7 October 2010
Tuberculosis (Tb) kills more people worldwide than any other bacterial disease. Recent research from the Malaghan Institute of Medical Research suggests that understanding how the immune system responds to Tb is the key to tackling this deadly disease.
Tuberculosis usually attacks the lungs, leading to a persistent cough, night sweats, and weight loss. It is spread through the air when an infected individual coughs or sneezes, and is more prevalent in conditions of household crowding and relative poverty.
Tb bacteria are very slow growing, so it can take several weeks, months or even years from the initial exposure before a person develops symptoms of disease - as evidenced by a recent case of Tb in a Palmerston North high school, which has been linked to a 2006 outbreak.
With current vaccines only having limited reliability, along with the emergence of drug-resistant strains, there is an increasing need for the development of more effective Tb vaccines.
"Our struggle to develop a more effective vaccine has stemmed in part from a poor understanding of the immune mechanisms that orchestrate protection against Tb," said Dr Joanna Kirman, who heads the Malaghan Institute Infectious Diseases research programme.
"If we can identify the critical players, and the factors that contribute to their protective nature, then we are far better placed to develop a better Tb vaccine," said Dr Kirman.
By taking a closer look at how the immune system responds to Tb infection, Dr Kirman and colleagues have revealed a new target for vaccine design and have just had their cutting-edge work published in the international European Journal of Immunology.
Identifying which components of the extensive network of cells, tissues and organs that constitute the immune system are the most critical for protecting against Tb, is akin to finding the proverbial needle in a haystack.
To get around this onerous undertaking, Dr Kirman and colleagues developed a novel strategy that involved trapping immune cells at specific sites in the body, and then looked to see how this influenced the ability of the immune system to protect against Tb.
In doing so, they were able to show that following vaccination, the immune cells present at the site of infection in the lungs play an essential role in controlling the growth of Tb bacteria in the early stages of disease.
"Our research suggests that a vaccine needs to drive the protective cells to the lung if we want to achieve good protection against Tb," said Dr Kirman.
This research will contribute to the strong international effort being made towards the development of an effective Tb vaccine.