Long Term Immunogenicity of Quadrivalent Human Papillomavirus Vaccine (Gardasil®)in HIV-infected Adolescents and Young Adults

Inclusion Criteria:

* For both HIV-infected and healthy subjects:

  * Subjects aged 13-27 years, females and males
  * Written informed consent from parent or guardian if applicable (age\<18 years)
* For HIV-infected subjects:

  * HIV-positive
  * Asymptomatic subjects (generalized lymphadenopathy is accepted)
  * Lymphocyte CD4+ count \> or equal to 350 cells/mm3
* For subjects receiving HAART:

  * Good compliance to therapy
  * At least two suppressed viral loads HIV-RNA (\<37copies/ml9 during 6 months prior to enrollment.

Exclusion Criteria:

* For female subjects (both HIV-infected and healthy)
* Pregnancy or breastfeeding
* Total hysterectomy. Participants who have undergone partial hysterectomy and have a cervix are not excluded.
* For both females and males (HIV-infected and healthy):
* Prior vaccination with quadrivalent HPV vaccine Gardasil before study entry.
* History of severe allergic reaction after previous vaccination or hypersensitivity to any vaccine component.
* Any serious chronic or progressive disease (other than HIV) according to the judgment of the investigator:
* Acute infection requiring therapy or fever at time of enrollment
* Chronic autoimmune or oncologic disease receiving chemotherapy
* Concomitant therapies (other than HAART):
* Chronic therapy (for more than 14 days consecutively) with immunosuppressive or immunomodulating agents or chemotherapy during the 6 months prior to study entry.
* Receipt of blood, blood products and/or plasma derivatives or any parenteral immunoglobulin preparation prior to study entry.
* Use of investigational agents within 4 weeks prior to study enrollment.
* Current drug or alcohol use or dependence.
* Documented history of non-adherence to antiretroviral treatment regimen within 12 months prior to study entry.