1 Introduction. A phage plaque is a clearing in a bacterial lawn . Plaques form via an outward diffusion of phage virions that is fed by bacterial infection. Anything that slows phage diffusion can impede plaque development and thereby plaque size.
What is a plaque in microbiology?
Plaque, in microbiology, a clear area on an otherwise opaque field of bacteria that indicates the inhibition or dissolution of the bacterial cells by some agent , either a virus or an antibiotic. It is a sensitive laboratory indicator of the presence of some anti-bacterial factor.
What is a virus or bacteriophage plaque?
Bacteriophages, also called phages, are viruses that specifically infect bacteria and we can confirm their presence and quantify them using a tool called the plaque assay. Bacteriophages infect their susceptible hosts by first attaching to the bacterial cell wall and injecting their genetic material.
What are the plaques in the bacteriophage plaque assay?
The basis of plaque assay is to measure the ability of a single infectious virus to form a “plaque” on a concurrent monolayer culture cells. A plaque is developed as a part of infection of one cell by a single virus particle that is followed by the replication of that virus, and finally, the death of the cell.
How is plaque formed in microbiology?
A viral plaque is a visible structure formed after introducing a viral sample to a cell culture grown on some nutrient medium . The virus will replicate and spread, generating regions of cell destruction known as plaques. ... Counting the number of plaques can be used as a method of virus quantification.
Do plaques enlarge indefinitely?
After several lytic cycles the local MOI increases and most of the cells are lysed, producing a plaque in the lawn of cells. As the cell lawn becomes saturated, the rate of cell growth slows down and, since lysis requires rapid metabolism, the plaque stops increasing in size .
How is plaque caused?
Plaque forms when bacteria in your mouth mix with sugary or starchy foods , such as milk, juice, soft drinks, bread, pasta and fruit. These bacteria release acids that break down carbohydrates in food and drinks.
How many viruses are needed to form a plaque?
One virus is enough to form a plaque. So for one-hit kinetics, the number of plaques is directly proportional to the first power of the concentration of the virus inoculated.
What is the purpose of a plaque assay?
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 award?
Plaque: A larger engraved wall plaque that is a type of recognition award. ... This is a traditional corporate recognition award that can be hung on a wall and admired for years to come .
How long do plaque assays take?
It takes almost 5 days for the plaque formation. I tried streaking the plaque on bacterial lawn. Even in that I was only able to visualize the clearance after a week.
What is a plaque count?
To determine the virus titer , the plaques are counted. To minimize error, only plates containing between 10 and 100 plaques are counted, depending on the size of the cell culture plate that is used. Statistical principles dictate that when 100 plaques are counted, the sample titer will vary by plus or minus 10%.
Why do we not use a TNTC or Tftc plaque assay plate?
Plates showing greater than 300 PFUs are too numerous to count (TNTC); plates showing fewer than 30 PFUs are too few to count (TFTC).
Why are Lambda plaques turbid?
Turbid plaques are usually produced by lysogenic phage such as lambda. In some of the cells the phage may lysogenize instead of continuing the lytic cycle, and if this happens with high enough frequency the plaque will look ‘turbid’.
How do you describe plaque morphology?
Plaque morphologies can include bull’s eyes , clear plaques, sectored or star-shaped plaques, the plaques of T-even phage wild-type versus rapid lysis mutants (which are small with rougher borders versus larger with smoother borders), plaques containing central zones of turbidity as often associated with temperate ...
What happens when you have plaque in your heart?
A buildup of plaque can narrow these arteries, decreasing blood flow to your heart . Eventually, the reduced blood flow may cause chest pain (angina), shortness of breath, or other coronary artery disease signs and symptoms. A complete blockage can cause a heart attack.
