Antivirals and Diagnostic Virology Flashcards
For influenza, what are the 3 classes of drugs?
- uncoating
- nueraminidase inhibitors
- cap-dependent endonuclease inhibitor
What do uncoating drugs do for influenza?
- rimantadine/amantadine blocks uncoating
- uncoating is what releases virus to infect
- can only be used on influenza A bc all other strains are resistant
What do neuraminidase inhibitors do for influenza?
- block release of virus by blocking viral neuraminidase
- most common: Tamiflu (Oseltamivir)
What do cap-dependent endonuclease inhibitors do for influenza?
- xofluza (baloxavir carboxyl) prevents virus from taking cellular mRNA caps and using them to make viral mRNA
- as a result= viral RNA can’t be transcribed into mRNA and viral proteins aren’t made
What is one of the non-specific drugs that can be used on respiratory syncytial virus, hep c virus, and hemorrhagic fever viruses?
Ribavirin
How does the MOA of ribavirin work?
- inhibits inosine monophosphate dehydrogenase which lowers guanine nucleotides in the cell… makes replication harder
- is a teratogen so must use 2 forms of birth control and not get pregnant for 6 months after use
What are the different classes of HIV drugs?
- entry inhibitors
- reverse transcriptase inhibitors (NRTI and NNRTI)
- integrase inhibitors
- protease inhibitors
How entry inhibitors for HIV work?
- block receptor/co-receptor binding or membrane fusion and entry
How do the 2 classes of reverse transcriptase inhibitors for HIV work?
- nucleoside reverse transcriptase inhibitors (NRTI): chain terminators prevent chain from being elongated
- non-nucleoside reverse transcriptase inhibitors (NNRTI): bind to reverse transcriptase and prevent its ability to make DNA
both block ability of virus to make a DNA copy of itself
How do integrase inhibitors work for HIV?
- prevent virus from inserting the viral DNA into cellular DNA
How do protease inhibitors work for HIV?
- block maturation of viral particle
How are chronic infections of HIV treated?
with 2 different classes of drugs
What are the classes of drugs for HCV?
- protease inhibitors
- RNA polymerase inhibitors
- NS5A inhibitors
How do protease inhibitors work for HCV?
- prevent polyprotein cleavage and block replication of RNA because it can’t cleave polyprotein to make an active viral polymerase
How do RNA polymerase inhibitors work for HCV?
- blocks ability of virus to replicate its RNA
How do NS5A inhibitors work for HCV?
- block RNA production and assembly/release of new viral particles
What do all herpesvirus antivirals act on?
viral DNA polymerase (bc DNA virus)
- Acyclovir compounds block viral polymerase and interfere with viral DNA production
- they all need to be activated by a viral thymidine kinase so will be preferentially activated in an infected cell that has the viral thymidine kinase
What is Valacyclovir for herpesvirus tx?
- it is a prodrug of acyclovir
- converted to acyclovir in body and requires less doing that acyclovir
- both tx HSV and VZV herpesvirus
What is the difference between famiciclovir and penciclovir?
- famciciclovir is oral
- penciclovir is topical
both same active compound that treat HSV and VZV herpesvirus
What are the downsides of valganciclovir and ganciclovir and what do they tx?
- have more side effects
- tx for herpesvirus CMV
How do lateral flow assays work?
- detect viral antigens or antibodies
- similar to ELISA. quick and easy
- downside: might not pick up new strain if virus undergoes antigen drift
- done in office or at home
How do nucleic acid amplification tests (NAAT) work?
- very sensitive and amplify small amounts of starting material
- usually pick up an infection if present
- specialized NAAT used to determine amount of virus in a person (amount of viral load)
- tests done in lab mostly so have to wait a few days for results… more recently started doing in office
- more expensive than lateral flow assays
- can test for multiple infections at once
Why is viral diagnostics important?
- usually used to confirm a diagnosis
- necessary for prescribing correct antiviral drugs
- help monitor chronic infections if it’s increasing/decreasing or if antiviral tx is working
- monitor prevalence of virus in community
Where are viruses usually grown for production of viruses?
- cell culture
- vaccines require large quantities of virus
How are viral infections determined in cytology?
- looking for viral inclusion bodies, syncytia, or using detector antibodies for viral proteins
What is rapidly replacing the need for cell culture for diagnosis of an infection?
- nucleic acid tests
How do antibodies/antigen ELISA (enzyme-linked immunosorbent assay) test work?
- used to detect antibodies present in body against one specific virus
- test can be for IgM: indicates an acute ingection
- test can also be for IgG: indicate acute, chronic, or past infection (chronic because in blood)
- test also to detect presence of a viral antigen: indicates an active infection
- test can help check vaccine efficacy (if antibodies were developed)
What is the sensitivity of the test determined by?
- how many people with the disease will test positive
ex: if 100 people who have the virus and only 70 test positive, the sensitivity of the test is 70%
What is the specificity of the test determined by?
- how many people who do not have the disease will test negative (false positives)
ex: if 100 people who do not have the virus and 5 people test positive, the specificity of the test is 95%
If you have a low prevalence of disease/infection, you have a low ________.
low/limited utility
