HPV Vaccines: today and in the Future

Exosome-like Systems: From Therapies to Vaccination for Cancer Treatment and Prevention-Exploring the State of the Art

Cancer remains one of the main causes of death in the world due to its increasing incidence and treatment difficulties. Although significant progress has been made in this field, innovative approaches are needed to reduce tumor incidence, progression, and spread. In particular, the development of cancer vaccines is currently ongoing as both a preventive and therapeutic strategy. This concept is not new, but few vaccines have been approved in oncology. Antigen-based vaccination emerges as a promising strategy, leveraging specific tumor antigens to activate the immune system response. However, challenges persist in finding suitable delivery systems and antigen preparation methods. Exosomes (EXs) are highly heterogeneous bilayer vesicles that carry several molecule types in the extracellular space. The peculiarity is that they may be released from different cells and may be able to induce direct or indirect stimulation of the immune system. In particular, EX-based vaccines may cause an anti-tumor immune attack or produce memory cells recognizing cancer antigens and inhibiting disease development. This review delves into EX composition, biogenesis, and immune-modulating properties, exploring their role as a tool for prevention and therapy in solid tumors. Finally, we describe future research directions to optimize vaccine efficacy and realize the full potential of EX-based cancer immunotherapy.

HPV16 L1 diversity and its potential impact on the vaccination-induced immunity

Human Papillomavirus 16 (HPV16) is the most oncogenic HPV and the most associated genotype with cervical cancer development and progression. Currently, all developed vaccines are targeting HPV16 and were designed based on the major L1 capsid protein. Thus, evaluation of the diversity of HPV16 L1 sequence, mainly in the antigenic regions, will be of a great interest to assess the efficacy of the prophylactic vaccines and to predict the impact of genetic variations in these regions on the vaccination-induced immunity. A total of 377 HPV16 L1 sequences, published in public domain GenBank database, from the Americas, Africa, Asia, and Europe were collected and assembled. A total of 626 mutation events affecting 83 distinct nucleotides into the five antigenic regions of L1 gene of HPV16 were reported, and most SNPs were located in DE (27.38%, 23/83) and FG (31%, 26/83) loops. Overall, 4 mutations were frequently found in HPV16 sequences: T176N and N181T in EF loop; A266T in the FG loop and T353P/I/N HI loop. Of particular interest, some SNPs are ubiquitous and were found in all populations whereas others were population specific and their presence was limited to one or 2 at the maximum. Association between mutations in the antigenic regions and ethnicity was also investigated and showed that mutations in BC and DE loops were present with no significant difference in sequences from Europe, Asia, America and Africa. However, most mutations in FG loop are reported in sequences from European cases and are less pronounced in cases from America and Asia, whereas mutations EF and HI loops prevail in Asian cases. These data highlight a high number of variant amino acid residues that could affect the vaccination-induced immunity and impact the effectiveness of the prophylactic vaccination to fight against HPV, warranting the need of further investigation for vaccines and natural history studies of HPV16.

Public-private knowledge transfer and access to medicines: a systematic review and qualitative study of perceptions and roles of scientists involved in HPV vaccine research

Background

Public research organizations and their interactions with industry partners play a crucial role for public health and access to medicines. The development and commercialization of the Human Papillomavirus (HPV) vaccines illustrate how licensing practices of public research organizations can contribute to high prices of the resulting product and affect accessibility to vulnerable populations. Efforts by the international community to improve access to medicines have recognised this issue and promote the public health-sensitive management of research conducted by public research organizations. This paper explores: how medical knowledge is exchanged between public and private actors; what role inventor scientists play in this process; and how they view the implementation of public health-sensitive knowledge exchange strategies.

Methods

We conducted a systematic qualitative literature review on medical knowledge exchange and qualitative interviews with a purposive sample of public sector scientists working on HPV vaccines. We explored the strategies by which knowledge is exchanged across institutional boundaries, how these strategies are negotiated, and the views of scientists regarding public health-sensitive knowledge exchange.

Results

We included 13 studies in the systematic review and conducted seven semi-structured interviews with high-ranking scientists. The main avenues of public-private medical knowledge exchange were publications, formal transfer of patented knowledge, problem-specific exchanges such as service agreements, informal exchanges and collaborative research. Scientists played a crucial role in these processes but appeared to be sceptical of public health-sensitive knowledge exchange strategies, as these were believed to deter corporate interest in the development of new medicines and thus risk the translation of the scientists’ research.

Conclusion

Medical scientists at public research institutions play a key role in the exchange of knowledge they generate and are concerned about the accessibility of medicines resulting from their research. Their scepticism towards implementing public health-sensitive knowledge management strategies appears to be based on a biased understanding of the costs and risks involved in drug development and a perceived lack of alternatives to private engagement. Scientists could be encouraged to exchange knowledge in a public health-sensitive manner through not-for-profit drug development mechanisms, education on industry engagement, and stronger institutional and legal backing.

Distribution and role of high-risk human papillomavirus genotypes in women with cervical intraepithelial neoplasia: A retrospective analysis from Wenzhou, southeast China

To add the growing literature on baseline of high-risk human papillomavirus (HR-HPV) genotype distribution in cervical intraepithelial neoplasia (CIN) before the widespread using of HPV vaccines in Chinese mainland and to improve risk stratification of HR-HPV-positive women. Retrospectively, the data of age, cervical HPV genotypes, cytology, and pathology were collected from 1166 patients who received loop electrosurgical excision procedure (LEEP). HPV genotypes were analyzed with Flowcytometry Fluorescence Hybridization Method. And then HPV prevalence, HR-HPV genotype distribution and the correlation of HR-HPV genotypes with CIN2+ (CIN2 or severer) were analyzed. The role of multiple HR-HPV types infection with or without HPV16/18 in the pathogenesis of CIN2+ was also analyzed. The 6 most common HR-HPV genotypes were HPV16, 58, 52, 33, 18, and 31 in descending order. Compared to HR-HPV-negative women, HPV16, 33 or 58 positive women had higher risk of CIN2+ (OR = 5.10, 95% CI = 2.68-9.70; OR = 3.09, 95% CI = 1.39-6.84; OR = 3.57, 95% CI = 1.85-6.89, respectively). And women who were infected by multiple HR-HPV types infection with HPV16/18 also had higher risk of CIN2+ (OR = 2.58, 95% CI = 1.35-4.92). However, multiple HR-HPV types infection without HPV16/18 did not increase the risk significantly (P = .08). Compare to bivalent Cervarix^® and quadrivalent Gardasil^® , HPV prophylactic vaccine targeting HPV31, 33, 52, and 58 might provide women more protection from HPV-induced cervical cancer in China. The women who infected by HPV16, 33, 58, or multiple HR-HPV types with HPV16/18 have higher risk of CIN2+ and need to be paid more attention in screening processes. And the role of multiple HR-HPV types infection without HPV16/18 needs be further identified in more studies.

Cervical Cancer Screening Among Arab Women in the United States: An Integrative Review

PROBLEM IDENTIFICATION

Arab American women are an ethnic minority and immigrant population in the United States with unique and nuanced sociocultural factors that influence preventive health behaviors. The aims of this article are to evaluate and synthesize the existing evidence on cervical cancer screening behaviors, as well as determine factors that influence these behaviors, among Arab American women.
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LITERATURE SEARCH

Extensive literature searches were performed using PubMed, CINAHL®, Scopus, Embase, and Cochrane databases; articles published through October 2015 were sought. 
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DATA EVALUATION

Of 17 articles, 14 explicitly identified Arab and/or Muslim women and cervical cancer screening in either the title or the abstract; the remaining three focused on cancer attitudes and behaviors in Arab Americans in general but measured cervical cancer screening. Eleven articles reported different aspects of one intervention. Because of methodologic heterogeneity, the current authors synthesized results narratively.
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SYNTHESIS

Key factors influencing cervical cancer screening were identified as the following.

CONCLUSIONS

Cervical cancer screening rates among Arab American women are comparable to other ethnic minorities and lower than non-Hispanic White women. Findings are inconsistent regarding factors influencing cervical cancer screening behaviors in this underrepresented group. 
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IMPLICATIONS FOR RESEARCH

Significant need exists for more research to better understand cervical cancer prevention behaviors in this group to inform culturally relevant interventions. Healthcare providers play a crucial role in increasing cervical cancer screening awareness and recommendations for Arab American women.

Suppressive Effect of Constructed shRNAs against Apollon Induces Apoptosis and Growth Inhibition in the HeLa Cell Line

Background:

Cervical cancer is the second most common female cancer worldwide. Inhibitors of apoptosis proteins (IAPs) block apoptosis; therefore, therapeutic strategies targeting IAPs have attracted the interest of researchers in recent years. Apollon, a member of IAPs, inhibits apoptosis and cell death. RNA interference is a pathway in which small interfering RNA (siRNA) or shRNA (short hairpin RNA) inactivates the expression of target genes. The purpose of this study was to determine the effect of constructed shRNAs on apoptosis and growth inhibition through the suppression of apollon mRNA in HeLa cell line.

Methods:

Three shRNAs with binding ability to three different target sites of the first region of apollon gene were designed and cloned in pRNAin-H1.2/Neo vector. shRNA plasmids were then transfected in HeLa cells using electroporation. Down-regulation effects of apollon and the viability of HeLa cells were analyzed by RT-PCR, lactate dehydrogenase assay, and MTT assay, respectively. Also, the induction and morphological markers of apoptosis were evaluated by caspase assay and immunocytochemistry method.

Results:

The expression of shRNA in HeLa cells caused a significant decrease in the level of apollon mRNA1. In addition, shRNA1 effectively increased the mRNA level of Smac (as the antagonist of apollon), reduced the viability of HeLa cells and exhibited immunocytochemical apoptotic markers in this cell line.

Conclusion:

Apollon gene silencing can induce apoptosis and growth impairment in HeLa cells. In this regard, apollon can be considered a candidate therapeutic target in HeLa cells as a positive human papillomavirus cancer cell line.

Using Facebook™ to Recruit College-Age Men for a Human Papillomavirus Vaccine Trial

College-age men were recruited using Facebook™ advertisements (ads), as well as traditional recruitment methods, for a randomized controlled trial to compare immunological responses to human papillomavirus vaccine administered in two dosing schedules. This study compares enrollees who were recruited through traditional recruitment methods versus social networking sites (SNSs), including Facebook. Potential participants were recruited using flyers posted on and off campus(es), and distributed at health fairs, classes, sporting, and other campus events; e-mails to students and student organizations; and print advertisements in student newspapers and on city buses. Facebook ads were displayed to users with specific age, geographic, and interest characteristics; ads were monitored daily to make adjustments to improve response. A total of 220 males, aged 18 to 25 years enrolled between October 2010 and May 2011. The majority of participants (51%) reported print advertisements as the method by which they first heard about the study, followed by personal contact (29%) and Facebook or other SNSs (20%). The likelihood of a SNS being the source by which the participant first heard about the study compared with traditional methods was increased if the participant reported (a) being homosexual or bisexual or (b) posting daily updates on SNSs. Facebook and other SNSs are a viable recruitment strategy for reaching potential clinical trial participants among groups who typically use social media to stay connected with their friends and hard-to-reach groups such as young men who self-identify as homosexual or bisexual.

Influence of Brucella abortus lipopolysaccharide as an adjuvant on the immunogenicity of HPV-16 L1VLP vaccine in mice

Brucella abortus lipopolysaccharide (LPS) has less toxicity and no pyrogenic properties in comparison with other bacterial LPS. It is a toll-like receptor 4 agonist and has been shown to have the potential use as a vaccine adjuvant. In this study, the immunostimulatory properties of LPS from smooth and rough strains of B. abortus (S19 and RB51) as adjuvants were investigated for the human papillomavirus type 16 (HPV16) L1 virus-like particles (L1VLPs) vaccines. C57BL/6 mice were immunized subcutaneously three times either with HPV-16 L1VLPs alone, or in combination with smooth LPS (S-LPS), rough LPS (R-LPS), aluminum hydroxide or a mixture of them as adjuvant. The humoral immunity was evaluated by measuring the specific and total IgG levels, and also the T-cell immune response of mice was evaluated by measuring different cytokines such as IFN-γ, TNF-α, IL-4, IL-10 and IL-17. Results showed that serum anti-HPV16 L1VLP IgG antibody titers was significantly higher in mice immunized with a combination of VLPs and R-LPS or S-LPS compared with other immunized groups. Co-administration of HPV-16 L1VLPs with R-LPS elicited the highest levels of splenocytes cytokines (IFN-γ, IL-4, IL-17 and TNF-α) and also effectively induced improvement of a Th1-type cytokine response characterized with a high ratio of IFN-γ/IL-10. The data indicate that B. abortus LPS particularly RB51-LPS enhances the immune responses to HPV-16 L1VLPs and suggests its potential as an adjuvant for the development of a potent prophylactic HPV vaccine and other candidate vaccines.

Human Papillomavirus and Oropharyngeal Squamous Cell Carcinoma of the Head and Neck: A Growing Epidemic

Human papillomavirus (HPV) is now considered a major causative agent in oropharyngeal squamous cell carcinoma (OP-SCC). The incidence of HPV+ OP-SCC is increasing dramatically, is higher in men, and is now more common than cervical cancer in the United States. HPV+ OPSCCs usually present as locally advanced, stage IV cancers, requiring intensive treatment with surgery, chemotherapy, and/or radiation that can cause tremendous morbidity. HPV vaccination is predicted to prevent HPV+ OP-SCC because over 90% are caused by vaccine-type HPV. However, current vaccination rates are not yet high enough to be effective at preventing HPV-associated malignancies at a population level.

[Pap test coverage and adequacy in the South and Northeast of Brazil]

Cervical cancer is the second most common cancer among women both in Brazil and elsewhere in the world and can be averted through early detection of precursor lesions. Pap smear is still the most effective and efficient screening test. This study focused on the coverage and adequacy of Pap test and associated factors. The authors adopted a cross-sectional design with a sample of 3,939 women who had given birth in the two previous years in 41 municipalities (counties) of Brazil. Lifetime Pap test coverage was 75.3% (95%CI: 74.0-76.7), and prevalence of adequacy was 70.7% (95%CI: 69.3-72.1). Adequacy was positively associated with age over 25 years, schooling, prenatal care in the last pregnancy, and gynecological visit in the previous year, and was less frequent among primiparous women and those with lower socioeconomic status. It is thus necessary to strengthen preventive measures in vulnerable subgroups and maximize situations for use of health services.

Modeling and molecular dynamics of the intrinsically disordered e7 proteins from high- and low-risk types of human papillomavirus

Cervical cancer affects millions of women worldwide each year. Most cases of cervical cancer are caused by the sexually transmitted human papillomavirus (HPV). The approximately 40 HPV types that infect the cervix are designated high- or low-risk based on their potential to lead to high-grade lesions and cancer. The HPV E7 oncoprotein is directly involved in the onset of cervical cancer and associates with the pRb protein and other cellular targets that promote cell immortalization and carcinogenesis. This is the first description of the modeling and molecular dynamics analysis of complete three-dimensional structures of high-risk (HPV types 16 and 18), low-risk (HPV type 11), and HPV type 01 E7 proteins. The models were constructed by a hybrid approach using homology (MODELLER) and ab initio (Rosetta) modeling, and the protein dynamics were simulated for 50 ns under normal pressure and temperature (NPT) conditions. The intrinsic disorder of the E7 protein sequence was assessed in silico. Complete models of E7 were obtained despite the predicted intrinsic disorder of the N-termini from the high-risk HPV types. The N-terminal domains of all of the E7 proteins studied, even those from high-risk strains, exhibited secondary structure after modeling. Trajectory analysis of E7 proteins from HPV types 16 and 18 showed higher instability in their N-terminal domains than in those of HPV types 11 and 01; however, this variation did not affect the secondary structure during the simulation. ANCHOR analysis indicated that the CR1 and CR2 regions of HPV types 16 and 18 contain possible targets for future drug-discovery studies.

Carcinoma of the collecting ducts of Bellini and renal medullary carcinoma: clinicopathologic analysis of 52 cases of rare aggressive subtypes of renal cell carcinoma with a focus on their interrelationship

Carcinoma of the collecting ducts of Bellini and renal medullary carcinoma are rare aggressive neoplasms of putative distal nephron origin. First described in 1949, case reports and review articles constitute a major source of information on collecting duct carcinoma, whereas Davis and colleagues and the pediatric tumor registry have contributed the seminal works on renal medullary carcinoma. Here we present a detailed study of collecting duct carcinoma (n=39) and renal medullary carcinoma (n=13), characterizing these rare neoplasms and analyzing their interrelationship. Both collecting duct carcinoma and renal medullary carcinoma exhibited significant similarities, such as predilection for the right kidney, tumor mass with an epicenter in the renal medulla, and a mean size of 7 cm. Overall, both tumors exhibited a poorly differentiated adenocarcinoma histology with desmoplastic stromal response (100%), inflammatory infiltrate (100%), frequent perinephric extension (collecting duct carcinoma: 97%; renal medullary carcinoma: 83%), lymphovascular invasion (100%), intraluminal mucin (collecting duct carcinoma: 42%; renal medullary carcinoma: 73%), high nuclear grade (97%), overlapping immunoreactivity for Ulex europaeus agglutinin 1 (collecting duct carcinoma: 75%; renal medullary carcinoma:55%), CK7 (collecting duct carcinoma: 44%; renal medullary carcinoma: 71%), and high-molecular weight cytokeratin (collecting duct carcinoma: 26%; renal medullary carcinoma: 29%), and nonimmunoreactivity for Ksp-cadherin. Histologically, collecting duct carcinoma frequently had tubular, tubulopapillary, or irregular glandular architecture, whereas renal medullary carcinoma commonly demonstrated islands of anastomosing tubules and cords forming irregular microcystic spaces. Multiple metastases to the lymph nodes, lung, bone, and liver were observed in both categories at presentation (collecting duct carcinoma: 17%; renal medullary carcinoma: 36%). Only patients with organ-confined small tumors were disease free beyond the median survival time. Differential clinical features between collecting duct carcinoma and renal medullary carcinoma included proclivity for younger male individuals of African ancestry with hemoglobin abnormalities and a shorter median survival of 17 weeks (vs. 44 wk for collecting duct carcinoma) for renal medullary carcinoma. The markedly overlapping clinical features, histology, immunophenotype, metastasis patterns, and uniformly aggressive outcome in collecting duct and renal medullary carcinomas suggest that renal medullary carcinoma is a distinctive clinicopathologic subtype within the entity of collecting duct carcinoma. The extremely poor prognosis and ongoing clinical trials with specific therapeutic protocols argue for their accurate distinction from other renal cell carcinoma subtypes.

Preventive and Therapeutic Vaccines against Human Papillomaviruses Associated Cervical Cancers

Cervical cancer is, globally known to be, one of the most common cancers among women especially in developing countries. More than 90% of cervical cancers are associated with high-risk human papillomaviruses (HPVs) particularly HPV types 16 and 18. Two major strategies have been developed for prevention and treatment of cervical cancer and other HPV-associated malignancies; the first one is based on HPV virus-like particles (VLPs) containing HPV structural proteins. VLP based vaccines can induce genotype specific virus neutralizing antibodies for preventing HPV infections. The other strategy is based on HPV early genes especially E6 and E7 for eliminating the established HPV infections; therefore they are classified as HPV therapeutic vaccines. This article reviews the preventive and therapeutic vaccines against HPV infections and cervical cancer.

Clinical perspectives on the role of the human papillomavirus vaccine in the prevention of cancer

The role of human papillomavirus (HPV) in the genesis of cervical cancer has been well documented, and an increasing body of literature exists with regard to the role of HPV in other cancers, including cancers of the head and neck. With the recent expansion of the United States Food and Drug Administration's approval of the quadrivalent HPV virus-like particle vaccine to include men and boys and approval of the bivalent vaccine this year, the controversies regarding who should be vaccinated, at what age is vaccination most appropriate, and the limitations of the available HPV vaccines are increasing. Health care providers are challenged with evaluating the current, but continually changing, clinical evidence when making critical decisions for their patients. A literature search of MEDLINE and SciVerse Scopus was conducted for articles published from 1998-April 2010 regarding HPV, HPV-related cancers, and HPV vaccines. Although both HPV vaccines were greater than 90% effective in the prevention of cervical cancer precursors in an according-to-protocol cohort, both vaccines were significantly less effective in the intent-to-treat population. In patients who achieved seroconversion, the geometric mean titers decrease dramatically within the first 2 years after vaccination, and then continue to decline at a slower rate. No effective antibody titer has been defined for either vaccine, and no studies have been conducted with documented HPV exposure after vaccination. With low efficacy rates in an intent-to-treat population and the potential for waning immunity, it is imperative for women to continue to receive regular Pap tests and gynecologic examinations. Although vaccine administration was shown to be cost-effective when administered to adolescent girls, many of these simulations overestimated the durability of protection, efficacy rates in sexually active women, impact of incomplete vaccination, or necessity of boosters in the future. Whereas the introduction of the HPV vaccine was an enormous advancement in the cancer prevention research arena, optimization of its clinical use is still needed.

Immunotherapy for persistent viral infections and associated disease

Persistent viral infections reflect a failure of the host's immune system to control infection, and in many cases, they are associated with the development of malignancies. So far, vaccines designed to boost viral immunity during chronic infection have not been successful. Infections with high-risk human papilloma viruses (e.g. HPV16) are acquired by a large segment of the population and persist in 5-10% of infected individuals, which causes the development of high-grade pre-malignant lesions. Recently we succeeded in causing regression of HPV16-induced disease in ∼50% of chronically infected patients by a novel therapeutic vaccine. Here, we summarize the parallels in immunity against HPV and other chronic viruses and discuss the general implications of our findings for the immunotherapy of chronic infections.

Hepatitis B virus and cancer prevention

Prevention of chronic hepatitis B virus (HBV) infection can successfully reduce the incidence of liver cancer. It is the first example of cancer-preventive vaccine in human, which proves that prevention of the infection of an infectious agent can prevent its related cancer.Chronic HBV infection can lead to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC). HCC is one of the five major cancers in the world population. Hepatitis B virus (HBV) is the most important etiologic agent of liver cancer globally, particularly in high-prevalence areas of liver cancer.The world's first universal HBV vaccination program was launched in Taiwan in July 1984. It has provided evidences that the prevalence of HBV infection has been reduced remarkably to approximately one-tenth of the original prevalence. Furthermore, reduction of the HCC incidence in children aged 6-14 years have been demonstrated in the vaccinated birth cohorts. Recently, we have further provided evidence that the prevention of HCC by this HBV vaccine extends from childhood to early adulthood.The risk of developing HCC for vaccinated cohorts was associated with incomplete HBV vaccination; prenatal maternal hepatitis B surface antigen (HBsAg) seropositivity; and prenatal maternal HBeAg seropositivity. Failure to prevent HCC results mostly from unsuccessful control of HBV infection by highly infectious mothers. Future strategies to increase the global coverage rate of HBV immunization and to interrupt mother-to- infant transmission may enhance the cancer prevention effect of HBV immunization.

Chloroplasts as expression platforms for plant-produced vaccines

Production of recombinant subunit vaccines from genes incorporated in the plastid genome is advantageous because of the attainable expression level due to high transgene copy number and the absence of gene silencing; biocontainment as a consequence of maternal inheritance of plastids and no transgene presence in the pollen; and expression of multiple transgenes in prokaryotic-like operons. We discuss the core technology of plastid transformation in Chlamydomonas reinhardtii, a unicellular alga, and Nicotiana tabacum (tobacco), a flowering plant species, and demonstrate the utility of the technology for the production of recombinant vaccine antigens.

A comparative analysis of gene expression patterns and cell phenotypes between cervical and peripheral blood mononuclear cells

Studies of the immunological environment in the female genital tract (FGT) are critical for the development of vaccines or microbicides to halt the spread of sexually transmitted infections. Challenges arise due to the difficulties of sampling from this site, and the majority of studies have been conducted utilising peripheral blood mononuclear cells. Identifying functional differences between immune cells of the FGT and peripheral blood would aid in our understanding of mucosal immunology. We compared the gene expression profile of mononuclear cells at these two sites. Messenger RNA expression analysis was performed using gene expression arrays on matched cervical mononuclear cells and peripheral blood mononuclear cells. Further cellular phenotyping was done by 10 colour flow cytometry. Of the 22,185 genes expressed by these samples, 5345 genes were significantly differentially expressed between the cell populations. Most differences can be explained by significantly lower levels of T and B cells and higher levels of macrophages and dendritic cells in the FGT compared with peripheral blood. Several immunologically relevant pathways such as apoptosis and innate immune signalling, and a variety of cytokines and cytokine receptors were differentially expressed. This study highlights the importance of the unique immunological environment of the FGT and identifies important differences between systemic and mucosal immune compartments.

One-step chromatographic purification of human papillomavirus type 16 L1 protein from Saccharomyces cerevisiae

The prophylactic human papillomavirus vaccine is based on recombinant L1 protein produced in yeast or insect cells. L1 is a major capsid protein that self-assembles into virus-like particles (VLP). Conventionally, several chromatography steps are required to purify it; the steps are time consuming, and they result in losses of the target protein. Ultracentrifugation using a sucrose cushions or cesium chloride density gradients, and size-exclusion chromatography, has also been routinely used for small scale purification of L1 protein. However, these methods require a great deal of time and labor, and are not suitable for industrial-scale purification. To resolve these problems, we have developed two simple one-step chromatography methods for purifying recombinant HPV16 L1 protein produced in Saccharomyces cerevisiae. Eighty percent of the contaminating protein was removed by ammonium sulfate precipitation and by precipitating contaminants prior to the chromatography step. One method uses heparin chromatography and the other, cation-exchange chromatography, and recoveries by the two methods were both about 60%, the highest recoveries of L1 protein achieved so far. We confirmed that HPV16 L1 protein purified by either method self-assembles into VLP. We anticipate that these one-step chromatography methods will reduce the time, cost and labor needed for purification of L1 protein, and facilitate the study of prophylactic HPV vaccines.

Singaporean men's knowledge of cervical cancer and human papillomavirus (HPV) and their attitudes towards HPV vaccination

Little is known of men's knowledge of cervical cancer and its links with human papillomavirus (HPV), or of their attitudes and beliefs about HPV vaccination. This is despite men's sexual behaviour contributing to HPV transmission and their potential role in deciding whether their children are vaccinated against HPV. To address this, a comprehensive survey was conducted in Singapore where plans are underway for an HPV vaccination program. A representative sample of 930 Singaporean men was found to have moderate knowledge of cervical cancer but poor knowledge and awareness of HPV. Although these men showed strong support for HPV vaccination, overall findings highlight the importance of including men in education campaigns that aim to decrease the incidence of cervical and other HPV-related cancers and to increase the uptake of HPV vaccination.