EnzyPha, An Engineered Helper Phage Developed to Overcome most of the Limitations Regarding Phage Titration and ELISA Tests

Document Type : Original Article


1 Department of Molecular Medicine and Genetic, Faculty of Medicine, Hamedan University of Medical Sciences, Hamedan, Iran

2 Department of Virology, Faculty of Medicine, Hamedan University of Medical Sciences, Hamedan, Iran

3 Department of Immunology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

4 Research Center for Molecular Medicine, Hamedan University of Medical Sciences, Hamedan, Iran


Introduction: The phage display method is a technology that enables the expression of exogenous polypeptides on the surface of bacteriophage particles. Phage titration and ELISA are applied to measure helper phage particles or polypeptide bearing phages and also evaluation the interaction between polypeptide bearing phages and coated antigens, respectively. Although several procedures have been introduced to perform phage titration and ELISA, they face some limitations, such as being time-consuming, expensive, and low reproducibility.
Materials and Methods: 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. To evaluate the idea, colorimetric phage titration and ELISA were performed and compared to the traditional methods.
Results: SapM enzyme was expressed on the pIX protein of M13KO7 properly. The colorimetric phage titration and phage ELISA showed better and comparable results against the traditional approaches.
Conclusions: The results showed that the proposed model would titrate phages more sensitively than the plating titration method through a shorter timeframe. Moreover, it could be a better alternative to the routine phage ELISA due to time-saving, cost-effectiveness, and higher sensitivity.