Every year, over fifty million people in the US suffer from allergic rhinitis, the most common type of allergy. Allergens such as pollen, dust, and dander result in nasal congestion, itching, burning, sneezing, and overall discomfort. Current treatments include over-the-counter antihistamines, however, side effects of these drugs include drowsiness, restlessness, and poor concentration. For patients suffering from chronic allergies and inflammation, there is a great need for an alternative strategy for combating allergic symptoms without causing significant side effects.

The 2009 Brown University iGEM team worked to treat allergic rhinitis by engineering Staphylococcus epidermidis, a microbe endogenous to the human nasal flora, to secrete a recombinant histamine-binding protein in response to the elevated histamine concentrations of an allergic response. The engineered strain of S. epidermidis will function as a self-regulating drug factory in the nose, providing relief, without any negative side effects.

 Learn more about Allergene: a synthetically engineered, self-regulating drug factory in the  nose.
 When an allergic response occurs, our system senses a change in histamine levels above  threshold and initiates an intracellular cascade, signaling cells to respond appropriately to  the increase in histamine concentration.
 EV131 is a high-affinity histamine binding protein, that originates from the saliva of a  female tick species.
 The chassis of choice for production and secretion of the Histamine Binding Protein is  Staphyloccocus Epidermidis, an organism endogenous to the human nasal flora. A quorum  sensing mechanism was also incorporated to regulate cell density.
All Together  What happens when an allergy attacks: Description of the overall construct mechanism in  S.epidermidis incorporating the histamine sensor, intracellular signal cascade, and  transcription of EV131 ligated to secretion peptide.

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