Naturally developed HPV16 antibodies and risk of newly detected cervical HPV infection outcomes.

Little is known about the protection conferred by antibodies from natural human papillomavirus (HPV) infection. Our objective was to evaluate the association between HPV16 seroreactivity and HPV16 redetection, newly detected HPV infections, and loss of HPV DNA detection during follow-up. We analyzed data from 2462 unvaccinated Brazilian women. HPV16 IgG and neutralizing antibodies at baseline were assessed by enzyme-linked immunosorbent assay (n = 1975) and by the pseudovirus-based papillomavirus neutralization assay (n = 487). HPV detection, genotyping, and viral load were assessed by PCR-based methods. The associations were analyzed by Cox proportional hazards models. We observed a positive association between HPV16 IgG seroreactivity and redetection of HPV16 infections. Age-adjusted hazard ratios (HR) with 95% confidence intervals (CI) ranged from 2.45 (1.04-5.74) to 5.10 (1.37-19.00). Positive associations were also observed between HPV16 IgG antibodies and (1) newly detected HPV infections by genotypes unrelated to HPV16 (age-adjusted HR [95% CI] = 1.32 [1.08-1.2]) and (2) loss of detection of HPV infections by genotypes unrelated to HPV16 (age-adjusted HR [95% CI] = 1.24 [1.03-1.50]). Naturally developed HPV16 antibodies do not prevent recurrent HPV infections. Overall HPV16 IgG and neutralizing antibodies seem to be serological markers for latent or past infections.

Correlation between cervical HPV DNA detection and HPV16 seroreactivity measured with L1-only and L1+L2 viral capsid antigens.

Introduction. Persistent human papillomavirus (HPV) type 16 infection is the main causal agent of cervical cancer. Most HPV infections clear spontaneously within 1-2 years. Although not all infected women develop detectable HPV antibodies, about 60-70 % seroconvert and retain their antibodies at low levels.Aim. We investigated if cervical HPV16 DNA positivity was associated with HPV16 seroreactivity measured with two different antigen formulations. We assessed if associations were influenced by co-infection with other HPV types and HPV16 viral load.Methodology. We used baseline data for women participating in the Ludwig-McGill cohort, a longitudinal investigation of the natural history of HPV infection and cervical neoplasia. The study enrolled 2462 Brazilian women from 1993 to 1997 (pre-vaccination). ELISA assays were based on L1-only or L1+L2 virus-like particles (VLPs). Seroreactivity was expressed as normalized absorbance ratios. HPV genotyping and viral load were evaluated by PCR protocols. Pearson's r was used to measure correlations between interval-scaled variables. Serological accuracy in HPV16 DNA detection was assessed using receiver operating characteristic (ROC) curves. We analysed the association between HPV DNA positivity and HPV16 seroreactivity by linear regression.Results. Correlations between L1+L2 and L1-only VLPs for detection of HPV16 were poor (r=0.43 and 0.44 for dilutions 1 : 10 and 1 : 50, respectively). The protocol with the best accuracy was L1+L2 VLPs at serum dilution 1 : 10 (ROC area=0.73, 95 % CI: 0.65-0.85). HPV16 DNA positivity was correlated with HPV16 seroreactivity and was not influenced by co-infection or viral load. To a lesser degree, HPV16 seroreactivity was correlated with infection by other Alpha-9 papillomavirus species.Conclusion. HPV16 DNA positivity and HPV16 seroreactivity are strongly correlated. L1+L2 VLPs perform better than L1-only VLPs for detecting IgG antibodies to HPV16 in women infected with HPV16 or other Alpha-9 HPV species. This study advances our understanding of humoral immune responses against HPV16 by providing insights about the influence of VLP antigen composition to measure humoral immune response against naturally acquired HPV infection.

Determinants of baseline seroreactivity to human papillomavirus type 16 in the Ludwig-McGill cohort study.

BACKGROUND: Immunity plays an important role in controlling human papillomavirus (HPV) infection and associated lesions. Unlike infections caused by other viruses, natural HPV infection does not always result in a protective antibody response. Therefore, HPV antibodies are also considered markers of cumulative exposure. The aim of this study was to identify determinants of HPV16 seroreactivity at enrollment among women from the Ludwig-McGill cohort, a natural history study of HPV infection and risk of cervical neoplasia. METHODS: HPV16 serology was assessed by ELISA for L1 and L2 capsid antigens, while HPV typing and viral load measurements were performed by PCR-based methods. The associations were analyzed by unconditional logistic regression. RESULTS: Of 2049 subjects, 425 (20.7%) were strongly seropositive for HPV16. In multivariate analysis, seroreactivity was positively correlated with age, lifetime number of sexual partners, frequency of sex, and HPV16 viral load, and negatively associated with duration of smoking. CONCLUSIONS: HPV16 seroreactivity is determined by factors that reflect viral exposure.

Seroprevalence of human papillomavirus 6, 11, 16, and 18 in young primiparous women in Sao Paulo, Brazil.

INTRODUCTION: Data on epidemiology of HPV infection are needed for the development of human papillomavirus (HPV) vaccine recommendations, especially in countries where HPV vaccination is not yet included in public vaccination programs. The aim of this study was to determine the prevalence of serum antibodies to HPV types 6, 11, 16, and 18 and associated factors among young women after birth of the first child. METHODS: This cross-sectional study was carried out in a large public maternity hospital in Sao Paulo, Brazil. Three hundred one women aged 15 to 24 years who gave birth to their first child were recruited between 43 and 60 days after delivery. Seroprevalence was performed using a type-specific enzyme-linked immunosorbent assay based on HPV Late protein 1 viruslike particles. The association of seroreactivity with these 4 HPV types with selected demographic and behavioral factors was assessed by Generalized Linear Model analysis. RESULTS: Fifty-eight (19.3%) women (95% confidence interval, 15.0%-24.2%) had antibodies to any of the 4 viruslike particles tested. The overall seroprevalence rates of the HPV types were: HPV16, 9.0%; HPV18, 7.0%; and HPV 6+11, 7.7%, which are targeted by the HPV prophylactic vaccines. In the multivariate analysis, only age (inversely, P = 0.044 for trend) and previous sexually transmitted disease (P = 0.008) were 2 factors independently associated with HPV seropositivity. CONCLUSIONS: These data offer additional information on the epidemiology of HPV in a group of young Brazilian women after first delivery and contribute to establish a baseline of HPV seroprevalence against which post-HPV vaccine era seroprevalence can be compared.

Human papillomavirus infection and reinfection in adult women: the role of sexual activity and natural immunity.

There is a paucity of data on whether or not women can be reinfected with human papillomavirus (HPV) types to which they were exposed to earlier in life and on the role of natural immunity. The observation of HPV infection at older ages may be explained by the reactivation of a latent infection or new exposure from sexual activity. Our objective was to analyze the association between reinfection and sexual activity. We analyzed data from 2,462 women enrolled in the Ludwig-McGill cohort and followed every 4 to 6 months for up to 10 years. We performed HPV typing and viral load measurements via PCR and determined HPV-16 seroreactivity at enrollment. Incidence of infection and reinfection were estimated for individual types. Adjusted relative risks (RR) for the association between infection/reinfection and new sexual partners were calculated using Cox regression. Rates of initial infection and reinfection postclearance were statistically comparable. RRs of initial infection or reinfection were consistently associated with new sexual partners [2.4 (95% confidence intervals; 95% CI, 2.0-3.1) for first infection, 3.7 (1.1-13.8) for reinfection with the same type, and 2.3 (1.5-3.7) for reinfection with a different type]. Reinfection in older women was also associated with new sexual partners (RR, 2.8; 95% CI, 1.4-5.3) as were new infections with HPV-16 among women with serologic evidence of prior HPV-16 exposure (RR, 3.0; 95% CI, 1.6-5.3). Viral loads at initial infection and at reinfection were comparable. HPV infection and reinfection were strongly associated with sexual activity. This study suggests that natural immunity does not play a role in controlling the extent of reinfections.

Use of the normalized absorbance ratio as an internal standardization approach to minimize measurement error in enzyme-linked immunosorbent assays for diagnosis of human papillomavirus infection.

The serological detection of antibodies against human papillomavirus (HPV) antigens is a useful tool to determine exposure to genital HPV infection and in predicting the risk of infection persistence and associated lesions. Enzyme-linked immunosorbent assays (ELISAs) are commonly used for seroepidemiological studies of HPV infection but are not standardized. Intra- and interassay performance variation is difficult to control, especially in cohort studies that require the testing of specimens over extended periods. We propose the use of normalized absorbance ratios (NARs) as a standardization procedure to control for such variations and minimize measurement error. We compared NAR and ELISA optical density (OD) values for the strength of the correlation between serological results for paired visits 4 months apart and HPV-16 DNA positivity in cervical specimens from a cohort investigation of 2,048 women tested with an ELISA using HPV-16 virus-like particles. NARs were calculated by dividing the mean blank-subtracted (net) ODs by the equivalent values of a control serum pool included in the same plate in triplicate, using different dilutions. Stronger correlations were observed with NAR values than with net ODs at every dilution, with an overall reduction in nonexplained regression variability of 39%. Using logistic regression, the ranges of odds ratios of HPV-16 DNA positivity contrasting upper and lower quintiles at different dilutions and their averages were 4.73 to 5.47 for NARs and 2.78 to 3.28 for net ODs, with corresponding significant improvements in seroreactivity-risk trends across quintiles when NARs were used. The NAR standardization is a simple procedure to reduce measurement error in seroepidemiological studies of HPV infection.

Opportunity for catch-up HPV vaccination in young women after first delivery.

BACKGROUND: Early age at first delivery has been identified as a risk factor for high-risk HPV-type infection and cervical cancer development. METHODS: A cross-sectional study was carried out in a large public maternity hospital in São Paulo, Brazil. During June 2006 to February 2007, 301 women aged 15-24 years who gave birth to their first child were recruited between 43 and 60 days after delivery. Detection of HPV DNA in cervical specimens was performed using a standardised PCR protocol with PGMY09/11 primers. The association of selected factors with HPV infection was assessed by using a Generalised Linear Model. RESULTS: HPV DNA was detected in 58.5% (95% CI 52.7% to 64.0%) of the enrolled young women. The most common types of HPV found were: HPV16, HPV51, HPV52, HPV58 and HPV71. The overall prevalence of HPV types targeted by the HPV prophylactic vaccines was: HPV 16-12.0%, HPV 18- 2.3% and HPV 6 and 11 4.3%. In the multivariate analysis, only age (inversely, p for trend=0.02) and smoking habits were independently associated with HPV infection. CONCLUSIONS: The findings show that these young primiparous women had high cervical HPV prevalence, suggesting that this is a high-risk group for cervical cancer development. Nevertheless, 17.3% were positive for any of the four HPV types included in HPV vaccines (HPV6, 11, 16 or 18), with 13.3% positive for HPV 16 or 18 and only 1.0% having both vaccine related-oncogenic HPV types. Thus, young primiparous women could benefit from catch-up HPV vaccination programmes.

How accurate is cytological diagnosis of cervical glandular lesions?

Gynecological cytology has some inaccurate morphological categorization and poor interobserver reproducibility especially for glandular lesions. Liquid-based cytology (LBC) preparations are presumed to reduce artifacts that interfere in diagnosis performance, but its value to correctly identify glandular alterations has not been sufficiently reported. The objective of this study was to compare the diagnostic performance and interobserver agreement of LBC and conventional Pap smear to identify histologically confirmed glandular lesions according to five cytologists. Sensitivity ranged from 55.8 to 73.1% and 32.7 to 48.1% for Pap smear and LBC, respectively. Specificity ranged from 66.1 to 87.1% and 69.4 to 94.4%, respectively. In general, agreement between pairs of cytologists was poor with kappa-values around 0.45. In conclusion, relying entirely on cervical cytology to rule out glandular lesions may be risky. The use of HPV DNA test alone or combined to screening glandular lesions may contribute to minimize the limitations of both conventional and LBC preparations to diagnose glandular abnormalities.

Avaliação da dinâmica da resposta imune humoral desencadeada pelo papilomavirus humano / Evaluation of the dinamics of the hummoral immune response triggered by human papillomavirus

Os anticorpos neutralizantes são cruciais na proteção contra doenças virais mediadas por vacinação. A elevada proteção adquirida contra infecções persistentes causadas pelo papilomavírus humano, por meio da imunização de mulheres com capsídios vazios de HPV-16, é conferida por este tipo de anticorpos. Os anticorpos neutralizantes detectados em amostras séricas de mulheres vacinadas foram capazes de neutralizar variantes divergentes de HPV-16... Neste trabalho detectaram-se anticorpos neutralizantes em amostras séricas obtidas de mulheres não vacinadas participantes de um estudo sobre os fatores de risco para o desenvolvimento de infecções pelo HPV e das neoplasias cervicais. O impacto da presença deste tipo de anticorpos foi analisado por meio das principais manifestações virais durante o curso natural da infecção pelo HPV... A eliminação de infecções HPV-16 induzidas não pareceu ter sido facilitada pela presença de altos níveis de nenhum tipo de anticorpos reativos a HPV-16 (anticorpos neutralizantes – OR: 0,64 [IC95%: 0,16-2,58] X ELISA – OR: 0,64 [IC 95%: 0,19-2,16]... Essas correlações não foram encontradas para os anticorpos detectados por meio de ELISA. Logo, títulos de anticorpos neutralizantes equivalentes à diluição 640 ou superiores atuam como marcadores extremamente específicos da infecção causada pelo HPV-16 durante o curso habitual natural da infecções por HPV (AU)

Neutralizing antibodies (NAb) are crucial for vaccine-mediated protection against viral diseases and presumably play the key role in the high degree of protection from persistent papillomavirus infection seen after virus-like particles (VLP) vaccination in recent clinicai trials. Neutralizing antibodies detected in serum samples of HPV-16 VLP vaccinated women were able to neutralize divergent variants of HPV-16 and their detection was achieved for serum samples collected from both vaccinated and non-vaccinated women through a HPV pseudovirus neutralization assay. However, little is known about the induction of NAb after genital HPV infections among nonvaccinated women and the putative role that these antibodies could play during the natural course of HPV infections. This work looked for HPV-16 NAbs in serum samples obtained from non-vaccinated women participating of a study for HPV infection and neoplasia risk factors. The impact of NAbs presence was analyzed through viral major outcomes during the natural course of HPV infection. The efficiency of Nabs was compared to HPV VLP ELISA seroreactivity in a 150 serum samples casuistic obtained at the enrollment of the study. The clearence of HPV-16 infection did not appear to be improved by the presence of high titers of any kind of anti-HPV-16 antibodies (Nabs- OR: 0,64 [CI 95o/o: O, 16-2,58] X ELISA- )R: 0,64 [CI95°/o: O, 19-2, 16]). Women with neutralizing antibodies titers equal ar superior to 640 dilutions showed higher risks of harboring the following HPV outcomes: cumulative HPV-16 infection (OR: 6,24 [CI95°/o: 0,88-270,1 ]), persistence of HPV-16 infection (OR: 5,17 [CI95°/o: 1,50-17,83] to OR: 27,33 [CI95°/o: 2,02-1376,6], according to the reference category used - transient or negative results, respectively), acquisition of new HPV-16 infection (OR: 3,45 [CI95°/o: O, 17-207 ,2]) and higher HPV vira I load (OR: 4,05 [CT95°/o: 1 ,05-15,66]). The same was not observed for women with higher titers of HPV-16 VLP seroreactivity. Neutralizing antibodies titers equal or superior to the 640 dilution play an important role as highly specific markers for HPV-16 infection during HPV natural history course (AU)

Prevalência de anticorpos (classes IgG e IgM) contra o Papilomavírus Humano em uma população de alto risco para o Câncer Cervical / Prevalence of antibodies (IgG and IgM) against the Human Papillomavirus in a population at high risk for Cervical Cancer

Os papilomavírus humanos (HPV) são vírus epiteliotrópicos responsáveis pela etiologia tanto de lesões intraepiteliais escamosas (SIL) quanto de carcinomas cervicais invasivos . O interesse mundial no desenvolvimento de vacinas contra esses vírus, com o intuito de impedir o surgimento posterior do carcinoma em indivíduos infectados e de auxiliar na erradicação de lesões já estabelecidas, adveio do estudo do comportamento da resposta imunológica dos indivíduos infectados com HPV. Anticorpos contra vírus-like particles (VLP) de HPV-16, em especial, vêm sendo associados à presença de SIL e de carcinomas invasivos, bem como a infecções virais persistentes. Neste estudo, a soroprevalência de anticorpos da classe IgG contra HPV-16 foram associados com a detecção de tipos de HPV alto risco, com infecções persistentes e com o desenvolvimento posterior de lesões cervicais, em especial de alto grau. A detecção dessa classe de anticorpos em amostras coletadas ao início do estudo prospectivo foi capaz de prever esses eventos. Além disso, demonstrou-se que diversas variáveis epidemiológicas, tais como idade, DST prévia, número de parceiros sexuais e gravidezes, escolaridade, tabagismo e idade ao primeiro coito associam-se significativamente com a detecção dessa classe de anticorpos gerados contra HPV-16. A soroprevalência de IgM, por sua vez, tendeu a associar-se mais fortemente com infecções por tipos de HPV de baixo risco e com a detecção de baixa carga viral nas amostras, mas a relevância desses dados ainda deve ser melhor investigada