24 March 2016
World Tuberculosis Day
The 24 March commemorates the day in 1882 when Dr Robert Koch announced to a group of scientists at the University of Berlin’s Institute of Hygiene that he had discovered the cause of tuberculosis, the TB bacillus.
Tuberculosis, or TB, is a contagious disease caused by a bacterium called Mycobacterium tuberculosis (MTB). It usually destroys the lungs, but can affect any other organ in the body, symptoms include: coughing, weight loss, high temperature, tiredness and night sweats. In the 1920s, a vaccine was developed however its effectiveness is limited.
It is estimated that more than 2 billion people, one third of the world’s population are infected with the bacteria (MTB) that can lead to TB. In 2014, 9.6 million people fell ill with TB and a total of 1.5 million people died from the disease and it is ranked alongside HIV as a leading cause of death worldwide. Between 1990 and 2015, it was recorded that the number of people falling ill with TB was declining and the TB death rate has dropped 47%, through a combination of diagnosis, treatment and awareness.
TB is becoming more resilient to the treatment and different strains of TB are becoming more multi drug resistant. This is increasing the demand to develop new tools and strategies to improve the screening methods to win the battle against the disease. The world requires a better, faster diagnostic, more effective treatment options and an effective vaccine to stop all virulent strains of TB.
How can Aptamers help?
Aptamers have great potential to be both effective diagnostic and therapeutic agents in the fight against TB. Enzyme linked oligonucleotide assays (ELONA) have been successfully developed using a sandwich aptamer approach to detect and quantify levels of a MTB protein, MPT40 in patients samples (Mozioglu et al., 2015). Importantly, anti-MTB aptamers have also been shown to be highly specific, capable of recognising differences between closely related species (Pan et al., 2014; Qin et al., 2015). Taken together, the data suggests that aptamers could play an important role in diagnosing TB. However, work is needed to translate these findings into field tests which could be used in resource poor environment.
In addition, several of the cellular effects of anti-MTB aptamers have been described in detail. In vitro studies have shown that aptamers raised against the TB strain H37Rv cause an increase in IFN-γ from CD4+ T cells, improving infection clearance (Chen et al., 2007). These aptamers were raised using a Cell-SELEX approach, allowing the identification of a wide range of aptamers recognising different epitopes of the protein surface. Moreover, aptamers have also shown to prevent MTB invasion into macrophages, preventing subsequent infection (Chen et al., 2012). Other targets identified on MTB as aptamer targets include the lipoglycan ManLAM, in which aptamer neutralisation caused a decrease of immunosuppression and increased antigen presenting activity of dendritic cells (Pan et al., 2014). Much of the evidence is also reproduced in in vivo studies, suggesting that the introduction of specific aptamers can reduce the progression of infection in mice and rhesus monkeys (Chen et al., 2007; Pan et al., 2014).
In summary, aptamers represent an exciting next generation tool for the diagnosis and treatment of TB. Aptamer Group are committed to the fight against TB and are continually looking for partners to help treat bacterial conditions and promote the aptamer platform.
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