Prevalence, Genotype Distribution, and Predictors against HPV Infections Targeted By 2-, 4-, 9-Valent HPV Vaccines among Japanese Males

Objectives: Epidemiological reports of sexual life and human papilloma virus (HPV) infection among Japanese men are scarce, and the necessity of HPV vaccines for males is regarded as a controversial topic in Japan. The objective of this study is to determine the prevalence, genotype distribution, and risk factors against HPV infections targeted by bivalent (2v), quadrivalent (4v), and 9-valent (9v) HPV vaccines among Japanese male patients who visited our urological clinics. Material and Methods: The study population consisted of 798 males aged 20 to 95 years (mean ± standard deviation, 55.4 ± 19.5 years). We collected scraping samples from the glans penis using cotton swabs from all patients for genotyping of HPVs. We compared patients’ characteristics and detected HPV genotypes in order to determine the risk factors against HPV infections. Results: Of 798 participants, 198 participants (198/798; 24.8%) had at least one genotype of any HPV infection. The total number of detected HPV genotypes was 328. Of 328 genotypes, 30% (n = 99; 99/328) were 9v HPV genotypes. Most frequently detected types of high-risk HPV infection were type 52 (n = 40; 40/328; 12.2%). Number of lifetime sex partners (≥21) and present or history of sexually transmitted infections were found to be predictors of any HPV infection with adjusted odds ratios of 3.106 (95% confidence interval (CI), 1.593–6.509) and 1.894 (95% CI, 1.185–3.026), respectively. Age of sex initiation was a predictor of 2v and 4v HPV infections with adjusted odds ratios of 100 (95% CI, 1.013–25.673) and 2.676 (95% CI, 1.037–6.905), respectively. Number of lifetime sex partners (≥21) was a predictor of 9v HPVs with adjusted odds ratios of 2.397 (95% CI, 1.060–5.424). Conclusions: Approximately, a quarter of Japanese male patients who visited urological clinics were exposed to HPV. Moreover, from the perspective of our multivariate logistic regression analysis, some kinds of sexual behavior aggravate the risk of typical HPV genotypes infections.


Introduction
More than 200 genotypes of human papilloma virus (HPV) have been identified to date [1]. Sexually transmitted HPV genotypes were classified into two groups, low-risk (LR) and high-risk (HR) types [2]. LR HPVs can cause warts around genitals, anus, mouth, and throat. On the other hand, long-lasting infection with HR HPVs can cause anogenital tract cancers, oropharyngeal cancers,

Ethical Issues
All protocols and assessments in this study were approved by the ethics committees of Asoka Hospital (ID: 00008) and Nagareyama Central Hospital (ID: 00001) in Tokyo. Written informed consent was obtained from all participants in this study.

Sample Collection
The method of sample collection was reported previously [9]. In brief, we recruited 872 male patients aged 20 to 94 years who visited our urological clinics (Asoka Hospital and Nagareyama Central Hospital) from September 2011 to October 2015. Scraping samples from the glans penis were collected by the urologists with a wet cotton swab at least twice. For patients with phimosis, the urologists inserted a wet cotton swab inside the foreskin to collect scraping samples.

Questionaieres
The questionnaires included their age, educational status, smoking status, sexual orientation, number of lifetime sex partners, age at sex initiation, marital status, history of divorce, existence of current sex partners, and the presence or history of a sexually transmitted infection (STI).

Statistical Analysis
Statistical analyses in this study were performed using a JMP Pro software version 14 (SAS, Cary, NC, USA). A logistic regression analysis was used for detecting risk factors of HPV infection. The same control group (HPV negative plus β-globin positive cases) was used in all logistic regression analysis. p values < 0.05 were considered statistically significant.

Results and Discussion
Of the 872 scraping samples, β-globin was positive in 798 samples (91.5%). The characteristics of the participants, after excluding those who had negative β-globin are summarized in Table 1. The prevalence of HPV infection in our cohort is shown in Table 2. One hundred ninety-eight participants (198/798; 24.8%) had at least one type of any HPV infection. The total number of males with HPV infection targeted by 2v, 4v, and 9v were 20, 35, and 79, respectively.
In 2013, Lenzi et al. reviewed five reports regarding the prevalence of HPV infection among patients attending the sexually transmitted disease clinic [13]. They reported that the prevalence of any HPV infection was 13.2% in Sweden [14], 44.9% in Denmark [15], 28.2% in the USA [16], 28.2% in the Netherlands [17], and 5.9% in Japan [18]. Regarding racial differences, Akogbe et al. reported that the prevalence of any HPV infection was significantly lower among Asians/Pacific Islander men (42.3%) compared to black (66.2%), Mexican (62.3%), and white (71.5%) men (p < 0.0001) [19]. Similar to the previous reports, the prevalence of any HPV infection among Japanese males in our study (24.8%) was relatively lower rather than other races because of fewer numbers of lifetime sexual partners. The most detected type of HPV among men was type 62 in Brazil (10.7%), type 59 in Mexico (7.2%), type 83 in the USA (7.2%) [20], and type 56 in Kenya (6.3%) [21]. According to the data of the British National Survey of Sexual Attitudes and Lifestyles, HPV DNA was detected in 17.4% and 29.0% of men and women, respectively [22]. In the study, the most detected HPV type was type 16 (2.3% and 4.2% of men and women, respectively). HPV type 52 was previously reported to be the most detected genotype (4.8%), which was also reported to be the most frequently detected genotype among young Japanese females [10,23]. In our study, HPV type 52 was the most frequently detected HR genotype among Japanese males.
In the multivariate logistic regression analysis, which included all cofounders that might interfere with each other, having ≥21 lifetime sex partners or a current or past STI were significant predictors against HPV infection with adjusted odds ratios (ORs) of 3.106 (95% confidence interval (CI), 1.593-6.059) and 1.894 (95% CI, 1.185-3.026), respectively ( Table 3). Age of sex initiation (≤19 years) was a significant predictor against HPV infection targeted by 2v and 4v HPV vaccines with adjusted ORs of 5.100 (CI, 1.013-25.673; Table 4) and 2.676 (CI, 1.037-6.905; Table 5), respectively. Number of lifetime sex partners (≥21 persons) was a significant predictor against HPV infection targeted by 9v HPV vaccine with adjusted ORs of 2.397 (CI, 1.060-5.424; Table 6). Number of lifetime female sex partners was reported to be associated with HPV infection among male [24,25]. A younger age at first sexual intercourse also became a risk of HPV infection [25,26]. Smoking [26,27] was reported to aggravate risk of HPV infection; however, smoking was not associated with HPV infection in our cohort.
Since April 2013, HPV vaccinations have been recommended for girls aged 13 to 16 years in Japan; the aggressive recommendation of HPV vaccinations had been withheld for 10 weeks because adverse events, such as a long-term pain, numbness, and autoimmune diseases, had occurred in some vaccinated girls [28]. The efficacy and safety of HPV vaccination for Japanese males has been revealed in clinical trial recently [29]. Therefore, gender-neutral vaccination should be recommended in our society.

Low-risk HPV
Type 6b b,c 5 8 13  Type 11 b,c  3  6  9  Type 26  0  1  1  Type 42  5  9  14  Type 44  3  4  7  Type 53  6  11  17  Type 54  3  1  4  Type 55  1  5  6  Type 61  4  9  13  Type 62  8  11  19  Type 66  2  11  13  Type 70  1  7  8  Type 71  11  12  23  Type 84  3  7  10  Type 90  13  13  26  Type CP6108  4  3  7 Single HPV: Only one genotype was detected in one participant. Multiple HPVs: More than two genotypes were detected in one participant. The genotype targeted by a 2v, b 4v, and c 9v.           The strength of our study included a large sample size of adult males of all ages. However, we did not obtain information regarding whether the participants had any sexual contact with commercial sex workers, and both Asoka Hospital and Nagareyama Center Hospital locate in urban areas, which might be the weakness of our study.
In conclusion, we found that approximately a quarter of Japanese male patients who visited the urological clinics were exposed to HPV and that some kinds of sexual behavior aggravate the risk of typical HPV infections.

Conclusions
Approximately a quarter of Japanese male patients who visited urological clinics were exposed to at least one type of HPV infection, and some kinds of sexual behavior (such as number of lifetime sex partners, age of sex initiation, and present or past history of STIs) were found to be predictors for typical HPV infections.