1 / 10

Introduction to Virology

Introduction to Virology. What are viruses ?. Submicroscopic particles. Nucleic acid contained within a protective protein coat Infect bacteria, plants, animals (inc humans). Differences from bacteria viruses CANNOT replicate outwith a cellular environment

layne
Download Presentation

Introduction to Virology

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. Introduction to Virology

  2. What are viruses ? Submicroscopic particles Nucleic acid contained within a protective protein coat Infect bacteria, plants, animals (inc humans) • Differences from bacteria • viruses CANNOT replicate outwith a cellular environment • viruses ARE NOT affected by antibiotics

  3. Virion (virus particle) structure 1. genome nucleocapsid 2. capsid ± 3. envelope envelope glycoproteins

  4. 1- Viral Nucleic Acids • DNA or RNA [cell genetic material is DNA] • ss or ds • linear or circular • segmented/non-segmented • size 2-300 kb(p) [cell genome 3x106kbp] Viral Proteins • Structural • Components of capsid (protective coat) and other components of the virion • Non-structural • Required for viral replication and interaction with host

  5. 2- Nucleocapsid • Capsid is protein coat that protects the nucleic acid: physical, chemical, enzymatic attack • Nucleocapsid comprises the capsid and enclosed nucleic acid • facilitates entry into cell and delivery of nucleic acid • exposed to immune system genome nucleocapsid capsid

  6. Icosahedral (or cubic) Some icosahedral animal viruses are enveloped 20 faces each face an equilateral triangle axes of 2-, 3- and 5-fold rotational symmetry Capsomer structure enclosing maximum volume herpesvirus adenovirus

  7. Helical Simple viruses with small genomes use this architecture to provide protection for the genome without the need to encode multiple capsid proteins. Rabies virus (rhabdovirus)

  8. Complex Virus Structures Most animal viruses fall into three structural classes, helical capsid (enveloped) icosahedral capsid (nonenveloped) or icosahedral capsid (enveloped) However, more complex structures do exist e.g. pox viruses

  9. 3 – Virus Envelope • Envelopes are LIPID BILAYERS acquired from cellular membranes e.g. endoplasmic reticulum, nuclear membrane, plasma membrane • viral proteins are associated with/inserted into membrane

  10. Stability of Viruses • Non enveloped viruses more ‘hardy’ than enveloped viruses • Different viruses have differential ability to survive • Sensitive to temperature, pH, dessication, lipid solvents, detergents • Most inactivated at >55-60oC • Detergents used to disrupt viral envelopes • Rotavirus survives pH of stomach

More Related