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14 Cards in this Set
- Front
- Back
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What would be the best available drug to treat primary infections with herpes simplex virus?
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Acyclovir
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What is acyclovir?
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Acyclovir is an analogue of deoxyguanosine that terminates DNA synthesis.
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How does acyclovir work?
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Acyclovir is recognized almost exclusively by the VIRAL thymidine kinase and is phosphorylated. Then, acyclovir monophosphate is converted to acyclovir triphosphate via host cell enzyme. Upon its incorpoation into viral DNA further DNA synthesis is blocked.
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For what diseases are acyclovir used as a treatment?
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Primary infection of herpes simplex viruses
All severe varicella-zoster virus infections |
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What is ganciclovir?
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It is a chain-termination analogue like acyclovir that is used primarily for cytomegalovirus infections.
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Which drug is used to treat cytomegalovirus? Can you use this in the neonates? How is the outcome for them?
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Ganciclovir/ or foscarnet can be used to treat neonatal infection of cytomegaloviruses. It significantly improves the outcomes such as hearing test and cognitive development.
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Which drug is used to treat herpes keratitis?
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Trifluridine. This treatment will reduce the risk of recurrent infection which can result in blindness. It is used locally in the eyes.
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Can you use trifluridine for systemic infections with herpes viruses?
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No, because some tissues have a rapid rate of DNA synthesis and a high thymidine kinase activity and thus are sensitive to trifluridine.
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Name two drugs that attack the DNA polymerase of herpes virus.
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Adenine arabinoside and Foscarnet
- The viral DNA polymerase of herpes viruses is different from the comparable cell enzyme. Thus, these drugs preferentially inhibit the viral DNA polymerase without marked toxicity to the host cell. |
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Describe the mechanism of foscarnet.
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Foscarnet is an analogue of pyrophosphate and inhibits the DNA polymerase of herpes viruses but has much less effect on the DNA polymerase of human cells.
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Describe the mechanism of adenine arabinoside.
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It is converted to adenine arabinoside triphosphate and and is incorporated into viral DNA by the viral DNA-polymerase. It blocks further DNA synthesis.
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Where are the progeny nucleocapsids of herpes virus assembled?
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Nucleus (--> nuclear inclusion bodies). They obtain their envelope from budding through the NUCLEAR membrane and into the plasma membrane.
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Compare the formation of multinucleate giant cells between herpes and measles viruses.
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The herpes viruses produce virus-encoded glycoproteins in the plasma membrane, resulting in cell fusion. The measles viruses eliminate the plasma membranes of ADJACENT cells to spread the infection, using viral Ag in the membrane of the first infected cell.
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What is the distinguising factor between Herpes simplex type I and II?
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Distinguished by type-specific monoclonal antibodies or PCR. But they are very closely related in their antigenicity.
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