Introduction_to_Virology_Medicaltechnology
- 1. INTRODUCTION TO VIROLOGY CHARMAINE C MIRANDILLA
- 2. WHAT IS VIRUS? -Smallest infectious agent - a minuscule, acellular, infectious agent usually having one or several pieces of nucleic acid—either DNA or RNA.
- 3. Why do we study Viruses? 1. Virus are everywhere ● Viruses infect all living things ● We regularly eat and breathe billions of virus particles ● We carry viral genomes as part of our own genetic material
- 4. Did you Know? ● There are more than 10^ 30 Bacteriophage in the world's oceans ● Whales are infected with Caliciviridae that causes rashes, blisters, intestinal problems and they excrete it 10^13 calicivirus particles
- 5. Why do we study Viruses? 2. Viruses can Cause Human Disease ● Small pox ● Influenza ● Hepatitis ● HIV ● Cervical cancer ● COVID 19
- 6. Why do we study Viruses? 4. Virus can be Beneficial ● Viral infections in the ocean kill 20 to 40% of marine microbes daily, converting these living organisms into particulate matter, and in so doing release essential nutrients that supply phytoplankton ● Infection of Hepatitis G in patient with HIV can decrease the progression of disease ● Murine herpesvirus are resistant with Listeria monocytogenes and Yersinia pestis ● Can stimulate Immune System
- 7. Why do we study Viruses? 5. Viruses are Unique Tools to Study Biology ● Bacteriophage is Foundation of Molecular Biology ● Tobacco mosaic virus was a landmark in structural biology ● Development of Recombinant DNA Technology ● Use of Viral Vector
- 11. Be careful: Avoid anthropomorphic analyses Viruses do NOT think! (or employ, ensure, exhibit, display, etc...) They do not achieve their goals in a human-centered manner Viruses are passive agents! Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University ©Principles of Virology, ASM Press
- 12. Viruses replicate by assembly of pre-formed components into particles many Make the parts, assemble the final product Not binary fission like cells Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University ©Principles of Virology, ASM Press
- 13. Go to: b.socrative.com/login/student room number: virus Which of the following is true concerning bacterial vs. viral replication? 1. 2. 3. 4. 5. Viruses must assemble using pre-formed components Bacteria do not replicate via binary fission Bacteria must assemble using pre-formed Viruses do not have an "eclipse" period Viruses replicate by binary fission as viruses do components 2 Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University
- 14. How old are viruses? Orthoceras, a nautiloid cephalopod, 488 Ma Nobu Tamura (http://spinops.blogspot.com) • Estimates of molecular evolution retroviruses >450 Ma, Ordovician Likely originated billions of years suggest marine period origin of some • ago - before cells? Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University ©Principles of Virology, ASM Press
- 15. Immunization • Variolation - China (11th century), Lady Montagu (1700s) No knowledge of agent Survivors of smallpox protected against disease 1790s - experiments by Edward Jenner in England establish vaccination • • • Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University
- 16. Concept of microorganisms • • • Leeuwenhoek (1632 - Pasteur (1822 - 1895) 1723) Koch (1843-1910) Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University ©Principles of Virology, ASM Press
- 17. The evolving concept of virus • As early as 1728, ‘virus’ was used to describe an infectious disease agent that causes • • Virus = Latin, poison; so thought to be liquids Pasteur (1822 - 1895): “Every virus is a microbe” Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University
- 18. Key event: Chamberland filter • Developed a porcelain filter to remove bacteria from drinking water • Pasteur thought found that rabies agent passed through it, it was a small bacterium Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University
- 19. Virology Lectures 2019 • Prof. Vincent Racaniello • Columbia University ©Principles of Virology, ASM Press
- 20. Filterable viruses • • 1898 - Loeffler & Frosch - agent of foot & mouth disease is filterable Key concept: agents not only small, in broth but replicate only in the host, not • • 0.2 micron filters (μm, one millionth of a meter) Still thought to be liquids Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University
- 21. Filterable virus discovery • • • • • • • 1901 1903 1906 1908 1911 1915 1933 - - - - - - - first human virus, rabies virus variola virus chicken leukemia yellow fever virus virus, poliovirus Rous sarcoma virus bacteriophages influenza virus ©Principles of Virology, ASM Press Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University
- 22. Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University ©Principles of Virology, ASM Press
- 23. 1939 - Viruses are not liquids! microscope • • Helmut Ruska built first electron 1933 First EM of bacteriophage, 1939 Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University
- 24. Key 1939 experiment proved that viruses were not simply small bacteria Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University ©Principles of Virology, ASM Press
- 25. ©Principles of Virology, ASM Press Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University
- 26. We know many details about viruses Virology Lectures 2019 • Prof. Vincent Racaniello • Columbia University Chemical formula for poliovirus: C 332,652 H 492,388 N 98,245 O 131,196 P 7,501 S 2,340
- 27. Virus classification • • • • Nature and sequence of nucleic acid Symmetry of protein shell (capsid) in virion Presence or Dimensions absence of lipid of virus particle membrane (envelope) ©Principles of Virology, ASM Press Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University
- 28. Virus classification http://ictvonline.org/ Classical hierarchical Kingdom Phylum Class Order (-virales) system: Family (-viridae) Genus (-virus) Species* Filoviridae Ebolavirus (filovirus family) Zaire ebolavirus
- 29. Virus discovery - Once driven only by disease Analyzed RNA from 220 invertebrate species, found 1,445 new viruses Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University http://www.nature.com/nature/journal/v540/n7634/full/nature20167.html
- 31. STRUCTURE OF VIRUS ●Viral genome: RNA or DNA ●Capsid: protein coat that encloses the genome ○Capsid + genome = Nucleocapsid ● Capsomere ○ represent clusters of polypeptides seen in icosahedral ●The entire virus particle is called virion
- 32. VIRAL GENOME ●Composed of either RNA or DNA ●4 category based on the virus genome ○ Double stranded DNA ○ Single stranded DNA ○ Double stranded RNA ■ Fungal viruses ○ Single stranded RNA ■ Plant viruses ●Basis of molecules ○ Linear ○ Circular
- 33. VIRAL PROTEIN ●As the size of genome increases the number of protein increases. ○Structural protein ■ Protects the virus genome ■ Attachment of the virion to a host cell ■ Fusion of the virion envelope to cell membrane ○Non structural Protein ■ enzymes, e.g. protease, reverse transcriptase ■ transcription factors ■ primers for nucleic acid replication ■ interference with the immune response of the host
- 34. CAPSID ●A Protein coat that encloses the genome ●Function: ○ the protection of the genome ○ To recognize and attach to a host cell. ●Capsomere ○ Cluster of polypeptide common in icosahedral viruses
- 35. FUNCTION OF CAPSID ●Protects the viral genome ● Is the site of receptors necessary for naked viruses to initiate infection ● Stimulates antibody production ●Is the site of antigenic determinants important in some serologic tests
- 36. Symmetry or Morphology ●Helical ○ Complete virion ○ Capsomere are in bagel shape ○ Rod shape capsid ●Icosahedral ○ Cube like ●Complex ○ Non forming symmetry ○ Example Poxviridae
- 38. OUTERMEMBRANE ENVELOPE ●Phospholipid labile covering ●Susceptible to inactivation ○ High temperature ○ Extreme pH ○ Chemical ●Host origin ●Peplomer (Spikes) ○ Virus encoded glycoprotein ●Cannot infect GI tract. NAKED/ NON ENVELOPE •Heat resistant •Lipid membrane
- 40. CLASSIFICATION OF VIRUSES ●Virion Morphology ○ Based on Size, shape, type of symmetry, presence or absence of peplomer ●Virus genome (Baltimore Classification) ○ Type of Nucleic Acid (DNA or RNA) ○ Whether it is linear or circular ○ Sense (positive, negative or ambisense) ○ Size of genome ○ Strandedness (Double or Single stranded) ●Physicochemical properties ●Virus Protein
- 41. CLASSIFICATION OF VIRUSES: DNA VIRUSES ●Herpesviridae ●Hepadnaviridae ●Poxviridae ●Parvoviridae ●Adenoviridae ●Papovaviridae •All DNA are Double Stranded except Parvoviridae •All DNA viruses are icosahedral except Poxviridae •Enveloped • Herpesviridae • Hepadnaviridae • Poxviridae
- 43. CLASSIFICATION OF VIRUSES: RNA VIRUSES ●Picornaviridae ●Caliciviridae ●Reoviridae ●Retroviridae ●Togaviridae ●Flaviviridae ●Bunyaviridae ●Arenaviridae •Filoviridae •Paramyxoviridae •Orthomyxoviridae •Reoviridae •Retroviridae •Rhabdoviridae
- 44. CLASSIFICATION OF VIRUSES: RNA VIRUSES ●All RNA viruses are Single Stranded, Helical and Envelope ●All are Single stranded except Reoviridae ●All are Helical except ○ Picronaviridae ○ Caliciviridae ○ Reoviridae ○ Retroviridae ○ Togaviridae ○ Flaviviridae
- 45. CLASSIFICATION OF VIRUSES: RNA VIRUSES ●All are envelope except Picornaviridae, Caliciviridae and Reoviridae ●Largest: Paramyxoviridae ●Smallest: Picornaviridae ●Arthropod borne or vector borne ○ Bunyaviridae ○ Flaviviridae ○ Togaviridae ●Replicate in Nucleus ○ Orthomyxoviridae and Retroviridae
- 48. There is an underlying simplicity and order to viruses because of two simple facts • All viral genomes are obligate molecular function after they replicate in a cell parasites that can only • All viruses must make mRNA that can be translated by host synthesis ribosomes: machinery they are all parasites of the host protein Virology Lectures 2020 • Prof. Vincent Racaniello • Columbia University