FEATURE-South Africa leads hunt for killer TB vaccine

* Trials for new TB vaccine to start in SAfrica in July

* SAF with highest TB rate, reversing yrs of underinvestment

* SAfrica government to target inequalities in health care

By Wendell Roelf

WORCESTER, South Africa, June 5 (Reuters) - Baby Hisinawa is permanently semi-comatose after TB spread to his brain, his board-stiff body shivering as a doctor pushes a rubber tube down his nose to clear away thick phlegm choking him.

Last December, the chubby two-year-old South African was talking and laughing. Now he has limited use of all four limbs and cannot swallow.

Hisinawa is a severe example of the debilitating symptoms of tuberculosis, which kills more people than any other treatable infectious disease. Trials for a new vaccine start in South Africa in July.

Scientists across the world are seeking a new vaccine against the contagious lung disease, which is largely under control in developed countries but still haunts the poor in the developing world. Up to one in three people have it globally.

"The world needs a new TB vaccine because the current one is not really effective in terms of preventing TB and that is manifest in the context of an increasing epidemic," Gregory Hussey, director of the South African TB Vaccine Initiative (SATVI) told Reuters.

With more resources and research committed by international and philanthropic organisations like the World Bank and the Bill and Melinda Gates Foundation, optimism for a new TB vaccine has reached heights last seen when the current TB vaccine, Bacille Calmette-Guerin (BCG), was developed in the 1920s.

The most clinically advanced of the nine vaccine candidates -- called MVA85A -- will be tested in South Africa next month among 2,874 children under the age of one. Researchers hope to register a new anti-TB vaccine by 2015.

"All of the clinical trials conducted to date with this vaccine (MVA85A) have shown that it is safe and it stimulates high levels of the type of immune response we believe is protective against tuberculosis," the vaccine inventor Dr Helen McShane of the University of Oxford, told Reuters.

The World Bank, which focuses on controlling TB by identifying and curing infectious patients, has said financial support for its treatment would bring an estimated economic gain of around $1.6 trillion between 2006 and 2015.

Without financial intervention, the economic burden of TB in badly hit countries like China could reach up to $1.2 trillion between 2006 and 2015, the World Bank said. Global efforts have been ramped up to meet a United Nations Millennium Development Goal of halving the global TB infection rate by 2015.