A virus-based vaccine may prevent cervical cancer

High-risk human papillomaviruses (HPVs) are now recognized as the etiologic agents of invasive cervical cancer, a major cancer in women. A single HPV type (type 16) is responsible for about 50% of the cancers. The major capsid protein of papillomaviruses, L1, when expressed by recombinant DNA technology, has the intrinsic ability to assemble into virus-like particles (VLPs). In a recent study, a vaccine based on HPV 16 VLPs was tested in a placebo-controlled proof-of-principle trial in young women in the United States. The vaccine was found to prevent 100% of incident persistent HPV 16 infections and HPV 16-associated cervical intraepithelial neoplasia. These results offer promise that cervical cancer will be preventable by an HPV-based vaccine. Studies planned or in progress are examining the efficacy of the vaccine in men, in HIV-infected individuals, and in other parts of the world. Attempts are being made to prepare vaccines that can be administered more easily to large populations.     

Genital human papillomavirus infection.

Genital human papillomavirus (HPV) infection is a common sexually transmitted disease that at the present time is not effectively controlled or treated. Many infections are inapparent and transient. However, some HPV infections result in persistent lesions that in some cases undergo carcinogenic progression. A subset of genital HPVs, designated high-risk types, are preferentially associated with high-grade dysplasias and carcinomas. About 90% of cervical cancers contain high-risk HPV DNA, most often HPV16. Development of a subunit vaccine against high-risk genital HPVs is a desirable and, it appears, an increasingly feasible long-term goal. The viral E6 and E7 oncoproteins are selectively maintained and expressed in progressed HPV tumors and could potentially be targets for therapeutic vaccines. The L1 major virion structural proteins have recently been shown to self-assemble into virus-like particles when expressed in insect cells. These particles might serve as the basis for a prophylactic vaccine to prevent genital HPV infection.     

Mixed Bacteriophage MS2-L2 VLPs Elicit Long-Lasting Protective Antibodies against HPV Pseudovirus 51

Three prophylactic vaccines are approved to protect against HPV infections. These vaccines are highly immunogenic. The most recent HPV vaccine, Gardasil-9, protects against HPV types associated with ~90% of cervical cancer (worldwide). Thus, ~10% of HPV-associated cancers are not protected by Gardasil-9. Although this is not a large percentage overall, the HPV types associated with 10% of cervical cancer not protected by the current vaccine are significantly important, especially in HIV/AIDS patients who are infected with multiple HPV types. To broaden the spectrum of protection against HPV infections, we developed mixed MS2-L2 VLPs (MS2-31L2/16L2 VLPs and MS2-consL2 (69-86) VLPs) in a previous study. Immunization with the VLPs neutralized/protected mice against infection with eleven high-risk HPV types associated with ~95% of cervical cancer and against one low-risk HPV type associated with ~36% of genital warts & up to 32% of recurrent respiratory papillomatosis. Here, we report that the mixed MS2-L2 VLPs can protect mice from three additional HPV types: HPV51, which is associated with ~0.8% of cervical cancer; HPV6, which is associated with up to 60% of genital warts; HPV5, which is associated with skin cancers in patients with epidermodysplasia verruciformis (EV). Overall, mixed MS2-L2 VLPs can protect against twelve HPV types associated with ~95.8% of cervical cancers and against two HPV types associated with ~90% of genital warts and >90% recurrent respiratory papillomatosis. Additionally, the VLPs protect against one of two HPV types associated with ~90% of HPV-associated skin cancers in patients with EV. More importantly, we observed that mixed MS2-L2 VLPs elicit protective antibodies that last over 9 months. Furthermore, a spray-freeze-dried formulation of the VLPs is stable, immunogenic, and protective at room temperature and 37 °C.     

HPV疫苗安全性与有效性的研究现状及进展

人乳头瘤病毒（human papillomavirus, HPV）感染是最普遍的性传播感染之一。研究发现在99.7％的宫颈癌标本中存在高危型HPV的DNA。现已明确HPV持续感染是HPV相关疾病如宫颈癌等恶性肿瘤的主要致病因素，因此通过接种HPV疫苗来预防HPV感染和治疗HPV相关疾病显得尤为重要。HPV疫苗分为两种：一种是预防性HPV疫苗，用于预防健康人被HPV感染；一种是治疗性HPV疫苗，具有对已出现的HPV感染和病变患者产生治疗效果的潜能。本文就HPV疫苗安全性与有效性的研究现状及进展展开综述。     

Epidemiologic correlates of antibody response to human papillomavirus among women at low risk of cervical cancer

A population at low risk for developing cervical cancer in Southern Brazil was studied to identify the main determinants of serological response to human papillomavirus (HPV). Enzyme-linked immunosorbent assay tests were performed in 976 women to detect serum IgG antibodies against HPV 16 L1 virus-like particles (VLPs) and HPVs 16, 18, 6 and 11 L1 VLPs as a mixture of antigens. Women with four or more sexual partners were more likely to be seropositive than women with one partner (HPV 16 serology odds ratio [OR]=3.06, 95% confidence interval [CI]: 2.0-4.8; HPV 6/11/16/18 serology OR=4.64, 95% CI: 3.0-7.2). HPV DNA and both serological responses were associated. Those positives to HPV 16 serology were twice as likely to have a cytological diagnosis of squamous intraepithelial lesions (SILs) than seronegatives (OR=2.07; 95% CI: 1.0-4.5, and OR=1.73; 95% CI: 0.8-3.8). Seropositivity to HPV 16 and HPV 6/11/16/18 antigens seem to be better markers of past sexual activity than current HPV infection, and humoral response to HPV 16 or HPV 6/11/16/18 may not be a strong indicator of cervical lesions in populations at low risk for cervical lesions.     

Cellular immune responses to human papillomavirus (HPV)-16 L1 in healthy volunteers immunized with recombinant HPV-16 L1 virus-like particles

The causal association between papillomavirus (HPV) infection and cervical cancer has been demonstrated; the development of a prophylactic vaccine to protect against HPV infection may therefore reduce the incidence of this cancer worldwide. Noninfectious HPV-like particles (VLPs), composed of the L1 major capsid protein, are current candidate vaccines for prevention of HPV infection and cervical neoplasia. Although neutralizing antibodies have a pivotal role in the prevention of initial infection, cellular immune responses to HPV antigens may have an important role in viral clearance. A phase II trial was conducted to further evaluate the immunogenicity of a recombinant HPV-16 L1 VLP vaccine administered intramuscularly, without adjuvant, at 0, 1, and 6 months. Cell-mediated immune responses (lymphoproliferation and cytokine production) to HPV-16 L1 VLPs were evaluated in peripheral blood mononuclear cells (PBMCs) from 43 individuals receiving the L1 VLP vaccine and from 10 individuals receiving placebo. Vaccination resulted, at months 2 and 7 (i.e., 1 month after the second immunization and 1 month after third immunization, respectively), in increases in T cell-proliferative response to HPV-16 L1 VLPs (P<.001). In addition, significant increases in cytokine (interferon-gamma, interleukin [IL]-5 and IL-10) responses to L1 VLPs were observed after vaccination (P<.001). The strongest cytokine responses at month 7 were observed in individuals with high antibody titers at month 2, suggesting that neutralizing antibodies generated by initial vaccination may augment T cell responses to subsequent booster vaccinations. No significant increases in lymphoproliferative or cytokine responses to L1 VLPs were observed in individuals receiving placebo. In summary, the HPV-16 L1 vaccine induces not only robust B cell responses but also L1-specific T cell responses detectable by proliferation of both CD4+ and CD8+ T cells and in vitro production of both Th1- and Th2-type cytokines. Future efficacy studies are needed to evaluate whether and/or how VLP vaccines confer protection against genital HPV infection and associated disease.     

Anti human-papillomavirus vaccines: concepts, aims and trials

PURPOSE: Human Papillomaviruses (HPV) are epitheliotropic for stratified malpighian epithelia such as those of the cervix. Among them, oncogenic viruses are detectable in 99.7% of cervical cancers. A great priority is to develop a vaccine either against primary infection (preventive vaccine) allowing protection against HPV infection or therapeutic vaccine in order to kill previously infected or transformed keratinocytes. CURRENT KNOWLEDGE AND KEY POINTS: Preventive vaccines against HPV contain virus like particles (VLP) 16 and 18 and induce a high titer of blood anti-VLP antibodies. They were recently tested in humans and have shown true efficiency for the prevention of cervical cancer. The therapeutic vaccines are therefore currently being developed in order to increase anti-HPV natural CD4+ and CD8+ T-cell immunity in women infected during their sexual activity. FUTURE PROSPECTS: The perspective of the prophylactic vaccines is to decrease both genital HPV infection and cervical cancer. The impact of preventive vaccine must be carefully analyzed in order to prevent collateral side effects. The therapeutic vaccines have also a future in women already infected by HPV and might have an efficiency similar to surgery in the treatment of cervical intraepithelial neoplasia.     

人乳头瘤病毒16型表位嵌合病毒样颗粒的构建及免疫原性研究

目的 制备E7_49-57表位嵌合病毒样颗粒,并进行免疫原性分析。方法 利用分子模拟软件Discovery Studio预测HPV16 L1的E7_49-57最佳嵌合位点,将E7_49-57表位嵌入预测位点。构建pET28a-16L1-E7_49-57重组质粒,于大肠杆菌中诱导表达HPV16L1-E7_49-57蛋白并利用镍柱进行亲和层析纯化。于体外重组VLPs后,进行动态光散射粒径和透射电镜分析。用E7_49-57嵌合VLPs免疫小鼠,假病毒中和试验检测免疫血清中和抗体滴度。流式多因子法检测Th1和Th2型细胞因子水平。结果 HI loop区355/356为最佳表位嵌合位点。正确表达了HPV16 L1-E7_49-57蛋白并组装E7_49-57嵌合VLPs。E7_49-57嵌合VLPs免疫小鼠3次后,小鼠血清中和抗体滴度log10平均值达到4.23,略低于野生型VLPs(log10平均值为4.45)。但是,相对于野生型VLPs,E7_49-57嵌合VLPs诱导产生Th1型细胞因子(INF-γ, IL-2, TNF-α)的水平显著提高。结论 本研究制备的E7_49-57嵌合VLPs 能刺激机体同时产生较强的体液和细胞免疫应答,可能兼具预防和治疗双重功效,为宫颈癌治疗性疫苗的研制奠定基础。     

Human Papillomaviruses; Epithelial Tropisms,and the Development of Neoplasia

Papillomaviruses have evolved over many millions of years to propagate themselves at specific epithelial niches in a range of different host species. This has led to the great diversity of papillomaviruses that now exist, and to the appearance of distinct strategies for epithelial persistence. Many papillomaviruses minimise the risk of immune clearance by causing chronic asymptomatic infections, accompanied by long-term virion-production with only limited viral gene expression. Such lesions are typical of those caused by Beta HPV types in the general population, with viral activity being suppressed by host immunity. A second strategy requires the evolution of sophisticated immune evasion mechanisms, and allows some HPV types to cause prominent and persistent papillomas, even in immune competent individuals. Some Alphapapillomavirus types have evolved this strategy, including those that cause genital warts in young adults or common warts in children. These strategies reflect broad differences in virus protein function as well as differences in patterns of viral gene expression, with genotype-specific associations underlying the recent introduction of DNA testing, and also the introduction of vaccines to protect against cervical cancer. Interestingly, it appears that cellular environment and the site of infection affect viral pathogenicity by modulating viral gene expression. With the high-risk HPV gene products, changes in E6 and E7 expression are thought to account for the development of neoplasias at the endocervix, the anal and cervical transformation zones, and the tonsilar crypts and other oropharyngeal sites. A detailed analysis of site-specific patterns of gene expression and gene function is now prompted.     

HPV-beyond cervical cancer (online resource center)

The human papillomavirus (HPV) causes more than 99% of all cervical cancers (see Am J Med Resource Center: http://supplements.amjmed.com/2011/HPV/). Exposure to HPV infections occurs in a high proportion of the overall population; however, 2 safe and effective vaccines, HPV2 and HPV4, are approved for the prevention of HPV-16 and HPV-18 infection, the most common causes of cervical cancer. Additionally, HPV4 prevents HPV-6 and HPV-11-related genital warts. While prevention of cervical cancer in women has been the initial aim of vaccination programs, it has now become apparent that HPV causes other types of cancer as well, including vulvar and vaginal cancers in women, penile cancer in men, and anal cancer in both sexes. Furthermore, these viruses have been implicated in head and neck cancers in both men and women as well. It is estimated that HPV-related cancers occur in 10,000 American males annually, suggesting that limiting vaccination programs to females may be underserving a significant proportion of the population. The efficacy of the 2 available vaccines against oncogenic HPV is more than 90% for both cervical and anal intraepithelial neoplasia. For those receiving the HPV4 vaccine, efficacy against genital warts is nearly 90%. Adverse effects are few and include episodes of syncope in the period immediately following vaccination. Benefits of vaccinating males include reduction in disease burden in men and enhanced herd immunity to reduce disease burden in women.     

人乳头瘤病毒16型L1的表达、病毒样颗粒组装及其免疫原性研究

目的 在原核表达系统中表达HPV16 L1蛋白,纯化后在体外自组装成VLPs并鉴定。方法 优化GenBank中HPV16 L1基因序列并截短C末端25个氨基酸,构建至原核表达载体pET-28a上,获得重组表达载体pET28a-16L1△C25。采用镍亲和层析法纯化超声上清,于体外解组装-重组装HPV16 VLPs,采用动态光散射和透射电镜进行形貌分析,纯化后于第0、2和4周免疫小鼠,假病毒中和试验检测HPV16 VLPs免疫后血清中和抗体。结果 双酶切和测序结果表明成功构建pET28a-16L1△C25重组质粒,诱导表达后,经SDS-PAGE和Western blotting分析显示表达的L1蛋白大部分以可溶性形式存在,纯化后的蛋白样品于体外重新组装,动态光散射和透射电镜能够观察到形态与天然病毒颗粒相似的VLPs,第6周小鼠血清中和抗体滴度Log10平均值达到4.43。结论 利用原核表达系统成功表达了截短型HPV16 L1蛋白,并于体外组装成结构完整的VLPs,且具有较好的免疫原性,为低成本HPV预防性疫苗的研发奠定基础。     

人乳头瘤病毒疫苗研究进展

宫颈癌的发病率和病死率在女性恶性肿瘤中排第2位,近年来年轻化趋势明显. 大量研究表明,高危型人乳头瘤病毒(human papillomavirus, HPV)感染是宫颈癌发生最主要的危险因素. 宫颈癌目前已成为惟一病因明确、可早期预防、早期发现并可能治愈的人类恶性肿瘤. 研发疫苗对预防及治疗女性HPV持续性感染,进而预防宫颈癌的发生,提高患者的生存质量,甚至保留年轻患者的生育功能均具有至关重要的作用,有效的HPV疫苗研发具有重大的社会意义和经济学价值.     

Therapeutic vaccines against HPV16-associated tumors. Minireview

Human papilloma viruses (HPV) were found to be closely associated with several types of anogenital tumors, particularly with cervical carcinomas (CC). Of more than 100 HPV types characterized until now, 11 have been classified as high-risk types and detected in human tumor tissue by molecular and immunological techniques. Immunological intervention against HPV can be envisaged at two levels, prophylactic and therapeutic. The therapeutic vaccines constructed to counteract tumors which are already developed utilize two nonstructural early proteins coded by HPV, the products of their E6 and E7 oncogenes. These E6/E7 oncoproteins are the only HPV-coded proteins expressed in CC; they are involved in malignant transformation of HPV-infected cells, their presence is necessary for the maintenance of the malignant phenotype of the cells, and their expression correlates with the transforming potential of HPV. Therefore, the E6/E7 oncoproteins are used for the construction of therapeutic vaccines against HPV-associated neoplasms. The purpose of this review is to discuss the results obtained with HPV16 E6/E7 oncoprotein based therapeutic vaccines in animal tumor models, as well as the prospects and limitations of the vaccines.     

人乳头瘤病毒感染及诊疗新动向

人乳头瘤病毒(human papillomavirus,HPV)感染是世界上最普遍的病毒感染之一,在不同种族、性别、年龄的人群中广泛传播。高危型HPV感染除了导致女性宫颈癌外,还可引起阴茎癌、肛门癌和口腔癌等HPV相关癌症。低危型以及皮肤型HPV感染引起肛门生殖器疣、皮肤疣、呼吸道乳头瘤等疾病,是全球尤其是发展中国家需要面对的重要公共卫生问题。HPV感染引起的疾病根据病情可选择不同的治疗方法,包括手术、激光、光动力疗法以及药物治疗。在发展中国家普及HPV疫苗的接种是宫颈癌防控工作的核心,而HPV疫苗对于多种HPV相关皮肤和黏膜疾病表现出的治疗作用还在研究中。     

What is the significance of the HPV epidemic?

Human papillomavirus (HPV) is the most common sexually transmitted infection. The incidence of this infection has been on the rise in recent times. It is estimated that approximately 6 million new HPV infections are acquired each year in the United States alone, and prevalence data suggest that as many as 24 million American adults--that is, 1 in 5--may be infected with HPV. Unfortunately, there is little public awareness and knowledge about the infection and its sequelae. It is well known that more than 90% of cases of anogenital warts are caused by HPV. HPV has been implicated in cancers of the cervix, vulva, vagina, penis, anus, and oropharynx. The virus is a necessary cause of cervical cancer. HPV DNA is detected in almost 100% of cases of cervical cancer. There have been major strides in recent years in the prevention of this infection and consequently, of diseases related to it. Vaccines are available and licensed in some countries. Two HPV vaccines are available: a quadrivalent (HPV types 6, 11, 16, and 18) vaccine and a bivalent (HPV types 16 and 18) vaccine. Both vaccines show a more than 90% protection against persistent HPV infection for up to 5 years after vaccination. The role of the vaccine in males is still controversial. The vaccination cost, however, is beyond the reach of many individuals in developing countries where 80% of cervical cancer cases of are found. Many countries in Africa are battling with HIV, malaria, tuberculosis, maternal mortality, and childhood illness. Nevertheless, with increased awareness, political will, and engagement by pharmaceutical countries, HPV vaccines may become affordable in these countries.     

Papillomvireninfektion und Tumorigenese

Anal carcinomas occur rarely in the general population. In certain risk groups, such as human immunodeficiency virus (HIV) positive men who have sexual contact with other men, the proportion is strongly increased. Anal canal carcinomas and cervical carcinomas are very similar from a biological point of view because in both high risk groups carcinomas are preceded by a persistent human papillomavirus (HPV) infection. The HPV infection is transmitted by sexual contact and infections are very common but in most cases successfully eliminated by the immune system. Persistence of an infection with HPV in high risk groups initiate malignant alterations due to deregulation of infected cells. The early oncoproteins E6 and E7 play an important role because they deactivate the tumor suppressor proteins pRB and p53 so that nothing stands in the way of unlimited growth of infected cells and leads to genomic instability. Anal cancer originates from precursors, anal intraepithelial neoplasms or high-grade lesions of squamous cells. These can be detected using anal swab examination or anoscopy and treated early. Primary prevention is by HPV inoculation.     

Multiple Neuraminidase Containing Influenza Virus-like Particle Vaccines Protect Mice from Avian and Human Influenza Virus Infection

Avian influenza virus remains a threat for humans, and vaccines preventing both avian and human influenza virus infections are needed. Since virus-like particles (VLPs) expressing single neuraminidase (NA) subtype elicited limited heterosubtypic protection, VLPs expressing multiple NA subtypes would enhance the extent of heterosubtypic immunity. Here, we generated avian influenza VLP vaccines displaying H5 hemagglutinin (HA) antigen with or without avian NA subtypes (N1, N6, N8) in different combinations. BALB/c mice were intramuscularly immunized with the VLPs to evaluate the resulting homologous and heterosubtypic immunity upon challenge infections with the avian and human influenza viruses (A/H5N1, A/H3N2, A/H1N1). VLPs expressing H5 alone conferred homologous protection but not heterosubtypic protection, whereas VLPs co-expressing H5 and NA subtypes elicited both homologous and heterosubtypic protection against human influenza viruses in mice. We observed that VLP induced neuraminidase inhibitory activities (NAI), virus-neutralizing activity, and virus-specific antibody (IgG, IgA) responses were strongly correlated with the number of different NA subtype expressions on the VLPs. VLPs expressing all 3 NA subtypes resulted in the highest protection, indicated by the lowest lung titer, negligible body weight changes, and survival in immunized mice. These results suggest that expressing multiple neuraminidases in avian HA VLPs is a promising approach for developing a universal influenza A vaccine against avian and human influenza virus infections.     

Papillomavirus vaccines in clinical trials

Cervical cancer remains a leading cause of death for women in the developing world, and the treatment of preneoplastic cervical lesions is a considerable public-health burden in the developed world. There is unambiguous evidence that human papillomaviruses (HPVs) trigger the development of cervical and other anogenital malignancies, and that continued expression of HPV antigens in the tumours drives the neoplastic progression. The viral cause of cervical cancer is also its Achilles heel. Prophylactic vaccines to prevent HPV infection and therapeutic vaccines targeted at the HPV tumour antigens are in clinical trials. A firm grasp of the molecular pathogenesis of HPVs and the natural history of genital HPV infections, combined with greater understanding of how to trigger effective immune responses, offers hope for the elimination of HPV-associated diseases.