CH 7 VIRUSES Flashcards
About how small are viruses?
0.02-0.3 mcg
Why are viruses different from living cells?
Cannot metabolize or reproduce independently
How are viruses classified?
By morphology and type of genetic material
Name two classification systems for viruses
- International committee for taxonomy of viruses
- Baltimore classification system
Name 2 general components of the viral covering
- Capsid
- Envelope
Name 2 general components of the viral core
- Nucleic acid
- Enzymes
What may surround the viral genome?
Nucleocapsid
What viral action causes tissue damage?
Reproduction
Viral capsule proteins that specialize in binding certain cell receptors determine the virus’s what?
Viral tropism
What are three mechanisms viruses use to enter through the cell membrane?
- Endocytosis
- Fusion
- Adherence and translocation
What is the cycle through which the viral genome is inserted into the host genome?
Lysogenic cycle
What is the cycle through which the virus directs the cell to produce new viral capsid proteins?
Lytic cycle
What are two ways viruses may exit the cell?
- Transport through vesicles
- Directly emerging through cell membrane
What are two reasons why some animal viruses are able to infect humans?
- Compatible viral receptor proteins
- Mutations of same
What are some cytopathic effects of viruses?
- Changes in morphology
- Abnormal fusion
- Gene mutation leading to atrophy, hyperplasia, or dysplasia
What advantage do enveloped viruses have?
A patch of the host cell’s membrane stay with the virus as it buds off, which helps it to integrate into the next cell.
Name 3 types of enveloped DNA viruses
- Poxviruses
- Herpesviruses
- Hepadnaviruses
Which enveloped DNA virus causes smallpox?
Variola virus
How is variola virus transmitted?
Contact
What tissue does variola virus target, and where does it multiply?
Respiratory tract, lymph nodes
Name 8 types of herpesviruses
- Herpes simplex 1
- Herpes simplex 2
- Varicella zoster
- Cytomegalovirus
- Epstein-Barr
- Human herpes 6
- Human herpes 7
- Human herpes 8
How are herpesviruses transmitted?
Contact and respiratory aerosol
After initial manifestation of a painful vesicle, where do herpesviruses go to enter latency?
Dosal root ganglia
Which enveloped DNA virus causes cold sores and oral herpes?
HSV1
Which enveloped DNA virus causes genital herpes?
HSV2
How are herpes simplex viruses activated?
Stress causes corticosteroid induced activation of JNK protein
Which enveloped DNA virus causes chickenpox and shingles?
Varicella zoster virus