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• The capsid is fundamentally icosahedral. • - Composed of three external proteins (VP1–3)• - VP4 protein subunits coat the interior and
help package the (+) strand RNA genome.
Poliovirus Structure
Figure 11.11B
• The poliovirus binds to poliovirus receptor (PVR) through its VP2 and VP3 subunits.
• - A conformational change in VP1 allows insertion of the genome into the cytoplasm.
Figure 11.12
• In the cytoplasm, the RNA is translated to make three large precursor peptides: P1–3.
• - All three peptides are eventually cleaved by proteases to generate 11 proteins.
Poliovirus Replication
Figure 11.13A
• The flu virus has no geometric capsid. • RNA genome is loosely contained by a shell of matrix
proteins.
Influenza Virus Structure
Figure 11.16
RNA segments are coated with nucleocapsid proteins (NPs).
Two major envelope proteins:- Neuraminidase (NA)- Hemagglutinin (HA)
• The key advantage of a segmented genome is that it facilitates recombination between two strains coinfecting the same cell.
• - Instant new strain can evade the immune system.
Figure 11.18B
• An icosahedral capsid houses the dsDNA genome.
Herpes Simplex Virus Structure
Capsid is surrounded by a protein tegument, which is contained within an envelope with spike proteins.
Figure 11.31A
• Within a plant, the thick cell walls prevent a lytic burst or budding out of virions.
• - Instead, plant viruses are transmitted to uninfected cells by plasmodesmata.
Figure 6.26