TB booster vaccine enters Phase II

By Katrina Megget

- Last updated on GMT

Related tags: Tuberculosis

A new booster vaccine aimed to up the immune response against
tuberculosis (TB) has entered Phase II trials in South Africa.

The new vaccine, MVA85A, developed by researchers at Oxford University, would be the first vaccine against the disease in more than 80 years. While other pharmaceutical companies were looking at reformulating the current BCG (Bacille Calmette-Guerin) vaccine, MVA85A co-developer Dr Helen McShane told in-PharmaTechnologist.com that the researchers wanted to look at significantly boosting the immune response. "There are others looking at [reformulating the BCG vaccine] but it's showing not to be safe in HIV people. We are wanting to boost the T-cells and this is the most efficient and effective way." The Mycobacterium tuberculosis​ bacterium, which is thought to kill two million people every year, is a complex pathogen which lives inside the cells of the host organism. This action means traditional antibody vaccines are ineffective against the bacterium, and rather, a T-cell immune response is required to attack the pathogen. MVA85A works in tandem to the BCG vaccine, which is a strain of the attenuated live bovine tuberculosis bacillus, by acting as a booster. Studies so far, show the immune response was increased by up to 20 times when the booster was used, McShane said. MVA85A uses the 85A antigen, a protein found in all strains of TB, which stimulates a higher T-cell response. 85A is already induced by the BCG vaccine, but the booster aimed to further increase the response, which is important as the effects of the BCG vaccine, given to infants, decrease after about 10 years and therefore offer limited protection against pulmonary disease in adults. "In children, the current vaccine provides some protection against severe forms of the disease, but there is clearly room for improvement," McShane said. "The rise in the number of cases of multi-drug resistant forms of TB plus the increasing number of cases of TB in people living with HIV means a new vaccine is essential. We can no longer rely on antibiotics to treat the disease - we need to help the body's immune system prevent disease." MVA85A had the possibility of being given six months after the BCG injection or in early adolescents when the effects of the BCG began to wear off, McShane said. The vaccine uses a virus as a delivery system for the protein, which is produced in chick embryo fibroblast (CEF) cells. The Phase II trial in South Africa's Western Cape, where one in 100 infants suffers from TB, would show whether the booster vaccine with BCG better protects adolescents and HIV-infected adults from TB than the BCG vaccine alone, before studies in infants would be initiated. A larger study would be conducted next year in South Africa to see if the booster actually stopped people getting the disease. If the results were positive, there was the possibility the new vaccine could be ready to use within eight years. The vaccine has been developed by Oxford University with funding from the Welcome Trust medical charity. McShane declined to comment on whether any pharmaceutical companies had shown an interest in the vaccine. Aeras Global TB Vaccine Foundation, a non-profit organisation founded to develop new vaccines to control and eliminated TB, aims to develop at least one new TB vaccine within the next decade. Crucell has also been working in conjunction with Aeras to develop a new vaccine.

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