Term
| What are features of viruses? |
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Definition
| Nonliving! DNA or RNA genomes covered by a capsid. Capsid may or may not have an outer envelope of glycoproteins |
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Term
| What is caused by Papillomavirus? |
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Definition
| 51 strains cause warts and cervical cancer |
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Term
| What are caused by Picornaviruses? |
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Definition
| Polio, Meningitis, Colds (Rhinovirus) |
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Term
| What virus is an Orthomyxovirus? |
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Definition
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Term
| What are the steps in DNA viral replication? |
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Definition
- Absorption into the cell membrane
- Capsid uncoats
- Genome replicates inside host cell. Viral proteins assembled
- Virions bud out, sometimes taking envelop with them |
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Term
| What are the steps in RNA viral replication? |
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Definition
- RNA virus makes contact and is absorbed by receptors
- A low pH allows release from endosome
- RNA translated to DNA --> protein.
- Viruses bud to release |
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Term
| What are the 2 major components of the Influenza virus? |
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Definition
- Hemagglutinin - recognizes cells containing sialic acid (in the lungs). Ligand for receptors
- Neuraminidase - Cleaves sialic acid so virus can bud off
**H1N1 = Hemagglutinin1 Neuraminidase1 |
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Term
| What are the 3 types of influenza virus? |
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Definition
- A - bird flu. Most virulent! Antigenic change in H and N
- B - No serotypes, less mutation
- C - humans and pigs only. Mild in children |
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Term
| What is the difference between H1N1 and H5N1 |
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Definition
- H1N1 - a human flu that spreads through contact. Uses 2-6 Sialic acids
- H5N1 - more severe bird flu, does not spread human-human. But it could with a 1 AA substitution!! |
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Term
| What is the cytokine storm? |
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Definition
| Caused by all flus, especially H5N1: A potentially fatal rxn by positive feedback of immune response and cytokines |
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Term
| What is the seasonal flu? |
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Definition
| Any flu not pandemic related. Vaccine consists of 3 strains each year they think will be most prevalent. |
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Term
| What dopamine mimics are used to treat the flu? |
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Definition
- Amantadine/Symmetrel - only Type A, within 48 hours and for prophylaxis. Crosses BBB
- Rimantadine/Flumantadine - Type A only, less CNS side effects
**Block M1/M2 channels in the endosome to prevent the virus from uncoating, virus dies in lysosome. Quickly become resistant |
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Term
| What neuraminidase inhibitors are used to treat the flu? |
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Definition
- Zanamivir/Relenza - type A/B. Good against resistance. Seeing mutations in H and N. Inhaled within 48 hours
- Oseltamivir/Tamiflu - active in GI and against H5NI in high doses. Sometimes given w/ probenecid. Resistant mutants exist
- Peramivir - unapproved, used for emergencies
**Virus cannot be released from host by competing w/ Sialic acid |
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Term
| What strains of herpes virus (HHV) cause human infection? |
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Definition
- HHV 1 and 2 - oral and genital herpes. HHV1 can cause blindness. HHV 2 is the most common cause of viral meningitis
- HHV 3 - chicken pox and shingles
- HHV 4 - Epstein Barr virus = mono
- HHV5 - CMV = infectious retardation
- HHV6 and 7 - Roseola, baby measles
- HHV8 - Kaposi's sarcoma, oncogenic |
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Term
| How does Varicella reinfect a host? |
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Definition
| Once a host has been infected with HHV3/chickenpox, HHV3 can hide in the nerves and affect individual dermatomes |
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Term
| What drug is the gold standard for herpes tx? |
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Definition
Acyclovir/Zovirax - a guanine analog. Acyclovir gets tri-phosphorylated and incorporated into DNA instead of guanine - obligate chain termination
**Requires thymidine kinase, a virus only enzyme. Mycophenolate potentiates effects even more.
**Resistance: mutation in thymidine kinase, altered specificity for guanine, affinity for viral DNA polymerase |
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Term
| What is the spectrum for Acyclovir and Valacyclovir? |
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Definition
| HSV 1 and 2, HHV 3 (shingles), EBV (Valtrex), CMV (Valtrex) |
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Term
| What other therapies for DNA viruses are obligate chain terminators? |
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Definition
| - Cidofovir/Vistide - used for acyclovir resistance, HPV, pox. Obligate chain terminator, replaces Cytosine. MANY side effects: give with probenecid to prevent nephrotoxicity. Mutagenic, teratogenic |
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Term
| What other therapies for DNA viruses are DNA kinkers? |
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Definition
- Penciclovir/Denavir - Very long half life, only used topically. Kinks the DNA due to structure
- Famciclovir/Famvir - Prodrug of denavir that's orally available. HSV, HHV3, HBV
- Ganciclovir/Cytovene - All HHV, especially CMV. A kinker. Used for Ocular CMV, tx of cancer by giving HSV TK first
- Valganciclovir/Valcyte - prodrug of ganciclovir, can use orally |
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Term
| What other therapies for DNA viruses interrupt hydrogen bonding? |
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Definition
Idoxuridine/Virudox
Trifluridine/Viroptic
**Thymine analogs, side chains affect hydrogen bonding, DNA falls apart. Polymerase has a high affinity for these drugs = only used topically |
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Term
| How does Vidarabine/Vira-A or Ara-A work? |
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Definition
| An adenosine analog that inhibits viral polymerase, inserted into growing chain. |
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Term
| What anti-viral is available OTC? |
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Definition
| Docosanol/Abreva - A saturated alcohol. Inhibits the fusion of HSV w/ host membrane - only approved for topical oral HSV |
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