What do nucleoside analogs inhibit?

What do nucleoside analogs inhibit?

Nucleoside analogs are synthetic, chemically modified nucleosides that mimic their physiological counterparts (endogenous nucleosides) and block cellular division or viral replication by impairment DNA/RNA synthesis or by inhibition of cellular or viral enzymes involved in nucleoside/tide metabolism (Figure 1).

How do nucleoside analogs inhibit DNA synthesis?

The nucleoside analogues resemble naturally occurring nucleosides and act by causing termination of the nascent DNA chain. These agents are generally safe and well tolerated as they are used by the viral, but not human polymerases in DNA replication.

Do nucleoside analogues make viral DNA useless?

Since nucleoside analogues require two phosphorylations to be activated, one carried out by a viral enzyme and the other by enzymes in the host cell, mutations in viral thymidine kinase interfere with the first of these phosphorylations; in such cases the drug remains ineffective.

What inhibits viral DNA synthesis?

Another type of drug that is a DNA synthesis inhibitor is foscarnet. It mimics pyrophosphate and inactivates the activity of the DNA polymerase. This inhibitor is active against the viral DNA polymerases at doses much lower than the ones needed to inhibit the human polymerases.

Which antiviral drug is thymidine analog?

The use of alternative nucleoside reverse transcriptase inhibitors (NRTIs) to the thymidine analogues stavudine (d4T) and zidovudine(ZDV) has been advocated as a means of limiting long-term NRTI-associated toxicity, particularly the development of lipoatrophy or fat wasting.

What’s the difference between a nucleotide and a nucleoside?

Simply speaking, a nucleotide consists of sugar, a nitrogenous base, and phosphate groups that number one to three. In contrast, a nucleoside involves a nitrogenous base that has a covalent attachment to sugar but with no phosphate group.

What are the types of antiviral agents?

Direct virus-targeting antiviral drugs include attachment inhibitors, entry inhibitors, uncoating inhibitors, protease inhibitors, polymerase inhibitors, nucleoside and nucleotide reverse transcriptase inhibitors, nonnucleoside reverse-transcriptase inhibitors, and integrase inhibitors.

Which of the following is an antiviral agent?

10.10: Antiviral Agents

Antiviral Brand Name
oseltamivir Tamiflu
acyclovir Zovirax
trifluridine Viroptic
famciclovir Famvir

Which drug selectively inhibits viral DNA synthesis?

The guanosine depicted in this specific image is used for RNA synthesis but acyclovir inhibits the synthesis of DNA synthesis. One of the most often used antiviral drugs that works with the described mechanism is acyclovir (aciclovir), a guanosine analogue.

What stage of a viral infection do antivirals block?

An antiviral agent must act at one of five basic steps in the viral replication cycle in order to inhibit the virus: (1) attachment and penetration of the virus into the host cell, (2) uncoating of virus (e.g., removal of the protein surface and release of the viral DNA or RNA), (3) synthesis of new viral components by …

Is acyclovir an antiviral nucleoside?

Antiviral drug. Acyclovir is a synthetic purine analogue (acyclic nucleoside analogue). It has antiviral activity against herpes virus. The action is related to the affinity for the enzyme thymidine kinase (TK).

Are there any antiviral drugs?

The CDC recommends the antiviral drugs baloxavir marboxil (Xofluza), oseltamivir (Tamiflu), and zanamivir (Relenza) for both flu prevention and treatment.. Baloxavir marboxil is taken orally and is approved for use in treatment of children 12 years of age and older.

How are nucleoside analogues used to treat HIV?

This chapter will focus on the antiviral nucleoside and nucleotide analogues. The nucleoside analogues used to treat HIV infection are often referred to as reverse transcriptase inhibitors (NRTIs). However, they have activity against both DNA dependent and RNA dependent DNA polymerases.

Are there any nucleoside analogues for reverse transcriptase?

There is a large family of nucleoside analogue reverse transcriptase inhibitors, because DNA production by reverse transcriptase is very different from normal human DNA replication, so it is possible to design nucleoside analogues that are preferentially incorporated by the former.

Where are antiviral nucleoside analogues blocked in DNA?

Many of the antiviral nucleoside analogues are blocked at the 3’ hydroxyl group of the deoxyribonucleic acid, which results in failure of elongation of the nascent DNA molecule.

How are antimetabolites similar to nucleoside analogues?

Once they are phosphorylated, they work as antimetabolites by being similar enough to nucleotides to be incorporated into growing DNA strands; but they act as chain terminators and stop viral DNA polymerase. They are not specific to viral DNA and also affect mitochondrial DNA. Because of this they have side effects such as bone marrow suppression.

This chapter will focus on the antiviral nucleoside and nucleotide analogues. The nucleoside analogues used to treat HIV infection are often referred to as reverse transcriptase inhibitors (NRTIs). However, they have activity against both DNA dependent and RNA dependent DNA polymerases.

There is a large family of nucleoside analogue reverse transcriptase inhibitors, because DNA production by reverse transcriptase is very different from normal human DNA replication, so it is possible to design nucleoside analogues that are preferentially incorporated by the former.

Once they are phosphorylated, they work as antimetabolites by being similar enough to nucleotides to be incorporated into growing DNA strands; but they act as chain terminators and stop viral DNA polymerase. They are not specific to viral DNA and also affect mitochondrial DNA. Because of this they have side effects such as bone marrow suppression.

Many of the antiviral nucleoside analogues are blocked at the 3’ hydroxyl group of the deoxyribonucleic acid, which results in failure of elongation of the nascent DNA molecule.