Lineages of oncogenic human papillomavirus types other than type 16 and 18 and risk for cervical intraepithelial neoplasia.

BACKGROUND: Data on clinical outcomes of infection with variants of oncogenic human papillomavirus (HPV) types other than HPV16 and HPV18 are rare. We investigated intratypic variations in non-HPV16/18 oncogenic types and their corresponding relationships with cervical intraepithelial neoplasia grades 2-3 (CIN2/3). METHODS: Study subjects were women who were positive for one or more of 11 non-HPV16/18 oncogenic types. Subjects were followed every six months for two years for detection of HPV and cervical lesions. Variant lineages were defined by sequencing the 3' part of the long control region and the entire E6/E7 region of HPV genome. Lineage-associated risk of CIN2/3 was assessed using logistic regression with generalized estimating equations. RESULTS: A total of 4591 type-specific HPV infections among 2667 women were included in the analysis. The increase in risk of CIN2/3 was statistically significant for women with HPV31 A or B compared with C variants, HPV33 A1 compared with B variants, HPV45 A3 or B2 compared with B1 variants, HPV56 B compared with A2 variants, and HPV58 A1 or A3 compared with C variants. For these five types, the adjusted odds ratio associated with CIN2/3 was 2.0 (95% confidence interval [CI] = 1.5 to 2.6) for infections with single-type high-risk (HR) variants, 1.7 (95% CI = 1.0 to 2.7) for infections with two or more types but only one HR variant, and 5.3 (95% CI = 3.1 to 8.4) for infections with HR variants of two or more types as compared with those with single-type non-HR variants. The likelihood of CIN2/3 was similar for women with HPV16 infection and for those with HPV58 A1 variant infection. CONCLUSIONS: These findings suggest that for a given HPV type, intratypic nucleotide changes may alter phenotypic traits that affect the probability of neoplasia.

Persistence of newly detected human papillomavirus type 31 infection, stratified by variant lineage.

Variants of human papillomavirus (HPV) type 31 have been shown to be related both to risk of cervical lesions and racial composition of a population. It is largely undetermined whether variants differ in their likelihood of persistence. Study subjects were women who participated in the ASCUS-LSIL Triage Study and who had a newly detected HPV31 infection during a two-year follow-up with six-month intervals. HPV31 isolates were characterized by sequencing and assigned to one of three variant lineages. Loss of the newly detected HPV31 infection was detected in 76 (47.5%) of the 160 women (32/67 with A variants, 16/27 with B variants and 28/66 with C variants). The adjusted hazard ratio associating loss of the infection was 1.2 (95% CI, 0.7-2.1) for women with A variants and 2.1 (95% CI, 1.2-3.5) for women with B variants when compared with those with C variants. Infections with A and C variants were detected in 50 and 41 Caucasian women and in 15 and 23 African-American women, respectively. The likelihood of clearance of the infection was significantly lower in African-American women with C variants than in African-American women with A variants (p = 0.05). There was no difference in the likelihood of clearance between A and C variants among Caucasian women. Our data indicated that infections with B variants were more likely to resolve than those with C variants. The difference in clearance of A vs. C variants in African-Americans, but not in Caucasians, suggests a possibility of the race-related influence in retaining the variant-specific infection.

Prevalence and risk factors for oncogenic human papillomavirus infections in high-risk mid-adult women.

BACKGROUND: The epidemiology of high-risk (hr) human papillomavirus (HPV) infections in mid-adult women with new sex partners is undefined. METHODS: We analyzed baseline data from 518 25- to 65-year-old women online daters. Women were mailed questionnaires and kits for self-collecting vaginal specimens for polymerase chain reaction-based hrHPV testing. Risk factors for infection were identified using Poisson regression models to obtain prevalence ratios (PRs). RESULTS: The prevalence of hrHPV infection was 35.9%. In multivariate analysis restricted to sexually active women, the likelihood of hrHPV infection was associated with abnormal Papanicolaou test history (PR = 1.42, 95% confidence interval [CI]: 1.10-1.84), lifetime number of sex partners >14 (compared with 1-4; PR = 2.13, 95% CI: 1.13-4.02 for 15-24 partners; and PR = 1.91, 95% CI: 1.00-3.64 for ≥25 partners), male partners with ≥1 concurrent partnership (PR = 1.34, 95% CI: 1.05-1.71), and male partners whom the subject met online (PR = 1.39, 95% CI: 1.08-1.79). Age was inversely associated with infection only in women who were sexually inactive (PR = 0.67 per 5-year age difference, adjusted for Papanicolaou history and lifetime number of partners). Compared with sexually inactive women, the likelihood of infection increased with increasing risk level (from low-risk to hr partners; P < 0.0001 by trend test). In multivariate analysis, infection with multiple versus single hrHPV types was inversely associated with ever having been pregnant (PR = 0.64, 95% CI: 0.46-0.90) and recent consistent condom use (PR = 0.56, 95% CI: 0.32-0.97), and positively associated with genital wart history (PR = 1.43, 95% CI: 1.03-1.99). CONCLUSIONS: Measures of both cumulative and recent sexual history were associated with prevalent hrHPV infection in this hr cohort of mid-adult women.

Rates and determinants of oral human papillomavirus infection in young men.

BACKGROUND: Little is known about the rates and determinants of oral human papillomavirus (HPV) infection, an infection that is etiologically linked with oropharyngeal cancers. METHODS: A cohort of male university students (18-24 years) was examined every 4 months (212 men, 704 visits). Oral specimens were collected via gargle/rinse and swabbing of the oropharynx. Genotyping for HPV-16 and 36 other α-genus types was performed by polymerase chain reaction-based assay. Data on potential determinants were gathered via clinical examination, in-person questionnaire, and biweekly online diary. Hazards ratios (HR) were used to measure associations with incident infection. RESULTS: Prevalence of oral HPV infection at enrollment was 7.5%, and 12-month cumulative incidence was 12.3% (95% confidence interval [CI], 7.0, 21.3). Prevalence of oral HPV-16 was 2.8% and 12-month cumulative incidence was 0.8% (95% CI, 0.1%-5.7%). None of the incident oral HPV infections and 28.6% of the prevalent oral HPV infections were detected more than once. In a multivariate model, incident oral HPV infection was associated with recent frequency of performing oral sex (≥1 per week: HR, 3.7; 95% CI, 1.4-9.8), recent anal sex with men (HR, 42.9; 95% CI, 8.8-205.5), current infection with the same HPV type in the genitals (HR, 6.2; 95% CI, 2.4-16.4), and hyponychium (HR, 11.8, 95% CI, 4.1-34.2). CONCLUSIONS: Although nearly 20% of sexually active male university students had evidence of oral HPV infection within 12 months, most infections were transient. Human papillomavirus type 16 was not common. Sexual contact and autoinoculation appeared to play independent roles in the transmission of α-genus HPV to the oral cavity of young men.

Association of human papillomavirus type 31 variants with risk of cervical intraepithelial neoplasia grades 2-3.

Although the lineages of human papillomavirus type 31 (HPV31) variants are recognized, their clinical relevance is unknown. The purpose of our study was to examine risk of cervical intraepithelial neoplasia Grades 2-3 (CIN2/3) by HPV31 variants. Study subjects were women who participated in the atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesion Triage Study and who had HPV31 infections detected at one or more visits. They were followed semi-annually over 2 years for detection of HPV DNA and cervical lesion. HPV31 isolates were characterized by DNA sequencing and assigned into 1 of 3 variant lineages. CIN2/3 was histologically confirmed in 127 (27.0%) of the 470 HPV31-positive women, 83 diagnosed at the first HPV31-positive visit and 44 thereafter. The odds ratio for the association of 2-year cumulative risk of CIN2/3 was 1.7 (95% CI: 1.0-2.9) for infections with A variants and 2.2 (95% CI: 1.2-3.9) for infections with B variants as compared to those with C variants. Among women without CIN2/3 at the first HPV31-positive visit, the risk of subsequent CIN2/3 was 2.2-fold greater for those with A variants (95% CI: 1.0-4.8) and 2.0-fold greater for those with B variants (95% CI: 0.9-4.9) as compared to those with C variants. Similar associations were observed when CIN3 was used as the endpoint. The findings from our study help to tag HPV31 variants that differ in risk of CIN2/3 and to explain in part why some HPV31 infections regress spontaneously and others lead to disease progression.

Circumcision and acquisition of human papillomavirus infection in young men.

BACKGROUND: The role of circumcision in male HPV acquisition is not clear. METHODS: Male university students (aged 18-20 years) were recruited from 2003 to 2009 and followed up triannually. Shaft/scrotum, glans, and urine samples were tested for 37 α human papillomavirus (HPV) genotypes. Cox proportional hazards methods were used to evaluate the association between circumcision and HPV acquisition. Logistic regression was used to assess whether the number of genital sites infected at incident HPV detection or site of incident detection varied by circumcision status. RESULTS: In 477 men, rates of acquiring clinically relevant HPV types (high-risk types plus types 6 and 11) did not differ significantly by circumcision status (hazard ratio for uncircumcised relative to circumcised subjects: 0.9 [95% confidence interval{CI}: 0.7-1.2]). However, compared with circumcised men, uncircumcised men were 10.1 (95% CI: 2.9-35.6) times more likely to have the same HPV type detected in all 3 genital specimens than in a single genital specimen and were 2.7 (95% CI: 1.6-4.5) times more likely to have an HPV-positive urine or glans specimen at first detection. CONCLUSIONS: Although the likelihood of HPV acquisition did not differ by circumcision status, uncircumcised men were more likely than circumcised men to have infections detected at multiple genital sites, which may have implications for HPV transmission.

Development of genital warts after incident detection of human papillomavirus infection in young men.

Determining the rate at which men develop genital warts after infection with alpha genus human papillomavirus (HPV) types will provide important information for the design of prevention strategies. We conducted a cohort study of 18-21-year-old men who underwent triannual genital examinations. The 24-month cumulative genital wart incidence was 57.9% (95% confidence interval [CI], 38.1%-79.1%) among 46 men with incident detection of HPV-6 or HPV-11 infection, 2.0% (95% CI, 0.5%-7.9%) among 161 men with incident detection of infection with other HPV types, and 0.7% (95% CI, 0.2%-2.8%) among 331 men who tested negative for HPV. Our results suggest that genital warts are common after HPV-6 or HPV-11 infection in young men.

Quantitative human papillomavirus 16 and 18 levels in incident infections and cervical lesion development.

Human papillomavirus (HPV) RNA levels may be a more sensitive early indicator of predisposition to carcinogenesis than DNA levels. We evaluated whether levels of HPV-16 and HPV-18 DNA and messenger RNA (mRNA) in newly detected infections are associated with cervical lesion development. Female university students were recruited from 1990 to 2004. Cervical samples for HPV DNA, HPV mRNA, and Papanicolaou testing were collected tri-annually, and women were referred for colposcopically directed biopsy when indicated. Quantitative real-time polymerase chain reaction of L1 and E7 DNA and E7 mRNA was performed on samples from women with HPV-16 and HPV-18 infections that were incidently detected by consensus PCR. Adjusting for other HPV types, increasing E7 cervical HPV-16 mRNA levels at the time of incident HPV-16 DNA detection were associated with an increased risk of cervical intraepithelial neoplasia grade 2-3 (HR per 1 log(10) increase in mRNA = 6.36, 95% CI = 2.00-20.23). Increasing HPV-16 mRNA levels were also associated with an increased risk of cervical squamous intraepithelial lesions; the risk was highest at the incident positive visit and decreased over time. Neither HPV-16 E7 DNA levels nor HPV-18 E7 DNA nor mRNA levels were significantly associated with cervical lesion development. Report of >1 new partner in the past 8 months (relative to no new partners) was associated with increased HPV mRNA (viral level ratio [VLR] = 10.05, 95% CI = 1.09-92.56) and increased HPV DNA (VLR = 16.80, 95% CI = 1.46-193.01). In newly detected HPV-16 infections, increasing levels of E7 mRNA appear to be associated with an increased risk of developing cervical pre-cancer.

Development and evaluation of a liquid bead microarray assay for genotyping genital human papillomaviruses.

We developed a liquid bead microarray (LBMA) assay for genotyping genital human papillomaviruses (HPVs) based on the MY09-MY11-HMB01 PCR system and the reverse line blot (RLB) assay probe sequences. Using individual HPV plasmids, we were able to detect as few as 50 copies per reaction. In two separate retrospective studies, the LBMA assay was compared to the RLB assay and to the Hybrid Capture II (hc2) assay. Testing was performed without knowledge of other assay results. In the first study, 614 cervical swab samples (enriched for HPV infection) from 160 young women were tested for HPV DNA, and 360 (74.8%) type-specific HPV infections were detected by both assays, 71 (14.8%) by the LBMA assay only, and 50 (10.4%) by the RLB assay only. Type-specific agreement for the two assays was excellent (99.1%; kappa=0.85; 95% confidence interval [95% CI], 0.82 to 0.88). Samples with discrepant LBMA and RLB test results tended to have low viral loads by a quantitative type-specific PCR assay. In the second study, cervical swab samples from 452 women (including 54 women with histologically confirmed cervical-intraepithelial neoplasia grade 2 or worse [>or= CIN2]) were tested initially by the hc2 and subsequently by the LBMA assay. The estimated sensitivities for >or= CIN2 were similar for the LBMA and hc2 assays (98.4% [95% CI, 95.0 to 100%] and 95.6% [95% CI, 89.2 to 100%], respectively). The percentages of negative results among 398 women without >or= CIN2 were similar for the LBMA and hc2 assays (45% and 50%, respectively). The repeat test reproducibility for 100 samples was 99.1% (kappa=0.92; 95% CI, 0.90 to 0.95). We conclude that the new LBMA assay will be useful for clinical and epidemiological research.

Persistence of genital human papillomavirus infection in a long-term follow-up study of female university students.

BACKGROUND: Little is known about the epidemiology of human papillomavirus (HPV) infections that persist for more than a few years. METHODS: Four to 12 years after participation in a longitudinal study of incident HPV infection, a cohort of former university students returned for a follow-up visit that included HPV genotyping of cervical and vulvovaginal swab specimens and collection of colposcopy-directed biopsy specimens. RESULTS: Of 147 women with HPV infection detected during their undergraduate years, 24 (16.3%) were positive for 1 or more of the same HPV types at follow-up. Overall, 27 (4.8%) of 567 type-specific HPV infections persisted, and DNA sequence analyses of a subset revealed that all were variant specific. Long-term HPV persistence was positively associated with frequent but sporadic detection of the same HPV type early during the course of the infection and with abnormal Pap tests and genital warts; it was negatively associated with marriage and was not associated with the number of intercurrent sex partners. CONCLUSIONS: HPV variant and behavioral risk factor analyses indicated that long-term detection of the same HPV type was more consistent with viral persistence than with reinfection. Although long-term persistence was not common, it was associated with detection of HPV-related pathologies.

Genital human papillomavirus infection in men: incidence and risk factors in a cohort of university students.

BACKGROUND: In contrast to the wealth of data on human papillomavirus (HPV) infections in women, much less is known about HPV in men. METHODS: Between June 2003 and March 2006, a total of 240 heterosexually active male university students 18-20 years of age were recruited for participation in a cohort study of HPV infection. Genital cell samples were collected, at 4-month intervals, for HPV-DNA analysis by polymerase chain reaction. The subjects maintained a Web-based journal of sexual activity. RESULTS: At 24 months, the cumulative incidence of new infection of any genital HPV type was 62.4% (95% confidence interval [CI], 52.6%-72.2%). Acquisition rates did not differ by genital site (i.e., glans, penile shaft, or scrotum) of initial detection (P=.86). The most commonly detected types were HPV-84 and HPV-16. In multivariate analysis, a report of a new sex partner during the prior 0-4 (hazards ratio [HR], 2.0 [95% CI, 1.3-3.0]) and 5-8 (HR, 1.8 [95% CI, 1.2-2.7]) months and a history of smoking (HR, 1.6 [95% CI, 1.1-2.4]) were associated with an elevated risk of HPV acquisition. CONCLUSION: Genital HPV infection is common and multifocal in young men, and its incidence is higher than that reported for similar cohorts of young women. The high rates of HPV infection in men should be considered when strategies for the prevention of HPV infection in female adolescents and young women are being developed.

Men's perceptions and knowledge of human papillomavirus (HPV) infection and cervical cancer.

The authors assessed young men's knowledge and perceptions of genital human papillomavirus (HPV) infection to identify factors that predict intention to make positive behavioral changes. Male university students aged 18 to 25 years completed a self-report instrument to assess knowledge and perceptions of genital HPV infection. If diagnosed with HPV, most men (95%) reported that they would use condoms with new partners. The intention to reduce number of sex partners was associated with an understanding that HPV may have severe consequences for women, whereas intention to encourage female sex partners to undergo Pap smear screening was associated with increased general knowledge of HPV infection. The authors concluded that it is important to include men in HPV education and prevention efforts, especially within the context that HPV may lead to cervical cancer in female partners.

Development and duration of human papillomavirus lesions, after initial infection.

BACKGROUND: To determine the potential value of human papillomavirus (HPV) vaccines, information concerning the incidence and duration of clinically important lesions is needed. METHODS: A total of 603 female university students were followed for a mean duration of 38.8 months. Triannual gynecologic examinations included cervical and vulvovaginal specimen collection for Pap and HPV DNA testing. Women with cytologic evidence of a high-grade squamous intraepithelial lesion (SIL) were referred for colposcopically directed biopsy. RESULTS: Among women with incident HPV infection, the 36-month cumulative incidence of cervical SILs found by cytologic testing (47.2%; 95% confidence interval [CI], 38.9%-56.4%) was higher than that of vaginal SILs (28.8%; 95% CI, 21.3%-38.2%). The median time to clearance of cervical and vaginal SILs was 5.5 and 4.7 months, respectively. Among women with incident HPV-16 or HPV-18 infection, the 36-month cumulative incidence of cervical intraepithelial neoplasia (CIN) grade 2 was 20.0% (95% CI, 10.8%-35.1%), and that of CIN grade 3 was 6.7% (95% CI, 2.5%-17.0%). The 36-month cumulative incidence of clinically ascertained genital warts among women with incident HPV-6 or HPV-11 infection was 64.2% (95% CI, 50.7%-77.4%). CONCLUSIONS: Intraepithelial lesions are common early events among women with incident HPV infection, and the interval between incident HPV-16 or HPV-18 infection and biopsy-confirmed CIN grade 2-3 appears to be relatively short.

Evaluation of genital sites and sampling techniques for detection of human papillomavirus DNA in men.

To evaluate methods for detection of genital human papillomavirus (HPV) DNA in men, samples were obtained from 3 consecutive groups of 10 men attending a sexually transmitted disease clinic by use of (1) a saline-wetted Dacron swab alone, (2) a saline-wetted cytobrush, or (3) emery paper (600A-grit Wetordry Tri-M-ite; 3M) abrasion followed by a saline-wetted Dacron swab. By use of a polymerase chain reaction-based assay, 45% of emery-paper samples were found to be positive for beta-globin, compared with 23% of swab-alone and 0% of cytobrush samples. Subsequently, emery paper and saline-wetted Dacron swabs were used to obtain penile shaft, glans, foreskin, and scrotum samples from 318 male university students. Urine samples were also obtained. Of 1323 samples tested, 1288 (97%) were found to be positive for beta-globin. HPV DNA was detected in samples from 104 men (33%): 24% from the penile shaft, 16% from the glans, 28% from the foreskin, 17% from the scrotum, and 6% in urine. The HPV prevalence was similar for circumcised and uncircumcised men. Testing multiple sites increased the number of men for whom HPV DNA was detected.

Characterization of IgA response among women with incident HPV 16 infection.

Previous studies have characterized the prevalence and duration of serum IgG antibodies to human papillomavirus type 16 (HPV 16) in a well-studied cohort of college women, using viruslike particle- (VLP) based ELISAs. In this study IgA antibodies in cervical secretions and sera were examined using a newly developed capsomer-based ELISA and the patterns observed for serum IgG, serum IgA, and cervical IgA antibodies were compared. The median time to antibody detection from the first detection of HPV 16 DNA was 10.5 months for IgA in cervical secretions and 19.1 months for serum IgA. Serum IgA antibody conversion was observed less frequently and occurred later than IgA conversion in cervical secretions (P = 0.011) or serum IgG conversion (P = 0.051). The median time to antibody reversion, following seroconversion, was 12.0 months for IgA in cervical secretions and 13.6 months for serum IgA, whereas approximately 20% of women with serum IgG antibodies reverted within 36 months. Thus, the duration of IgA in cervical secretions and sera was shorter than the duration of serum IgG (P = 0.007 and 0.001).

Clinical findings among young women with genital human papillomavirus infection.

OBJECTIVE: The purpose of this study was to identify clinical signs and symptoms associated with detection of human papillomavirus (HPV) DNA in the female genital tract. STUDY DESIGN: A total of 516 university students (18 to 24 years old) enrolled in a cohort study that included the collection of genital specimens for HPV DNA testing every 4 months for up to 4 years. Reported symptoms and objective clinical findings of women with and without HPV DNA were compared by multivariate analysis. RESULTS: Acute and persisting HPV infections were not associated with discharge, itching, burning, soreness, or fissures. Clinical evidence of genital warts was statistically associated only with HPV types 6 and 11. Detection of any HPV DNA was associated with bacterial vaginosis (BV). Furthermore, a time lag analysis suggests that HPV infection usually precedes detection of BV. CONCLUSION: Most women who acquire genital HPV infection are asymptomatic; some, however, are at increased risk for BV.

Genital human papillomavirus infection: incidence and risk factors in a cohort of female university students.

Incidence data on human papillomavirus (HPV) infection are limited, and risk factors for transmission are largely unknown. The authors followed 603 female university students in Washington State at 4-month intervals between 1990 and 2000. At each visit, a sexual and health questionnaire was completed and cervical and vulvovaginal samples were collected to detect HPV DNA. At 24 months, the cumulative incidence of first-time infection was 32.3% (95% confidence interval: 28.0, 37.1). Incidences calculated from time of new-partner acquisition were comparable for enrolled virgins and nonvirgins. Smoking, oral contraceptive use, and report of a new male sex partner--in particular, one known for less than 8 months before sex occurred or one reporting other partners--were predictive of incident infection. Always using male condoms with a new partner was not protective. Infection in virgins was rare, but any type of nonpenetrative sexual contact was associated with an increased risk. Detection of oral HPV was rare and was not associated with oral-penile contact. The data show that the incidence of HPV associated with acquisition of a new sex partner is high and that nonpenetrative sexual contact is a plausible route of transmission in virgins.

The effect of vaginal speculum lubrication on the rate of unsatisfactory cervical cytology diagnosis.

OBJECTIVE: Nonlubricated plastic specula can adhere to the vaginal introitus and cause discomfort with pelvic examination. We wanted to see if application of water-soluble gel lubricant to the plastic vaginal speculum would change the unsatisfactory cervical cytology diagnosis rate. METHODS: Five public health family planning clinic sites were randomized to either water-soluble gel or water only as lubricant during speculum examination for cervical cytology collection. The pathologists were unaware of the assignment of lubricant use. The cumulative rates of cervical cytology diagnoses were calculated for 6 months before, 6 months during, and 6 months after the intervention. RESULTS: From July 1998 through December 1999, 8534 Papanicolaou smears were collected, with 1440 using gel lubrication from January 1999 through June 1999. Rates of unsatisfactory smears for lubricant use clinics were 1.4% during use of lubricant and 1.4% without use (odds ratio [OR] 1.0; 95% confidence interval [CI] 0.6, 1.8). Rates of unsatisfactory smears for lubricant use versus nonlubricant use clinics during the gel intervention period were 1.4% versus 1.3% (OR 1.1; 95% CI 0.6, 2.0). There were no significant differences for the rates of atypical squamous cells of undetermined significance, low-grade squamous intraepithelial lesion, high-grade squamous intraepithelial lesion, or atypical glandular cells of undetermined significance within or between lubricant and nonlubricant clinics for each 6-month period. There were no cases of invasive cancer. CONCLUSION: The use of a small amount of water-soluble gel lubricant on the outer inferior blade of the plastic vaginal speculum does not change cervical cytology results in a young, reproductive-age population.

Acquisition and natural history of human papillomavirus type 16 variant infection among a cohort of female university students.

Analogous to the epidemiology of different types of human papillomaviruses (HPVs), variants of a single type such as HPV16 may differ in the natural course of infection. A prospective study was conducted in a cohort of female university students who did not have HPV16 DNA or antibody at enrollment. Subjects were followed every 4 months with Pap smear and colposcopic examinations and tests for HPV DNA and antibody. Of 528 women, 62 acquired HPV16 infection during follow-up. The 5-year cumulative incidence was 12.6% for infection with HPV16 prototype-like variants and 3.1% for infection with non-prototype-like (NPL) variants. Among those with incident HPV16 infection, the adjusted odds ratio of detecting NPL variants was 6.0 [95% confidence interval (CI), 1.3-27.5)] for nonwhite women or white women who had had nonwhite sex partners compared with white women who had not had nonwhite sex partners. As compared with women who had not used hormonal contraceptives in the 8 months prior to the first HPV16-positive detection, the adjusted odds ratio of detecting NPL variants increased from 1.6 (95% CI, 0.3-9.1) for those who had used hormonal contraceptives for 1-4 months to 5.4 (95% CI, 1.0-28.3) for those who had used hormonal contraceptives for 5-8 months (P for trend = 0.04). There was no difference in HPV16 seroconversion rates between women with prototype-like variants and women with NPL variants. The increased risk for biopsy-confirmed cervical intraepithelial neoplasia grades 2 or 3 associated with detection of incident infection by NPL variants was not explained by differences in persistence between the two variant groups, indicating that biological mechanisms other than viral persistence may be responsible for the observed difference in risk for cervical intraepithelial neoplasia grades 2 or 3.