Picornavirus and Myxovirus Flashcards
picornavirus genome
- single stranded RNA, plus strand
- can be immediately translated
picornavirus early events
- receptor mediated absorption
- entry by endocytosis
- fusion of capsid with cell mem
- genome enters cytolasm
translation of picornavirus
-association of genome with cellular ribosomes yields the viral polyprotein
picornavirus polyprotein cleavage
-polyprotein is cleaved into viron proteins: VpG, protease, and replicase
picrornavirus replication
- viral RNa replication uses VpG protein as a primer
- minus stands are more efficient templates therefore there is a preponerance of plus strands made
picornavirus capsid assembly
- at an adequate concentration Vp’s assemble into capsids
- capsids are stuffed with RNA
(ortho) myxovirus
- widespread
- resevoir in water fowl
- ause of mostly respiratory ingections of hmans and other animals
- two mahjor types, A and B
- divided by antigenicity of the surface proteins hemagglutinin (HA) and neuraminidase (NA) into serotypes: H1N1, H2N2
- high level of genetic mixing (recombination) to generate novel serotypes associated with occasional pandemics
- antigenic drift and shift
genome of myxovirus
- single stranded RNA minus strand
- 8 segments of RNA
- each encodes for a different protein
- no poly A tail or 5’ cap
myxocirsu composition/structure
- hemagglutinin (HA)
- neuraminidase (NA)
- matrix protein (M1)
- 8 nucleocapsids: nucleoprotein (NP), transcriptase, and RNA genome
agglutination assay for viral adsorption
- measure the amount of virus
- type the virus with antibody
myxovirus early events
- adsorption via interaction of HA with sialic acid on cell surface
- penetration by recepto mediated endocytosis
- pH triggered fusion and uncoating
- transport of RNa to nucleus, RNA must be in nucleus to replicate
myxovirus transcription
- steal 5’ caps from cellular mRNA. synthesize viral + mRNA using stolen caps as primer. Add polyA through a viral mech
- transport mRNA to cytoplasm
myxovirus translation
- synthesis of viral proteins
- soluble proteins transported to nucleus
- membrane proteins trafficked to plasma membrane
myxovirus replication
- plus and minus stand RNA replication
- NP protein is the critical factor
- presence of NP protein allows synthesis of plus strand to serve as template for synthesis of genomes
myxovirus membrane assembly and release
-release of virions by budding
