Whereas in patients with a more serious form of leprosy, a protein associated with a viral response - interferon-beta - was prominent.

BBC: 'Wrong' immune response aids TB

Not only is interferon-beta an ineffective weapon against bacteria, it can block the action of interferon gamma - which is when bacteria can gain a foothold, the researchers said.

BBC: 'Wrong' immune response aids TB

Two trials, published in the Lancet medical journal, compared the effectiveness of alemtuzumab with a first-choice drug, interferon beta-1a.

BBC: Multiple sclerosis: New drug 'most effective'

Charities would say that this isn't the issue - beta interferon is the only drug treatment for MS and there are no alternatives.

BBC: Beta interferon: Rights and wrongs

In MS, beta-interferon, the most effective treatment produced so far, holds back the number of attacks but does not prevent eventual disease progression.

BBC: DNA vaccines 'could fight MS'

Beta-interferon has also been shown in studies to benefit to those with "relapsing-remitting" MS, in which the sufferer's condition is stable in between "attacks", which prove gradually more disabling.

BBC: MS drug 'should be restricted'

There are 80, 000 people in the UK with multiple sclerosis - theoretically beta interferon could help about 10% of them, but the reality is that only about 2% actually receive it.

BBC: Beta interferon: Rights and wrongs