A Study to Test Three Experimental HIV Vaccines in Healthy Adults.

Inclusion Criteria: * Healthy male and female as assessed by a medical history, physical exam, and laboratory tests. * At low risk of HIV infection and willing to maintain low-risk behaviour for the duration of the trial. Individuals from key populations are not excluded provided they are assessed to be at low risk of HIV infection at screening and are willing to maintain low-risk behaviour during the study. * At least 18 years of age on the day of screening and have not reached their 51st birthday on the day of the first vaccination. * Willing and able to give informed consent for participation in the trial before any study-related procedures are performed. Volunteers will pass an Assessment of Understanding before signing the consent form. * Willing to comply with the requirements of the protocol and be available for follow up for the planned duration of the study. * Willing to undergo HIV testing, risk reduction counselling, receive HIV test results * All sexually active males (unless anatomically sterile or in a monogamous relationship with a female partner who uses a documented non-barrier method of birth control) must be willing to use an effective method of contraception (such as consistent condom use) from the day of first vaccination until 4 months after the last vaccination. * If a female of childbearing potential, willing to use an effective non-barrier method of contraception (hormonal contraceptive or intrauterine device) from at least 2 weeks prior to first vaccination until at least 4 months after the last study vaccination. If not of childbearing potential: postmenopausal (\>45 years of age with amenorrhea for at least 2 years, or any age with amenorrhea for at least 6 months and a serum follicle stimulating hormone (FSH) level \>40 IU/L) or surgically sterile: no additional contraception required. * All female volunteers must be willing to undergo urine pregnancy tests at time points indicated in the Schedule of Procedures and must test negative prior to each study vaccination. * Willing to forego donations of blood or any other tissues during the trial and, for those who test positive for HIV antibodies due to vaccination (vaccine-induced seropositivity/ reactivity), until the anti-HIV antibody titres become undetectable. Exclusion Criteria: * Confirmed HIV-1 or HIV-2 infection * Receipt of any vaccine in the previous 28 days or planned receipt within 28 days of Investigational Medicinal Product. Volunteers who expect to receive any adenoviral vectored vaccines within the next three months after ChAdOx1.tHIVconsv1 vaccine administration should not participate due to the risk of immune interference with the study vaccine. * Participation in another clinical trial of an Investigational Medicinal Product (IMP) currently, within the previous 3 months or expected participation during the study. * Receipt of another investigational HIV vaccine candidate or investigational adenoviral vectored vaccine (Note: receipt of an HIV vaccine placebo will not exclude a volunteer from participation if documentation is available and the Medical Monitor gives approval). * Receipt of blood transfusion or blood-derived products within the previous 4 months or expectation of receiving blood products during the study period. * Receipt of immunoglobulin products within the previous 3 months. * If female, pregnant or planning a pregnancy during the period of enrolment until 4 months after the last study vaccination; or lactating. * Any clinically relevant abnormality on history or examination such as: * Any confirmed or suspected history of immunodeficiency including recurrent severe infections; * Use of systemic corticosteroids for \>14 days (use of topical or inhaled steroids is permitted) within the previous 6 months; * Immunosuppressive, anti-cancer, anti-tuberculosis or other medications considered significant by the investigator within the previous 6 months. * History of splenectomy. * History of autoimmune disease * Bleeding disorder diagnosed by a physician (e.g., factor deficiency, coagulopathy or platelet disorder that requires special precautions). (Note: a volunteer that states that he or she has easy bruising or bleeding but does not have a formal diagnosis and has intramuscular injections and blood draws without any adverse experience is eligible) * History of myocarditis, pericarditis, cardiomyopathy, congestive heart failure with permanent sequelae, or clinically significant arrhythmia (including any arrhythmia requiring medication, treatment, or clinical follow up). * History of cancer (except basal cell carcinoma of the skin) * Asthma that is not well controlled. * History of allergic disease or reactions likely to be exacerbated by any component of the vaccine * History of severe local or systemic reactogenicity to vaccines (e.g., anaphylaxis, respiratory difficulty, angioedema). * History of Guillain-Barre syndrome. * Confirmed diagnosis of active or chronic hepatitis B, hepatitis C, active syphilis and/or active tuberculosis * Seizure disorder: an individual who has had a seizure in the last 3 years is excluded (Not excluded: an individual with a history of seizures who has neither required medication nor had a seizure for three or more years). * History of serious psychiatric conditions or any psychiatric condition that precludes compliance with the protocol. Specifically excluded are persons with psychoses, ongoing risk for suicide, or history of suicide attempt or gesture within the past 3 years. * Substance abuse disorder that precludes compliance with the protocol as assessed by the investigator. * Any clinically significant acute or chronic medical condition that is considered unstable/progressive, or in the opinion of the Investigator, may either put the volunteer at risk because of participation in the study, or may influence the result of the study, or the volunteer's ability to participate in the study * Abnormal clinically significant abnormal finding on screening biochemistry or haematology blood, or urinalysis, including but not limited to: Haematology: * Haemoglobin - \<9.5 g/dl in females; \<11.0 g/dl in males * Absolute Neutrophil Count (ANC) - ≤1,000/mm3 * Absolute Lymphocyte Count (ALC) - ≤650/mm3 * Platelets - \<100,000 cells/mm3 Chemistry * Creatinine \>1.1 x upper limit of normal (ULN) * Aspartate aminotransferase (AST) \>1.25 x ULN * Alanine aminotransferase (ALT) \>1.25 x ULN Urinalysis Clinically significant abnormal dipstick confirmed by microscopy: * Protein = 2+ or more * Blood = 2+ or more (not due to menses) * Any other finding which in the opinion of the investigators would significantly increase the risk of having an adverse outcome from participating in the study * If, in the opinion of the Principal Investigator, it is not in the best interest of the volunteer to participate in the trial.