Immunoglobulin G responses against human papillomavirus type 16 virus-like particles in a prospective nonintervention cohort study of women with cervical intraepithelial neoplasia

The use of vaccines in treating cervical cancer: present status and future prospects

HPV types are carcinogenic agents in cervical cancer. This view is supported by epidemiological and biological evidence. The oncogenic products and capsid proteins of high risk HPV types are potential targets against which effective immunity may be generated by vaccination. Both therapeutic and prophlylactic immunisation are potential strategies to deal with the widespread problem of HPV infection and possibly established cervical neoplasia. Clinical trials are now underway to evaluate candidate vaccines.

Balance of IgG subclasses toward human papillomavirus type 16 (HPV16) L1-capsids is a possible predictor for the regression of HPV16-positive cervical intraepithelial neoplasia

Human papillomavirus type 16 (HPV16) is known to be a major causative agent of cervical cancer. To test the hypothesis that an enhanced Th1 response favors the natural course of cervical intraepithelial neoplasia (CIN), we measured IgG subclasses toward HPV16 L1-capsids because IgG1/IgG2 balance reflects Th2 and Th1 responses, respectively. We examined IgG2/IgG1 ratios in sera from 67 anti-HPV16 L1-positive women; 18 were cytologically normal women, 29 were CIN patients, and 20 were cervical cancer patients. The IgG2 dominance (IgG2/IgG1 ratio >1) was observed in 94, 48, and 5%, respectively (p < 0.001). The regression rate of CIN lesions was significantly different between patients with and without IgG2 dominance: 83.3% (5/6) versus 16.7% (1/6), respectively (p < 0.05). These findings raise the possibility that IgG2 dominance toward HPV16 L1-capsids, i.e., Th1 dominance, may be a useful marker to predict viral clearance or the regression of HPV16-positive CIN.

No excess risk of cervical carcinoma among women seropositive for both HPV16 and HPV6/11

Human papillomavirus (HPV) types 16 and 18 are the major risk factors for cervical carcinoma, whereas HPV types 6 and 11 cause benign genital lesions. We wanted to study the joint effect of simultaneous infections with the oncogenic and non-oncogenic HPV types on risk of subsequent development of cervical carcinoma. A cohort of 530,000 women who had donated blood samples to Nordic serum banks between 1973 and 1994 was followed up by linkage to national cancer registries. We identified 182 prospective cases with invasive cervical carcinoma and selected 538 matched controls at random. HPV 6, 11, 16, 18 and 33 seropositivity was used as a marker for the different HPV infections, and seropositivity for Chlamydia trachomatis and cotinine were used as markers for risk-taking sexual behavior and smoking respectively. The adjusted odds ratio (OR) of cervical squamous-cell carcinoma (SCC) was 2.2 for HPV6/11 among HPV16 seronegatives and 5.5 for HPV16 among HPV6/11 seronegatives. Assuming multiplicative joint effect, the expected OR for seropositivity to both HPV6/11 and HPV16 would have been 12, but the observed OR was 1.0. The antagonistic interaction was statistically significant (p = 0.001) and present also under deterministic considerations of possible misclassification bias. Antagonistic interactions were also detected for combinations of HPV16 and HPV18 and of HPV16 and HPV33. The results are in line with the concept that HPV-specific immunity protects against SCC and support primary prevention of SCC by vaccination against the HPVs.

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

The importance and natural history of HPV infections in childhood is incompletely understood. We performed a survey for presence of serum antibodies to HPV capsids among 1031 children aged 0 to 13 years, resident in Stockholm, Sweden. The HPV seroprevalence among these children was 3.0% for HPV16, 0.6% for HPV18 and 2.7% for HPV33. By comparison, among simultaneously analyzed positive control panels comprising women with CIN or healthy women with type-specific cervical HPV DNA, seroprevalence of HPV 16, 18 and 33 was 69%, 58% and 63% respectively. The results suggest that HPV infection in childhood is not common.

Prospective study on cervical neoplasia IV. Presence of HPV antibodies

Sera collected in the course of a prospective study carried out in Prague in 1975-1983 were assayed for the presence of human papillomavirus (HPV) antibodies. Women with cervical neoplasia proven by biopsy at enrollment possessed antibodies to peptides derived from E2, E4 and E7 proteins of HPV16 and to virus-like particles (VLPs) of HPV16, -18 and -33 significantly more frequently than matched controls. Women without cervical neoplasia at enrollment who developed the disease in the course of the study differed from matched controls by a higher prevalence of antibodies against VLPs of HPV16 and -18 but not against early antigens of HPV16. In 19 of the latter subjects, paired serum specimens were tested, the first samples having been taken at enrollment and the second at diagnosis. Development of the disease was associated with seroconversion from negativity to positivity to at least one HPV antigen in 11 (57.9%) women.

HPV 16 antibody prevalence in Jamaica and the United States reflects differences in cervical cancer rates

Human papillomavirus (HPV) is widely accepted as the primary etiologic agent in the development of cervical cancer. DNA of a particular HPV type, HPV 16, is found in about half of tumors tested. Inconsistent with this causal relationship, however, population-based studies of HPV DNA prevalence have often failed to find high rates of anogenital HPV infection in countries with high cervical cancer rates. To examine this issue, we used serology to compare HPV 16 exposure in healthy volunteer blood donors in the United States (n = 278) and similar subjects from a country with 3-fold higher cervical cancer rates, Jamaica (n = 257). Jamaican sexually transmitted disease (STD) patients (n = 831) were also studied to examine in detail the relation of HPV 16 antibodies with sexual history. Serology was conducted using an ELISA employing HPV 16 virus-like particles (VLPs). Age-adjusted seroprevalence rates were greatest among male (29%) and female (42%) STD patients, intermediate in male (19%) and female (24%) Jamaican blood donors and lowest among male (3%) and female (12%) U.S. blood donors. The higher seroprevalence in women was significant, and prevalence tended to increase with age. In multivariate logistic regression, controlling for age and gender, Jamaican blood donors were 4.2-fold (95% CI 2.4-7.2) and STD patients 8.1-fold (95% CI 5.0-13.2) more likely to have HPV 16 VLP antibodies than U.S. blood donors. Among STD patients, HPV 16 antibodies were associated with lifetime number of sex partners and years of sexual activity, as well as other factors. Our data suggest that HPV 16 VLP antibodies are strongly associated with sexual behavior. Moreover, exposure to HPV 16 appears to be much greater in Jamaica than in the United States, consistent with the high rate of cervical cancer in Jamaica.

High risk genital papillomavirus infections are not spread vertically

The Medline-indexed literature on risk factors for HPV infection and HPV transmission is critically reviewed. Principles for assay validation and interpretation, reliability of different study designs and principles for interpretation of conflicting reports are discussed. The conclusions arrived at can be summarised as: (1) There is overwhelming epidemiological evidence that the only quantitatively important mode of transmission of infection with oncogenic genital HPV types is sexual. (2) There is also evidence that benign genital HPV types can be transmitted sexually, but the epidemiological data on the benign virus types are less extensive and less clear. (3) Perinatal HPV transmission is unequivocally demonstrated only for the rare disease juvenile respiratory papillomatosis.

Trends in seroprevalence of human papillomavirus type 16 among pregnant women in Stockholm, Sweden, during 1969-1989

To assess long-term trends in the prevalence of oncogenic human papillomavirus (HPV) infection, we performed a cross-sectional serosurvey of the seroprevalence of the major oncogenic HPV type, HPV16, among 3,512 pregnant women undergoing population-based serological screening at the first trimester of pregnancy in the same catchment area in Stockholm, Sweden, during 1969, 1983 or 1989. The overall HPV16 seroprevalence rates were 16% in 1969, 22% in 1983 and 21% in 1989. Seroprevalence was significantly increased, comparing both 1969 vs. 1983 (p = 0.0005) and 1969 vs. 1989 (p = 0.008). By comparison, the previously reported herpes simplex 2 (HSV-2) seroprevalence in the same women increased from 17% in 1969 to 32% in 1983 and 33% in 1989, whereas the seroprevalence rates of HSV-1 were the same (69% in 1969, 63% in 1983 and 68% in 1989). Odds ratios for HPV 16-positive women to also be HSV-2-positive were 1.8 in 1969 (p < 0.005), 1.1 in 1983 (p = NS) and 1.0 in 1989. Our results suggest that both HSV-2 and HPV16 became more generally spread in the Swedish population between 1969 and 1983 but that the spread has been stable during the 1980s.

Immunoglobulin-A and -G responses against virus-like particles (VLP) of human papillomavirus type 16 in women with cervical cancer and cervical intra-epithelial lesions

Immunoglobulin-A and -G (IgA and IgG) responses against HPV-16-like particles (VLP) were tested by ELISA in 104 women with cervical abnormalities, 26 atypical cells of undetermined significance (ASCUS) and 14 cytologically normal women with HPV DNA. As controls, 130 age-matched cytologically normal women with no HPV DNA were selected from the population in which the cases were generated. The existence of HPV DNA in cervical samples was tested by a PCR-based method. The normal women positive with HPV-16 DNA were followed up at 4- to 7-month intervals for 16 to 24 months. IgA and IgG antibodies against HPV-16 VLP were frequently detected in these women repeatedly positive with HPV-16 DNA, suggesting that persistent HPV infection is crucial for effective antibody responses against the viruses. IgA response appears earlier and persists longer than IgG response. Women with HPV DNA of types 16, 31/33/35, 58 and unknown types showed significantly higher seropositivity for both IgA and IgG antibodies than the controls (p < 0.05 for both). No significant seropositivity for IgA or IgG was detected in the HPV-18/45-DNA-positive group. HPV 31/33/35, 58 appear to be types close to HPV 16, whereas HPV 18/45 appears to be distinct from HPV 16 in antigenicity. IgA and IgG responses against HPV-16 VLP were more frequently observed in women with normal cervices with HPV DNA, ASCUS, HSIL and cervical cancer than in the controls. Strong IgA and IgG responses depended on HPV-16 infection in HSIL and cervical cancer, but there was no correlation between the serological responses and the status of HPV DNA in ASCUS and LSIL. Antibody positivity reflects persistent viral infection that may increase the risk for malignant progression of the cervix. This serological assay using HPV-16 VLP may therefore be useful as a new diagnostic tool supplementing cervical cytological tests.