Epidemiology and Natural History of Human Papillomavirus Infections and Type-Specific Implications in Cervical Neoplasia
ABSTRACT Worldwide human papillomavirus (HPV) prevalence in women with normal cytology at any given point in time is approximately 10% indicating that HPV is one of the most common sexually transmitted infections. HPV-16 is consistently the most common type and HPV-18 the second with some minor regional differences. Furthermore, across the spectrum of cervical lesions, HPV-16 is consistently the most common HPV type contributing to 50-55% of invasive cervical cancer cases strongly suggesting that this viral type has a biological advantage for transmission, persistency and transformation. The same phenomenon is observed albeit at a lower level for HPV-18 and HPV-45. Sexual behavioral patterns across age groups and populations are central to the description of the HPV circulation and of the risk of infection. The concept of group sexual behavior (in addition to individual sexual behavior) is important in exploring HPV transmission and has implications for defining and monitoring HPV and cancer prevention strategies. In natural history studies, the pattern of HPV DNA prevalence by age groups is similar to the patterns of HPV incidence. Rates of exposure in young women are high and often include multiple types. There is a spontaneous and rapid decrease of the HPV DNA detection rates in the middle-age groups followed by a second rise in the post-menopausal years. This article reviews: 1) the evidence in relation to the burden of HPV infections in the world and the contributions of each HPV type to the spectrum of cervical cellular changes spanning from normal cytology to invasive cervical cancer; 2) the critical role of the patterns of sexual behavior in the populations; and 3) selected aspects of the technical and methodological complexity of natural history studies of HPV and cervical neoplasia.
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ABSTRACT: The aim of this study was to examine the knowledge of Belgian university students about the human papillomavirus (HPV) and HPV-vaccination. During a period of two months we administered an online questionnaire, which contained 29 questions, to 3332 students of the Free University of Brussels. Of the 433 completed questionnaires, 346 were included by age (18-30 years) and completeness of responded questionnaires. These formed the study group. Of the 346 included questionnaires (76% female), 48% were completed by medical students. The majority (65%) knew that both genders could be infected with HPV. Ninety-five percent of all medical students were aware of the existence of HPV, while 92% knew of the possibility to be vaccinated against the virus. Ninety percent of them were aware of the causal relationship between HPV infection and cervical cancer. 46% of the medical students were aware that HPV can cause anogenital cancers, and only 28% knew that HPV-vaccination could protect them against genital warts. Sixty percent of all female students were fully vaccinated against HPV, without any difference between medical and non-medical students. A very small part of all students (3%) believed that vaccination against HPV could enhance a promiscuous lifestyle. Almost 80% of respondents were aware of the existence of the human papillomavirus, its morbid potential and the HPV-vaccination.
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ABSTRACT: In this paper, we review the published evidence about the long-term efficacy of the available human papillomavirus (HPV) vaccines and their safety profile. Two prophylactic HPV vaccines - bivalent (bHPV) and quadrivalent (qHPV) - are now available, and vaccination programs are being widely implemented, primarily targeting adolescent girls. Efficacy has been widely demonstrated for both vaccines. Since the risk of HPV exposure potentially persists throughout a woman's sexual life, vaccine duration of protection is critical to overall effectiveness. Interpreting the results of long-term efficacy studies for the two HPV vaccines can be puzzling, due to the heterogeneity of studies, different methods used in the assessment of immunogenicity, histopathological and virological end points, and statistical power issues. Moreover, an immunologic correlate of protection has not yet been established, and it is unknown whether higher antibody levels will really result in a longer duration of protection. Disease prevention remains the most important measure of long-term duration of vaccine efficacy. To date, the longest follow-up of an HPV vaccine has been 9.4 years for the bHPV vaccine. Long-term follow-up for qHPV vaccine goes up to 8 years. The vaccine continues to be immunogenic and well tolerated up to 9 years following vaccination. All randomized controlled clinical trials of the bHPV and the qHPV vaccines provide evidence of an excellent safety profile. The most common complaint reported is pain in the injection site, which is self-limiting and spontaneously resolved. The incidence of systemic adverse events (AEs), serious AEs, and discontinuations due to a serious AE reported in clinical studies are similar between the two vaccines and their control groups. In particular, no increased risk of autoimmune disease has been shown among HPV-vaccinated subjects in long-term observation studies. As these are crucial topics in HPV vaccination, it is important to establish systems for continued monitoring of vaccine immunogenicity, efficacy, and safety over time.International Journal of Women's Health 01/2014; 6:999-1010. DOI:10.2147/IJWH.S50365
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ABSTRACT: Human papilloma virus (HPV)-16 is the prevalent genotype associated with cervical tumours. Virus-like-particle-based vaccines have proven to be effective in limiting new infections of high-risk HPVs, but their high cost has hampered their use, especially in the poor developing countries. Avipox-based recombinants are replication-restricted to avian species and represent efficient and safe vectors also for immunocompromised hosts, as they can elicit a complete immune response. A new fowlpox virus recombinant encoding HPV-L1 (FPL1) was engineered and evaluated side-by-side with a FP recombinant co-expressing L1 and green fluorescent protein (FPL1GFP) for correct expression of L1 in vitro in different cell lines, as confirmed by Western blotting, immunofluorescence, real-time PCR, and electron microscopy. Mice were also immunised to determine its immunogenicity. Here, we demonstrate that the FPL1 recombinant better expresses L1 in the absence of GFP, correctly assembles structured capsomers into virus-like particles (VLPs), and elicits an immune response in a preclinical animal model. To our knowledge, this is the first report of HPV VLPs assembled in eukaryotic cells using an avipox recombinant. Copyright © 2015. Published by Elsevier B.V.Antiviral Research 02/2015; 116. DOI:10.1016/j.antiviral.2015.01.012 · 3.43 Impact Factor