Synthetic biology is an investigative and constructive means of understanding the complexities of biology. Substantial progress in the fields has resulted in the creation of synthetic gene circuits, which when uploaded into the appropriate nanoliposomal vehicle, can be used for a tunable response in a cell. These tunable elements can be applied to treat diseased condition for a transition to a healthy state. Though in its nascent stage of development synthetic biology is beginning to use its constructs to bring engineering approaches into biomedicine for treatment of infectious disease leishmaniasis.

With the advent of synthetic biology in medicine many synthetic or engineered proteins have made their way to therapeutics and diagnostics. In this paper, the downstream gene network of CD14-TNF-EGFR pathway in leishmaniasis, a tropical disease, is reconstructed. Network analysis showed that NFkB links the signaling and gene network, used as a point of intervention through a synthetic circuit embedded within the negative autoregulatory feedback loop. A chimeric protein kinase C (PKC) is incorporated in the synthetic circuit, under the transcriptional regulation of Lac repressor and IPTG, as an inducer. The chimeric PKC_ζα via IκKb phosphorylation activates NFκB, and modulates the gene expression from an anti-inflammatory to a pro-inflammatory phenotype in in vitro L. major infected macrophage model. This is the first ever report of a synthetic device construction in leishmania.

Cutaneous leishmaniasis is the most common form of lesihmaniasis, caused by and is spread by the bite of a sandfly This species infects the Leishmania major . macrophages and dendritic cells Due to multi-drug resistance, there is a need for a new therapeutic technique. Recently, a novel molecular motor of , Myosin XXI, was classified and characterized. In addition, the drug Leishmania resistance in this organism has been linked with the overexpression of ABC transporters. Systems biology aims to study the simulation and modeling of natural biological systems whereas synthetic biology deals with building novel and artificial biological parts and devices Together they have contributed enormously to drug discovery, vaccine design and development, infectious disease detection and diagnostics. Synthetic genetic regulatory networks with desired properties, like toggling and oscillation have been proposed to be useful for gene therapy. In this work, a nanocircuit with coupled bistable switch -repressilator has been designed, simulated in the presence and absence of inducer, using Tinker Cell. When inducer is added, the circuit has been in silico, shown to produce reporter at high levels, which will impair the activity of Myosin XXI and ABC transporters. Validation of the circuit was also performed using GRENITS and BoolNet. The influence of inducer on the working of the circuit, i.e., the type of gene expression, response time delay, the steady states formed by the circuit and the quasipotential landscape of the circuit were performed. It was found that the addition of inducer reduced the response time delay in the graded type of gene expression and removed the multiple intermediate attractors of the circuit. Thus, the inducer increased the probability of the circuit to be present in the dominant stable state with high reporter concentration and hence the designed nanocircuit may be used for the treatment of leishmaniasis.

Stochastic variations in the transcription factor target gene network influences the dynamics of protein levels. The mathematical model built, here, is useful to study the cytokine response and the resulting dynamical patterns in leishmaniasis. The fluctuations produced affect the expression rate of its target in the regulatory synthetic circuit designed by means of a negative feedback loop insertion. Thus, the faster the response time, smaller is the fluctuation of the system observed and it can be justified that the TFTG network embedded can be understood with the recurring dynamics of the designed synthetic circuit.