Module 10 Flashcards
2 types of RNA viruses
Positive and negative stranded
Which RNA virus strand can immediately be translated?
positive strand
Which RNA virus strand cannot be immediately translated?
negative strand
What enzyme is necessary for RNA viruses to transcribe a negative strand virus?
RNA-dependent RNA polymerase
What enzyme for RNA transcription do humans not possess?
RNA-dependent RNA polymerase
This RNA virus can incorporate into the host genome
retroviruses (like HIV)
This is the only virus group with a dsRNA genome
Reoviridae (like rotavirus)
What type of strand do most DNA viruses have?
both positive and negative strands
What makes parvoviruses an exception to DNA virus genome rules?
they’re ssDNA
2 types of viral capsids
icosahedral and helical
What type of viruses have helical symmetry
RNA viruses
Capsid shape of rhabdoviruses (like rabies)
bullet shaped
What type of viruses have icosahedral symmetry?
DNA viruses
How do viruses acquire a viral envelope
by budding through a host cell nuclear or cytoplasmic membrane and taking a piece with it
List the DNA viruses
think HHAPPPy: Hepadna, Herpes, Adeno, Papova, Parvo, Pox
List the RNA viruses
just think it’s everything except HHAPPPy
4 steps of viral replication
adsorption and penetration, uncoating of the virus, synthesis and assembly of viral products, and release of virions from the host cell by lysis or budding
passage of virion from surface of the cell across the cell membrane and into the cytoplasm
penetration
cell membrane invaginating that encloses a virion in an endocytic vesicle
receptor-mediated endocytosis
How do some enveloped viruses, like HIV, enter a host cell?
membrane fusion of the viral envelope with the host plasma membrane
stepwise process of disassembly of a virion that enables the expression of viral genes that carry out replication
uncoating
Where do viral DNA transcription and replication occur?
host cell nucleus
What form of mRNA codes for capsid structural proteins?
late mRNA
2 problems RNA viruses encounter
no host cell RNA polymerase to use and usually eukaryotic mRNA only produces one polypeptide
Type I RNA virus replication
ssRNA with + polarity that replicates via complementary (-) strand intermediate
Type II RNA virus replication
ssRNA with - polarity that replicates via a complementary (+) strand intermediate
Type III RNA virus replication
Viruses with a dsRNA genome- have to have RNA dependent RNA polymerase/transcriptase in order to transcribe
Type IV RNA virus replication
ssRNA of + polarity that is replicated by a DNA intermediate (uses reverse transcriptase, or RNA-dependent DNA polymerase)
Assembly of RNA viral nucleocapsids happens in the:
cytoplasm
Assembly of DNA viral nucleocapsids happens in the:
nucleus
Difference in release of naked virions vs enveloped virions
naked are exocytosed and enveloped virions bud out
4 possible outcomes from viral infection in a cell
non permissive (virus can’t replicate or cell dies too fast), permissive (virus replicates but doesn’t do anything), latent viral state, host cell death and viral release through lytic cycle
viral family that includes all influenza viruses
orthomyxoviridae
viral family that includes mumps, measles, RSV, and parainfluenza
paramyxoviridae
Flu symptoms that differentiate it from a cold or other viral infection
muscle aches, high fever, and headaches
structure of orthomyxoviridae virions
spherical, with 8 negative stranded RNA with a nucleocapsid with helical symmetry capsid
2 types of glycoprotein spikes on orthomyxoviridae
hemagglutinin activity (HA) and neuraminidase activity (NA)
What does hemagglutinin attach to?
sialic acid receptors on the surface of erythrocytes