According to a study published in the journal Immunity, viral infections and malignancies can lead to the weakening of the immune system, particularly T cells, known as immunological "exhaustion." In the study, the researchers from Melbourne found a way to overcome immunological exhaustion and strengthen the immune response in the face of serious viral infections.

In the study, they observed that some T cells lost their function and became exhausted within days, while others, called Tpex cells, were able to maintain their function for a long period. Hence, they identified a mechanism explaining how Tpex cells can maintain their fitness over long periods.

The study showed that mTOR, a nutrient sensor that coordinates cellular energy production and expenditure, is reduced in Tpex cells compared to those that were becoming exhausted. As a result, Tpex cells can dampen their activity and remain functional for a longer time.

They claimed that flicking this switch was a balancing act. But they also suggested that one should not dampen the response too much to the point where it becomes ineffective. Hence, the next step was to find the mechanism that enabled this.

They exposed the TPE cells to increased amounts of an immunosuppressive molecule, the transforming growth factor (TGF), as seen in the body during an infection. After exposure, they found that this molecule acts as a brake, reducing the activity of mTOR and thereby dampening the immune response. 

(Source: https://www.tribuneindia.com/news/health/study-reveals-new-method-to-boost-immunity-and-fight-viral-infections-466211 )