Inclusion Criteria:
1. Male participants aged 18-45 years at the time of the first vaccination.
2. Be able to comprehend the trial procedures and comply with the protocol requirements (e.g., providing biological samples, completing diary/contact cards, and attending scheduled follow-up visits), and provide written informed consent.
3. No more than 5 sexual partners so far.
4. Participants who agree to adopt effective contraceptive measures within 30 days after each vaccination.
5. No prior history of HPV-related anal-genital lesions (e.g., genital warts, penile/perineal/perianal intraepithelial neoplasia, penile/perineal/perianal cancer, anal intraepithelial neoplasia, and anal cancer).
Exclusion Criteria:
1. Participants who have received or plan to receive any other HPV vaccine during the study period, or have participated in any other HPV-related clinical trial.
2. Axillary temperature \> 37.0°C.
3. Engagement in sexual activity (including vaginal/anal intercourse, or any genital contact) within 48 hours prior to any swab/anal cytology specimen collection visit, or any other behavior that may affect the anal-genital examination and specimen collection (anal procedures only applicable to MSM participants).
4. Presence of clinically vident genital warts, external genital lesions, or anal lesions which may suggest sexually transmitted diseases on the day of enrollment.
5. Participants who received immunosuppressed, immunoregulation therapy or corticosteroid systemic therapy (≥14 consecutive days) within 6 months prior to enrollment, except local treatment (e.g., ointment, eyedrops, inhalants or nasal sprays).
6. Administration of immunoglobulin and/or blood products 3 months prior to vaccination or intending to use them within 7 months after the first dose.
7. Use of any investigational or non-registered product (drug or vaccine) within 30 days prior to vaccination, or intending to use them or participate in another clinical trial during the study period.
8. Administration of inactivated vaccine within 14 days or live vaccine within 21 days before vaccination.
9. Any acute illness requiring systemic antibiotic or antiviral treatment within 5 days prior to vaccination, or axillary temperature ≥38.0°C within 3 days prior to vaccination.
10. A state of immunocompromised condition as inquiried by study investigator, e.g., congenital or acquired immunodeficiency diseases, HIV infection, immune diseases (including systemic lupus erythematosus, rheumatoid arthritis, asplenia or splenectomy, or any other condition that may affect immune response), primary diseases or cancer of major organs (such as heart, liver, spleen, lungs, kidneys).
11. History of severe allergy, including serious adverse reactions (e.g., dyspnea, angioedema) to any previous vaccination, or severe allergy to any component of the trial vaccine (recombinant VLP protein, sodium dihydrogen phosphate, disodium hydrogen phosphate, polysorbate, aluminum hydroxide).
12. Asthma, with unstable condition over the past two years requiring emergency treatment, hospitalization, oral or intravenous corticosteroid administration.
13. History of hypertension or hypotension, not stably controlled despite regular medication, or systolic blood pressure ≥160 mmHg or diastolic blood pressure ≥100 mmHg, or systolic blood pressure \<90 mmHg, measured in both arms at rest.
14. History of severe medical conditions (with unstable condition that may require emergency treatment or hospitalization), as inquiried by study investigator.
15. Self-report past coagulation disorders or abnormal coagulation function.
16. Epilepsy, excluding febrile epilepsy under 2 years of age, alcoholic epilepsy 3 years prior to abstinence or simple epilepsy that did not require treatment in the past 3 years.
17. Any medical, psychological, social, occupational, or other condition that may affect the conduct of the clinical trial, according to the investigator's judgment after medical history and physical examination.
