1. VIRUS

2. A little bit of history 10 th century: Muhammad ibn Zakarīya Rāzi (Rhazes) wrote the Treatise on Smallpox and Measles 1020’s: Avicenna described virus diseases in The Canon of Medicine 1392 : “Virus” (from Latin which means poison) first used in English 1400’s: “Virulent” (means poisonous) first used 14 th century: Ibn Al-Khtib wrote about Black Death Plague in On the Plague 1892: Dmitry Ivanovsky discovered tobacco mosaic virus Late 18 th century: Edward Jenner found smallpox vaccine Early 20 th century: Frederick Twort discovered bacteriophage 1931: Ernest William Goodpasture demonstrated the growth of influenza and several other viruses in fertile chicken eggs 1935: Wendell Stanley crystallized the tobacco mosaic virus 1949: John Franklin Enders, Thomas H. Weller and Frederick Chapman Robbins together developed a technique to grow polio virus in cultures of living animal cells

3. What is virus? Virus is a genetic element containing either RNA or DNA that replicate only in specific host cells but is characterized by having an extracellular state In the extracellular state, virus is a submicroscopic particle, also called virion, containing nucleic acid surrounded by protein and occasionally other macromolecular component Virion is only a structure which carries virus genome between host cells and it has no metabolic activity

4. Virus Structural Properties Nucleic acid located within particle: dsDNA, ssDNA, dsRNA, or ssRNA Capsid: protein coat surrounding nucleic acid Morphological units or capsomeres: units which form capsid, visible under electron microscope Structural subunits: protein molecules which form capsomeres Nucleocapsid: a complete complex of nucleic acid and protein coat Some viruses have lipid bilayer which enveloped its nucleocapsid, and are called enveloped virus. The ones which don’t have envelope are called naked virus

5. A = naked virus B = enveloped virus 1 = capsid 2 = nucleid acid 3 = capsomer 4 = nucleocapsid 5 = virion 6 = envelope 7 = spikes Icosahedral Viruses

6. Helical Viruses

7. Complex viruses

8. Virus Multiplication Attachment/Adsorption Penetration Uncoating Biosynthesis Assembly Release

10. Biosynthesis Method

11. Virus Classification ICTV = International Committee on Taxonomy of Viruses Hierarchy of virus classification: – Ordo: -virales – Family: -viridae – Subfamily: -virinae – Genus: -virus – Species Species concept: A polythetic class of viruses that constitute a replicating lineage and occupies a particular ecological niche

12. Virus Classification Basis morphology (size, shape, enveloped/naked) physicochemical properties (molecular mass, buoyant density, pH, thermal, ionic stability) genome (RNA, DNA, segmented sequence, restriction map, modifications etc) macromolecules (protein composition and function) antigenic properties biological properties (host range, transmission tropism etc)

13. Current Data According to 7 th Report of the ICTV (2000), there are: – 3 orders, – 56 families, – 9 subfamilies, – 233 genera – and 1550 virus species

14. Other Methods of Virus Classification Baltimore classification: based on nucleic acid type and replication method --> divide viruses into seven groups Holmes classification: based on host --> divide viruses into three groups LHT classification: based on chemical and physical characters like nucleic, Symmetry, presence of envelope, diameter of capsid, number of capsomers Casjens and Kings classification: based on type of nucleic acid,presence of envelope, symmetry and site of assembly --> divide viruses into four groups

15. Baltimore Classification

16. Plant Viruses

17. Plant Viruses Infection Plant cells have thick cell wall and plasmodesmata Plant viruses do not appear to specifically interact with host cell membranes or cell walls, as do bacterial and animal viruses Infection mechanism appear to be: 1.passive carriage through breaches in the cell wall in the first instance 2.followed by later cell-to-cell spread in a plant by means of specifically-evolved "movement" functions, and perhaps spread via conductive tissue as whole virions

18. Passive Carriage of Plant Viruses a purely mechanical injury that breaches the cell wall and transiently breaches the plasma membrane of underlying cells; similar gross injury due to the mouthparts of a herbivorous arthropod, such as a beetle; injection directly into cells through the piercing mouthparts of sap-sucking insects or nematodes; carriage into plant tissue on or in association with cells of a fungal parasite; vertical transmission through infected seed or by vegetative propagation; transmission via pollen; and grafting of infected tissue onto healthy tissue.

19. Animal Viruses

20. Animal Viruses Infection

21. Fate of Infected Cells

22. Animal Virus Release

23. Bacteria Viruses

24. Bacteriophage Infection The phage tail fibres are the attachment sites; these individually bind the bacterial cell surface - specifically to certain lipopolysaccharides and to the surface outer membrane protein. After tail fibre binding has consolidated, the baseplate then settles down onto the surface and binds firmly to it. After this occurs, a comformational changes takes place in baseplate and sheath protein structures, and the tail sheaths contracts, pushing the tail core through the cell wall, possibly in an ATP-driven process: this is aided by a lysozyme activity associated with the baseplate assembly. DNA is then extruded from the phage head.

25. Bacteriophage Cycles

26. TERIMA KASIH