1. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Attachment, Penetration, and Uncoating Figure 13.14

2. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Release of an enveloped virus by budding Figure 13.20

3. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Multiplication of DNA Virus Figure 13.15 Virion attaches to host cell Virion penetrates cell and its DNA is uncoated Early transcription and translation; enzymes are synthesized 1 2 3 DNA Late transcription; DNA is replicated 4 Late translation; capsid proteins are synthesized 5 Virions mature 6 Capsid Papovavirus Host cell DNA Cytoplasm Virions are released 7 Capsid proteins mRNA

4. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Pathways of Multiplication for RNA-Containing Viruses Figure 13.17

5. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Multiplication of a Retrovirus Figure 13.19 Retrovirus penetrates host cell. Virion penetrates cell and its DNA is uncoated The new viral DNA is tranported into the host cell’s nucleus and integrated as a provirus. The provirus may divide indefinitely with the host cell DNA. 1 2 3 DNA Transcription of the provirus may also occur, producing RNA for new retrovirus genomes and RNA that codes for the retrovirus capsid and envelope proteins. 4 Mature retrovirus leaves host cell, acquiring an envelope as it buds out. 5 Capsid Reverse transcriptase Virus Two identical + stands of RNA DNA of one of the host cell’s chromosomes Provirus Host cell Reverse transcriptase Viral RNA RNA Viral proteins Identical strands of RNA

6. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Activated oncogenes transform normal cells into cancerous cells. Transformed cells have increased growth, loss of contact inhibition, tumor specific transplant and T antigens. The genetic material of oncogenic viruses becomes integrated into the host cell's DNA. Cancer

7. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Oncogenic DNA Viruses Adenoviridae Heresviridae Poxviridae Papovaviridae Hepadnaviridae Oncogenic Viruses Oncogenic RNA viruses Retroviridae Viral RNA is transcribed to DNA which can integrate into host DNA HTLV 1 HTLV 2

8. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Latent Viral Infections Virus remains in asymptomatic host cell for long periods Cold sores, shingles Persistent Viral Infections Disease processes occurs over a long period, generally fatal Subacute sclerosing panencephalitis (measles virus)

9. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Infectious proteins Inherited and transmissible by ingestion, transplant, & surgical instruments Spongiform encephalopathies: Sheep scrapie, Creutzfeldt-Jakob disease, Gerstmann-Sträussler- Scheinker syndrome, fatal familial insomnia, mad cow disease PrP C, normal cellular prion protein, on cell surface PrP Sc, scrapie protein, accumulate in brain cells forming plaques Prions

10. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Prions Figure 13.21 PrP c PrP Sc 1 2 34 5 678 Endosome Lysosome

11. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.22 Plant Viruses Plant viruses enter through wounds or via insects Viroids Viroids are infectious RNA; potato spindle tuber disease

12. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Some Plant Viruses Table 13.6