A tuberculosis medicine funded in part by a donation from the Bill and Melinda Gates Foundation is ready to start clinical trials. 

Biotechnology company Crucell plans to start testing the vaccine in the second quarter of next year, the company said at a conference in Berlin. 

Clinical tests mark the phase after the medicine has been tested on animals. Following the trials, the maker could file for approval with the US federal drug governing bodies.

The Gates Foundation manages $28.8bn of the Microsoft chairman's fortune. It donated $82.9m to the Aeras Global TB Vaccine Foundation in February 2004 which in turn invested $2.9m with Crucell. The investment guaranteed funding for the project up to the clinical trial phase. 

About a third of the world's population suffers from tuberculosis, which kills two million people every year, according to Aeras. It is the primary cause of death for HIV-infected individuals in Third World countries.

Current medications for the disease have only limited effectiveness and are hard to come by in developing countries.

Gates prefers to focus his charitable donations on areas where his money can make a large impact through projects in education and health.

The Foundation recently gave $750m to the Global Alliance for Vaccines and Immunization to help children in the Third World.