dsRNA produced during infection cleaved by DICER into small RNAs - termed small-interfering RNAs
siRNAs are loaded into RISC (RNA Induced Silencing Complex)
RISC identifies viral mRNAs containing identical sequences
Slicer, a nuclease in RISC, cleaves viral RNA
PAMP: pathogen-associated molecular pattern
detects the pathogen; must identify specific aspects
Common PAMPS:
dsRNA or ssRNA in endosomes
DNA in the cytoplasm or unique nuclear compartments
specific viral proteins
interaction of PRRs with viral nucleic acids leads to activation of signaling cascades
cascades require unique signaling platform proteins
result in activation of transcription factors that go to the nucleus and initiate transcription of IFN genes
IFN: interferon; interfered with virus replication
IFN secreted from the cell
bind to receptor which initiates another signaling cascade involving JAK-STAT signaling
STAT proteins are phosphorylated which induced their translocation to the nucleus
STAT proteins act as transcription factors to initiate transcription of genes
final result: production of IFN stimulated genes or ISGs
APOBEC3G: cytodine deaminase (mutates viral DNA)
Zinc-antiviral protein (ZAP): binds viral RNA at CG dinucleotides and recruits cellular enymes to degrade it
Tetherin: binds to viral particles and prevents their release
IFITM3 (IFN transmembrane 3): blocks entry of enveloped viruses
Ly6E: prevents membrane fusion of enveloped viruses
TRIM5alpha: inhibits HIV uncoating
Dicer
RISC
siRNA
dsRNA
cytoplasmic DNA
ssRNA
Mda-5
RIG-1
cGAS
myD88
MAVs
STING
ZAP
Tetherin
STATS
NFkB
IRF-3