viruses Flashcards
(25 cards)
TLRs for Viruses
3 for dsdna in endosome leads to IFN B
7 for ssRNA leads to IFN a and b
Innate response to viruses
Infected cells produce IFN a and b, IL6, IL12, chemokines
- self to increase IFN exp
- paracrine - alert cells to virus state and increase DAI a transL inhib
- Increases MHC exp for CTL NK and DC recog
Adaptive response to viruses
Recruit TH1 via MHC 1 to resolve
Recruit TH2 to make antiviral Abs
Timeframe of virus
Acute - influenze Latent - chickenpox
Viral evasion strategies
- Ag variation
- downreg mhc 1
- downreg LFA3 and Icam
- Infect immunopriveledged sites
- Infect immune system
Helical enveloped viruses
Paromyxovirus, Rabies - dev protomer with nuc acid with each polypeptide
Icosahedral viruses
Adenovirus; can be empty
Enveloped virus
HIV; peplomers on envelope
Complex virus
doub membrane; smallpox
Stages of viral infection
attach, penetrate, uncoat, macromolec synth and rep, assembly, progent
Penetration stage of infection
- Surface fusion - ph indep, membrane fusion leading to syncytia ex: pesvirus, paramyxovirus, HIV
- Endosomal fusion (enveloped viruses) - ph dep via receptor to endosome to nuc, influenze
- Lysosomal uncoat - adenovirus, binds r, naked to endosome, release in cytoplasm, nucleoplasmid with coat binds nuc envelope and injects
- Pore formation - poliovirus, virus docks, endo, and releases nuc from endosome via pore
HIV binding
gp120CD4, CCR5, gp41 penetration, membrane fusion
Replication sites
- Cytoplasm: most RNA viruses (except = Retrovirus) and Poxvirus (DNA)
- Nucleus: most DNA viruses (except = Poxvirus) and Orthomyxovirus (RNA)
1 and 2: Retrovirus and Hep (DNA virus)
dsDNA rep
Herpes, papillomavirus - uses host DNA and RNA poly (ex = poxvirus brings own DNA and RNA poly
ssDNA
Parovirus - uses host DNA and RNA poly
dsDNA
Rotavirus - makes own RNA transcriptase and RNA replicase
ssRNA + sense
+ taken by ribosome to polyproteins (degraded to form functional units) to make viral RNA poly to transC - RNA and viral RNA poly to rep (ex = Poliovirus, Rhinovirus, Flavivirus)
ss - sense RNA
Influenza Measles - packed with RNA polymerase, use RF as needs + to rep, synth of proteins via polycistronic and segmented genome
ss + sense RNA with DNA intermediate
Retrovirus and HIV, Has viral reverse transcriptase to make RNA/DNA hybrid to dsDNA and uses host RNA poly
partially dsDNA w/RNA intermediate
HepB; moves to nuc as circ DNA, uses host RNA poly to make - sense strand, brings reverse transcriptase with DNA poly
Segmented Genome
allows genomic mixing, reassortment ie 2 variants infect cell and create noval virus
Phenotypic mixing
2 diff viruses same cell - change coat and therefore tropism
Diag inclusion bodies
Negri bodies - Rabies; Owl Eyes - CMV
HAI Assay
Hemagglutination inhib for antiviral titer so dot = virus
