Inclusion Criteria:

• Healthy adults aged 18 to 50 years
• Willingness to allow the investigators to discuss the volunteer's medical history with the volunteer's HIV lead physician (and GP, if appropriate)
• BCG vaccinated
• HIV antibody positive; diagnosed at least 6 months previously
• CD4 count >350; nadir CD4 not < 300
• HIV viral load not > 100,000 copies per millilitre
• Written informed consent

Exclusion Criteria:

• Any clinically significant abnormal finding on screening biochemistry or haematology blood tests or on urinalysis
• Any ARV therapy within the past 6 months
• Any AIDS defining illness
• CXR showing TB or evidence of other active infection
• Prior receipt of a recombinant MVA or Fowlpox vaccine
• Use of any investigational or non-registered drug, live vaccine or medical device other than the study vaccine within 30 days preceding dosing of study vaccine, or planned use during the study period
• Administration of chronic (defined as more than 14 days) immunosuppressive drugs or other immune modifying drugs within six months of vaccination. (For corticosteroids, this will mean prednisolone, or equivalent, ≥ 0.5 mg/kg/day. Inhaled and topical steroids are allowed.)
• History of allergic disease or reactions likely to be exacerbated by any component of the vaccine, e.g. egg products
• Presence of any underlying disease that compromises the diagnosis and evaluation of response to the vaccine (including evidence of cardiovascular disease, history of cancer (except basal cell carcinoma of the skin and cervical carcinoma in situ), history of insulin requiring diabetes mellitus, any ongoing chronic illness requiring ongoing specialist supervision (e.g., gastrointestinal), and chronic or active neurological disease)
• History of > 2 hospitalisations for invasive bacterial infections (pneumonia, meningitis)
• Suspected or known current drug and/or alcohol abuse (as defined by an alcohol intake of >42 units a week)
• Seropositive for hepatitis B surface antigen (HBsAg) and/ or hepatitis C (antibodies to HCV)
• Evidence of serious psychiatric condition
• Any other on-going chronic illness requiring hospital specialist supervision
• Administration of immunoglobulins and/or any blood products within the three months preceding the planned administration of the vaccine candidate
• Pregnant/lactating female and any female who is willing or intends to become pregnant during the study
• Any history of anaphylaxis in reaction to vaccination
• PI assessment of lack of willingness to participate and comply with all requirements of the protocol, or identification of any factor felt to significantly increase the participant's risk of suffering an adverse outcome