EnzyPha, an Engineered Helper Phage Developed to Overcome Most of the Limitations Regarding Filamentous Phage Titration and ELISA Tests.

BACKGROUND Phage display method is a technology which enables expression of exogenous polypeptides on the surface of bacteriophage particles. Phage titration and ELISA are applied for measuring helper phage particles or polypeptide bearing phages and also evaluation of the interaction between polypeptide bearing phages and coated antigens, respectively. Although, several procedures have been introduced to perform phage titration and ELISA but they faced to some limitations such as being time consuming and expensive and also low reproducibility. OBJECTIVE We developed a new system called EnzyPha by engineering the M13KO7 expressing Secreted Acid Phosphatase of Mycobacterium tuberculosis (SapM enzyme) on its pIX protein for applying in colorimetric phage titration and ELISA methods. METHODS For this purpose, to evaluate the idea, colorimetric phage titration and ELISA were performed and compared to the traditional methods. RESULTS SapM enzyme was expressed on pIX protein of M13KO7 properly. The colorimetric phage titration and phage ELISA showed better and comparable results against the traditional approaches. CONCLUSION The results showed that the proposed model would titrate phages more sensitive than plating titration method through a shorter timeframe. Moreover, it could be a better alternative to the routine phage ELISA due to time saving, cost effective and higher sensitivity.