RNA 2 Flashcards
List the respiratory viruses.
Picorna- (rhino, some entero) Paramyxo Orthomyxo Corona Adeno (naked DNA)
Influenza
orthomyxo family
enveloped, helical, negative strand, ss
naturally infect a variety of species
RNA Segments for Influenza A
1, 2, 3, 5, 8 = non-structural
4 = hemagluttinin, attachment
6 = neuramininidase, virus release
7 = matrix (M1, M2 proteins) = genome export, M2 important for getting genome out
Why are viral surface proteins important?
- Entry & Release
2. Targets of neutralizing Abs
Hemagglutinin
binds sialic acid for ATTACHMENT AND ENTRY of virus
trimer, highly variable AA sequence
HA0 = cleaved by cellular proteases in resp. epithelium into HA1, HA2
HA 1 = attachment
HA 2 = fusion
HA 1
attachment
HA 2
fusion
Neuraminidase
cleaves sialic acid during release (when virus exits cell)
tetramer, spreading factor by dissolving mucus
allows for viral budding/spreading by cleaving virus from excess sialic acid and mucus
critical for release of virus from cell
Neuraminidase is target for which drugs?
Tamiflu, Relenza
Subtypes of HA, NA
18, 3 in humans
11, 2 in humans
What is the fusion peptide?
the newly formed amino terminal of HA2 is hydrophobic and inserts into endosomal membrane to initiate fusion with the viral envelope
M1
matrix
M2
ion channel/nuclear pore
Galactose + Sialic Acid 2 Different Linkages
Alpha (2,3) linkage – cleavage in LOWER RT – avian
Alpha (2,6) linkage – cleavage in UPPER RT – human
Antiviral Drugs for Influenza
Amantadine & Rimantadine = A only, targets M2 ion channel and blocks virion fusion – stops viral spread
Zanamivir (Relenza) & Oseltamavir (Tamiflu) = A&B, target virus release by inhibiting NA – cant dump its genome
