The research is leading the way in efforts to find a longer-lasting vaccine to combat the disease, which globally is on the rise.

The research team, led by Professor Ian Orme, has provided the first demonstration that previously vaccinated mice can be successfully boosted at later ages.

The data gathered by the team suggests that, not only can a boosting vaccination restore specific resistance in older mice back to levels expressed by young animals, but lung tissue damage and degeneration also appear to be dramatically reduced. The research findings appear in the April issue of Infection and Immunity.

Since the 1920s, bacillus Calmette Guerin, or BCG, has been the only vaccine for tuberculosis. Eighty-seven percent of all newborn children worldwide get a BCG vaccination. However, although effective in children, the protection is not sustained into adulthood, nor can adults be reinoculated.

Most individuals appear to lose immunity between the ages of 10 to 15 years, leaving them highly susceptible to TB. In areas of the world where incidence of TB is very high, such as India or China, that loss of immunity can be devastating.

Researchers have been scrambling in recent years to discover a new, longer-lasting vaccine against Mycobacterium tuberculosis. Although many promising candidates have emerged, none as yet has been able to pass the testing phase.

Since BCG is still the most effective weapon against TB, Orme and his team took another approach -- a booster vaccine given to individuals already inoculated.

In Orme's study, mice were vaccinated, then boosted at 9 and 15 months of age with Ag85A, a mycolyl transferase A protein purified from the bacterium. The mice were later exposed to a virulent strain of TB, which they successfully resisted.

"TB remains a serious global problem, with around 8 million new cases and approximately 3 million deaths annually. There is a desperate need to develop new vaccines to deal with this emergency," Orme said.

The problem is not limited to developing countries, Orme emphasized. Tuberculosis often is found in the elderly, the homeless and those with compromised immune systems. In the elderly, it is usually a reactivation of an infection contracted years earlier but which has been dormant.

"In the United States, for instance, people over the age of 65 have for some time now represented the fastest growing segment of the overall population," he said. "A further major factor in the spread of TB is the ongoing AIDS epidemic. Those infected with HIV also seem to be the most easily reactivated, since the virus turns on the TB faster than other 'opportunistic infections.'"

Colorado State University Research Foundation, which is responsible for managing intellectual property created at the university, has indicated patent protection is under way. CSURF has licensed this technology to Mycos, LLC, a Fort Collins company, for commercialization. CSURF officials emphasized that this technology represents an important development in TB vaccine research.

[Contact: Karen Wheeler ]

11-Apr-2001