Game Theory Applications in Host-Microbe Interactions: Mycobacterium tuberculosis infection as an example

The game theory describes the interactions between two players and the pay-off from wining, losing or compromising. Mycobacterium tuberculosis (Mtb)-host interactions were used as an example for the application of the game theory to describe and predict the possibilities of victory for any players. The gene expression for eight main markers of host response and three Mtb virulence factors were assessed in broncho-alveolar lavage of TB+ and TB- patients. The game theory showed that a variety of paths exist that players can use, in response to the behaviour of the counterpart. Briefly, according to the "Nash equilibrium", Ag85B is the main virulence factor for Mtb in active phase, however it is the most immunogenic factor if the host can respond by high expression of T-bet and iNOS. In this situation, Mtb can express high levels of ESAT-6 and CFP10 and change the game to the latency, in which host responses by medium expression of T-bet and iNOS and medium level of TGF-{beta} and IDO. Consistently, The IDO expression was 134-times higher in TB+s than the TB-s, and the T-bet expression, ~200-times higher in the TB-s than the TB+s. Furthermore, Mtb-Ag85B had a strong positive association with CCR2, T-bet and iNOS, but had a negative correlation with IDO.