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VIRUS

VIRUS. THE TYPICAL VIRUS. NUCLEIC ACIDS. GENOME DNA OR RNA SINGLE STRANDED DOUBLE STRANDED LINEAR CIRCULAR SEGMENTED. CAPSIDS. ENCLOSES NUCLEIC ACID MAKES UP MOST OF MASS CAPSOMERES. ENVELOPE. MEMBRANE COVERING ENDOPLASMIC RETICULUM GOLGI BODY NUCLEAR MEMBRANE CELL MEMBRANE.

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VIRUS

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  1. VIRUS

  2. THE TYPICAL VIRUS

  3. NUCLEIC ACIDS • GENOME • DNA OR RNA • SINGLE STRANDED • DOUBLE STRANDED • LINEAR • CIRCULAR • SEGMENTED

  4. CAPSIDS • ENCLOSES NUCLEIC ACID • MAKES UP MOST OF MASS • CAPSOMERES

  5. ENVELOPE • MEMBRANE COVERING • ENDOPLASMIC RETICULUM • GOLGI BODY • NUCLEAR MEMBRANE • CELL MEMBRANE

  6. ADVANTAGES OF AN ENVELOPE • SIMILAR TO HOST CELL MEMBRANES • HIDE FROM HOST IMMUNE SYSTEM • ATTACHMENT TO HOST CELLS

  7. DISADVANTAGES OF AN ENVELOPE • DAMAGED EASILY BY: • INCREASED TEMPERATURE • FREEZING • THAWING • pH ABOVE 8 OR BELOW 5 • LIPID SOLVENTS • CHEMICAL DISINFECTANTS

  8. ENZYMES • MOST HAVE ONLY NUCLEIC ACID IN CORE • SOME HAVE INACTIVE ENZYME • HIV

  9. VIRAL SHAPE AND SIZE • RANGE FROM 25-300NM • SHAPE DETERMINED BY CAPSOMERES OR ENVELOPE

  10. HELICAL CAPSID

  11. POLYHEDRAL CAPSID

  12. COMPLEX CAPSID

  13. BULLET SHAPED CAPSID

  14. ENVELOPED VIRUS

  15. HOST RANGE • ALL THE HOSTS A PARTICULAR VIRUS CAN INFECT • MOST ARE LIMITED TO ONE HOST AND SPECIFIC CELLS AND TISSUES • POLIO • RABIES

  16. VIRAL SPECIFICITY • SPECIFIC KINDS OF CELLS ATTACKED • PAPILLOMA VERY SPECIFIC • CYTOMEGALOVIRUSES VERY GENERAL

  17. FACTORS THAT AFFECT VIRAL SPECIFICITY • ABILITY TO ATTACH • ABILITY TO PENETRATE & ESTABLISH INFECTION • HOST ENZYMES, PROTEINS AND ORGANELLES

  18. CLASSIFICATION OF VIRUSES • PLANT, ANIMAL, BACTERIAL • DERMATOTROPIC, NEUROTROPIC, VISCEROTROPIC OR PNEUMOTROPIC • INTERNATIONAL COMMITTEE ON TAXONOMY OF VIRUSES (ICTV) • FAMILIES, GENUS AND SPECIES

  19. VIRAL NAMES • ENGLISH COMMON NAMES • FAMILY-RHABDOVIRIDAE • GENUS-LYSSA VIRUS • SPECIES-RABIES VIRUS • FAMILY-RETROVIRIDAE • GENUS-LENTIVIRUS • SPECIES-HUMAN IMMUNODEFICIENCY VIRUS

  20. VIRAL NAMES • OFTEN HAS GROUP NAME AND NUMBER • HIV 1 • HIV 2

  21. HOW VIRUSES ARE NAMED • NUCLEIC ACID TYPES • CAPSID SYMMETRY • ENVELOPE • SIZE

  22. THE ICTV HAS ASSIGNED MORE THAN 4000 VIRUSES TO 71 FAMILIES, 11 SUBFAMILIES AND 175 GENERA

  23. NUCLEIC ACID CLASSIFICATION • EITHER RNA OR DNA • NUCLEAR STRANDS

  24. TYPES OF RNA • SINGLE STRANDED -- ssRNA • DOUBLE STRANDED -- dsRNA • RNA VIRUSES MUST CARRY ENZYMES TO COPY RNA MOLECULES OR DNA TO CODE FOR THOSE ENZYMES

  25. POSITIVE ssRNA • RNA ACTS LIKE mRNA • CAN BE TRANSLATED BY HOST RIBOSOMES

  26. NEGATIVE ssRNA • RNA ACTS AS TEMPLATE DURING TRANSCRIPTION TO MAKE COMPLEMENTARY POSITIVE SENSE mRNA • POSITIVE SENSE mRNA IS TRANSLATED BY HOST RIBOSOMES • VIRION MUST CARRY RNA POLYMERASE

  27. DNA VIRUSES • SINGLE STRANDED DNA -- ssDNA • DOUBLE STRANDED DNA -- dsDNA

  28. VIRAL REPLICATION

  29. ADSORPTION

  30. PENETRATION

  31. BIOSYNTHESIS

  32. ASSEMBLY

  33. RELEASE

  34. BACTERIOPHAGES • ATTACK BACTERIA • DOUBLE OR SINGLE STRANDED RNA OR DNA • T EVEN PHAGES: T 2, T 4, T 6 • OBLIGATE PARASITE OF E. COLI

  35. LIFE CYCLE OF THE T 4 BACTERIOPHAGE • ADSORPTION • PENETRATION • BIOSYNTHESIS • MATURATION • RELEASE

  36. ECLIPSE • TIME FROM PENTRATION TO BIOSYNTHESIS • MATURE VIRIONS CANNOT BE FOUND IN CELL

  37. LATENT PERIOD • PENETRATION TO RELEASE • INCLUDES ECLIPSE

  38. MATURATION

  39. RELEASE

  40. BURST TIME • TWENTY TO FORTY MINUTES • ADSORPTION TO RELEASE IS BURST TIME

  41. BURST SIZE • YIELD SIZE • NUMBER OF VIRIONS RELEASED • 50 TO 200 NEW PHAGES

  42. GROWTH OF PHAGES • GROWTH CURVE BASED ON OBSERVING BACTERIAL COLONIES

  43. PLAQUE ASSAY • SEIAL DILUTIONS WITH PLAQUE SUSPENSIONS • PLAQUE FORMING UNITS

  44. LYSOGENY • LYTIC PHAGES DESTROY HOSTS • LYSOGENIC PHAGES ESTABLISH LONG TERM RELATIONSHIP WITH HOST • TEMPERATE • PROPHAGE

  45. LYSOGENIC PATHWAY

  46. LYSOGENIC CONVERSION • TOXIC EFFECTS OF CORYNEBACTERIUM DIPTHERIAE AND CLOSTRIDIUM BOTULINUM • PROPHAGES • CAN REMAIN DORMANT FOR LONG PERIODS • MAJORITY OF BACTERIOPHAGES

  47. ANIMAL VIRUSES • ADSORPTION • PENETRATION • BIOSYNTHESIS • MATURATION • RELEASE • DIFFER FROM BACTERIOPHAGES

  48. ADSORPTION • NO CELL WALLS • RECOGNITION FACTORS • NAKED VIRUSES HAVE ATTACHMENT SITES ON CAPSIDS

  49. ADSORPTION

  50. PENETRATION • OCCURS QUICKLY • BOTH NUCLEIC ACID AND CAPSID ARE TAKEN IN USUALLY • ENDOCYTOSIS • UNCOATING OCCURS

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