A survey of seroprevalence of human papillomavirus types 16, 18 and 33 among children

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.

Antibody response to human papillomavirus vaccination and natural exposure in individuals with Fanconi Anemia

Fanconi anemia (FA) is a rare genetic disorder associated with predisposition to head and neck and gynecological squamous cell cancers. In the general population, these cancers are commonly linked to human papillomavirus (HPV) infection. Antibodies to natural HPV infection and HPV vaccination were evaluated in 63 individuals with FA while considering host immune factors. Approximately 30% of reportedly unvaccinated participants were seropositive (HPV6-38%, HPV11-25%, HPV16-26%, and HPV18-26%). Seropositivity was significantly associated with having had sex regardless of age (p=.007). Most participants showed seropositivity after HPV vaccination (HPV6-100%, HPV11-100%, HPV16-100% and HPV18-92%). Interestingly, titers for all 4 subtypes were significantly lower in the post-hematopoietic stem cell transplant (HSCT) participants compared to those who received the vaccine, but had not undergone HSCT (HPV6-p=.030, HPV11-p=.003, HPV16-p=.018, HPV18-p=<.001). It is unclear if these titers sufficiently protect from new infection since protective serologic cut offs have not yet been defined for the HPV vaccine. Individual immune functions were not associated with HPV seropositivity, however, underlying heterogeneous immune deficiency may explain higher rates of seropositivity in our younger unvaccinated participants (age 4-13 years). To better measure the efficacy of HPV vaccination in those with FA and other immune-compromised or cancer-prone disorders, future well-controlled vaccine studies are required.

Recent advances in understanding and preventing human papillomavirus-related disease

High-risk human papillomaviruses (hrHPV) are responsible for anogenital and oropharyngeal cancers, which together account for at least 5% of cancers worldwide. Industrialised nations have benefitted from highly effective screening for the prevention of cervical cancer in recent decades, yet this vital intervention remains inaccessible to millions of women in low- and middle-income countries (LMICs), who bear the greatest burden of HPV disease. While there is an urgent need to increase investment in basic health infrastructure and rollout of prophylactic vaccination, there are now unprecedented opportunities to exploit recent scientific and technological advances in screening and treatment of pre-invasive hrHPV lesions and to adapt them for delivery at scale in resource-limited settings. In addition, non-surgical approaches to the treatment of cervical intraepithelial neoplasia and other hrHPV lesions are showing encouraging results in clinical trials of therapeutic vaccines and antiviral agents. Finally, the use of next-generation sequencing to characterise the vaginal microbial environment is beginning to shed light on host factors that may influence the natural history of HPV infections. In this article, we focus on recent advances in these areas and discuss their potential for impact on HPV disease.

Counseling about the HPV vaccine: desexualize, educate, and advocate

Information is provided for clinicians who treat adolescents and adult women to use when counseling patients about human papillomavirus (HPV) vaccine. A literature search was done to determine: (1) reasons for refusal of the vaccine, including cost and concerns that immunization against HPV will lead to promiscuity; (2) potential for non-sexual transmission of HPV; (3) non-genital locations of HPV; (4) non-genital cancers associated with HPV. Vaccines for Children Program and the Affordable Care Act eliminate many costs.Neither biological nor behavioral evidence supports the idea that sexual behavior changes after immunization. HPV is transmitted from person to person by non-sexual routes including mother to child at birth and apparently by touch after birth. HPV is persistent in the environment, including medical environments. It has been found on apparently sterilized instruments used in vaginal exams. Pathogenic HPV has been recovered from breast tissue, sinonasal areas, and nipples as well as from hair follicles on arms, legs, scalps, eyebrows, and pubic hair. Pathogenic HPV was found in 6.5% of the oral cavities of a random sample of Americans. HPV is known to cause anal and oral cancers. It has also been associated with skin cancers, breast tumors, and prostate cancers. It is not known if the vaccine is protective against these cancers, but it is useful to educate about these other routes of transmission and non-genital HPV linked cancers so that patients/parents do not just focus on the sexual nature of the human papillomavirus.

Serum antibodies to human papillomavirus (HPV) pseudovirions correlate with natural infection for 13 genital HPV types

BACKGROUND

Serology for human papillomaviruses (HPV) types -16 and -18 is established as an important tool for studies of HPV vaccinology and epidemiology. However, as there are a large number of oncogenic genital types of HPV there is a need for development of high-throughput, validated HPV serological assays that can be used for more comprehensive seroepidemiological studies and for research on multivalent HPV vaccines.

OBJECTIVES

To develop a multiplexed pseudovirion-based serological assay (PsV-Luminex) encompassing 21 HPV types and validate the method by correlating the serology with the presence of type specific HPV DNA in cervical samples.

STUDY DESIGN

Cervical swabs from 3,291 unvaccinated women attending organized cervical screening in Slovenia were tested with 3 different HPV DNA detection methods and presence of HPV DNA compared to presence of serum antibodies to pseudovirions from 15 genital HPV types (HPV-6,-11,-16,-18,-31,-33,-35,-39,-45,-52,-56,-58,-59,-68,-73).

RESULTS

On average 51% of the HPV DNA positive women were seropositive for the same HPV type that was detected in the cervical specimen. We found a strong correlation with presence of HPV DNA and antibodies to the same HPV type for 13/15 genital HPV types (median OR = 5.7, CI 95% = 2.4-12.9). HPV-52 serology failed the validation and HPV-11 serology could not be validated because only a single woman was positive for HPV-11 DNA. The correlation between serology and HPV DNA status tended to be stronger among women infected with single HPV type (median OR=10.5, CI 95% = 2.4-48.4) than among women with multiple HPV infections (median OR = 4.6, CI 95% = 1.8-11.7).

CONCLUSIONS

A multiplexed HPV PsV-Luminex assay has been developed and validated to correlate with natural HPV infection for 13 HPV types, thus enabling more comprehensive studies in HPV epidemiology and vaccine research.

Age-specific human papillomavirus antibody and deoxyribonucleic acid prevalence: a global review

PURPOSE

Global data on human papillomavirus (HPV) serological and deoxyribonucleic acid (DNA) prevalence are essential to optimize HPV prophylactic vaccination strategies.

METHODS

We conducted a global review of age-specific HPV antibody and studies with both antibody and DNA prevalence for HPV-16, -18, -6, and -11.

RESULTS

One hundred seventeen studies were included; participants' ages ranged from several hours to >90 years. HPV-16 seroprevalence was generally higher in Africa, Central and South America, and North America, more prevalent among women than among men, and peaked around ages 25-40 years. HPV-18 seroprevalence was generally lower than HPV-16 with a later age peak. Data were limited for HPV-6 and -11, both of which peaked at ages similar to HPV-18. Among 9-26-year-old females, HPV-16 seroprevalence ranged from 0%-31% in North America, 21%-30% in Africa, 0%-23% in Asia/Australia, 0%-33% in Europe, and 13%-43% in Central and South America. HPV-16/-18 DNA prevalence peaked 10-15 years before corresponding HPV-16/-18 antibody prevalence.

CONCLUSIONS

Females within the HPV vaccine-eligible age-group (9-26 years) had a range of dual HPV-16 DNA and serology negativity from 81%-87%, whereas 90%-98% were HPV-16 DNA negative. Serology and DNA data are lacking worldwide for females younger than age 15 years, the prime target group for vaccination.

Seroprevalence and correlates of human papillomavirus 16/18 seropositivity among young women in Costa Rica

BACKGROUND

Serological indicators of human papillomavirus (HPV) infection are being used to differentiate HPV-naïve from previously infected women in vaccine and epidemiologic/clinical studies. We investigated HPV16 and 18 seroepidemiology among young, unvaccinated women aged between 18 and 25.

MATERIALS AND METHODS

We conducted a cross-sectional evaluation of the enrollment visit in the ongoing community-based HPV16/18 Costa Rica Vaccine Trial. Prevaccination serum immunoglobulin G (IgG) antibodies were measured against HPV16 and HPV18 by enzyme-linked immunosorbent assay; cervical samples were tested for HPV DNA using Hybrid Capture 2 and SPF10/LiPA25. Seroprevalence and its correlates were evaluated using unconditional logistic regression.

RESULTS

Among 5871 nonvirginal women, HPV16 and 18 seroprevalences were 30.8% and 28.1%, HPV16 and HPV18 DNA prevalences were 8.3% and 3.2%, respectively. About 37% of HPV16 DNA-positives and 42% of HPV18 DNA-positives were seronegative. Seroprevalence increased with time since sexual debut, whereas DNA prevalence did not. The correlates of HPV16 and/or 18 seropositivity were related to sexual behaviors, particularly higher number of lifetime sexual partners. There was no evidence of assay cross-reactivity as HPV16 seroprevalence was similar (approximately 34%) among women singly infected with genetically and nongenetically related species (α9 and non-α9); likewise, seropositivity to HPV18 was similar (approximately 30%) among women singly infected with α7 and non-α7 species.

CONCLUSIONS

The increasing seroprevalence observed with time since first sex suggests that HPV serology is a cumulative marker of HPV exposure. However, many DNA infected women were seronegative; thus, serology is an imperfect measure of past exposure to cervical HPV, at best. Additionally, we found no evidence of assay cross-reactivity.

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.

Model-based estimation of viral transmissibility and infection-induced resistance from the age-dependent prevalence of infection for 14 high-risk types of human papillomavirus

Viral transmissibility and natural resistance to infection are key determinants in assessing the population impact of human papillomavirus (HPV) vaccination, yet information on these parameters is scarce. Using data from 2 large-scale surveys on sexual behavior in the Netherlands (carried out in 2005-2006), the authors employed a Bayesian framework to fit a transmission model to the cross-sectional age-dependent prevalence of HPV DNA in cervical smears (data collected in 1992-2002), assuming that the prevaccine situation reflected an endemic equilibrium, and calculated type-specific estimates of transmissibility and infection-induced resistance. The posterior median transmission probability per heterosexual partnership covered a range of 0.43-0.94 among the 14 high-risk types of HPV. The transmission probability of HPV-16 was estimated at 0.80 (95% posterior interval: 0.60, 0.99) and that of HPV-18 at 0.93 (95% posterior interval: 0.72, 1). The model predicted that the decrease in HPV prevalence with age could not solely be explained by sexual activity and screening but also by resistance to reinfection, which is lost at a rate of 0.014-0.047 (1%-5%) per year. These results support the notion that HPV infection is highly transmissible, and they suggest a gradual loss of type-specific immunity over time. Because high transmission potential is associated with a low impact of herd immunity, extensive vaccination coverage will be required to substantially reduce cervical cancer incidence.

Validation of multiplexed human papillomavirus serology using pseudovirions bound to heparin-coated beads

This study developed and validated a high-throughput human papillomavirus (HPV) serology method based on Luminex technology, using pseudovirions (PsVs) of eight mucosal HPV types (HPV-6, -11, -16, -18, -31, -45, -52 and -58) and two cutaneous HPV types (HPV-5 and -38) bound to heparin-coated beads. Analysis with neutralizing type-specific monoclonal antibodies against the included HPV types indicated the type specificity of the assay. Analysis of negative-control serum samples from 63 children and 71 middle-aged women with up to one lifetime sexual partner indicated high specificity. Positive-control serum samples from subjects with known HPV DNA status or clinical diagnosis found expected sensitivities for most of the HPV types in 219 European serum samples, but lower than expected in 124 samples from Africa. HPV-45 and -52 did not react as expected with the human serum samples. The PsV-Luminex method was used to determine the HPV-seropositivity-associated relative risk for future cervical cancer using 208 serum samples from a prospective study of 18 814 women followed for 23 years, analysed previously with standard HPV-16 ELISA. The PsV-Luminex method gave similar results to ELISA (kappa=0.77). As expected, HPV seropositivities assayed using the PsV-Luminex method found an increased risk of cervical cancer for HPV-16 [odds ratio (OR)=7.7, 95 % confidence interval (CI)=2.6-23] and HPV-31 (OR=4.1, 95 % CI=1.6-10.8), non-significant tendencies for increased risk for other mucosal HPV types and no risk for the cutaneous HPV types. In summary, multiplexed HPV serology using mammalian-derived PsVs selected for native conformation by binding to heparin-coated beads was validated as a high-throughput HPV serological method for most of the analysed HPV types.

Seroprevalences of herpes simplex virus type 2, five oncogenic human papillomaviruses, and Chlamydia trachomatis in Katowice, Poland

Herpes simplex virus type 2 (HSV-2), human papillomaviruses (HPVs), and Chlamydia trachomatis are the most common pathogens causing sexually transmitted infections (STIs). There is limited information about the prevalences of these STIs in Poland. Here, we estimated the occurrence of immunoglobulin G (IgG) antibodies against HSV-2, HPV, and C. trachomatis in 199 blood donors and 110 patients of both genders attending an STI clinic in Katowice in southern Poland. The seroprevalences of HSV-2 were 5% for blood donors and 14% in the STI cohort. The seroprevalences of the five potentially oncogenic HPV types 16, 18, 31, 35, and 51 were 15%, 7%, 5%, 5%, and 17%, respectively, in blood donors and 37%, 8%, 12%, 5%, and 21%, respectively, in the STI cohort. The majority of HPV-infected individuals showed antibodies against more than one type, i.e., had been infected with multiple HPV types. Anti-C. trachomatis IgG antibodies were detected in 6% of blood donors and 13% of individuals attending the STI clinic. The relatively high prevalence of HPV-51 may have implications for future vaccine programs, as the newly introduced HPV vaccines are based on the potentially oncogenic HPV types 16 and 18.

Prevalence of human papillomavirus in the oral cavity/oropharynx in a large population of children and adolescents

OBJECTIVE

Human papillomavirus (HPV) in the oral cavity or oropharynx is associated with an increased risk of laryngeal papillomatosis, head and neck cancer, and cervical and other genital cancers. We evaluated the prevalence of HPV DNA in the oral cavity/oropharynx in a cross section of children aged 2 weeks to 20 years.

METHODS

A risk factor questionnaire and oral exfoliated cells were collected from children (N = 1235). HPV DNA was detected using PCR, dot blot hybridization, and DNA sequencing.

RESULTS

The HPV prevalence was 1.9% in the oral cavity/oropharynx of children. A bimodal age distribution was observed with the highest HPV prevalence in the youngest and oldest groups: 2.5% aged <1 year, 0.8% aged 1 to 4 years, 1.2% aged 5 to 11 years, 1.5% in aged 12 to 15 years, and 3.3% in aged 16 to 20 years. The prevalence of the HPV quadrivalent vaccine types (HPV-6, 11, 16, 18) reached 0.9% in the 16- to 20-year age group. In this age group, female gender [odds ratio (OR): 6.9, P = 0.04], genital warts (OR: 19.3, P < 0.01), and current smoker (OR: 6.5, P = 0.01) were associated with a higher risk of being detected with an oral HPV infection. No risk factors in parents were identified with transmission of HPV to infants.

CONCLUSIONS

The age-specific prevalence rates of HPV in this large cross section of children and adolescents demonstrate that HPV infection is acquired gradually in childhood. These data support a target age for HPV vaccination before puberty to prevent serious HPV-related genital and oral diseases.

Prevalence of human papillomavirus antibodies in young female subjects in England

Sera from 1483 female subjects in England aged 10–29 years were tested. The age-standardised seroprevalence was 10.7% (95% confidence intervals 9.0–12.3) for human papillomavirus (HPV) 6, 2.7% (1.8–3.6) for HPV 11, 11.9% (10.2–13.6) for HPV 16, 4.7% (3.5–5.8) for HPV 18, and 20.7% (18.6–22.7) for any of the four types.

Prophylactic HPV vaccines: prospects for eliminating ano-genital cancer

Virtually all cases of cervical cancer and its precursor intra-epithelial lesions are a result of infection with one or other of a subset of genital human papillomaviruses (HPVs), suggesting that prevention of HPV infection by prophylactic vaccination would be a highly effective anticancer strategy. Two HPV L1 virus-like particle vaccines have been developed, a quadrivalent HPV16/18/6/11 product and a bivalent HPV16/18 product; both have been shown to be highly immunogenic with a good safety profile and 100% efficacy against HPV16/18-related high-grade cervical intra-epithelial neoplasia (CIN2/3), implying that they will be effective at preventing HPV16/18-related cervical cancer.

Human papillomavirus: the burden of infection

Vaccines for preventing human papillomavirus (HPV) infection are far along in clinical development and testing, and hold great promise for reducing HPV infections and HPV-associated disease. HPV is the most common sexually transmitted infection in the United States, affecting an estimated 75% of the U.S. population. HPV infection is highly prevalent in sexually active adolescents and young adults. Sexual activity is the most important risk factor for infection, with 64% to 82% of sexually active adolescent girls testing positive for HPV. Clinical manifestations of HPV infection include genital warts, cervical intraepithelial neoplasia (CIN), and invasive cervical cancer, all of which cause significant morbidity and, in the case of cervical cancer, mortality. The majority of HPV-associated disease is caused by 4 HPV types: HPV 6 and 11 are responsible for low-grade genital lesions and more than 90% of genital warts, and HPV 16 and 18 both account for approximately 70% of all high-grade CIN or dysplasia and invasive cervical cancer. Although current screening methods have proven effective in reducing cervical cancer incidence and associated mortality, more than 10,000 women are diagnosed annually and 4000 U.S. women die from the disease each year.

Detection of human papillomavirus type 18 E6 and E7-specific CD4+ T-helper 1 immunity in relation to health versus disease

The most common high-risk human papillomavirus types, HPV16 and 18, differ markedly with respect to their interaction with the host. Clearance of HPV18 infections generally takes longer and HPV18-positive cancers have a poorer prognosis. We therefore evaluated Th1-type immunity against the E6 and E7 oncoproteins of HPV18 in healthy subjects and in patients with HPV18-positive genital cancer, and compared the results to our previously obtained data for HPV16. Approximately 20% of the healthy individuals displayed immunity against HPV18 E6. In contrast, none of the patients showed such responses, despite the presence of HPV18-positive lesions. Several of the patients did respond to HPV18 E7, whereas this immunity is rarely found in healthy subjects. This pattern of immune reactivity is essentially similar to that previously found for HPV16. It is unlikely that this similarity is the result of immunological cross-reactivity between the E6 and E7 antigens of HPV types 16 and 18. Our data confirm the relation between failure of E6-specific Th1 immunity and high-risk HPV-induced cervical neoplasia and argue that parameters other than these determine the differences in pathological impact between HPV types 16 and 18.

Distinct regulation and impact of type 1 T-cell immunity against HPV16 L1, E2 and E6 antigens during HPV16-induced cervical infection and neoplasia

Cervical cancer is the possible outcome of a genital infection with high-risk human papillomavirus type 16 (HPV16) and is preceded by a phase of persistent HPV infection during which the host immune system fails to eliminate the virus. Our previous work showed that failure is reflected by the absence of type 1 T-cell immunity against HPV16 early antigens E2 and E6 in patients with HPV16+ cervical lesions. We now show that a majority of both patients with cervical lesions and healthy subjects display HPV16 L1 peptide-specific type 1 T-cell responses with similar magnitude. The T-cell response in patients was directed at a broad range of peptides within L1, suggesting that during persistent or repeated exposure to HPV16 L1, the immune system maximizes its efforts to counter the viral challenge. Unlike the type 1 T-cell responses against HPV16 early antigens E2 and E6, type 1 T-cell immunity against L1 does not correlate with health or disease. This argues that T-cell responses against early and late HPV16 antigens essentially differ in the manner in which they are induced and regulated, as well as in their impact on the subsequent stages of HPV16-induced cervical disease.

Prevalence and stability of human serum antibodies to simian virus 40 VP1 virus-like particles

Possible human infection with simian virus 40 (SV40) has been of great concern ever since SV40 was discovered in polio vaccines. Human populations are SV40-seropositive, but because of serological cross-reactivity between SV40 and the human polyomaviruses BK virus (BKV) and JC virus (JCV), it is debatable whether these antibodies are specific. An SV40-specific serological assay was established, based on purified virus-like particles (VLPs), where the SV40 VLPs were blocked with hyperimmune sera to BKV and JCV. Competition with SV40 hyperimmune sera was used as a confirmatory test. Among 288 Swedish children of between 1 and 13 years of age, 7.6 % had SV40-specific antibodies. SV40 seroprevalence reached a peak of 14 % at 7-9 years of age. Among 100 control patients with benign tumours, 9 % were SV40-seropositive. However, SV40 DNA was not detectable in corresponding buffy-coat samples. In serial samples taken up to 5 years apart from 141 Finnish women participating in the population-based serological screening for congenital infections, only two of 141 women were SV40-seropositive in both samples. Six women seroconverted and eight women had a loss of antibodies over time. None of the SV40-seropositive samples contained detectable SV40 DNA. In conclusion, there is a low prevalence of SV40-specific antibodies in the Nordic population. The SV40 antibodies appear to have a low stability over time and their origin is not clear.

Heparin-based ELISA reduces background reactivity in virus-like particle-based papillomavirus serology

The interaction between human papillomavirus (HPV) particles and cell surface heparan sulfate requires intact conformation of the HPV particles. Type-specific HPV serology is currently based on virus-like particles (VLPs) with intact conformation. Presence of incorrectly folded VLPs in VLP preparations is recognized as an important cause of cross-reactivity in HPV serology. Heparin-coated microtitre plates were evaluated for capturing conformationally correct VLPs and improving the type specificity of HPV serology. Hybrid VLPs between HPV16 and HPV11, which had been found to have significant reactivity with children's sera and a batch of HPV18 VLPs that had failed the quality control because of significant reactivity with sera from virginal women, were tested in parallel with heparin ELISA, ordinary ELISA and type-specific mAb capture ELISA. Control sera from children that had detectable reactivity with HPV16/11 hybrid VLPs in ordinary ELISA did not react in heparin-based ELISA, but some hybrid VLPs also had background reactivity in capture ELISAs. Control sera from virginal women that had some reactivity with a poor quality HPV18 VLP preparation in ordinary ELISA had no reactivity in heparin or capture ELISA, suggesting that certain VLP preparations expose cross-reactive epitopes that are not exposed on VLPs with heparin-binding ability. As the sensitivity was similar or only marginally affected by the use of heparin plates, use of heparin-coated plates may improve the type specificity of VLP-based ELISAs and reduce interassay variability attributable to variable quality of different VLP batches.

Maternal human polyomavirus infection and risk of neuroblastoma in the child

To investigate if polyomavirus infection during pregnancy is linked to development of neuroblastoma in the child, serum samples of 115 index mothers from the pregnancy where the child eventually developed neuroblastoma were identified and matched with serum samples from 8 control mothers per index mother. The samples were tested for specific IgG and IgM antibodies to BK and JC virus using enzyme immunoassays based on purified yeast-expressed virus-like particles (VLPs). The serum samples as well as 10 neuroblastoma cell lines were also analyzed using Real Time (TaqMan) PCR for detection and quantification of BK virus DNA. The BK virus IgG seroprevalence was similar among index mothers (80%) and control mothers (83%) [OR 0.8; 95% confidence interval (95% CI): 0.5-1.3]. BK virus IgM was also not associated with neuroblastoma risk (OR was OR = 0.6; 95% with CI, 0.2-1.9). Also JC virus had no association, neither for IgG (OR = 0.9; 95% CI, 0.6-1.4) nor for IgM (OR = 0.9; 95% CI, 0.4-1.9). All serum samples and all neuroblastoma cell lines were negative for BKV DNA. In summary, a comprehensive cohort using both serology and polyomavirus DNA detection found no evidence for association between BKV or JCV polyomaviruses and neuroblastoma.

Papillomavirus vaccines in clinical trials

Cervical cancer remains a leading cause of death for women in the developing world, and the treatment of preneoplastic cervical lesions is a considerable public-health burden in the developed world. There is unambiguous evidence that human papillomaviruses (HPVs) trigger the development of cervical and other anogenital malignancies, and that continued expression of HPV antigens in the tumours drives the neoplastic progression. The viral cause of cervical cancer is also its Achilles heel. Prophylactic vaccines to prevent HPV infection and therapeutic vaccines targeted at the HPV tumour antigens are in clinical trials. A firm grasp of the molecular pathogenesis of HPVs and the natural history of genital HPV infections, combined with greater understanding of how to trigger effective immune responses, offers hope for the elimination of HPV-associated diseases.

Mapping of human serum-reactive epitopes in virus-like particles of human papillomavirus types 16 and 11

Most human antibodies against HPV16 can be blocked by the monoclonal antibody H16.V5. To investigate whether H16.V5 and human sera recognize similar epitopes, hybrid capsids containing different parts of HPV16 and HPV11 were evaluated for reactivity with human sera. The antibody responses among HPV 16-/HPV11+sera to HPV11 and to hybrid capsids containing the HPV11 C-terminus were strongly correlated. The antibody responses among HPV 16+/HPV11-sera to HPV16 and to a hybrid containing the HPV16 C-terminus were correlated and there was also reactivity with a hybrid containing the H16.V5 epitope in the HPV11 backbone. Several HPV16-/11- children's sera were reactive with hybrid capsids, implying that a native capsid structure is essential for serological specificity. For both HPV16 and HPV11, the major serologic reactivity was directed toward the C-terminal part of the protein and the H16.V5 binding site appeared to be a major serologically reactive epitope of HPV16.

Seroepidemiology of the human polyomaviruses

To assess the stability of polyomavirus antibodies in serial samples over time and the incidence and age-specific prevalence of polyomavirus infections, we established enzyme immunoassays (EIAs) using purified yeast-expressed virus-like particles (VLPs) containing the VP1 major capsid proteins of JC virus (JCV) and the AS and SB strains of BK virus (BKV). A random subsample of 150 Finnish women who had serum samples taken during the first trimester of pregnancy and had a second pregnancy during a 5 year follow-up period was selected, grouped by age of first pregnancy. The polyomavirus antibody levels were similar in samples taken during the first and second pregnancies (correlation coefficient 0.93 for BKV SB and 0.94 for JCV). Analysis of serum samples from 290 Swedish children aged 1-13 years, grouped by age in 2 year intervals, demonstrated that BKV seropositivity increased rapidly with increasing age of the children, reaching 98 % seroprevalence at 7-9 years of age, followed by a minor decrease. JCV seroprevalence increased only slowly with increasing age and reaching 72 % positivity among mothers >25 years of age. The age-specific seroprevalence of the human polyomaviruses measured using this VLP-based EIA was similar to previous serosurveys by other methods. The stability of the antibodies over time indicates that polyomavirus seropositivity is a valid marker of cumulative virus exposure, and polyoma VLP-based EIAs may therefore be useful for epidemiological studies of these viruses.

A prospective study of the relationship between prediagnostic human papillomavirus seropositivity and HPV DNA in subsequent cervical carcinomas

Several prospective studies with invasive carcinoma as endpoint have supported Human Papillomavirus as a cause of cervical carcinoma. However, the largest study used seroepidemiology and did not analyse presence of Human Papillomavirus DNA in the subsequent tumour. Linkage of serum bank registries and cancer registries had identified 196 women with a registered cervical carcinoma after donation of a serum sample. For the present study, biopsies for 127 cases could be located, verified to contain invasive carcinoma and be amplified by PCR. Three control women who had remained alive and without cervical carcinoma during an equal length of follow-up had been matched to each of the case women and tested for HPV antibodies. Presence of Human Papillomavirus DNA in the tumours was analysed by general primer and type specific PCR. HPV16-seropositive women had a relative risk of 4.4 (95% CI: 2.2-8.8) to develop cervical carcinoma carrying HPV16 DNA. By contrast, there was no excess risk for Human Papillomavirus 16-seropositive women to develop cervical carcinoma devoid of HPV16 DNA. Prediagnostic HPV16 seropositivity was strongly correlated with later HPV16 DNA positivity of the tumour (P<0.001) and prediagnostic HPV18 seropositivity correlated with HPV18 DNA in the tumour (P<0.03). The link between prediagnostic seropositivity and type of viral DNA in the cancer implies that the carcinogenic effect of infection with these viruses is dependent on persistent presence of type-specific viral DNA.

Serologic response to human oncogenic papillomavirus types 16, 18, 31, 33, 39, 58 and 59 virus-like particles in colombian women with invasive cervical cancer

The serologic response against virus-like particles (VLP) from 7 high risk genital papillomaviruses was investigated by ELISA in 147 Colombian women with invasive cervical cancer and 147 age-matched cytologically normal and HPV-DNA negative women. Anti-VLP antibodies were detected in 82% of the invasive cervical cancer patients and in 56% of the controls. Detection of antibodies against multiple HPV types is the rule and the presence of high antibody titers was associated with higher survival of cancer patients. Higher anti-VLP seroprevalence was observed in younger cancer patients. In those followed serologically for 1 year, antibodies generally remained at the same level. However, in some patients an increase or decrease in antibody levels occurred simultaneously for multiple HPV types, suggesting cross-reactivity between the HPV types investigated. Investigation of seroreactivity between 8 high risk HPVs suggested that there is some cross-reactivity between phylogeneticaly-related types such as 16, 31, 33 and 58; and 18, 45 and 59. In conclusion, our results confirmed (i) the high rate of HPV infections in Colombia, both in patients with cervical cancer and in the general population, and the particularly high rate of infections due to HPV 31 and 58; and (ii) the validity of anti-VLPs as a marker of present or past HPV infection. The simultaneous appearance or disappearance of antibodies against multiple HPV VLPs suggests that the antibodies detected by ELISA are not always type specific.

Immunity to oncogenic human papillomaviruses

The establishment of human papillomavirus (HPV) infection as a major cause of several human cancer forms, notably cervical cancer, has spurred development of prophylactic and/or therapeutic HPV vaccines for prevention of cervical neoplasia. Knowledge of the immunity to HPV forms the basis for such endeavors.

METHOD

A literature review of humoral and cellular immunity to HPV. The overview on human leukocyte antigen (HLA) and cervical cancer was expanded to a formal metaanalysis, where relevant articles were located by Medline search and citation analysis and graded by preassigned quality criteria on study design.

RESULTS

The antibody response to the HPV particle is dominated by a neutralizing antibody response to a typespecific, conformationally dependent immunodominant epitope. Vaccines based on viral particles lacking the viral genome (virus-like particles, VLPs) have been highly successful in preventing and treating HPV infection in several animal model systems. In humans, the serum antibody response to VLPs is stable over time, also after the HPV infection has been cleared, resulting in HPV serology being used as a marker of cumulative HPV exposure in spite of the fact that a significant proportion of HPV-exposed subjects fail to seroconvert. More than 90% of HPV infections will clear spontaneously. The factors that determine whether an HPV infection is cleared or persists and increases the risk for cancer are not known, but cellular immunity is implicated. Several HLA class II haplotypes are associated with cervical cancer: DQw3 increases and DR13 decreases the risk for cervical cancer in general (odds ratios (OR) and 95% confidence intervals (CI): 1.25(1.15-1.37) and 0.69 (0.56-0.85), respectively); DR15 increases the risk for HPV16-carrying cancer (OR: 1.47; CI: 1.20-1.81); and DR7 may be either protective or increase the risk. Most cervical cancers have downregulated the expression of at least one HLA class I antigen, whereas class II expression is increased in infected epithelium. A Th2 cytokine profile is associated with progression to cervical cancer. HPV-antigen-specific proliferative responses have been detected in many studies, although it is not entirely clear whether these responses are HPV type specific or may be cross-reactive between HPV types. Specific cytotoxic T lymphocyte (CTL) responses were originally reported in only a minority of infected subjects, typically cancer patients, but with advancing technology, specific CTLs can be stimulated from about half of the women with HPV-carrying disease. In animal model systems, CTL responses can mediate clearance.

CONCLUSION

The antibody response to HPV is a mediator of type-specific protective immunity, which forms the basis for prophylactic vaccine candidates. The cellular immunity to HPV is implicated as an important factor in cervical carcinogenesis, but the main targets and types of responses that mediate HPV clearance are not established.

The role of human papillomavirus vaccines in cervical neoplasia

Cervical cancer is the second most common cause of cancer-related death in women, in some developing countries accounting for the highest cancer mortality. The evidence for the association of high-risk human papillomavirus types with the aetiology of cervical neoplasia is firmly established, human papillomavirus being detected in virtually all cervical cancers. The risk of progression of precursor cervical intra-epithelial neoplasia lesions is associated with persistence of human papillomavirus infection. One strategy for the management of cervical neoplasia worldwide could be the development of prophylactic and/or therapeutic human papillomavirus vaccines. This chapter will discuss the natural history of human papillomavirus infection, viral immunity and the clinical course of resultant disease as the background to the effective design and use of human papillomavirus vaccines for protection or therapy. The progress of ongoing phase I and II clinical trials for several different vaccine preparations and the challenges for establishing their future use will be discussed.

Prevention of cervical cancer with vaccines

Worldwide, cervical cancer is one of the most common cancers in women. This is especially true in developing countries, where Papanicolaou smear screening, an effective preventive measure against cervical cancer, is insufficiently implemented. With growing evidence for human papillomavirus as a central etiologic factor in cervical neoplasia, development of a vaccine against this virus has emerged as an important objective in prevention of cervical cancer. International efforts in vaccine development have culminated in advancement of various vaccine strategies and initiation of human clinical trials. Reports from animal vaccine trials and early phase I human trials indicate markedly enhanced immune response through vaccination. However, the clinical significance of these results requires confirmation from long-term human trials.

Human papillomavirus infection as a risk factor for squamous-cell carcinoma of the head and neck

BACKGROUND

Oncogenic human papillomaviruses (HPVs), especially HPV type 16 (HPV-16), cause anogenital epithelial cancers and are suspected of causing epithelial cancers of the head and neck.

METHODS

To examine the relation between head and neck cancers and HPVs, we performed a nested case-control study within a joint Nordic cohort in which serum samples were collected from almost 900,000 subjects. Samples collected at enrollment from 292 persons in whom squamous-cell carcinoma of the head and neck developed, on average, 9.4 years after enrollment and from 1568 matched controls were analyzed for antibodies against HPV-16, HPV-18, HPV-33, and HPV-73 and for cotinine levels as a marker of smoking habits. Polymerase-chain-reaction (PCR) analyses for HPV DNA were performed in tumor tissue from 160 of the study patients with cancer.

RESULTS

After adjustment for cotinine levels, the odds ratio for squamous-cell carcinoma of the head and neck in subjects who were seropositive for HPV-16 was 2.2 (95 percent confidence interval, 1.4 to 3.4). No increased risk was observed for other HPV types. Fifty percent of oropharyngeal and 14 percent of tongue cancers contained HPV-16 DNA, according to PCR analysis.

CONCLUSIONS

HPV-16 infection may be a risk factor for squamous-cell carcinoma of the head and neck.

Natural HPV immunity and vaccination strategies

BACKGROUND

the task of preventing premature death in women may be delivered by vaccinating against the high-risk papillomaviruses associated with various malignancies.

OBJECTIVES

we will discuss the immune mechanisms likely to be relevant to the control of an HPV infection in the cervix and assess the limited evidence for such immune recognition in the natural history of infection.

CONCLUSION

the next generation of vaccination strategies should include the use of HPV 16 early (E2 and/or E6 and/or E7) and late gene targets (L1 and L2) expressed as VLPs with their clinical and immunological evaluation aimed at therapy as well as prophylaxis. Important clinical efficacy assessment may be deliverable in relatively short-term studies by targeting patients with HPV 16 associated vulval intraepithelial neoplasia.

Trends over time in the incidence of cervical neoplasia in comparison to trends over time in human papillomavirus infection

INTRODUCTION

The establishment of human papillomavirus (HPV) infection as a major cause of cervical neoplasia has resulted in major efforts to develop prophylactic HPV vaccines for prevention of cervical neoplasia. Cervical cancer and the other HPV-associated cancers constitute a major public health burden and eradication of the major causative infection is certainly the most appealing long-term preventive measure. Nevertheless, the effects of preventive HPV vaccination will need to be estimated and compared for (cost-) efficacy with other primary prevention and with secondary prevention programs. However, estimating the effects of preventing a causative exposure is complicated when the exposure is a transmissible infection. The spread of the epidemic is dynamic and may change over time depending e.g. on the changes in human behavior. Depending on the circumstances, prevention of an infection may have either greater or lesser effects than the prevention of a non-infectious exposure. Estimating the time trends in HPV infections and the underlying trends in the risk of cervical neoplasia is important for estimating effects of interventions.

METHOD

A literature review on recent evidence on time trends in cervical neoplasia, compared with evidences on time trends in HPV infections and interactions between different types of HPV infections.

RESULTS

In Finland, there has between 1991 and 1995 been a 60% increase in the incidence of cervical cancer among women <55 years of age. Trends in detection rates of cervical cancer precursor lesions are consistent with an increase in the background cervical cancer risk. From the 1960s to 1980s, there has been a major increase in HPV seroprevalences over time in the Nordic countries. Increasing trends are also seen for other sexually transmitted diseases and smoking. Several studies indicate the existence of interaction between benign and oncogenic HPV types, thus making the relationship between the incidences in HPV infections and in cervical neoplasia complex.

CONCLUSION

The increase in cervical cancer is paralleled by increases in HPV infection, other STDs and smoking and changes in screening practices, all of which may have contributed. Prediction of the effect on cervical cancer incidence of changes in HPV incidences is complicated by the existence of several risk factors, the protective effect of screening and by the population dynamics of HPV infections.

Prospects for phase III-IV HPV vaccination trials in the Nordic countries and in Estonia

BACKGROUND

oncogenic, i.e. high risk human papillomavirus (hrHPV) types are the major cause of invasive cervical cancer (ICC). Putatively licensable vaccines against the hrHPVs have been developed and are approaching clinical phase III trials that use persistent HPV infection as end point. Direct extension of the phase III trials towards long-term end points (ICC and its immediate precursors: carcinoma in situ and severe dysplasia, i.e. cervical intraepithelial neoplasia grade III, CINIII) is important, to avoid early contamination of the target population by opportunistic use of licensed HPV vaccines. Country-wide registration on population and health events in a stable population of 25 million make Estonia and the Nordic countries a unique venue for long-term evaluation of cervical cancer control measures. Mass-screening programmes exist in all Nordic countries, but not in Estonia.

AIM

design of phase III-IV trials for evaluation of protection against ICC and CINIII by preventive HPV vaccines based on cancer registry follow-up.

RESULTS

in the Nordic countries, population based randomisation of all 15-year-old women to the vaccination (vaccine and placebo) and reference cohorts entering conventional Pap-smear screening after a clinical phase III trial would assure comparability of the cohorts. Enrollment of 10094 vaccinees +10094 placebo vaccinees +30282 other hrHPV negative women without vaccination at the age of 16 would give 80% power for the demonstration of 70% vaccine efficacy (VE) against ICC in 20 years by cancer registry follow-up. On the other hand, vaccination of 8303 Estonian hrHPV negative women among the entire 15-year-old female birth cohort (about 10000 women) with an already licensed HPV vaccine would enable demonstration of 70% VE against ICC by 20 years of registry follow-up of these and comparable 16606 women identified among the 16-19-year-old birth cohorts.

CONCLUSIONS

evaluation of the protective effect of an HPV vaccine against ICC is possible both in countries with or without mass-screening. The effects of vaccination on spread of different HPVs in the population would need to be monitored, especially in Estonia. Ethical aspects, cost-benefit evaluation and comparisons with other new means of cervical cancer control warrant further investigation.

Seropositivity to multiple sexually transmitted infections is not common

BACKGROUND

Seropositivity for several sexually transmitted infections (STIs) is often used as a surrogate measure of sexual behavior. The authors assessed the concomitant seropositivity for STIs in women.

GOAL

To estimate the excess of concomitant seropositivity for four STIs among fertile-aged women assuming no coinfections above what would be expected at random.

STUDY DESIGN

Antibodies to herpes simplex virus type 2, human papillomavirus type 16, HIV, Chlamydia trachomatis, and Treponema pallidum were determined from a random sample of 1110 pregnant women in Tallinn, Estonia.

RESULTS

A total of 310 combinations of the concomitant seropositivity were observed, whereas only 193 were expected by chance. Among persons seropositive for two STIs, 78 extra combinations were observed, whereas for three STIs, 35 extra combinations were observed. For four STIs, 3.8 extra combinations were found.

CONCLUSIONS

Seropositivity to multiple STIs is not common. This fits the concept of different transmission probabilities and the spread of the STIs, and suggests that seropositivity alone should be used with caution as a surrogate to sexual behavior in women.

The effect of low-dose acetylsalicylic acid on bleeding after transurethral prostatectomy--a prospective, randomized, double-blind, placebo-controlled study

OBJECTIVE

An increase in the loss of blood after ingestion of acetylsalicylic acid (ASA) has been reported after several types of surgery, but randomized placebo-controlled studies have exclusively been performed after coronary artery bypass surgery. The reported effects of ASA on bleeding after transurethral prostatectomy (TURP) have been conflicting. We have studied the effect of low doses of ASA (150 mg) on bleeding after TURP in a prospective, randomized, double-blind, placebo-controlled trial.

PATIENTS AND METHODS

Patients were randomized to receive either 150 mg ASA (n = 26) or placebo (n = 27) 10 days before surgery. The weight of resected tissue, operation time and blood loss, transfusion requirements and complications were recorded.

RESULTS

There was no significant difference in the median operative blood loss between the groups (p = 0.528), but postoperatively the blood loss in the ASA group (median 284; quartiles 196-660 ml) was significantly higher than in the placebo group (median 144; quartiles 75-379 ml), (p = 0.011). No significant difference was observed between the groups regarding the amount of resected tissue (p = 0.209) or the operating time (p = 0.297). In both groups the operative blood loss was significantly related to the amount of resected tissue (p < 0.005) and the operating time (p < 0.005). No significant difference in transfusion requirements (p = 0.280), time to catheter removal (p = 0.455) and hospital stay (p = 0.820) were observed between the groups.

CONCLUSION

Long-term low-dose ASA therapy is associated with a significant increase in the postoperative blood loss after TURP, and although no significant difference in transfusion requirements was observed more units of blood were used in the ASA group. We advise that ASA therapy should be withdrawn 10 days before TURP.

High prevalence of human papillomavirus type 16 infection among children

Infection with high-risk human papillomaviruses (HPV), is the most significant risk factor for cervical cancer and it may be possible to prevent this malignancy by immunisation. Before immunisation programmes can be designed, however, it is necessary to know the age of acquisition and all routes of infection for these viruses. Sexual transmission is well documented and vertical transmission has also been demonstrated, although the frequency of transmission remains controversial. We previously showed that vertical transmission frequently results in persistent infection, and now present data on the prevalence of HPV-16 DNA (the most prevalent high-risk HPV type) in healthy children. Buccal samples from 267 healthy children aged 3-11 years were tested for HPV DNA by generic PCR (MY09/MY11), and a HPV-16 specific nested PCR. Reverse transcriptase (RT)-PCR was used to determine the prevalence of transcriptionally active HPV-16 infection in a subset of children. HPV-16 DNA was detected by nested PCR in 138 of 267 (51.7%) samples, whereas HPV DNA was detected in only 45 (16.8%) specimens by generic PCR, that has a lower analytical sensitivity. There were no significant differences in prevalence according to age or sex. Early region mRNA was detected by RT-PCR in six (11.3%) of 53 HPV-16 E5 DNA positive samples. HPV-16 E5 DNA sequences from 10 children confirmed the identity of the sequences detected and identified 13 HPV-16 variants.

Seroresponses to human papillomavirus types 16, 18, 31, 33, and 45 virus-like particles in South African women with cervical cancer and cervical intraepithelial neoplasia

The aim of the study was to determine the prevalence of antibodies to human papillomavirus (HPV) types 16, 18, 31, 33, and 45 in woman in Cape Town with cervical intraepithelial neoplasia (CIN) (n = 95), cervical cancer (n = 40), female blood donors (n = 95) and children (n = 110). The enzyme-linked immunosorbent assay (ELISA) made use of baculovirus synthesised HPV virus like particles (VLPs) as antigen. Antibodies to at least one HPV type were detected in sera from 75% of cancer patients, 71.6% of CIN patients, 44.2% of blood donors and 27.3% of children. Sera from 95 women with CIN were compared with age-matched female blood donors. There was a significant association of seropositivity to VLP-16 (P = 0.006) and VLP-45 (P = 0.008) with CIN compared with the blood donors. There was also a significant difference in the seropositivity of women with CIN to any of the five virus-like particle (VLP) types compared to the blood donors (P = 0.0002: OR = 3.2). Thirty-nine of sixty-nine (56.5%) women with CIN were found to be HPV-16 DNA positive. The average age of women in this group that were VLP-16 seropositive was 34 years and those found to be VLP-16 seronegative was 52 years of age. Antibodies to all five VLP types were detected in these populations, thus an ideal vaccine should induce protection from infection by a wide range of HPV types.

Seroresponses to virus-like particles of human papillomavirus types 16, 18, 31, 33, and 45 in San people of Southern Africa

Virus-like particles (VLPs) of the high-risk human papillomavirus (HPV) types 16, 18, 31, 33, and 45 were used as antigen in enzyme-linked immunosorbent assay (ELISA) to determine the prevalence of serum IgG in a group of San people originally from Namibia, now residing in South Africa. The San children had low seroprevalence to all VLP types, but 26/115 (22.6%) of the children were seropositive to at least 1 VLP type. Among the adults, seroprevalence was significantly higher. The seroprevalence of antibodies in 101 San women to VLP-16 was 16.8%, VLP-18 18.8%, VLP-31 12.9%, VLP-33 17.8%, and VLP-45 22.8%. Five of the 11 men were seropositive: 2 for VLP-31, 1 for VLP-18, 1 for VLP-33, and 1 for VLP-45. Seroreactivity appeared to be type specific, except possibly to VLP-18 and -45. Of the adults, 50.5% were seropositive to at least 1 VLP type and 24.8% were seropositive to >1 VLP type. From this study, it is concluded that the San people are exposed to HPV-16, -18, -31, -33, and -45, with antibodies to VLP-45 being the most prevalent.

The serological response to papillomaviruses

The antibody response to papillomaviruses is a key determinant of protective immunity. HPV serology is also an important epidemiological tool for the assay of past and present HPV infections and for prediction of HPV-associated cancers and their precursor lesions. This review focuses on the assay of antibody responses to the HPV capsid, its use as a marker of cumulative HPV exposure and surveys how HPV seroepidemiology has been used to elucidate the spread of HPV infection in various populations, the natural history of HPV infection and that exposure to HPV is associated with increased risk for several human cancers.