How do plaques form during a phage overlay assay?

What causes the formation of plaques in a bacteriophage assay?

Bacteriophage replication generates clear zones, or plaques, caused by host cell lysis.

How are phage plaques formed?

If a phage lysogenized a host cell immediately upon infection, it would never form a plaque. Instead, when temperate phage infects a population of exponentially growing cells, each phage produces a plaque with a “bulls-eye” plaque morphology, a turbid center surrounded by a ring of clearing.

How are plaques 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.

What is plaque in phage titration?

The process of determining phage concentration by dilution and plating with susceptible cells is called titering or the plaque assay. This method determines the number of viable phage particles in a stock suspension. A bacteriophage capable of productively infecting a cell is called a plaque-forming unit (PFU).

What are the plaques in the plaque assay quizlet?

Plaques: a clear area in a lawn of bacteria on a plate.

How does a plaque assay work?

In a plaque assay the host cells and virus are incubated together for a short time to allow the virus to attach to and enter the host cell. Then the mixture in plated within a semi-solid agar. This semi-solid agar is poured onto a “bottom agar” that serves to supply adequate nutrients for the host cell.

What does a plaque represent and how is it formed?

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.

Do temperate phages form plaques?

All of the phage isolates formed turbid plaques on the bacterial host lawns, and turbid plaques are the typical plaque morphology of temperate phages.

Why is soft agar used in plaque assay?

The use of soft agar allows the phage to easily diffuse through the medium giving more consistent plaque formation. It also eliminates the problem of uneven absorption of the bacterial-phage solution into the hard agar that often caused uneven plaque formation on the plate (Ellis and Delbrück, 1939).

How many phage particles form a plaque?

When genetic libraries in phage vectors are screened for positive clones, the plates that are being screened should have approximately 50-500 phage plaques per plate for optimal results.

How is plaque assay titer calculated?

4. Determining Viral Titers

  1. Count the plaques in each well, taking the average for any technical replicates of the same dilution. …
  2. Determine the viral titer of the stock sample by taking the average number of plaques for a dilution and the inverse of the total dilution factor.

What is a plaque reduction assay?

The plaque reduction neutralization test is used to quantify the titer of neutralizing antibody for a virus. The serum sample or solution of antibody to be tested is diluted and mixed with a viral suspension. This is incubated to allow the antibody to react with the virus.

What is tooth plaque?

Plaque is a sticky film of bacteria that constantly forms on teeth. Bacteria in plaque produce acids after you eat or drink. These acids can destroy tooth enamel and cause cavities and gingivitis (gum disease). Plaque can also develop under the gums on tooth roots and break down the bones that support teeth.

What is the importance of a plaque assay in microbiology lab 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 Microneutralization assay?

MICRONEUTRALIZATION ASSAY TO TEST INHIBITION OF VIRUS BY ANTIBODIES (PURIFIED ANTIBODIES OR SERUM/PLASMA) This protocol can be used to assess the extent to which antibodies are able to neutralize SARS‐CoV‐2 in vitro.

What is CPE microbiology?

cytopathic effect (CPE), structural changes in a host cell resulting from viral infection. CPE occurs when the infecting virus causes lysis (dissolution) of the host cell or when the cell dies without lysis because of its inability to reproduce.

What is virion in microbiology?

virion, an entire virus particle, consisting of an outer protein shell called a capsid and an inner core of nucleic acid (either ribonucleic or deoxyribonucleic acid—RNA or DNA). The core confers infectivity, and the capsid provides specificity to the virus.

What structures are used by bacteriophages to attach?

The tail of the bacteriophage includes the tail sheath, base plate and tail fibers, which are made of different proteins. The long tail fibers are used by the bacteriophage to attach itself to the bacterium and the virus then inserts its genetic material inside of the host cell to begin the replication process.

What is Syncytium in microbiology?

Syncytia is formed by fusion of an infected cells with neighboring cells leading to the formation of multi-nucleate enlarged cells. This event is induced by surface expression of viral fusion protein that are fusogenic directly at the host cell membrane.

How is syncytium formed in some organisms?

Syncytium may be formed by the fusion of two or more cells, forming a giant cell. An example of syncytium can be found in skeletal muscles, which is essential since it allows rapid coordinated contraction of muscles along the entire length. Word origin: New Latin syn- (together with) + cyto (cell) + -ium.

What is syncytium example?

The muscle cell that makes up animal skeletal muscle is a classic example of a syncytium cell. The term may also refer to cells interconnected by specialized membranes with gap junctions, as seen in the heart muscle cells and certain smooth muscle cells, which are synchronized electrically in an action potential.

What is the functional syncytium?

The pacemaker cells can also respond to various hormones that modulate heart rate to control blood pressure. The wave of contraction that allows the heart to work as a unit, called a functional syncytium, begins with the pacemaker cells.

What is digestive syncytium?

Gastrointestinal smooth muscle forms an electrical syncytium whereby the impulse that induces contraction of the first muscle cell results in efficient transmission to a sheet of sequentially linked cells in the transverse and longitudinal axes of the intestine.

What is Coenocytic and syncytium?

A coenocyte (English: /ˈsiːnəsaɪt/) is a multinucleate cell which can result from multiple nuclear divisions without their accompanying cytokinesis, in contrast to a syncytium, which results from cellular aggregation followed by dissolution of the cell membranes inside the mass.