What is plaque forming assay?
The plaque assay is a well established method for measuring virus concentration as it relates to infectious dose. The assay relies on determining the number of plaque forming units (pfu) created in a monolayer of virus-infected cells.
How does the plaque assay work?
Plaque assays are used to count infectious particles. Samples are diluted and aliquots of each dilution are added to cultured cells. The cells are covered with an agaroseoverlay. Virus produced from an infected cell can infect nearby cells.
What is a plaque assay in microbiology?
Plaque assay is one of the widely used approaches for determining the quantity of infectious virus in a sample. Only viruses that cause visible damage to cells can be assayed in this way. Plaque assay was first developed to calculate the titers of bacteriophage stocks.
How is PFU calculated?
PFU is the Virus titer (Virus per ml). MOI is the ratio between the number of viral particle and the number of cells. So basically, MOI= PFU/cell.
How do you calculate plaque assay from PFU?
Calculating PFU Divide the number of plaques by the dilution factor, (ex. 10-6 for the most diluted sample) toobtain the number of Plaque Forming Units (PFU) in 100 μL of phage mixture. Note: If performing the assay in triplicate, use the average number of plaques from the three plates.
What causes the formation of plaques in a bacteriophage assay?
A viral plaque is a visible structure formed within a cell culture, such as bacterial cultures within some nutrient medium (e.g. agar). The bacteriophage viruses replicate and spread, thus generating regions of cell destructions known as plaques.
What is the importance of a plaque assay?
The advantage of using plaque assays to determine viral titers lies in their ability to quantitate the actual number of infectious viral particles within the sample. As multiple virions could potentially infect a single cell, the terminology of units versus virons is used during plaque titrations1,2.
What does PFU stand for?
PFU
| Acronym | Definition |
|---|---|
| PFU | Programmable Function Unit |
| PFU | Physical Fitness Uniform |
| PFU | Particle Flux Unit |
| PFU | Plan de Formation de l’Unité (French: Training Plan of Unity) |
How long does it take for a plaque to form in a cell?
Plaque assay- additional notes (2) • The infected cell area will create a plaque (an area of infection surrounded by uninfected cells) which can be seen visually or with an optical microscope. Plaque formation can take 3 – 14 days, depending on the virus being analyzed.
How is the number of plaque forming units determined?
Viral plaque assays determine the number of plaque forming units (pfu) in a virus sample, which is one measure of virus quantity. This assay is based on a microbiological method conducted in petri dishesor multi-well plates.
How is the plaque assay used in virology?
Plaque assay- additional notes • Plaque assay • Viral Plaques of Herpes Simplex Virus • Plaque-based assays are the standard method used to determine virus concentration in terms of infectious dose. Viral plaque assays determine the number of plaque forming units (pfu) in a virus sample, which is one measure of virus quantity.
How is a viral plaque formed in a cell?
A viral plaque is formed when a virus infects a cell within the fixed cell monolayer. The virus infected cell will lyse and spread the infection to adjacent cells where the infection-to-lysis cycle is repeated. 19.