Using an eye-catching video, KNCV Tuberculosis Foundation recently raised awareness of the fact that tuberculosis (TB), a disease whose name is often used informally in Dutch swearwords, is unfortunately still very much an issue. Every day, nearly 5,000 patients all over the world die of the consequences of ‘Mycobacterium tuberculosis’ infection.
This makes TB the most deadly infectious disease in the world. An estimated two billion (!) people are believed to have latent TB, meaning that there is always a risk of a TB outbreak and a spreading of the disease. New therapies must be developed as a matter of urgency.
Why we need better drugs
For nearly a century now, we have had an effective vaccine against the consequences of infection at a young age: BCG (Bacille Calmette-Guérin), which is believed to save the lives of more than one hundred thousand children every year. However, this vaccine has been found to be insufficiently effective against life-threatening tuberculous pneumonia at a later age. Therefore, we need a better vaccine (or vaccine programme) to combat tuberculosis. Although medications are available on top of BCG, infection with Mycobacterium tuberculosis requires treatment that will take several months, or even over a year in some cases. Moreover, drug-resistant strains of TB are increasingly common.
Quick development of effective therapies is hard
It is clear that we need better vaccines and medications. However, it is proving quite hard to develop effective therapies quickly. What is stopping us is 1) a limited understanding of the mechanisms protecting humans, and 2) Mycobacterium tuberculosis's immunoevasive strategies. Macaques may play a vital part in our studies focusing on the prevention and treatment of TB.
The predictive power of macaques
Macaques are very similar to humans, in terms of the hereditary similarity and genetic affinity of our immune systems. The same is true for their susceptibility to tuberculosis and the way in which the disease presents. For this reason, macaques have greater predictive power for humans than any other animal model available.
Room for improvement
BPRC would like to note that the degree to which BCG protects the lungs from tuberculosis differs from macaque to macaque. Both in human beings and in non-human primates, the BCG vaccine suppresses the disease, but does not necessarily protect us from being infected with Mycobacterium tuberculosis. Therefore, there is room for improvement. And this room gives us the opportunity to evaluate the efficacy of new therapies in a model that resembles human beings.
Following extensive preliminary studies, BPRC tests potential vaccines in primate models for safety (are there any adverse reactions?), immunogenicity (does the vaccine have the ability to provoke an immune response in the animal's body?) and protective mechanism (does it prevent infection or the onset of a disease?). Moreover, our studies allow us to examine complex interactions between pathogens and the bodies harbouring them under controlled conditions, which results in a better understanding of this infectious disease and allows us to develop improved therapies.
For the time being, TB will continue to be the world's No 1 killer infectious disease, but extensive and unrelenting research will eventually help us eradicate this serious disease.