Phage Burst Size Assay

Creative Biolabs is a leading service provider that focuses on phage therapy. Based on years of experience and advanced platforms, now we can provide novel phage burst size assays for our clients all over the world.

Introduction of Phage Burst Size

Viruses with the ability to attack bacteria are called phages or bacteriophages. Phage infection is the process by which bacteriophages attach to susceptible bacteria and infect host cells. The phage then hijacks the bacterium's cellular machinery to produce viral components. During this process, plaque counts are relatively constant over time because only one plaque is produced per infected bacterium. Plaque-forming units (PFUs) rise as bacteria are lysed and newly synthesized phages are released. These released phage particles remain free in the culture medium because they cannot encounter susceptible bacteria. Phage burst size can be defined as the average number of progeny phage released per host cell into the extracellular environment upon cell lysis. Depending on the phage types and the host genotype, this value may range from few to several thousand. For example, the burst size of DNA transducing phages is ranging from 10 to 100.

Fig.1 Schematic illustration of different phases of the one step growth curve of virus replication. (Ranasinghe, 2019)

Phage Burst Size Assay

For phage burst size determination assay, a mid-exponential phase E. coli cultures were incubated on ice for 10 minutes and centrifuged, then bacterial cultures were resuspended in minimal medium and mixed with phage. After a brief incubation, dilute the mixture 100- and 10,000-fold in LB at 37 °C. The number of free phages was assessed by plaque assay after centrifugation. Please note that pfu enumeration is necessary before the onset of lysis.

BS= (Vmax−Vmin) / (Hmax−Hmin)

Where, Vmin and Vmax refer to the minimal and maximal phage concentrations, respectively. Hmin and Hmax refer to the minimal and maximal host abundances.

The common methods for burst size determination are transmission electron microscopy (TEM). What's more, one-step growth curves, phage FISH, gene ELISA, plaque forming assay, and most probable number assay are also novel methods to complete the phage burst size assay.

As a forward-looking researcher as well as a leading custom service provider in the field of phage-based therapy, Creative Biolabs has won good reputation among our worldwide customers for successfully accomplishing numerous challenging projects. We offer a variety of solutions to fit your specific research needs. If you are interested in our services, please do not hesitate to contact us for detailed information.

Reference:

1. Ranasinghe, R.M. Literature study of virus size, burst size, latent period and genome size across different lytic eukaryotic and prokaryotic virus groups-an overview of traits and possible trade-offs. The University of Bergen. 2019.