Type-specific human papillomavirus infections among young heterosexual male and female STI clinic attendees.

BACKGROUND: Baseline genotype-specific human papillomavirus (HPV) prevalence rates and associated risk factors per gender enable future assessment of the impact of vaccination on HPV dynamics. METHODS: Before the start of national HPV vaccination for girls, data were collected cross-sectionally in nationwide Dutch sexually transmitted infections (STI) clinics among heterosexual males (n = 430) and females (n = 1136) aged 16 to 24 years. Self-collected vaginal or penile swabs were analyzed by a sensitive polymerase chain reaction (SPF10) and genotyped with line probe assay. Logistic regression was applied to estimate determinants of HPV prevalent infections. RESULTS: HPV prevalence was 54% among males and 72% among females. High-risk (HR) HPV was present in males and females, 40% and 58%, respectively. Independent risk factors for HR-HPV infection were female gender, number of lifetime sex partners and a history of chlamydia or gonorrhea. In addition, not having a casual partner and consistent condom use were protective factors in women, but not in men. For low-risk (LR) HPV, the odds were smaller. Multiple HR-HPV and sexual risk behavior showed a stronger association compared with a single HR-HPV infection. CONCLUSIONS: Prevalence of HR-HPV is high in both genders. Infection with multiple HR-HPV types was more associated with high-risk sexual behavior than infection with LR-HPV types or a single HR-HPV type.

Hepatitis C virus seroprevalence in the Netherlands.

A population-based anti-hepatitis C virus (HCV) prevalence is important for surveillance purposes and it provides an insight into the burden of disease. In The Netherlands, a recent HCV seroprevalence estimate is not available. This national population-based cross-sectional serosurvey (PIENTER-2) resulted in a weighted national HCV seroprevalence of 0.30% (95% confidence interval 0.05-0.55%). About 70% of the HCV positive individuals found were born in an HCV-endemic country.

Age-specific HPV seroprevalence among young females in The Netherlands.

OBJECTIVES: To obtain insight into the age-specific seroprevalence for human papillomavirus (HPV) 6, 11, 16 and 18 among females before introduction of HPV vaccination in The Netherlands. METHODS: In a population-based study in The Netherlands, 637 sera of 11-26-year-old females were tested for HPV6/11/16/18 antibodies. Sera were tested using a competitive Luminex assay with neutralising monoclonal antibodies specific for each serotype. Associations between HPV seropositivity, demographics, and sexual behaviour were studied with logistic regression. Seroprevalences were standardised for age and urbanisation degree to the general female population in The Netherlands. RESULTS: The overall prevalence of antibodies against HPV6/11/16/18 was 7.9%. 4.3% had antibodies against HPV types 6/11, and 4.4% had antibodies against HPV types 16/18. HPV seropositivity significantly increased with age (OR 1.2; 95% CI 1.1 to 1.4), starting at the age of 16 years (median age of sexual debut in The Netherlands). A former diagnosis with sexually transmitted infections was also significantly associated with HPV seropositivity (OR 6.3; 95% CI 2.2 to 17.9). CONCLUSIONS: In addition to 12-year-old girls who are targeted for routine HPV vaccination, also girls up to 16 years are likely to benefit substantially from HPV16/18 vaccination. Testing for the presence of HPV antibodies in females after introduction of vaccination makes it possible to monitor the impact of immunisation at the population level.

Assessing the potential effects and cost-effectiveness of programmatic herpes zoster vaccination of elderly in the Netherlands.

BACKGROUND: Herpes zoster (HZ) is a painful disease affecting a considerable part of the elderly. Programmatic HZ vaccination of elderly people may considerably reduce HZ morbidity and its related costs, but the extent of these effects is unknown. In this article, the potential effects and cost-effectiveness of programmatic HZ vaccination of elderly in the Netherlands have been assessed according to a framework that was developed to support evidence-based decision making regarding inclusion of new vaccines in the Dutch National Immunization Program. METHODS: An analytical framework was used combining a checklist, which structured relevant data on the vaccine, pathogen and disease, and a cost-effectiveness analysis. The cost-effectiveness analysis was performed from a societal perspective, using a Markov-cohort-model. Simultaneous vaccination with influenza was assumed. RESULTS: Due to the combination of waning immunity after vaccination and a reduced efficacy of vaccination at high ages, the most optimal cost-effectiveness ratio (21716 euro per QALY) for HZ vaccination in the Netherlands was found for 70-year olds. This estimated ratio is just above the socially accepted threshold in the Netherlands of 20000 euro per QALY. If additional reduction of postherpetic neuralgia was included, the cost-effectiveness ratio improved (approximately 10000 euro per QALY) but uncertainty for this scenario is high. CONCLUSIONS: Vaccination against HZ at the age of 70 years seems marginally cost-effective in the Netherlands. Due to limited vaccine efficacy a considerable part of the disease burden caused by HZ will remain, even with optimal acceptance of programmatic vaccination.

Molecular sequence data of hepatitis B virus and genetic diversity after vaccination.

The effect of vaccination programs on transmission of infectious disease is usually assessed by monitoring programs that rely on notifications of symptomatic illness. For monitoring of infectious diseases with a high proportion of asymptomatic cases or a low reporting rate, molecular sequence data combined with modern coalescent-based techniques offer a complementary tool to assess transmission. Here, the authors investigate the added value of using viral sequence data to monitor a vaccination program that was started in 1998 and was targeted against hepatitis B virus in men who have sex with men in Amsterdam, the Netherlands. The incidence in this target group, as estimated from the notifications of acute infections with hepatitis B virus, was low; therefore, there was insufficient power to show a significant change in incidence. In contrast, the genetic diversity, as estimated from the viral sequence collected from the target group, revealed a marked decrease after vaccination was introduced. Taken together, the findings suggest that introduction of vaccination coincided with a change in the target group toward behavior with a higher risk of infection. The authors argue that molecular sequence data provide a powerful additional monitoring instrument, next to conventional case registration, for assessing the impact of vaccination.

Simultaneous vaccination with Prevenar and multicomponent vaccines for children: interference or no interference?

Multicomponent vaccines against as many as six infectious diseases are often given simultaneously with monovalent or multivalent vaccines against meningococcus and pneumococcus. Detailed analysis of simultaneous vaccinations, which can lead to suboptimal induced immune responses, should precede their combined use in national immunization programmes. By combining the results of the only two published studies evaluating simultaneous vaccinations with Infanrix hexa and Prevanar in a random-effect meta-analysis, we show that the one-sided 95% confidence interval of the HBV seroconversion rate includes the 95% limit that should be reached in universal programs. We advocate better assessment of potential interferences in immune responses after simultaneous vaccinations. Registration of new vaccines should include this assessment.

The polio eradication effort has been a great success--let's finish it and replace it with something even better.

The polio eradication campaign has greatly reduced the effects of this disease, but many new challenges have emerged. These challenges include the occurrence of polio outbreaks caused by wild-type polioviruses or circulating vaccine-derived polioviruses (cVDPVs) in areas where vaccination coverage is low, the existence of people who excrete poliovirus persistently, and the inability to know definitely that poliovirus has gone. As a result, there is uncertainty about if, when, and how we can end polio immunisation. In this article, we discuss several scenarios for the future of polio control. Because the emergence of cVDPVs necessitates discontinuing the use of live oral polio vaccine, we propose to strive towards a global coverage of near 100% vaccination against all major childhood infections using combination vaccines that contain inactivated poliovirus vaccine. Such a policy will present multiple challenges.

Modifications of the 3'-UTR stem-loop of infectious bursal disease virus are allowed without influencing replication or virulence.

Many questions regarding the initiation of replication and translation of the segmented, double-stranded RNA genome of infectious bursal disease virus (IBDV) remain to be solved. Computer analysis shows that the non-polyadenylated extreme 3'-untranslated regions (UTRs) of the coding strand of both genomic segments are able to fold into a single stem-loop structure. To assess the determinants for a functional 3'-UTR, we mutagenized the 3'-UTR stem-loop structure of the B-segment. Rescue of infectious virus from mutagenized cDNA plasmids was impaired in all cases. However, after one passage, the replication kinetics of these viruses were restored. Sequence analysis revealed that additional mutations had been acquired in most of the stem-loop structures, which compensated the introduced ones. A rescued virus with a modified stem-loop structure containing four nucleotide substitutions, but preserving its overall secondary structure, was phenotypically indistinguishable from wild-type virus, both in vitro (cell culture) and in vivo (chickens, natural host). Sequence analysis showed that the modified stem-loop structure of this virus was fully preserved after four serial passages. Apparently, it is the stem-loop structure and not the primary sequence that is the functional determinant in the 3'-UTRs of IBDV.

Correction: Genetic Diversity in the Major Capsid L1 Protein of HPV-16 and HPV-18 in the Netherlands.

[This corrects the article DOI: 10.1371/journal.pone.0152782.].

Genetic Diversity in the Major Capsid L1 Protein of HPV-16 and HPV-18 in the Netherlands.

OBJECTIVES: Intratypic molecular variants of human papillomavirus (HPV) type-16 and -18 exist. In the Netherlands, a bivalent vaccine, composed of recombinant L1 proteins from HPV-16 and -18, is used to prevent cervical cancer since 2009. Long-term vaccination could lead to changes in HPV-16 and -18 virus population, thereby hampering vaccination strategies. We determined the genetic diversity of the L1 gene in HPV-16 and -18 viral strains circulating in the Netherlands at the start of vaccination in order to understand the baseline genetic diversity in the Dutch population. METHODS: DNA sequences of the L1 gene were determined in HPV-16 (n = 241) and HPV-18 (n = 108) positive anogenital samples collected in 2009 and 2011 among Dutch 16- to 24-year old female and male attendees of the sexually transmitted infection (STI) clinics. Phylogenetic analysis was performed and sequences were compared to reference sequences HPV-16 (AF536179) and HPV-18 (X05015) using BioNumerics 7.1. RESULTS: For HPV-16, ninety-five single nucleotide polymorphism (SNPs) were identified, twenty-seven (28%) were non-synonymous variations. For HPV-18, seventy-one SNPs were identified, twenty-nine (41%) were non-synonymous. The majority of the non-silent variations were located in sequences encoding alpha helix, beta sheet or surface loops, in particular in the immunodominant FG loop, and may influence the protein secondary structure and immune recognition. CONCLUSIONS: This study provides unique pre-vaccination/baseline data on the genetic L1 diversity of HPV-16 and -18 viruses circulating in the Netherlands among adolescents and young adults.

Correlation between viral load, multiplicity of infection, and persistence of HPV16 and HPV18 infection in a Dutch cohort of young women.

BACKGROUND: Persistent high-risk human papillomavirus infection precedes the development of cervical cancer. Here we evaluated the contribution of HPV16/18 viral load and the presence of infections with multiple HPV types to persistence and clearance of HPV16/18 infections. METHODS: Vaginal self-swabs were obtained from young women (16-29 y) with one year interval. HPV genotyping was performed using the highly sensitive SPF10-DEIA-LiPA25 system. HPV16/18 DNA loads were quantified via an adapted, highly sensitive qPCR protocol targeting the L1 gene. RESULTS: We identified 227 HPV16 and 111 HPV18 infections with follow-up. For HPV16 132/227 (58%) were persistent and 95/227 cleared. For HPV18 49/111 (44%) infections were persistent and 62/111 cleared. Baseline viral load was significantly higher in persistent infections than in clearing infections for both HPV16 (p=0.022) and HPV18 (p=0.013). At baseline, only HPV16 viral load was significantly higher in multiple HPV infections compared with single infections (p=0.003). In logistic regression analysis HPV16 and HPV18 viral load were found to contribute to persistency with OR=1.279 (95%CI=1.074-1.524) and OR=1.256 (95%CI=1.028-1.533) per log-unit increase HPV16 and HPV18 viral load respectively. The presence of multiple HPV type infections was not associated with higher persistency. CONCLUSION: HPV16/18 viral load might be used as a marker for persisting infections and is affected by the presence of multiple HPV infections. Evaluation of these parameters at the population level may be of value to assess the presence of persistent or clearing HPV16/18 infections as an early marker, and may provide useful quantitative information in (epidemiological) vaccine monitoring studies.

Rapid RT-PCR amplification of full-length poliovirus genomes allows rapid discrimination between wild-type and recombinant vaccine-derived polioviruses.

Poliomyelitis outbreaks in areas that were free for a long time of wild-type polioviruses have been reported. Characterization at nucleotide level of the causative agents showed that the isolated viruses were recombinant oral polio vaccine (OPV)-derived polioviruses. To allow rapid identification and detailed analysis of such recombinant polioviruses, a robust full-length reverse transcriptase-PCR (RT-PCR) was developed using SuperScript II (RT) and expand (PCR). Without extensive purification, it was possible to amplify and characterize the full-length genomes of all selected vaccine, wild-type, and recombinant vaccine-derived polioviruses within a week. Endonuclease nuclease analysis (SpeI) of the full-length amplicons allowed easy discrimination between recombinant and non-recombinant polioviruses. Furthermore, sequence analysis of cloned full-length amplicons of a recombinant vaccine-derived poliovirus strain showed that the quasi-species nature of a viral stock is preserved during the RT-PCR procedure. This robust and rapid RT-PCR method will allow rapid characterization of (recombinant) poliovirus strains in case of a local poliomyelitis outbreak, and will help to assess the risk of the appearance of such strains after wild-type poliovirus has been eradicated globally.

Six-month incidence and persistence of oral HPV infection in HIV-negative and HIV-infected men who have sex with men.

OBJECTIVES: Our aim was to assess incidence and persistence of oral HPV infection in HIV-negative and HIV-infected men who have sex with men (MSM). METHODS: MSM aged ≥18 years were included in Amsterdam (the Netherlands) in 2010-2011, and followed up 6 months later. Participants completed risk factor questionnaires. HPV DNA was analyzed in oral-rinse and gargle specimens using the SPF10-PCR DEIA/LiPA25 system (version 1). A subset of oral samples was subjected to SPF10 sequencing to identify additional HPV types. Multivariable logistic regression analyses using generalized estimating equations (GEE) were performed to assess determinants for oral high-risk HPV incidence and persistence. RESULTS: 689/795 participant MSM provided both baseline and 6-month data. Baseline prevalence of high-risk HPV was 9.4% in HIV-negative and 23.9% in HIV-infected MSM (P<0.001). 56/689 MSM acquired ≥1 high-risk HPV infection (6-month incidence 8.1%; 95%CI 6.2-10.4%); incidence was 4.1% in HIV-negative and 14.1% in HIV-infected MSM (P<0.001). HIV infection and recent use of cannabis were both independently associated with high-risk HPV incidence. Persistent high-risk HPV was observed in 48/130 (36.9%) infections. CONCLUSION: Incidence of oral high-risk HPV infection in MSM is substantial, and is associated with HIV infection. Over a third of HPV infections persisted over a 6-month period.

Varicella zoster virus infection occurs at a relatively young age in The Netherlands.

INTRODUCTION: To date, there is no universal varicella vaccination in the Netherlands. We studied the seroprevalence of varicella zoster virus (VZV) specific antibodies and determinants for seropositivity among participants of a serosurveillance study, conducted in 2006/2007 among Dutch inhabitants 0-79 years of age. MATERIALS AND METHODS: Serological testing of 6386 blood samples for VZV was performed with a fluorescent bead-based multiplex immunoassay. Seroprevalence and geometric mean concentration (GMC) were weighted for age, sex, ethnicity, and urbanization rate to the total Dutch population. Determinants for VZV seropositivity were identified among children younger than 6 years of age using a logistic regression model. RESULTS: The overall seroprevalence of VZV specific antibodies in the Dutch population was 94.6% (95% CI: 93.2-96.0%). This seroprevalence increased rapidly with age: at 6 years of age, more than 95% were seropositive. Determinants associated with lower VZV seropositivity were: young age, first-generation non-Dutch ethnicity, and low frequency of attendance at a day care center or nursery school. The GMC increased with age and was lower for women than for men from the age of 20 years onwards. CONCLUSIONS: This study confirmed that VZV infection occurs at a younger age in the Netherlands compared to other countries, which might explain the low disease burden due to varicella. Introduction of universal varicella vaccination is not a foregone conclusion in the Netherlands. Changes in migration and day care usage will influence the age-specific risk on varicella and should therefore be monitored. Further research might elucidate the sex differences in VZV specific GMC.

Selective hepatitis B virus vaccination has reduced hepatitis B virus transmission in the Netherlands.

BACKGROUND & AIMS: In the Netherlands, a selective hepatitis B virus (HBV) vaccination programme started in 2002 for men having sex with men, drug users, commercial sex workers and heterosexuals with frequent partner changes. We assessed the programme's effectiveness to guide policy on HBV prevention. METHODS: We analysed reports of acute HBV infection in the Netherlands between 2004 and 2010 requesting serum from patients for HBV-genome S- and C-region sequencing. We used coalescence analyses to assess genetic diversity of nonimported genotype-A cases over time. RESULTS: 1687 patients with acute HBV infection were reported between 2004 and 2010. The incidence of reported acute HBV infection decreased from 1.8 to 1.2 per 100,000 inhabitants, mostly due to a reduction in the number of cases in men who have sex with men. Men were overrepresented among cases with an unknown route of transmission, especially among genotype A2 cases mainly associated with transmission through male homosexual contact. The genetic diversity of nonimported genotype-A strains obtained from men who have sex with men decreased from 2006 onwards, suggesting HBV incidence in this group decreased. CONCLUSIONS: The selective HBV-vaccination programme for behavioural high-risk groups very likely reduced the incidence of HBV infection in the Netherlands mainly by preventing HBV infections in men who have sex with men. A considerable proportion of cases in men who did not report risk behaviour was probably acquired through homosexual contact. Our findings support continuation of the programme, and adopting similar approaches in other countries where HBV transmission is focused in high-risk adults.

Patterns of human papillomavirus DNA and antibody positivity in young males and females, suggesting a site-specific natural course of infection.

BACKGROUND: To monitor the impact of human papillomavirus types 16 and 18 vaccine on HPV infection dynamics in the Netherlands, we started an ongoing study in sexually transmitted infection (STI) clinics in 2009. Here, we analyze baseline type-specific HPV DNA and HPV-specific antibody positivity rates. METHODS: We enrolled 3569 men and women, 16-24 years of age, from 14 STI clinics, and estimated genital and anal HPV DNA and antibody positivity rates of 7 main carcinogenic HPV types. Generalized estimating equations regression analyses were applied to determine risk factors for, and associations between, type-specific HPV DNA and antibody positivity. RESULTS: Genital HPV DNA positivity rates were higher in women than in men; anal HPV DNA was especially high in men who have sex with men (MSM). HPV antibody seropositivity rates were also highest in women and MSM. High-risk sexual behavior was predictive of both HPV DNA and antibody positivity. Despite a strong correlation in serological profiles for multiple HPV types, seropositivity was independently associated with homologous HPV DNA detection. CONCLUSIONS: HPV DNA and antibody positivity rates are higher in women and MSM than in heterosexual men, but their association is similar across gender. This suggests a site-specific natural course of infection.

Oral human papillomavirus infection in HIV-negative and HIV-infected MSM.

OBJECTIVE: Oral infection with human papillomavirus (HPV) is associated with a subset of head and neck cancers. We compared prevalence of, and risk factors for, oral HPV infection among HIV-negative and HIV-infected MSM. DESIGN: Analysis of baseline data from a prospective cohort study. METHODS: MSM aged 18 years or older were recruited from three study sites in Amsterdam, the Netherlands. Participants completed a self-administered risk-factor questionnaire. Oral-rinse and gargle specimens were analyzed for HPV DNA and genotyped using a highly sensitive PCR and reverse line blot assay [short PCR fragment (SPF)10-PCR-DNA Enzyme Immuno Assay (DEIA)/LiPA25 system]. RESULTS: In 2010-2011, 794 MSM were included, of whom 767 participants had sufficient data for analysis. Median age was 40.1 years [interquartile range (IQR) 34.8-47.5] and 314 men were HIV-infected (40.9%). Any of 25 typable HPV types was present in 24.4% of all oral samples. Oncogenic HPV types were detected in 24.8 and 8.8% of oral samples from HIV-infected and HIV-negative MSM, respectively (P < 0.001). Of these high-risk types, HPV-16 was the most common (overall 3.4%). Oral infection with high-risk HPV was associated with HIV infection in multivariable analysis (P < 0.001). Increasing age was significantly associated with oral HPV infection in HIV-negative, but not in HIV-infected MSM. CONCLUSION: Oral HPV infection is very common among MSM. HIV infection was independently associated with high-risk oral HPV infection, suggesting an important role of HIV in oral HPV infection.

Prevalence, incidence and persistence of genital HPV infections in a large cohort of sexually active young women in the Netherlands.

BACKGROUND: We assessed age- and type-specific HPV prevalence, incidence and persistence and their associated risk factors in young women prior to vaccination, to enable monitoring of the impact of introduction of HPV vaccination in the years before participation in the cervical screening program. METHODS: The HPV status was assessed in 3282 women aged 16-29 who participated in a Chlamydia trachomatis screening implementation program, of which 2014 women (61%) participated in two rounds (one year apart). Self-collected vaginal swab were analyzed by SPF(10) LiPA on the presence of HPV DNA. Risk factors for prevalent, incident and persistent HPV infections were calculated using generalized estimating equation. RESULTS: The prevalence of any HPV in the first round amounted to 54%, while 34% of the women who participated in the second round had a persistent infection and 45% an incident infection. The five most common HPV types found in this study were HPV16, -51, -52, -31 and -53. HPV16 and/or HPV18 prevalence, incidence and persistence in the second round were 15%, 8% and 9%, respectively and for HPV6 and/or HPV11 6%, 4% and 2%, respectively. Relatively to other HPV genotypes, hrHPV types were found more often as a persistent infection than as an incident infection. Furthermore, there is an age-dependent increase within this age range for persistent infections but not for incident infections. CONCLUSION: The HPV prevalence (54%), incidence (45%) and persistence (34%) is high among sexually active young women in the Netherlands. The different HPV type distribution and risk factors for prevalent, incident and persistent infections, as well as the observed age-trends should be taken into account in interpreting data obtained after vaccine introduction. Repeating measurements post-immunization are particularly relevant until the age when screening starts (i.e. 30 years in the Netherlands).