Lec 62: Basic Virology Flashcards
What is unique about viral replication compared to other pathogens?
- Obligate Parasites: cannot replicate on their own, lack the machinery to repliate genome
- Must infecy host to replicate
What are the key structural components of the viruses?
- proteins
- envelope
- nucleic acids
Describe the types and characteristics of viral proteins.
- Found in all viruses
- Capsids
- structural proteins
- Icosahedra, Helical
- Enzymes
- M proteins
Describe the components of the enveloped vs. non-enveloped viruses.
- enveloped
- found only in some viruses
- composed of lipids
- makes virus susceptible to detergents
- non-enveloped
- glycoprotein layer
- very hearty, resistant
What are the classifications of DNA viruses?
- Enveloped
- dsDNA (linear)
- dsDNA (circular)
- Non-enveloped
- dsDNA (circular)
- ssDNA (linear)
- dsDNA (linear)
What are the classifications of RNA viruses?
- Enveloped
- retrovirus (+ssRNA —> DNA intermediate)
- -ssRNA
- +ssRNA
- Non-enveloped
- +ssRNA
- dsRNA
What are the 7 virus types according to Baltimore Classification?
- Group I: dsDNA
- Group II: +ssDNA
- Group III: dsRNA
- Group IV: +ssRNA
- Group V: -ssRNA
- Group VI: +ssRNA (reverse transcription)
- Group VII: dsRNA (reverse transcription)
What are the goals of viral replication?
- make viral proteins
- duplicate viral genome
Where do RNA viruses generally replicate? Where do DNA viruses generally replicate?
RNA: cytoplasm
DNA: nucleus
Describe the major viral replication enzymes, their roles, and their sources.
-
RNA-dependent RNA polymerase
- replicates RNA from RNA template
- source: all RNA virses
-
RNA-dependent DNA polymerase
- reverse transcriptase, reverse transcribes RNA to DNA
- source: virus
-
DNA-dependent RNA polymerase
- transcribes RNA from DNA template
- source: host
-
DNA polymerase
- replicates DNA from DNA
- source: host/virus
What are the steps in the viral replication cycle?
- attachment & entry into host cell
- viron uncoating
- transcription of viral mRNA
- translation of viral mRNA (viral protein production)
- replication of viral genome
- assembly of virons (viral proteins encapsulate viral genes)
- virons released from host cell via budding or lysis
What do all viruses transcribe before protein translation?
mRNA (+ssRNA)
What is the general process of viral protein synthesis?
**General Process: **Viral DNA/RNA –> mRNA –> proteins
Exception: Viral RNA retrovirus –> DNA –> mRNA –> proteins
+ssRNA replication
-ssRNA replication