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Animal and Plant viruses Plate Culture of Animal Viruses Figure 6.33 Figure 6.20 Papillomavirus (DNA) Life Cycle Figure 6.22 Picornavirus (RNA) Life Cycle Figure 6.23 Figure 11.15 Poliovirus Structure • 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. 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 Poliovirus Replication • 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. Figure 11.13A Influenza Virus Structure • The flu virus has no geometric capsid. • RNA genome is loosely contained by a shell of matrix proteins. Figure 11.16 RNA segments are coated with nucleocapsid proteins (NPs). Two major envelope proteins: - Neuraminidase (NA) - Hemagglutinin (HA) Influenza virus: note envelope The Genome of Influenza A Virus Figure 11.17 • 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 Influenza Virus Entry • Animation: Influenza Virus Entry into a Cell Click box to launch animation Figure 11.21 Influenza Virus Replication • Animation: Influenza Virus Replication Click box to launch animation Herpes Simplex Virus Structure • An icosahedral capsid houses the dsDNA genome. Capsid is surrounded by a protein tegument, which is contained within an envelope with spike proteins. Figure 11.31A Figure 11.32 Herpes Virus Replication • Animation: Herpes Virus Replication Click box to launch animation • 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 Fig. 19-11 tRNA-like structure Stop codon Cap MTH RNP MP CP A viroid Figure 6-6 Viroids: infective RNA. Figure 6-7 Prion disease.