Viruses Flashcards
Influenza Genome
ssRNA
Influenza structure (main proteins) (4)
HA, NA, M2, M1
Influenza cell entry (5)
(1) three spikes of HA bind to sialic acid on HC
(2) receptor mediated endocytosis occurs
(3) low endosomal pH triggers fusion of viral and endosome membrane - low pH induces conformational change in shape of H0 - leads to exposure of HA2 fusion peptide
(4) low pH also opens M2 proton selective channel - acidifies viral core
(5) release of vRNP so free to enter host cell cytoplasm
Influenza transcription and replication (2)
(1) converted to positive sense RNA by RNA dependent RNA polymerase (RdRp)
(2) cellular RNA polymerase II binds to DNA and starts transcripiton
Influenza immune responses (3)
- induces strong IFN production - induces non-permissive state in neighbouring cells
- humoral mediated immunity - HA specific antibodies found
- RIG-1 is main PRR against influenza virus infections
Influenza M2 ion channel inhibiting drugs
Amantadine and Rimantadine
Influenza RNA polymerase inhibitor
Favipiravir
Influenza NA inhibitor
Zanamivir
Herpes Genome
dsDNA
HHV-1
Herpes simplex - cold sore - trigeminal ganglion infection (60% US prevalance)
HHV-2
Herpes simplex - genital herpes - sacral ganglion (20% US prevalence)
HHV-3
Varicella (chicken pox) Zoster (shingles) virus
HHV-4
Epstein Virus
Herpes Cell entry (6)
- gC and gB bind to heparan sulfate
- gD binds to HVEM, nectin-q, or 3-0 sulfated heparan sulphate
- nectin receptors produce cell-cell adhesion
- gD (once bound to HVEM), changes conformation and interacts with gH and gL
- interaction results in hemifusion state
- gB interaction with gH/gL results in creation of entry pore
Herpes Virus immune evasion (4)
- Block MHC I expression and promote degradation
- inhibit proteosome
- block TAP transporter
- block expression of activatory NK ligands
Herpes virus treatment (1)
acyclovir and glancyclovir - thymidine anlogues
HIV genome
ssRNA
HIV cell entry (4)
- Gp120 binds to CD4
- co-receptor binding (CCR5/CXCR4)
- interaction between CD4 and gp120 allows exposure of fusion proteins in the gp41 subunit - inserts into host cell membrane and acts as a tether
- mixing of lipids which compose the membranes and entry
HIV replication (4)
Uses Reverse Transcriptase
- polymerase center uses host cell tRNA to use viral RNA as a template - RNA-DNA strand formed
- RNaseH center used to degrade RNA component
- dsDNA formed
- integrase effectively cuts and pastes the viral DNA in to the gebome
HIV transcription
- immediately after replication, only Tat and Rev produced
- Tat increases transcription of HIV-1 genes by recruiting cellular transcription factors
- primary RNA transcripts undergo extensive splicing - results in over 40 different mRNAs
HIV antiviral drugs (3)
Tak-220 - prevents binding of CCR5 to gp120
Enfuvirtide - targets membrane fusion
Zidovudine - thymidine analogue which prevents action of RT
Hepatitis Genome
dsDNA
