15th October 2018

researchgate

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What is the delta CT?

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Ct (threshold cycle) is the intersection between an amplification curve and a threshold line. It is a relative measure of the concentration of target in the PCR reaction. Fold change for each target gene is calculated in the following way: DeltaCt(gene) = Ct(gene, sample) - Ct(gene, control)

What is a CT in qPCR?

In a real time PCR assay a positive reaction is detected by accumulation of a fluorescent signal. The Ct (cycle threshold) is defined as the number of cycles required for the fluorescent signal to cross the threshold (ie exceeds background level).

What is relative quantification?

In absolute quantification using the standard curve method, you quantitate unknowns based on a known quantity. In relative quantification, you analyze changes in gene expression in a given sample relative to another reference sample (such as an untreated control sample).

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What is the meaning of real time PCR?

RT-PCR: a highly sensitive technique for the detection and quantitation of mRNA (messenger RNA). The synthesis of cDNA (complementary DNA) from RNA by reverse transcription (RT) and. The amplification of a specific cDNA by the polymerase chain reaction (PCR).

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How is Cdna made from RNA?

cDNA is known to be synthesized, or manufactured from an mRNA or messenger RNA template. It is synthesized in a reaction that is catalyzed by the reverse transcriptase and DNA polymerase enzymes. Essential to note is that cDNA is usually used to clone eukaryotic genes in prokaryotes.

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What is the RT PCR test?

RT-PCR is a PCR test that is designed to detect and measure RNA. The reverse transcriptase allows a single strand of RNA to be translated into a complementary strand of DNA. Once that reaction occurs, the routine PCR method can then be used to amplify the DNA.

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What is a fold change?

Fold change is a measure describing how much a quantity changes going from an initial to a final value. For example, an initial value of 30 and a final value of 60 corresponds to a fold change of 2 (or equivalently, a change to 2 times), or in common terms, a one-fold increase.

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What is reverse transcriptase and what does it do?

Reverse transcriptase. A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. It is mainly associated with retroviruses.

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How does the virus recognize its host cell?

A virus identifies its host by fitting its surface proteins to receptor molecules on the surface of the host cell. Some may enter cells by endocytosis, if the viruses are enveloped, they can also enter a host cell by fusing with the plasma membrane of the host cell and releasing the capsid into the cell's cytoplasm.

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Why is it called a retrovirus?

The Human Immunodeficiency Virus (HIV) is called a retrovirus because the RNA genome transcribes or copies back into the DNA in the host cell. This is by way of reverse transcriptase - a viral enzyme. HIV can only replicate itself within living cells. It uses cells' replication enzymes to makes these copies of itself.

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How is a retrovirus different from any other virus?

Retroviruses do not kill the host cell at first because they can insert their genome into the host genome. This process is called reverse transcription and is done by the viral protein reverse transcriptase. In the case of HIV, viral protein integrase then inserts the HIV DNA into host DNA.

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What disease is caused by a retrovirus?

Besides human immunodeficiency virus (HIV), the virus that causes AIDS, there a two other retroviruses that can cause human illness. One is called human T-lymphotropic virus type 1 (HTLV-1) and the other is called human T-lymphotropic virus type 2 (HTLV-II).

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Is hepatitis retrovirus?

The life cycle of hepatitis B virus is complex. Hepatitis B is one of a few known non-retroviral viruses which use reverse transcription as a part of its replication process. Because the virus multiplies via RNA made by a host enzyme, the viral genomic DNA has to be transferred to the cell nucleus.

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Is the influenza virus A retrovirus?

A retrovirus looks about the same as any other virus, but it functions significantly different that your run-of-the-mill influenza. HIV is the most significant retrovirus that infects humans; others include hepatitis B and human T-lymphotropic virus. Viruses are essentially just genes, encapsulated in a protein.

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How is a retrovirus different from a virus?

However, retroviruses function differently, as their RNA is reverse-transcribed into DNA, which is integrated into the host cell's genome (when it becomes a provirus), and then undergoes the usual transcription and translational processes to express the genes carried by the virus.

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What kind of virus is the flu?

There are four types of influenza viruses: A, B, C and D. Human influenza A and B viruses cause seasonal epidemics of disease almost every winter in the United States. The emergence of a new and very different influenza A virus to infect people can cause an influenza pandemic.

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Is flu type A worse than Type B?

Unlike type A flu viruses, type B flu is found only in humans. Type B flu may cause a less severe reaction than type A flu virus, but occasionally, type B flu can still be extremely harmful. Influenza type B viruses are not classified by subtype and do not cause pandemics.

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What is the contagious period for the flu?

Although the typical incubation period for influenza is about one to four days, some adults can be contagious from about one day before onset of symptoms for up to two weeks. Other people who develop complications, such as pneumonia, may extend the contagious period for a week or two.

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How long does flu virus live on bedding?

Flu viruses capable of being transferred to hands and causing an infection can survive on hard surfaces for 24 hours. Infectious flu viruses can survive on tissues for only 15 minutes. Like cold viruses, infectious flu viruses survive for much shorter periods on the hands.

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How long should you stay home from work if you have the flu?

CDC recommends that you stay home for at least 24 hours after your fever is gone except to get medical care or other necessities. Your fever should be gone without the need to use a fever-reducing medicine, such as Tylenol®.

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