Serum Immunoglobulin G Antibodies to Human Papillomavirus Type 6 L1, E2, E4, E6, and E7 Proteins Among Children Prospectively Followed up for 3 Years

BACKGROUND

Current knowledge implicates that human papillomavirus (HPV) infection can be acquired at an early age. However, the role of HPV-specific passive immunization from mother to neonate is nearly unexplored, especially against the HPV early proteins. We analyzed immunoglobulin G (IgG) antibodies against HPV-6 early (E2, E4, E6, E7) and late (L1) proteins in children prospectively followed up for 3 years.

METHODS

A total of 272 children and their mothers from the Finnish Family HPV Study were included in these analyses. Serum samples were obtained from pregnant mothers at their third trimester and from newborn/infants at 1-, 2-, 6-, 12-, 24-, and 36-month visits after birth. Antibodies were analyzed by multiplex serology based on glutathione S-transferase fusion protein capture to fluorescent beads.

RESULTS

Maternal antibodies to all tested HPV-6 proteins were transferred to neonates, concordance between maternal and neonates' antibody levels being highly significant (P < .001). Seropositivity of HPV-6 L1 in the neonates declined during the first 6 months of life, whereas changes in the E protein antibodies were less obvious. After the maternal antibodies had vanished, seroconversion to HPV-6 L1 at 12 months (median) and to the HPV-6 E proteins between 23 and 35 months was observed.

CONCLUSIONS

IgG antibodies against HPV-6 E and L proteins are transferred from mothers to their children. Seroconversion against HPV-6 L1, E2, E4, E6, and E7 does occur in early childhood, as a sign of acquired HPV-6 infection by vertical or horizontal transmission starting at 12 months of age.

Maternal HPV-antibodies and seroconversion to HPV in children during the first 3 years of life

To assess the dynamics of human papillomavirus (HPV) serology, we analyzed HPV6-,11-,16-,18-, and 45 antibodies in infants during the first 36 months of their life. Serial serum samples of 276/327 mother–child pairs were collected at baseline (mothers) and at months 1, 2, 6, 12, 24 and 36 (offspring), and tested for HPVL1-antibodies using the GST-L1 assay. Concordance between maternal and infant HPV-antibody levels remained high until month-6 (p <  = 0.001), indicating maternal antibody transfer. At 1 month, 40–62% of the infants tested seropositive to any of the 5 HPV-types. Between 1–3 years of age, 53% (58/109) of the children born to HPV-seronegative mothers tested HPV-seropositive. Times to positive seroconversion varied between13.4 and 18.7 months, and times to negative seroconversion (decay) between 8.5 and 9.9 months. Significant independent predictors of infants’ seroconversion to LR-HPV were hand warts and mother’s history of oral warts and seroconversion to LR-HPV. No predictors of seroconversion to HR-HPV were identified. Maternal HPV-IgG-antibodies are transferred to her offspring and remain detectable for 6 months, corroborating the IgG molecule’s half-life. Seroconversion to HPV-genotypes 6, 11, 16 and 18 was confirmed among children born to HPV-seronegative mothers, implicating an immune response to these HPV-genotypes during early infancy.

Seroprevalence of mucosal and cutaneous human papillomavirus (HPV) types among children and adolescents in the general population in Germany

Background

In Germany, HPV vaccination of adolescent girls was introduced in 2007. Nationally representative data on the distribution of vaccine-relevant HPV types in the pre-vaccination era are, however, only available for the adult population. To obtain data in children and adolescents, we assessed the prevalence and determinants of serological response to 16 different HPV types in a representative sample of 12,257 boys and girls aged 1–17 years living in Germany in 2003–2005.

Methods

Serum samples were tested for antibodies to nine mucosal and seven cutaneous HPV types. The samples had been collected during the nationally representative German Health Interview and Examination Survey for Children and Adolescents in 2003–2006. We calculated age- and gender-specific HPV seroprevalence. We used multivariable regression models to identify associations between demographic and behavioral characteristics and HPV seropositivity.

Results

We found low but non-zero seroprevalence for the majority of tested HPV types among children and adolescents in Germany. The overall seroprevalence of HPV-16 was 2.6%, with slightly higher values in adolescents. Seroprevalence of all mucosal types but HPV-6 ranged from 0.6% for HPV-33, to 6.4% for HPV-31 and did not differ by gender. We found high overall seroprevalence for HPV-6 with 24.8%. Cutaneous HPV type seroprevalence ranged from 4.0% for HPV-38 to 31.7% for HPV-1. In the majority of cutaneous types, seroprevalence did not differ between boys and girls, but increased sharply with age, (e.g., HPV-1 from 1.5% in 1–3-years-old to 45.1% in 10–11-years-old). Associations between behavioral factors and type-specific HPV prevalence were determined to be heterogeneous.

Conclusions

We report the first nationally representative data of naturally acquired HPV antibody reactivity in the pre-HPV-vaccination era among children and adolescents living in Germany. These data can be used as baseline estimates for evaluating the impact of the current HPV vaccination strategy targeting 9–14-years-old boys and girls.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07028-8.

Antibodies to human papillomavirus types 6, 11, 16 and 18: Vertical transmission and clearance in children up to two years of age

Background: There is a paucity of data on the dynamics of human papillomavirus (HPV) antibodies in children. We aimed to describe the vertical transmission and clearance of antibodies against HPV6, 11, 16 and 18 in children. Methods: We used data from pregnant women recruited into the HERITAGE cohort study between 2009 and 2012 who were positive for HPV-DNA at baseline. Dried blood spots were collected during the first trimester in pregnant participants, and at birth, 6, 12, and 24 months of age in children. The level of total immunoglobulin G (IgG) against HPV6, 11, 16 and 18 were measured using Luminex immunoassays. Spearman's coefficients were used to correlate HPV antibody levels between newborns and mothers. Panel and Kaplan-Meier graphics described antibody dynamics in the first 24 months of life. Findings: Antibodies from newborns and mothers (n = 58 pairs) were moderately to highly correlated with coefficients of 0·81 (95% confidence intervals (CI):0·70-0·88), 0·68 (95% CI:0·5-0·80), 0·90 (95% CI:0·83-0·94) and 0·85 (95% CI:0·76-0·91) against HPV6, 11, 16 and 18, respectively. In newborns seropositive at birth, anti-HPV antibodies were cleared by 80% and 100% at 12 and 24 months, respectively. Only two children presented detectable HPV antibodies at 24 months. The first child had no detectable antibodies at birth and the second presented increasing levels after two undetected measures. Interpretation: Correlation between mother and newborn IgG antibodies against HPV suggests vertical transfer. Most children cleared anti-HPV antibodies within six to 12 months. Funding: The Canadian Institutes of Health Research (CIHR).

Felis catus papillomavirus type 2 DNA loads on kittens are transient and do not reflect their susceptibility to infection

Objectives Felis catus papillomavirus type 2 (FcaPV-2) commonly infects the skin of domestic cats, and mounting evidence suggests that the virus could be involved in a subset of feline skin cancers. The reason why some cats develop FcaPV-2-induced disease and others do not is currently unknown. However, it has been shown that kittens in different litters have markedly different FcaPV-2 DNA loads and the aim of this study was to determine whether these differences could be due to inherent differences in susceptibility to infection. Such differences could potentially explain why only a small proportion of cats develop FcaPV-2-associated skin disease. Methods Repeated skin swabs were taken to measure FcaPV-2 DNA loads in queens and kittens in a research colony. The kittens either stayed in their original litters or were moved between litters; eventually, all of the kittens were housed together. A subset of samples was also analysed for FcaPV-2 mRNA. Results While there were initially large differences in FcaPV-2 DNA loads between litters of kittens, these differences disappeared when the kittens were moved between litters or housed together. Importantly, the viral DNA loads changed too rapidly to be due to the acquisition or clearance of infection. In contrast, the differences in viral DNA loads between the different queens were sustained throughout the experiment. FcaPV-2 mRNA was also detected in samples from 1- to 8-day-old kittens. Conclusions and relevance The results suggest that the FcaPV-2 DNA load in a swab sample from an individual kitten largely reflects the overall level of FcaPV-2 shedding in the group of in-contact cats, rather than the infection status of the individual kitten. Therefore, there was no evidence for inherent differences in susceptibility to infection. However, the finding of FcaPV-2 mRNA suggests that at least some kittens do become infected with FcaPV-2 early in life.

Is administration of the HPV vaccine during pregnancy feasible in the future?

Despite the strong evidence supporting the efficacy of the HPV vaccine, the uptake rate remains low. One reason for this is that young females do not interact frequently with the healthcare system. In fact, pregnancy is often the first time young women experience multiple scheduled visits to a health provider. We review the data regarding safety of administering the HPV vaccine during pregnancy and consider the possibility of incorporating vaccination into prenatal care. Although the optimal time for vaccination is prior to sexual debut, this does not always occur, and as such, a broader approach to HPV vaccination may be necessary. Increasing the vaccine uptake rate among young women who did not initiate or complete the series earlier may significantly contribute to the decline in HPV-associated diseases.

Characteristics of HPV-specific antibody responses induced by infection and vaccination: cross-reactivity, neutralizing activity, avidity and IgG subclasses

OBJECTIVES

In order to assess HPV-specific IgG characteristics, we evaluated multiple aspects of the humoral antibody response that will provide insight in the HPV humoral immune response induced by HPV infection and vaccination.

METHODS

Cross-reactivity of HPV-specific antibodies induced by infection or vaccination was assessed with VLP16 or 18 inhibition using a VLP-based multiplex immunoassay (MIA) for HPV16, 18, 31, 33, 45, 52 and 58. HPV16/18 specific IgG1-4 subclasses and avidity were determined with the VLP-MIA in sera after HPV infection and after vaccination. Neutralizing antibodies were determined in a small subset of single-seropositive and multi-seropositive naturally derived antibodies.

RESULTS

Naturally derived antibodies from single-positive sera were highly genotype-specific as homologue VLP-inhibition percentages varied between 78-94%. In multi-positive sera, cross-reactive antibodies were observed both within and between α7 and α9 species. After vaccination, cross-reactive antibodies were mainly species-specific. Avidity of vaccine-derived HPV-specific antibodies was 3 times higher than that of antibodies induced by HPV infection (p<0.0001). IgG1 and IgG3 were found to be the predominant subclasses observed after HPV infection and vaccination. In the small subset tested, the number of single-positive sera with neutralizing capacity was higher than of multi-positive sera.

CONCLUSION

Naturally derived HPV-specific antibodies from single-positive samples showed different characteristics in terms of cross-reactivity and neutralizing capacity compared with antibodies from multi-positive sera. Post-vaccination, HPV antibody avidity was approximately 3 times higher than antibody avidity induced by HPV infection. Therefore, antibody avidity might be a potential surrogate of protection.

Seroprevalence of seven high-risk HPV types in The Netherlands

BACKGROUND

To obtain insight into the age-specific seroprevalence for seven high-risk human papillomavirus (hr-HPV) serotypes (HPV16, 18, 31, 33, 45, 52, and 58) among the general population in the pre-vaccination era in The Netherlands.

METHODS

From a cross-sectional population-based study (ISRCTN 20164309) performed in 2006/2007 6384 sera of men, women and children were tested for seven hr-HPV specific antibodies using a fluorescent bead-based multiplex immunoassay with virus-like particles of the seven HPV serotypes.

RESULTS

An increase in seroprevalence was observed in adolescents, especially for the most prevalent HPV type 16 (up to 11.3%). The increase was most pronounced in women, but was less clear for the other six HPV serotypes. Relatively stable seroprevalences were found in the middle aged cohorts and a slight decrease in the elderly. For the age cohorts >14 years, the seroprevalence among women (25.2%) was higher compared with men (20.3%) (p=0.0002). We found that 10.1% of the population was seropositive for multiple HPV serotypes.

CONCLUSIONS

The HPV vaccination program is targeted at preadolescents as is justified by the results in this study in which a step-up in HPV seroprevalence is observed at ages of sexual debut. Although direct interpretation of seroprevalence data are hampered by cross-reactivity and seroconversion rate, these data are useful as baseline to evaluate long-term population effects of the HPV16/18 vaccination program.

Human papillomavirus genotypes present in the oral mucosa of newborns and their concordance with maternal cervical human papillomavirus genotypes

OBJECTIVES

To elucidate the concordance of human papillomavirus (HPV) genotypes between the mother and her newborn and to identify risk factors for the vertical transmission of HPV.

STUDY DESIGN

HPV genotypes present in 329 pregnant women, their newborns, cord blood, and placenta samples were determined by molecular techniques, including using pure DNA for nested polymerase chain reaction. HPV antibodies were tested using multiplex HPV serology. Kappa statistics and the Wilcoxon test were used to assess concordance, and regression analysis was used to calculate ORs and 95% CIs.

RESULTS

HPV DNA was detected in 17.9% of oral samples from newborns and in 16.4% of the cervical samples of the mothers. At delivery, mother-newborn pairs had similar HPV-genotype profiles, but this concordance disappeared in 2 months. Oral HPV carriage in newborns was most significantly associated with the detection of HPV in the placenta (OR=14.0; 95% CI, 3.7-52.2; P=.0001). The association between status of the cord blood and oral HPV was also significant at delivery (OR=4.7; 95% CI, 1.4-15.9; P=.015) but disappeared within 1 month. HPV antibodies in infants were of maternal origin (OR=68; 95% CI, 20.1-230.9; P=.0001).

CONCLUSIONS

HPV is prevalent in oral samples from newborns. The genotype profile of newborns was more restricted than that of the maternal cervical samples. The close maternal-newborn concordance could indicate that an infected mother transmits HPV to her newborn via the placenta or cord blood.

Mother-infant transfer of anti-human papillomavirus (HPV) antibodies following vaccination with the quadrivalent HPV (type 6/11/16/18) virus-like particle vaccine

The exploratory immunogenicity objective of this analysis was to characterize the titer of vaccine human papillomavirus (HPV)-type immunoglobulins in both peripartum maternal blood and the cord blood of infants born to women who received blinded therapy. Data were derived from a randomized, placebo-controlled, double-blind safety, immunogenicity, and efficacy study (protocol 019; NCT00090220). This study enrolled 3,819 women between the ages of 24 and 45 years from 38 international study sites between 18 June 2004 and 30 April 2005. Data in the current analysis are from subjects enrolled in Philippines and Thailand. For each of HPV types 6, 11, 16, and 18, maternal anti-HPV was found in cord blood samples. Furthermore, HPV titers in cord blood samples were highly positively correlated with maternal HPV titers. Additionally, there were instances when anti-HPV antibodies were no longer detectable in maternal serum samples and yet were detected in matched cord blood samples. These results demonstrate that quadrivalent HPV (qHPV) vaccine-induced antibodies cross the placenta and could potentially provide some benefit against vaccine-type HPV infection and related diseases such as recurrent respiratory papillomatosis.

Current concepts on human papillomavirus infections in children

Current evidence is strong enough to conclude that human papillomavirus (HPV) can be transmitted both sexually and non-sexually. The debate on HPV infections in children still continues but it is more focused on HPV prevalence than on transmission modes. HPV DNA detection in amniotic fluid, foetal membranes, cord blood and placental trophoblastic cells all suggest HPV infection in utero, i.e. prenatal transmission. Based on recent meta-analysis, vertical transmission occurs in approximately 20% of cases. Most of the mucosal HPV infections in infants are incident, persistent infections in oral and genital mucosa being found in less than 10% and 2% respectively. The mother seems to be the main transmitter of HPV to her newborn, but subsequent HPV infections are acquired horizontally via saliva or other contacts. Bimodal peak prevalence is seen for skin warts, oral papillomas and recurrent respiratory papillomatosis (RRP) in younger and older age groups, suggesting similar epidemiology. Of the clinical HPV diseases, juvenile-onset-RRP and genital condylomata are problematic; the former because of its life-threatening potential and the latter because of possible sexual abuse. HPV6 and 11 are the most common genotypes in both the lesions. Early in life, infections by the high-risk HPV genotypes may also remain persistent for a considerable period, and should be of considerable importance for HPV vaccination strategies.