investigated using a sensitive and specific sandwich ELISA.

RESULTS

Anti-Hepatitis E virus (HEV) antibodies were detected in 26% of control population, and in 36% and 44% of forestry and pig farm workers, respectively. In addition, an increase in seroprevalence from the north to the south of France was observed (30.2% versus 40.7%). Consumption of pork liver sausage (AOR 4.4, p < 10(-4)), occupational contact with animals (AOR 1.58, p = 0.038 for forestry workers and AOR 2.51, p < 10(-4) for pig farm workers), and living in southern France (AOR 1.47, p = 0.02), were independent risk factors. Wearing working gloves and boots might reduce HEV infection.

CONCLUSIONS

Occupational exposure to animals and consuming raw or undercooked pork liver sausage or pork liver play a significant role in HEV transmission in industrial countries.

Merkel cell polyomavirus infection occurs during early childhood and is transmitted between siblings

Merkel cell polyomavirus (MCPyV) is thought to be the etiological agent of Merkel cell carcinoma, but little is known about its distribution and modes of transmission. We conducted seroepidemiological surveys in more than 1000 individuals, from two populations from Cameroon. Overall MCPyV seroprevalence was high in both populations (>75% in adults). Data from the first population, comprising mainly children, indicated that MCPyV infections mostly occurred during early childhood, after the disappearance of specific maternal antibodies. Results from the second family-based population provided evidence for familial aggregation of MCPyV infection status. We observed significant sib-sib correlation (odds ratio=3.42 [95% CI 1.27-9.19], p=0.014), particularly for siblings close together in age, and a trend for mother-child correlation (OR=2.71 [0.86-8.44], p=0.08). Overall, our results suggest that MCPyV infection is acquired through close contact, possibly involving saliva and/or the skin, especially between young siblings and between mothers and their children.

Human Merkel cell polyomavirus: virological background and clinical implications

The Merkel cell polyomavirus (MCPyV), identified in humans in 2008, is associated with a relatively rare but aggressive neuroendocrine skin cancer, the Merkel cell carcinoma (MCC). MCC incidence is increasing due to the advancing age of the population, the increase in damaging sun exposure and in the number of immunocompromised individuals. MCPyV must be considered as the etiological agent of MCC and thus is the first example of a human oncogenic polyomavirus. MCPyV infection is common, and seroprevalence studies indicate that widespread exposure begins early in life. The majority of adults have anti-MCPyV antibodies and there is a growing body of evidence that healthy human skin harbors resident or transient MCPyV suggesting that MCPyV infection persists throughout life. However, the mode of transmission, the host cells, and the latency characteristics of this virus remain to be elucidated. In addition, it is still not clear whether MCPyV is associated with diseases or lesions other than Merkel cell carcinoma. The etiologic role of MCPyV in MCC opens up opportunities to improve the understanding of this cancer and to potentially improve its treatment.

Lipid nanocapsule functionalization by lipopeptides derived from human papillomavirus type-16 capsid for nucleic acid delivery into cancer cells

Plasmid DNA (pDNA) and small interfering RNAs (siRNAs) are very useful tools for the treatment of cancer. However, pDNA and siRNAs efficacy is restricted by their negative charge and susceptibility to degradation by endonucleases that prevent them penetrating tissue and cellular barriers such as the plasma and endolysosomal membranes. Viral vectors have some advantages but their use is largely limited by their immunogenicity. On the other hand, synthetic nanoparticles have advantage of being relatively non-immunogenic but their ability to deliver nucleic acids remains less efficient than their viral counterparts. The present study is focussed on the development and evaluation of biomimetic lipid nanocapsules (LNCs) functionalized with a L1 papillomavirus type-16 capsid-derived lipopeptide on their surface, for transfection of U87MG glioma cells and Caco-2 colorectal adenocarcinoma cells with pDNA or siRNAs. Since the L1-peptide has been described as a nuclear localization signal able to complex with nucleic acids and bind to heparan sulfate on the cell surface, the structure and function of L1-peptide bound to LNCs (L1-LNCs) were investigated. Although L1-LNCs were shown to complex with both pDNA and siRNAs, the pDNA-L1-LNC complexes showed only weak transfection efficiency. In contrast, siRNA-L1-LNC complexes appeared as effective repressors of targeted messengers.

Vitamin D deficiency is associated with greater tumor size and poorer outcome in Merkel cell carcinoma patients

BACKGROUND

Merkel cell polyomavirus has been recognized to be associated with Merkel cell carcinoma (MCC), but the evolution of this cancer probably depends on various factors. Vitamin D deficiency, defined by serum 25-hydroxyvitamin D levels <50 nmol/L, seems to influence cancer behavior and progression, but has never been assessed in MCC patients.

OBJECTIVES

First, to evaluate whether vitamin D deficiency was associated with tumor characteristics and prognosis in a cohort of MCC patients. Second, to assess expression of the vitamin D receptor (VDR) in MCC tumors.

METHODS

Clinical findings, Merkel cell polyomavirus markers and vitamin D status were assessed in a cohort of French MCC patients. The study was limited to the 89 patients for whom the serum sample had been collected within 3 years after the diagnosis of MCC. Correlation between vitamin D deficiency and MCC characteristics and outcome were determined in regression analyses. VDR expression in MCC tumours was assessed by immunohistochemistry.

RESULTS

Vitamin D deficiency was noted in 65.1% of the patients and was independently associated with greater tumor size at diagnosis (P = 0.006) and with metastasis recurrence (HR, 2.89; 95% CI, 1.03 to 8.13; P = 0.043), but not with death from MCC, although there was a trend (HR, 5.28; 95% CI, 0.75 to 36.96; P = 0.093). VDR was found to be strongly expressed in all 28 MCC tumor specimens investigated.

CONCLUSION

The association between vitamin D deficiency and MCC characteristics and outcome, together with detection of the VDR in MCC cells, suggest that vitamin D could influence the biology of MCC.

Seroprevalence and cross-reactivity of human polyomavirus 9

Many humans have antibodies against simian lymphotropic polyomavirus (LPyV), but its DNA has not been found in humans. Identification of human polyomavirus 9 (HPyV9) led us to compare the seroprevalence and cross-reactivity of LPyV and HpyV9. Results could indicate that humans who have antibodies against LPyV are infected by HPyV9.

High Levels of Antibodies Against Merkel Cell Polyomavirus Identify a Subset of Patients With Merkel Cell Carcinoma With Better Clinical Outcome

Purpose

A new human polyomavirus, Merkel cell polyomavirus (MCV), was identified in 2008 in tumor tissue of patients with Merkel cell carcinoma (MCC), a relatively rare human skin cancer. In this study, we investigated patients with MCC and controls for the presence of antibodies against MCV and their association with clinical characteristics.

Patients and Methods

Antibodies against MCV were investigated by enzyme-linked immunosorbent assay in 68 patients with MCC and 82 controls using VP1 virus-like particles produced in insect cells.

Results

Antibodies against MCV were detected in all patients with MCC and in 85% of controls. However, high antibody titers (> 10,000) were rarely observed in controls (7.3%) and they were detected in 64.7% of patients with MCC (P < .001) in contrast to the absence of VP1 expression in tumor samples. In addition, the geometric mean titer of anti-MCV in patients with MCC was around 14 times higher than that observed in MCV-positive controls (P < .001) and was not correlated with tumor viral load. High antibody titers were not found to be associated with any subject or tumor characteristics, but better progression-free survival was observed in patients with high antibody titers (hazard ratio, 4.6; 95% CI, 1.7 to 12.2; P = .002).

Conclusion

High titers of MCV antibodies in a much higher proportion of patients with MCC than in controls confirmed the association between MCV infection and MCC. The findings also indicated that a better progression-free survival occurred in patients with high MCV antibody titers and suggested that there are at least two distinct etiologic causes of MCC.

Seroprevalence of antibodies against human papillomavirus (HPV) types 16 and 18 in four continents: the International Agency for Research on Cancer HPV Prevalence Surveys

BACKGROUND

Few human papillomavirus (HPV) seroprevalence studies have been carried out in women from low-resource countries.

METHODS

Seroprevalence of antibodies against HPV16 and HPV18 was assessed in 7,074 women ≥15 years of age (median 44 years) from eight world areas. Serum antibodies against HPV16 and HPV18 were tested for using enzyme-linked immunosorbent assay. HPV DNA was assessed using a general primer GP5+/6+-mediated PCR.

RESULTS

HPV16 and HPV18 seroprevalence both ranged from <1% (Hanoi, Vietnam) to >or=25% (Nigeria). Of women who were HPV16 or HPV18 DNA-positive, seropositivity for the same type was 39.8% and 23.2%, respectively. Seropositivity for either type was directly associated with markers of sexual behavior. HPV16 and/or 18 (HPV16/18)-seropositive women had an increased risk of having cytologic abnormalities only if they were also HPV DNA-positive. A high international correlation was found between HPV16/18 seroprevalence and overall HPV DNA prevalence (r = 0.81; P = 0.022). However, HPV16/18 seroprevalence was substantially higher than the corresponding DNA prevalence in all study areas (although to different extents) and, contrary to DNA, tended to increase from young to middle age, and then decline or remain fairly constant. In all study areas, the vast majority of the information on the burden of exposure to HPV16/18 derived from serology.

CONCLUSIONS

The correlation between HPV DNA and HPV serology was not very good at an individual woman level, but high at a population level.

IMPACT

HPV serology is a poor marker of current infection or related lesions, but it can contribute, together with DNA, in evaluating the variations in the burden of HPV infection worldwide.

Papillomavirus pseudovirions packaged with the L2 gene induce cross-neutralizing antibodies

BACKGROUND

Current vaccines against HPVs are constituted of L1 protein self-assembled into virus-like particles (VLPs) and they have been shown to protect against natural HPV16 and HPV18 infections and associated lesions. In addition, limited cross-protection has been observed against closely related types. Immunization with L2 protein in animal models has been shown to provide cross-protection against distant papillomavirus types, suggesting that the L2 protein contains cross-neutralizing epitopes. However, vaccination with L2 protein or L2 peptides does not induce high titers of anti-L2 antibodies. In order to develop a vaccine with the potential to protect against other high-risk HPV types, we have produced HPV58 pseudovirions encoding the HPV31 L2 protein and compared their capacity to induce cross-neutralizing antibodies with that of HPV L1 and HPV L1/L2 VLPs.

METHODS

The titers of neutralizing antibodies against HPV16, HPV18, HPV31 and HPV58 induced in Balb/c mice were compared after immunization with L2-containing vaccines.

RESULTS

Low titers of cross-neutralizing antibodies were detected in mice when immunized with L1/L2 VLPs, and the highest levels of cross-neutralizing antibodies were observed in mice immunized with HPV 58 L1/L2 pseudovirions encoding the HPV 31 L2 protein.

CONCLUSIONS

The results obtained indicate that high levels of cross-neutralizing antibodies are only observed after immunization with pseudovirions encoding the L2 protein. HPV pseudovirions thus represent a possible new strategy for the generation of a broad-spectrum vaccine to protect against high-risk HPVs and associated neoplasia.

Identification of neutralizing conformational epitopes on the human papillomavirus type 31 major capsid protein and functional implications

The aim of this study was to characterize the conformational neutralizing epitopes of the major capsid protein of human papillomavirus type 31. Analysis of the epitopes was performed by competitive epitope mapping using 15 anti-HPV31 and by reactivity analysis using a HPV31 mutant with an insertion of a seven-amino acid motif within the FG loop of the capsid protein. Fine mapping of neutralizing conformational epitopes on HPV L1 was analyzed by a new approach using a system displaying a combinatorial library of constrained peptides exposed on E. coli flagella. The findings demonstrate that the HPV31 FG loop is dense in neutralizing epitopes and suggest that HPV31 MAbs bind to overlapping but distinct epitopes on the central part of the FG loop, in agreement with the exposure of the FG loop on the surface of HPV VLPs, and thus confirming that neutralizing antibodies are mainly located on the tip of capsomeres. In addition, we identified a crossreacting and partially crossneutralizing conformational epitope on the relatively well conserved N-terminal part of the FG loop. Moreover, our findings support the hypothesis that there is no correlation between neutralization and the ability of MAbs to inhibit VLP binding to heparan sulfate, and confirm that the blocking of virus attachment to the extracellular matrix is an important mechanism of neutralization.

[HPV immunization for the prevention of cervical cancer]

CONTEXT

Human Papillomaviruses (HPV) infect epithelial cells of the skin and mucosae. Mucosal high-risk HPV types (mainly HPV 16 and 18) are involved in the development of cervical cancer, one of the most common cancers in young women. HPV infection is usually asymptomatic and clears spontaneously, but 10 - 15 % of high-risk HPV infections are persistent and increase the risk of precancerous and cancerous lesions of the cervix. Two HPV vaccines have been licensed to provide protection against cervical cancer.

OBJECTIVES

To report the different aspects of HPV infection in order to improve the understanding of the particular problems of HPV vaccination and to review the most recent findings related to HPV vaccines, particularly regarding the protective efficacy of vaccines and the roles of adjuvants and immune response in protection.

METHODS

Articles were selected from the PubMed database (National Library of Medicine- National Institute of Health) with the following Keywords "HPV", "Prevention", "HPV vaccines", "Immune response", "Antibody". Abstracts of oral presentations from international meetings were also selected for the more recent findings. a critical analysis of the majority of papers published was undertaken and relevant information summarized.

RESULTS

Virus-like particle production by expressing the major protein of the HPV capsid was carried out in the early 90's, leading to the recent development of two HPV vaccines. These vaccines are now licensed in many countries and have been demonstrated to be highly immunogenic. In subjects that are non-infected at the time of vaccination, HPV vaccines are highly effective in preventing persistent HPV 16 - 18 infections (90 %) and precursors lesions of cervical cancer associated with these two HPV types (close to 100 %). Clinical trials have also confirmed that HPV vaccines are well tolerated by recipients.

CONCLUSIONS

The present paper is a detailed review published in French on HPV vaccines, their efficacy in the prevention of HPV infections and unresolved questions regarding the use of HPV vaccines. This report also includes biological and immunological information to improve the understanding of HPV vaccination.

Merkel cell polyomavirus strains in patients with merkel cell carcinoma

We investigated whether Merkel cell carcinoma (MCC) patients in France carry Merkel cell polyomavirus (MCPyV) and then identified strain variations. All frozen MCC specimens and 45% of formalin-fixed and paraffin-embedded specimens, but none of the non-MCC neuroendocrine carcinomas specimens, had MCPyV. Strains from France and the United States were similar.

Human papillomavirus L1 protein expressed in tobacco chloroplasts self-assembles into virus-like particles that are highly immunogenic

Cervical cancer is the second most prevalent cancer in women worldwide. It is linked to infection with human papillomavirus (HPV). As the virus cannot be propagated in culture, vaccines based on virus-like particles have been developed and recently marketed. However, their high costs constitute an important drawback for widespread use in developing countries, where the incidence of cervical cancer is highest. In a search for alternative production systems, the major structural protein of the HPV-16 capsid, L1, was expressed in tobacco chloroplasts. A very high yield of production was achieved in mature plants (approximately 3 mg L1/g fresh weight; equivalent to 24% of total soluble protein). This is the highest expression level of HPV L1 protein reported in plants. A single mature plant synthesized approximately 240 mg of L1. The chloroplast-derived L1 protein displayed conformation-specific epitopes and assembled into virus-like particles, visible by transmission electron microscopy. Furthermore, leaf protein extracts from L1 transgenic plants were highly immunogenic in mice after intraperitoneal injection, and neutralizing antibodies were detected. Taken together, these results predict a promising future for the development of a plant-based vaccine against HPV.

BK virus and cancer in Uganda

As part of an epidemiological study of cancer in Uganda, we investigated the titre of antibodies against BK virus among 821 people with different cancer types and benign tumours. Among study participants, 790 were considered seropositive for anti-BK virus antibodies and all analyses were conducted on transformed data. The mean optical density (a measure of antibody titre) for all patients combined (including the 31 who were considered seronegative) was 1.03 (standard error 0.01), but was 5% higher in women than in men (P=0.05), and 8% higher among HIV seropositive than seronegative people (P=0.002). Otherwise, there were few consistent associations between anti-BK virus antibodies and any social and lifestyle factor investigated. Differences in the mean optical density for each cancer type were estimated using multivariate analysis of variance with adjustment for sex, age group and HIV serostatus, using all other patients as controls. The mean optical density was about 17% lower among those with oral cancer (optical density 0.86, standard error 0.06; P=0.01, based on 30 patients) and about 20% higher among those with prostate cancer (optical density 1.22, standard error 0.09; P=0.01, based on 11 cases) than among all other patients combined. The number of cases of each cancer was too small to exclude the possibility of these findings arising by chance. No other cancer site or type was significantly associated with low, or with high anti-BK virus antibody titres.

[Human papillomavirus (HPV) vaccines]

In the last 15 years, fifteen of the human papillomaviruses (HPVs) that infect the genital tract have been recognized as the etiological agents of cervical cancer. Cervical cancer is thus a cancer that could be prevented by immuniza- tion. The recently licensed HPV subunit vaccine and the availability of another prophylactic vaccine in the near future for types 16 and 18 make this a realizable goal. The safety, immunogenicity and efficacy demonstrated for two vaccines are very promising. Phase I and phase II clinical trials have determined the tolerance, immunogenicity, dose and schedule of injections and phase IIb and phase III clinical trials have demonstrated the high efficacy of these vaccines. More than 80 % protection against incident infections was observed and close to 100 % protection was observed against persistent infections associated with cervical lesions. Anti-HPV antibodies persisted for 4-5 years, with antibody titers 5 to 17 times higher than observed in control subjects with anti-HPV antibodies ac- quired after natural infection. However, there are still some unresolved questions such as duration of protection, need for booster dose, protective level of anti-HPV antibodies, and whether there is protection against infection with HPV types closely related to HPV-16 and HPV-18 but not incorporated in the vac- cines. For a maximum efficacy, papillomavirus vaccines must be administered to pre-adolescents and adolescents before the beginning of sexual activity. Vaccine coverage and hence the overall efficacy of vaccination against HPV will depend on public health policies, social attitudes and cost of the vaccines. HPV immu- nization should significantly reduce the incidence of cervical cancers in 10 to 30 years, and should reduce the number of treatments due to a significant reduction in precancerous lesions in the shorter term. These vaccines also have the potential to reduce the incidence of other cancers such as anal, vulval, vaginal, and penial cancers for which the HPV prevalence is lower or the association with HPV infection is weaker. HPV vaccination and screening of precancerous cervical lesions are complementary measures and the implementation of HPV vaccination is an opportunity to strengthen the health policies for prevention of cervical cancer.

Chapter 15: HPV vaccine use in the developing world

Human papillomavirus (HPV)-related morbidity and mortality from cervical cancer primarily occurs in the developing world, where, unfortunately, access to vaccines in general, and expensive newer vaccines in particular, is often more limited than in the industrialized world. In addition, secondary prevention methods such as HPV screening, Pap testing, or visual inspection are uncommon in the developing world. The HPV vaccine will be first introduced into the industrialized countries and it will then, over the course of time, become used in the developing countries. HPV vaccine should be introduced in the framework of comprehensive cervical cancer control, and offers an opportunity to bring together a wide range of constituents who have not to date worked closely on vaccination. Ultimately, the decision of whether and when a vaccine will be introduced will depend on individual countries. To prepare for decisions on HPV vaccine use, the sexual and reproductive health (SRH; including adolescent health), immunization, and cancer control communities need to work together to analyze the appropriate data and build international and national consensus. The timeframe for other newer vaccines, such as hepatitis B and Hib, has been measured in decades, and the challenge to the public sector is to greatly shorten the time needed to make HPV vaccines available and affordable for the developing world, where their impact will be greatest.

Identification of type-specific and cross-reactive neutralizing conformational epitopes on the major capsid protein of human papillomavirus type 31

The majority of the neutralizing epitopes of papillomaviruses (PV) are conformation-specific and have not been fully characterised. Studies have, to date, been limited to a few HPV types only. We analysed the epitopes on the major capsid protein (L1) of Human papillomavirus (HPV) type 31 using monoclonal antibodies (MAbs) generated against HPV-31 virus-like particles (VLPs). The type-specific MAbs against HPV-31 were all found to be neutralizing and recognized conformation-dependent epitopes. Two other MAbs directed against a conformational epitope were found to be cross-reactive with other HPV types, and one of them was found to be cross-neutralizing. Cross-reactive antibodies were further investigated using wild-type HPV-16 L1 VLPs and two mutants. The results obtained suggested the existence of a cross-neutralizing conformational epitope at the N-terminal part of the FG loop of the major capsid protein, and the other four cross-reactive MAbs recognized epitopes also located at the N-terminal part of the FG loop.

Antibody levels against BK virus and prostate, kidney and bladder cancers in the EPIC-Oxford cohort

In a case–control study nested within the EPIC-Oxford cohort, there were no statistically significant differences in the prevalence or titre of antibodies against BK virus measured in plasma taken prior to diagnosis between cases with cancer of the prostate (n=31), kidney (n=5) or bladder (n=9) and controls (n=45).

Genetic diversity of hepatitis B virus strains derived worldwide: genotypes, subgenotypes, and HBsAg subtypes

Sequences of 234 complete genomes and 631 hepatitis B surface antigen genes were used to assess the worldwide diversity of hepatitis B virus (HBV). Apart from the described two subgenotypes each for A and F, also B, C, and D divided into four subgenotypes each in the analysis of complete genomes supported by significant bootstrap values. The subgenotypes of B and C differed in their geographical distribution, with B1 dominating in Japan, B2 in China and Vietnam, B3 confined to Indonesia, and B4 confined to Vietnam, all strains specifying subtype ayw1. Subgenotype C1 was common in Japan, Korea, and China; C2 in China, South-East Asia, and Bangladesh, and C3 in the Oceania comprising strains specifying adrq-, and C4 specifying ayw3 is encountered in Aborigines from Australia. This pattern of defined geographical distribution was less evident for D1-D4, where the subgenotypes were widely spread in Europe, Africa, and Asia, possibly due to their divergence having occurred a longer time ago than for genotypes B and C, with D4 being the first split and still the dominating subgenotype of D in the Oceania. The genetic diversity of HBV and the geographical distribution of its subgenotypes provide a tool to reconstruct the evolutionary history of HBV and may help to complement genetic data in the understanding of the evolution and past migrations of man.

Mutations on the FG surface loop of human papillomavirus type 16 major capsid protein affect recognition by both type-specific neutralizing antibodies and cross-reactive antibodies

The aim of this study was to further characterize the conformational neutralizing epitopes present on the surface-exposed FG loop of human papillomavirus (HPV) type 16 L1 major capsid protein. We have generated previously two chimeric L1 proteins by insertion of a foreign peptide encoding an epitope of the hepatitis B core (HBc) antigen within the FG loop. In addition, three other chimeric L1 proteins were obtained by replacing three different FG loop sequences by the HBc motif and three others by point mutations. All these chimeric L1 proteins retained the ability to self-assemble into virus-like particles (VLPs), with the exception of the mutant with substitution of the L1 sequence 274-279 by the HBc motif. The eight chimeric VLPs were then analyzed for differential reactivity with a set of six HPV-16 and HPV-31 monoclonal antibodies that bound to conformational and linear epitopes. The binding patterns of these monoclonal antibodies confirmed that the FG loop contained or contributed to neutralizing conformational epitopes. The results obtained suggested that the H31.F7 antibody, an anti-HPV-31 cross-reacting and neutralizing antibody, recognized a conformational epitope situated before the 266-271 sequence. In addition, H16.E70 neutralizing antibody reactivity was reduced with L1 VLPs with an Asn to Ala point mutation at position 270, suggesting that Asn is a part of the epitope recognized by this antibody. This study contributes to the understanding of the antigenic structure of HPV-16 and -31 L1 proteins by confirming that the FG loop contributes to neutralizing epitopes and suggesting the existence of both type-specific and cross-reactive conformational epitopes within the FG loop.

Positively charged synthetic peptides from structural proteins of papillomaviruses abrogate human papillomavirus infectivity

Human papillomavirus (HPV) virus-like particles (VLP) and synthetic peptides corresponding to positively-charged sequences of the major and minor capsid proteins were tested for their efficacy in inhibiting the infectivity of HPV 31 pseudovirions by blocking virus entry into cells. A greater than 80% reduction of transfection was observed with one HPV-31 peptide at a concentration of 10 microg/ml. Moreover, the blocking was not type-specific since similar reduction in transfection was observed with peptides from other HPV types at a concentration of 60 microg/ml. This concentration was non-toxic for the cells. These findings indicate that some of the positively-charged sequences of the L1 and L2 HPV capsid proteins of papillomavirus are compounds that might be locally active against sexually transmitted papillomavirus. The findings provide further evidence that cellular glycosamino-glycans (GAGs) are functional receptors for HPVs.

Human papillomaviruses and cancer in Uganda

In a case-control study in Uganda, we examined associations between different cancer sites or types in relation to antibodies against human papillomaviruses (HPV)-16, -18 and -45. For each cancer site or type, the control group comprised all other cancers excluding those known, or thought to be associated with HPV infection (cancers of the uterine cervix, penis and eye). Among controls the seroprevalence of antibodies was 11% (68/616) against HPV-16, 5% (29/605) against HPV-18 and 6% (35/605) against HPV-45. Antibodies against HPV-16 were significantly associated with only two cancers: uterine cervix [prevalence of antibodies 27% (51/191); odds ratio (OR) 2.0, 95% confidence interval (CI) 1.2-3.1, P=0.01] and penis [prevalence of antibodies 27% (4/15); OR 6.4, 95% CI 1.7-24.3, P=0.01]. For both cancers, the risk increased with increasing anti-HPV-16 antibody titre (Ptrend=0.01 for each). No cancer site or type was significantly associated with antibodies against HPV-18 and -45.

Serology for human papillomavirus

Difficulties with serology for papillomavirus are associated with the large number of human papillomavirus, cross-reactions between papillomavirus, and to the diversity of lesions and target sites for infection. In addition, the expression of the papillomavirus in the superficial layers of the epithelium gives rise to the weak presentation to immunocompetent cells of viral antigens, which in turn gives rise to a weak serological response. Distinct efforts have been made in previous decades to develop more specific and sensitive serological assays. These former studies use fusion proteins and synthetic peptides, although they remain on the whole uninteresting, due to their lack of sensitivity and specificity. Only in the last few years, and principally due to the advent of various virus-like particles (VLP), have more sensitive and specific assays become available. This paper is available too at: http://www.insp.mx/salud/index.html.

Insertion of a foreign sequence on capsid surface loops of human papillomavirus type 16 virus-like particles reduces their capacity to induce neutralizing antibodies and delineates a conformational neutralizing epitope

The aims of this study were to generate chimeric human papillomavirus (HPV)-16 L1 virus-like particles (VLPs) in order to identify immunogenic domains and conformational neutralizing epitopes, and to characterize the regions where a foreign epitope could be introduced. We hypothesized that these regions could be on L1 protein loops since they are exposed on the surface of VLPs. The aims of this study were achieved by mutating HPV-16 L1 proteins. Six amino acids encoding for the epitope 78-83 (DPASRE) of the hepatitis B core (HBc) antigen were introduced within the different loops of the L1 protein at positions 56/57, 140/141, 179/180, 266/267, 283/284 or 352/353. All these chimeric L1 proteins were capable of self-assembly into VLPs. The antigenicity and immunogenicity of some of these VLPs were reduced compared to the levels observed with wild-type VLPs. All were nevertheless able to induce neutralizing antibodies. VLPs with insertion at position 266/267 induced lower levels of neutralizing antibodies, suggesting the involvement of residues situated on FG loop in L1 neutralizing epitopes. All the chimeric L1 proteins except the one with insertion at position 56/57 were also able to induce anti-HBc antibodies, thus suggesting exposure of the HBc epitope on the VLP surface. Taken together, our findings indicate the possibility of designing HPV-derived vectors that are less immunogenic and suggest positions for insertion of defined immune epitopes or cell ligands into L1 protein to be exposed on the surface of VLPs.

Population-based human papillomavirus prevalence in Lampang and Songkla, Thailand

To investigate the prevalence and determinants of human papillomavirus (HPV) infection, the primary cause of cervical cancer, we studied 1741 women >/=15 years of age from Lampang and Songkla, Thailand. Exfoliated cervical cells were collected for Papanicolaou smear screening and DNA detection of 36 different HPV types. Serum immunoglobulin G antibodies against L1 virus-like particles (anti-VLPs) of HPV-16, -18, -31, -33, and -58 were evaluated using enzyme-linked immunosorbent assay. Overall, 110 women (6.3%) were HPV DNA positive; the most common types were HPV-16, -52, and -72. The age-standardized prevalence of HPV DNA was higher among the 1035 women from Lampang (9.1%; 95% confidence interval [CI], 7.1-11.1) than among the 706 women from Songkla (3.9%; 95% CI, 2.3%-5.6%). Anti-VLPs were found in 21.8% of all women and were more frequent among women from Lampang (29.2%) than among women from Songkla (10.9%). Major risk factors for cervical HPV DNA were age <35 years, HSV-2 seropositivity, and having a husband with extramarital sexual partners.

Human papillomavirus types 16, 31, and 58 use different endocytosis pathways to enter cells

The early steps of the intracellular trafficking of human papillomavirus type 16 (HPV-16), -31, and -58 pseudovirions were studied by investigating the effects of drugs acting at defined points of endocytosis pathways on virus-like particle-mediated pseudoinfection by overexpression of a dominant-negative form of the Eps15 protein to inhibit clathrin-mediated endocytosis and by electron microscopy. The results obtained suggested the involvement of clathrin-mediated endocytosis in HPV-16 and HPV-58 entry and caveola-mediated endocytosis in HPV-31 entry.

Prevalence of human papillomavirus infection in women in Busan, South Korea

To investigate the prevalence of and the risk factors for human papillomavirus (HPV) infection in South Korea, we interviewed and examined a randomly selected sample of 863 sexually active women (age range = 20-74 years, median 44) and 103 self-reported virgins from Busan. The presence of DNA of 34 different HPV types in cervical exfoliated cells was tested among sexually active women by means of a PCR-based assay. IgG antibodies against L1 virus-like particles (anti-VLPs) of HPV types 16, 18, 31, 33 and 58 were also evaluated by means of ELISA. The overall prevalence of HPV DNA was 10.4% (95% confidence interval, CI: 8.5-12.7%). The most often found HPV DNA types were HPV 70, HPV 16 and HPV 33; 19.8% (95% CI: 17.2-22.0) of sexually active women had antibodies against one or more HPV types. The most common anti-VLPs were against HPV 18, 31 and 16. Prevalences standardized by age on the basis of the world standard population were 13.0% for HPV DNA and 17.1% for anti-VLPs. The concordance between the 2 HPV markers at an individual level was modest, but the risk factors for detection of HPV DNA and anti-VLPs were similar: number of lifetime sexual partners (odds ratio, OR for >/= 4 vs. 1 = 3.5 and 5.4, respectively), seropositivity for herpes simplex virus-2 antibodies (OR = 2.6 and 2.5, respectively) and being single or divorced. HPV DNA, but not anti-VLPs, were elevated among women whose husbands were thought by their wives to have extra-marital affairs and those who had undergone vasectomy. Among 103 virgins, 4.9% had anti-VLPs (1/73 among those aged 24 years or less).

Positively charged sequences of human papillomavirus type 16 capsid proteins are sufficient to mediate gene transfer into target cells via the heparan sulfate receptor

Using synthetic peptides we have shown that positively charged sequences present at the C terminus of the L1 protein and the N and C termini of the L2 protein of human papillomavirus type 16 (HPV-16) bind to both DNA and heparan sulfate receptors. Moreover, these short amino acid sequences are sufficient to mediate gene transfer in COS-7 cells. The L1 proteins of other HPVs were shown to contain one or two DNA- and heparin-binding sequences that have the capacity to transfer genes. These DNA-binding sequences also recognized the enhancing packaging sequence of bovine papillomavirus type 1. The results suggest that the L2 protein could participate in DNA packaging during maturation of virions.

Cervical cancer control, priorities and new directions

Cervical cancer is caused by infection with a range of high risk "oncogenic" human papillomavirus (HPV) types, and it is now accepted that >99% of cervical cancer is initiated by HPV infection. The estimated lifetime risk of cervical cancer is nevertheless relatively low (less than 1 in 20 for most community based studies). Although sensitivity and specificity of the available diagnostic techniques are suboptimal, screening for persistent HPV infection is effective in reducing the incidence of cervical cancer. Infection can be detected by molecular techniques or by cytological examination of exfoliated cervical cells. Persistent infection is the single best predictor of risk of cervical cancer. The latest findings of HPV and cervical cancer research need to be widely disseminated to the scientific and medical societies that are updating screening and management protocols, public health professionals, and to women and clinicians. This report reviews current evidence, clinical implications and directions for further research in the prevention, control and management of cervical cancer. We report the conclusions of the Experts' Meeting at the EUROGIN 2003 conference.

The epidemiology of conjunctival squamous cell carcinoma in Uganda

As part of a larger investigation of cancer in Uganda, we conducted a case-control study of conjunctival squamous cell carcinoma in adults presenting at hospitals in Kampala. Participants were interviewed about social and lifestyle factors and had blood tested for antibodies to HIV, KSHV and HPV-16, -18 and -45. The odds of each factor among 60 people with conjunctival cancer was compared to that among 1214 controls with other cancer sites or types, using odds ratios, estimated with unconditional logistic regression. Conjunctival cancer was associated with HIV infection (OR 10.1, 95% confidence intervals [CI] 5.2-19.4; P<0.001), and was less common in those with a higher personal income (OR=0.4, 95% CI 0.3-0.7; P<0.001)[corrected]. The risk of conjunctival cancer increased with increasing time spent in cultivation and therefore in direct sunlight (chi2 trend=3.9, P=0.05), but decreased with decreasing age at leaving home (chi2 trend=3.9, P=0.05), perhaps reflecting less exposure to sunlight consequent to working in towns, although both results were of borderline statistical significance. To reduce confounding, sexual and reproductive variables were examined among HIV seropositive individuals only. Cases were more likely than controls to report that they had given or received gifts for sex (OR 3.5, 95% CI 1.2-10.4; P=0.03), but this may have been a chance finding as no other sexual or reproductive variable was associated with conjunctival cancer, including the number of self-reported lifetime sexual partners (P=0.4). The seroprevalence of antibodies against HPV-18 and -45 was too low to make reliable conclusions. The presence of anti-HPV-16 antibodies was not significantly associated with squamous cell carcinoma of the conjunctiva (OR 1.5, 95% CI 0.5-4.3; P=0.5) and nor were anti-KSHV antibodies (OR 0.9, 95% CI 0.4-2.1; P=0.8). The 10-fold increased risk of conjunctival cancer in HIV infected individuals is similar to results from other studies. The role of other oncogenic viral infections is unclear.