FA - Micro - Virology Flashcards
Viral genetics - Reassortment?
When viruses with segmented genomes (e.g., influenza virus) exchange segments.
==> 2009 novel H1N1 influenza A pandemic ==> Complex reassortment of genes from HUMAN + SWINE + AVIAN viruses.
==> POTENTIAL FOR ANTIGENIC SHIFT.
Viral genetics - Recombination?
Exchange of genes between 2 chromosomes by crossing over within regions of significant base sequence homology.
Viral genetics - complementation?
When 1 OF 2 viruses that infect the cell has a mutation that results in a NON FUNCTIONAL PROTEIN.
==> The NON MUTATED virus “complements” the mutated one by making a functional protein that serves BOTH viruses.
Viral genetics - phenotypic mixing?
- Occurs with SIMULTANEOUS infection of a cell with 2 VIRUSES.
- Genome of virus A can be partially or completely coated (forming pseudovirion) with the surface proteins of virus B.
- Type B protein coat determines the tropism (infectivity) of the hybrid virus.
- The progeny from this infection have a type A coat that is encoded by its type A genetic material.
Live attenuated vaccines - mechanism?
Induce humoral AND cell-mediated immunity - have reverted to virulence on RARE occasions.
Killed/inactivate vaccines - mechanism?
Induce ONLY HUMORAL immunity but are stable.
Live attenuated vaccines - mention some?
- Smallpox
- Yellow fever
- Chickenpox (VZV)
- Sabin polio virus
- MMR
- Influenza (Intranasal)
Live attenuated vaccines - need a booster?
NO BOOSTER.
Killed vaccines - mention some?
- Rabies
- Influenza (injected)
- Salk Polio
- HAV vaccines
Recombinant vaccines - 2 examples?
- HBV (antigen= HBsAg)
2. HPV (types 6, 11, 16, 18).
All DNA viruses are ds, EXCEPT?
Parvo (Latin for small)
All DNA viruses are linear, EXCEPT?
- Papilloma
- Polyoma
- Hepadna
(circular)
All RNA viruses are ss, EXCEPT?
Reo (Repeato-virus ==> ds).
Positive-stranded RNA viruses?
- Retro
- Toga
- Flavi
- Calici
- Picorna
- Corona
- Hepevirus
Naked viral genome infectivity?
Purified nucleic acids of most dsDNA (EXCEPT pox and HBV) and +strand ssRNA –> INFECTIOUS.
NON infectious naked nucleic acids?
Naked nucleic acids of (-)strand ssRNA and dsRNA viruses are NOT infectious –> Require polymerases contained in the complete virion.
DNA viruses - viral replication?
ALL IN THE NUCLEUS (except POX).
RNA viruses - viral replication?
ALL in the CYTOPLASM - except INFLUENZA and RETRO.
Viral envelopes - Naked?
DNA ==> 1. Papilloma 2. Polyoma 3. Adeno 4. Parvo RNA ==> 5. Calici 6. Picorna 7. Reovirus 8. Herpes
Generally, how do enveloped viruses acquire their envelopes?
From plasma membrane when they exit the from cell.
EXCEPT HERPESVIRUSES ==> Acquire envelopes from nuclear membrane.
General rule - ALL DNA viruses are?
- HHAPPPPy –> Hepadna, Herpes, Adeno, Pox, Parvo, Polyoma, Papilloma.
- DOUBLE-STRANDED
- LINEAR GENOMES
- ICOSAHEDRAL –> except pox (complex)
- NUCLEUS for replica –> except pox (carries OWN DNA-dependent RNA poly).
Herpesviruses - envelope?
Yes.
Herpesviruses - DNA structure?
DS and linear.
HSV-1 - disease?
- Gingivostomatitis.
- Keratoconjunctivitis.
- Herpes labialis.
- Herpetic whitlow on finger.
- Temporal lobe encephalitis.