DD- HOST RESPONSE Flashcards
Virus Structure/Function
Gene expression. Decode the information in the genome (make mRNA and translate proteins)
Replication. Make more copies of the genome
Assembly. Package the new genomes in infectious particles
All RNA viruses encode an:
RNA-dependent RNA polymerase RdRp
Seven Classes of Viral Genomes and Replication schemes
dsDNA Gapped circular DNA ssDNA dsRNA ss(+)RNA ss(+)RNA with DNA intermediate ss(-)RNA
Production of virus particles depends on host cell machinery:
Assembly
- cellular proteins that catalyze or assist the folding of individual protein molecules
- cell transport systems move viral proteins and nucleic acids to sites of assembly
- Membrane proteins enter the secretory pathway
- Nuclear proteins use nuclear import machinery
- Subunits move on the cytoskeleton using cellular motors
For helical nucleocapsids: Viral genomic RNA is generally _______during synthesis of the genome.
coated with nucleocapsid protein
For icosahedral capsids Viral genomic RNA is generally _______during synthesis of the genome.
The capsid assembles around the virus genome.
The genome is “fed” into preformed capsids
Enveloped viruses acquire the envelope from a variety of cellular membranes by
budding
- cellular proteins that catalyze or assist the folding of individual protein molecules
Viral Assembly
Viruses that bud into the plasma membrane are released into the extracellular environment ______
directly
Viruses that bud into the membranes of the Golgi apparatus or endoplasmic reticulum are secreted from the _____.
infected cell
- cell transport systems move viral proteins and nucleic acids to sites of assembly
Viral Assembly
Viruses are obligate intracellular parasites, therefore we generally cannot see virus infection & replication, and instead we see the effects of viral infection & replication on_______
infected cells and tissues.
The ______specific virus and the specific cell or target tissue.
result of viral infection of a cell depends on the
- Membrane proteins enter the secretory pathway
Viral Assembly
Viruses are _______, therefore a delicate balance with host is necessary for survival
obligate intracellular parasites
______ or primary defenses are immediate and non- specific.
Innate
- Nuclear proteins use nuclear import machinery
Viral Assembly
Indirect cell damage from a virus can result from
- integration of the viral genome
- induction of mutations in the host genome
- inflammation
- host immune response
________ result in the destruction of the host cell
Lytic infections
Enveloped viruses acquire the _____ from a variety of cellular membranes by budding
envelope
- Subunits move on the cytoskeleton using cellular motors
Viral Assembly
Viruses are _______, therefore we generally cannot see virus infection & replication, and instead we see the effects of viral infection & replication on infected cells and tissues.
obligate intracellular parasites
Innate or primary defenses are immediate and non- specific.
Adaptive immunity is acquired during infection and results in immunologic memory, that is a quantitatively and qualitatively _______ upon second exposure.
enhanced response
__________ include enveloped viruses that are released by budding (without lysis of the cell) and may occur over relatively long periods of time
Persistent infections
________show a delay between the infection and appearance of symptoms.
Latent infections
_________ can be caused by some viruses, conferring cell growth without restraint. These are called oncogenic viruses.
Transformation
Innate defenses include:
natural barriers, cells, soluble factors
Type I IFNs (include IFNa and IFNb)
- antiviral cytokines transiently produced and secreted by most infected cells within hours of infection.
Type II IFN (IFNg) is produced:
mainly by T cells and NK cells, more restricted than Type I IFN production.
Cells respond to _____ through receptor activation of Jak/Stat signaling
IFN
________ and the inflammatory response are critical precursors to the adaptive immune response to viruses.
Innate immunity
IFN alters transcription of more than ______ cellular genes
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