1 / 21

Survey of Viruses

Survey of Viruses. Chapter 24. Definition of a Virus. Sub microscopic entity consisting of a single nucleic acid surrounded by a protein coat and capable of replication only within the living cells of bacteria, animals or plants. Definition of a Virus. Obligate Intracellular Parasite.

azriel
Download Presentation

Survey of Viruses

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Survey of Viruses Chapter 24

  2. Definition of a Virus Sub microscopic entity consisting of a single nucleic acid surrounded by a protein coat and capable of replication only within the living cells of bacteria, animals or plants.

  3. Definition of a Virus Obligate Intracellular Parasite

  4. Lipid Envelope Nucleic Acid Protein Capsid Virion Associated Polymerase Spike Projections Virion Structure

  5. Virion Morphology • Simple Structure • Repetitive Structure • High Level of Redundancy

  6. Helical Icosahedral Virus Morphology

  7. 1 Virus attachment and entry 1 2 Uncoating of virion 3 Migration of genome nucleic 5 acid to nucleus 4 Transcription 4 2 5 Genome replication 6 Translation of virus 3 mRNAs 7 Virion assembly 7 8 Release of new virus particles 6 8 Virus Replication

  8. Transmission of Viruses • Respiratory transmission • Influenza A virus • Faecal-oral transmission • Enterovirus • Blood-borne transmission • Hepatitis B virus • Sexual Transmission • HIV • Animal or insect vectors • Rabies virus

  9. In vivo Disease Processes • Cell destruction • Virus-induced changes to gene expression • Immunopathogenic disease

  10. Acute Virus Infections • Localised to specific site of body • Development of viraemia with widespread infection of tissues

  11. Poliovirus

  12. Poliovirus Properties of the virus • Enterovirus. • Possesses a RNA genome. • Transmitted by the faecal oral route. • Cause of gastrointestinal illness and poliomyelitis.

  13. Influenza A virus Properties of the virus • Myxovirus • Enveloped virus with a segmented RNA genome • Infects a wide range of animals other than humans • Undergoes extensive antigenic variation • Major cause of respiratory infections

  14. Influenza A virus Infection • Spread by respiratory route • Virus infects cells of the respiratory tract • Destruction of respiratory epithelium • Secondary bacterial infections • Altered cytokine expression leading to fever • e.g interleukin-1 and interferon

  15. Spread of influenza virus

  16. Respiratory Tract

  17. Other Viral Infections • Herpes • Hepatitis • Rhinovirus • HIV • Ebola • Measles • Mumps • Smallpox • Chickenpox

  18. Human H2N2 Human H3N2 Genetic Reassortment Avian H3N8 Point mutation of HA and NA genes Generation of Novel Influenza A Viruses ANTIGENIC SHIFT ANTIGENIC DRIFT

  19. Antiviral Targets • Attachment/Entry • Nucleic acid replication • Virus protein processing • Virus maturation

  20. Problems with Antivirals • Identification of virus-specific target. • Generation of resistant variants.

More Related