The Power of Phages

Phages are highly specific viruses that use their host bacterial cells as factories for their own replication and have the ability to display peptides or proteins on their surfaces—a technology known as phage display. Phage display can be used as a powerful tool to screen for affinity reagents for all kinds of targets, ranging from small molecules to proteins and even cells. Because phages are host-specific, able only to infect specific species or even strains, phage typing is useful in differentiating bacterial isolates and may be used to identify and characterize outbreak-associated strains. Individual phages may recognize a multitude of different surface-associated molecules.

In a traditional antibody detection approach, for instance, antigens or certain proteins are used to elicit a specific humoral immune response that produces antibodies to the bacterium. These proteins represent one out of several mechanisms that are involved in any given immune response.

By contrast, the recognition elements utilized by phage for identification of their host represent the only possibility to propagate. The proper function of these proteins thereby underlies the highest selective pressure; they are indispensible to phage survival. Their function as “sensing” receptors offers advantages over methods that are based on antibodies: their efficient immobilization, the possibility of using different detection methods due to easy labeling, and the easy regeneration of their functionality after immobilization.

Additionally, the phage proteins can be modified, thus enhancing their stability, affinity, and specificity and facilitating the functionalization of nanoparticles and surfaces. These advantages enable phage recombinant proteins to meet the requirements of sensitivity and stability that are necessary for the detection of bacterial pathogens and food contaminants in their natural matrices.

Replacing antibodies with phage proteins in commercially available diagnostic tests allows for the development of assays capable of detecting even low levels of contamination by dangerous bacteria.

Innovative Screening

While many food testing assays efficiently detect common foodborne pathogens, considerations such as performance, ease of use, speed (time to results), potential for error, degree of automation, and cost are also critical factors that must be taken into account by any food company choosing its technology for pathogen detection.

Phage technology has been available for more than 40 years. However, its effective use in bacterial pathogen detection is relatively recent due to advances in the development of biochemically re-engineered phage proteins, as well as highly specific assays by innovative companies in the space. Thanks to the efforts of expert microbiologists and food safety researchers, phage recombinant proteins can offer unrivaled specificity and sensitivity for the targeted capture and detection of bacteria from a given food sample.

Replacing traditional antibodies with bacteriophage proteins improves the sensitivity and specificity of methods and allows for more rapid detection of bacterial pathogens from a variety of food and environmental samples. This shorter time to detection helps to lower the incidence of foodborne illness outbreaks.

Additionally, recent data show that phage technology is as sensitive as molecular technology in identifying foodborne pathogens. Assays such as the VIDAS UP technology, developed to identify the presence of specific bacterial pathogens using phage proteins, have been incorporated into one simple test, comprising only one broth and one strip. This test can deliver results in as little as eight hours, whereas traditional methods can take up to two days. This approach also has the flexibility of analyzing a broader range of sample sizes, allowing for greater productivity in the lab and more effective management of quality control processes and risk management for the food industry overall.n