This study evaluates whether a 7-day course of Raltegravir 400mg bd or Raltegravir 400mg/lamivudine 150mg bd can prevent HIV from infecting genital tissue and will relate the level of drug in the blood to the level of drug in genital tissue and to the ability to of HIV to infect genital tissue. As well as determining whether these regimes can provide ex vivo protection against HIV, this study will also determine speed to provision of protection and a 48 hour PK/PD decay profile of Raltegravir following drug cessation after attaining steady state concentrations. The results will also inform all future HIV pre-exposure prophylaxis studies of Raltegravir and form the basis for large scale clinical trials without the need for tissue sampling. To date, efficacy studies assessing PrEP regimens have utilized HIV-acquisition endpoints with the consequence being such studies are required to be large in subject number in order to power observations. In addition the study will provide for the first time data on HIV protection rather than just Raltegravir drug levels in tissue, and allow assessment of the possibility of Raltegravir being used as an intermittent dosing regimen in PrEP.

This is a multi-site, open-label, randomised, pharmacokinetic (PK) and pharmacodynamic (PD) trial whereby 36 individuals (18 women and 18 men) will be randomised according to gender 1:1:1:1:1:1 to one of 6 arms (A 1 A 2 A 3 B 1 B 2 B 3). The result being 3 women and 3 men will be in each arm. The letter dictates the ART regimen order and the number dictates the time points that tissue sampling will occur on and off ART. Two ART regimes will be investigated and all individuals will receive both regimes separated by a one month wash out.

Arm A (A 1 A 2 A 3): will start with 7 days Raltegravir 400mg bd and then have a one month wash out before then starting 7 days Raltegravir 400mg /lamivudine 150mg bd.

Arm B (B 1 B 2 B 3): will start with 7 days Raltegravir 400mg /lamivudine 150mg bd and then have a one month wash out before then starting 7 days Raltegravir 400mg bd. This will remove sequential selection bias. All individuals will receive tissue sampling at baseline for ex vivo analysis to ensure biopsies are infectable on challenge assays. Sampling from women will avoid menstruation and if possible focus on the luteal phase of the menstrual cycle. Individuals will receive another set of tissue sampling during and after ART in phase 1, have a 4 week wash out period and then have another set of sampling during and after ART in phase 2. Individuals will therefore have 5 sets of sampling during the trial.

Inclusion Criteria:

1. The ability to understand and sign a written informed consent form prior to participation in any screening procedures and must be willing to comply with all trial requirements.
2. Male or non-pregnant, non-lactating females
3. Age between 18 to 60 years, inclusive.
4. Body Mass Index (BMI) of 16 to 35 kg/m2, inclusive.
5. Negative antibody/antigen combined test for HIV.
6. Absence of any significant health problems (in the opinion of the investigator) on the basis of the screening procedures; including medical history, physical examination, vital signs.
7. Women participating in sexual intercourse that could result in pregnancy -must use an adequate form of contraception throughout the study and for two weeks after the study. This includes intrauterine device, condoms, anatomical sterility in self or partner. Oral hormonal methods and implant contraceptives are allowed but only in combination with the additional protection of a barrier method.
8. Female participants may not use any vaginal products or objects or have vaginal sex for 48 hours before and after the collection of vaginal fluid and vaginal biopsies. This list includes tampons, female condoms, cotton wool, rags, diaphragms, cervical caps (or any other vaginal barrier method),douches, lubricants, vibrators/dildos, and drying agents.
9. Males participating in sexual intercourse that could result in pregnancy must use condoms during the duration of the study.
10. Men and women cannot use anal products or objects including but not exclusive to douches, lubricants and vibrators/dildos, butt plugs or urethral sounds or have receptive anal intercourse for 48 hours before and after the collection of rectal biopsies.
11. Willing to abstain from multivitamins and antacids for the study duration.

Exclusion Criteria:

1. Any significant acute or chronic medical illness.
2. Evidence of organ dysfunction or any clinically significant deviation from normal in physical examination, vital signs or clinical laboratory determinations.
3. Positive blood screen for syphilis, hepatitis B (HBs Ag) and/or C antibodies.
4. Positive blood screen for HIV antibodies.
5. Positive screen for sexually transmitted infections at screening visit
6. High-risk behaviour for HIV infection which is defined as having one of the following within three months before trial day 0 (first dose): had unprotected vaginal or anal sex with a known HIV infected person or a casual partner. engaged in sex work for money or drugs. acquired a bacterial sexually transmitted disease in the past 3 months. having a known HIV positive partner either currently or in the previous six months Females who are pregnant or breast-feeding.
7. Clinically significant laboratory abnormalities (according to normal range as defined by central laboratory).
8. Participation in a clinical trial of an Investigational product within 1 month of planned baseline enrolment in this study.
9. Ingestion of H2 receptor antagonists or proton pump inhibitor drugs in the preceding 14 days
10. Current of planned use of anti-epileptics

Adverse event data was collected for the duration each subject participated in the trial, this being from enrollment to final visit, which is approximately 55 days.

All adverse event data that was captured as part of trial participation, including that of individuals withdrawn from the trial, were used in analysis