To assess the immunogenicity of M. bovis BCG (SSI strain), given intrademally in the standard dose used in clinical practice and to measure the development of the immune response in the first six months after administration. M. bovis BCG is a fully licensed vaccine that has been in routine clinical use for the last 50 years. It is the most widely administered vaccine in the world today and has an excellent safety record.

Volunteers for the study will be recruited through advertisements. Each volunteer will have received an information sheet concerning the study and will have agreed to participate in writing.

Volunteers will be given at least 48 hours between reading the information leaflet and agreeing to participate. Female volunteers will have a pregnancy test prior to enrollment. Volunteers will give signed consent for their GP's to be notified about their participation in the trial. The GP will be faxed a letter on the day of screening and asked to reply if they know of a reason why the volunteer should not take part. The signed consent form will also be faxed with the letter.

A week after the screening visit and after a negative Heaf test, subjects will receive a single intradermal injection of 106 cfu M. bovis BCG in 0.1ml just inferior to the insertion of the deltoid muscle. Blood tests will be taken at the screening visit and day of immunisation, 1 and 2 weeks, and 1, 2, 3 and 6 months after the immunisation. 75mls will be taken on the screening visit, and 60mls will be taken on all subsequent visits. Screening samples will be tested for full blood count, biochemical screen and immunological assays to determine vaccine immunogenicity. Peripheral blood mononuclear cells will be prepared for cellular immunological assays to be performed without or following cryopreservation. Other serological measures of immune response, i.e.

antibody titres, will be assayed on frozen plasma samples. All blood tests will be taken within 1-3 days of the due date as described in the schedule above.

Inclusion Criteria:

• Healthy adult aged 18-65 years.
• Normal medical history and physical examination.
• Normal urine dipstick, blood count, liver enzymes, and creatinine.

Exclusion Criteria:

• Exposure to TB/BCG vaccination at any point. Previous residence in a TB endemic area.
• Clinically significant history of skin disorder (eczema, psoriasis, etc.), allergy, immunodeficiency, cardiovascular disease, respiratory disease, endocrine disorder, liver disease, renal disease, gastrointestinal disease, neurological illness, psychiatric disorder, drug or alcohol abuse.
• Oral or systemic steroid medication or the use of immunosuppressive agents.
• Positive HIV or core HBV antibody test.
• Positive Heaf test
• Positive ANA or serum anti-DNA antibody.
• Confirmed pregnancy