Ch. 13: Viruses Flashcards
1
Q
Viruses are entities that…
A
- contain DNA or RNA
- contain a protein coat
- multiply inside living cells by using the synthesizing machinery of the cell
- cause the synthesis of specialized structures that can transfer the viral nucleic acid to the other cells
2
Q
Virion
A
- complete, fully developed
- infectious particle
- composed of nucleic acid, protein coat, evenlopem and spikes
3
Q
Genome
A
- RNA or DNA but never both
- HIV has RNA
4
Q
Capsid
A
- protected by capsid
- composed of proteins called capsomeres (identification)
- used for: protective layer, transmission and adherence
5
Q
Envelope
A
- made up of lipids, proteins, and carbohydrates
- used for protection
- nonenveloped viruses: capsid is protection
6
Q
Spikes
A
- may cover envelope
- made up of carbohydrates-protein complex
- used for identification and adherence
- HA spike- used for hemaggulation (destroy RBCs)
- NA spike- separate vision from host
7
Q
RNA synthesis: Retro virus
A
- retroviruses enters by fusion between attachment spikes and the host cell receptors
- uncoating releases 2 viral RNA genomes and the viral enzymes reverse transcriptase
- reverse transcriptase copies viral RNA o produce double-stranded DNA
- viral DNA then integrates into a host cell chromosome as a provirus (protected from host’s immune system and antiviral drugs)
- provirus may be replicated when the host cell replicates (cancer- convert host cell) or become latent
- transcription of the provirus, producing RNA for new retrovirus capsid, enzymes, and envelope proteins
- viral proteins move to the host plasma membrane
- mature retrovirus leaves the host cell
8
Q
Latent Infection
A
- virus can remain in equilibrium with the host and not actually produce disease for a long period of time
- cold sores: Herpes 1
- Shingles: Herpes 3
9
Q
Progression of HIV
A
*normal HelperT cells = 1000-1500 Stage 1: Helper T cells= 500 - lympth-adenopathy Stage 2: Tcells= 200-499 - causes: persistant fever and diarrhea, fungus- Candida albicans, Shingelles, Oral hair leukoplaki, precervical cancer Stage 3: " Clinical AIDS' - Tcell= below 200 - causes: infections of bronchi, trachea, or lungs; eye infections, TB, pneumonia, brain degeneration, Kapok's sarcoma
10
Q
HIV: infectiveness and pathogenicity
A
- attaches to CD4 by spikes
- viral RNA is released and transcribed into DNA by reverse transcriptase
- viral DNA becomes integrated into chromosomal DNA of host cell- may control production
- may become latent as provirus
- have a high mutation rate compared to DNA viruses- lack the proofreading capacity of DNA viruses
11
Q
Treatment
A
- difficult due to mutations
- ART: antiretroviral
- reduces number of virions formed
12
Q
HIV: Spread
A
- blood: 10-1000 IPs- transfusion, IDV, needle pricks
- semen: 10-50 IP- intercourse or anal
- myth: saliva only has 1IP (kissing)
13
Q
Cancer
A
- Herpes 4- Burkitt’s lymphoma (1)
- Nasopharyngeal carcinoma
14
Q
Persistent Infection
A
- produce new virions
- measles: causes brain degeneration
15
Q
Lytic Infections
A
- death of host cell
- cold viruses
- cause acute infection
