History and Nature of Viruses PDF 2024

FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY- - GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 History of Viruses Prof. Dr. Sahar Abd El Rahman Prof. Of Virology  FACULTY OF VETERINARY MEDICINE...

FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY- - GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 History of Viruses Prof. Dr. Sahar Abd El Rahman Prof. Of Virology  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 Perhaps the first written record of a virus infection consists of a heiroglyph from Memphis, the capital of ancient Egypt, drawn in approximately 3700BC, which depicts a temple priest called Ruma showing typical clinical signs of paralytic poliomyelitis.  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY– GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023  Smallpox was endemic in China by 1000BC.  Recognized that survivors of smallpox outbreaks were protected.  variolation involved inhalation of the dried crusts from smallpox lesions, or in later modifications, inoculation of the pus from a lesion into a scratch on the forearm of a child.  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023  In the late 18th century, Edward Jenner observed and studied Miss Sarah Nelmes, a milkmaid who had previously caught Cowpox and was subsequently found to be immune to Smallpox, a similar, but devastating virus.  On 14th May 1796, Edward Jenner used cowpox-infected material obtained from the hand of Sarah Nelmes, a milkmaid from his home village of Berkley in Gloucestershire to successfully vaccinate 8 year old James Phipps.  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 - On 1st July 1796, Jenner challenged the boy by deliberately inoculating him with material from a real case of smallpox ! He did not become infected !!! - Jenner developed the first vaccine, based on these findings, and smallpox is currently all but wiped out.(Read the Demon in the Freezer) - Although initially controversial, vaccination against smallpox was almost universally adopted worldwide during the 19th century.  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 Robert Koch (1843-1910) Louis Pasteur (1822-1895) Cartoon by James Gillray, 1802  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY– GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 Koch's postulates : -The agent must be present in every case. -The agent must be isolated from the host and in vitro. - The disease must be reproduced when a pure culture of the agent is inoculated into a healthy susceptible host. -The same agent must be recovered once again from the experimentally infected host. - However, it was not until Robert Koch & Louis Pasteur jointly proposed the 'germ theory' of disease in the 1880s that the significance of these organisms became apparent.  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 In the late 19th century Charles Chamberland developed a porcelain filter. This filter was used to study the first documented virus, tobacco mosaic virus. Shortly afterwards, Dimitri Ivanovski published experiments showing that crushed leaf extracts of infected tobacco plants were still infectious even after filtering the bacteria from the solution. At about the same time, several others documented filterable disease- causing agents, with several independent experiments showing that viruses were different from bacteria, yet they could also cause disease in living organisms. These experiments showed that viruses are orders of magnitudes smaller than bacteria. The term virus was coined by the Dutch microbiologist Martinus Beijerinck.  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 - In the early 20th century, Frederick Twort discovered that bacteria could be attacked by viruses. - Felix d'Herelle, working independently, showed that a preparation of viruses caused areas of cellular death on thin cell cultures spread on agar. - Counting the dead areas allowed him to estimate the original number of viruses in the suspension. - The invention of Electron microscopy provided the first look at viruses. In 1935 Wendell Stanley crystallised the tobacco mosaic virus and found it to be mostly protein. - A short time later the virus was separated into protein and nucleic acid parts.  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 Viruses: The first as filterable agents - Viruses: ----- Animals, Human and Plant - Yellow fever virus in mice and successfully p vaccine - the 17D strain. Theiler's vaccine was so safe and effective that it is still in use today! This work saved millions of lives and set the model for the production of many subsequent vaccines. For this work, Theiler was awarded the Nobel Prize in 1951. 1931: Woodruff and Goodpasteur, ECE  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 Techniques help in development of Virology: - Cell Culture - Ultracentrifugation - Electron Microscopy - Immunological techniques - Radioisotopes - Gel Electrophorsis - Recombinant DNA techniques  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 Definition of virus Alternative Definitions Differences , Similarities and Unique criteria between Virus and other Unicellular MO (Lwoff and Tournier, 1967)>>> (Table 2) Property Bacteria Mycoplasm Chlamydi Rickettsia Virus a a NA DNA+RN DNA+RNA DNA+RNA DNA+RNA DNA A or RNA NA _ _ _ _ Some Infection + Ribosome + + + + _ s Interfero No No Inhibit No Inhibit n growth Replic ation BF + + + + _ Artificial + + _ _ _ Media Coat+Mu + _ + + _ rameric Acid Antibiotic + + + + -  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 Are Viruses Cells or MO? Are Viruses Infectious Agent? Property Viruses Cells NA DNA or RNA DNA+ RNA Proteins Few Many Lipoprotein + some + all Membrane Ribosomes _ + Mitochonderia _ + Enzymes _ or few Many BF or Mitosis _ +  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 Are Viruses alive? - Most virologists consider them non-living, - They are similar to obligate intracellular parasites - But unlike parasites, viruses??? - Both living and non-living particles - For those who consider viruses living, viruses are an exception to the cell theory as viruses are not made up of cells.  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY– GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 - A virus is a sub-microscopic “particle” that can infect the cells - Viruses can only replicate themselves by infecting a host cell and therefore cannot reproduce on their own. - Viruses consist of genetic material contained within a - protective protein coat called a capsid. - A virus that infects bacteria is known as a bacteriophage, - often shortened to phage. - The word virus comes from the Latin, poison (syn. venenum).  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 ORIGIN OF THE VIRUSES 1- Regressive or degenerative theory 2- Discard or Escape theory 3- Coevolution theory  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY– GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 IMPORTANCE OF VIROLOGY - Dangerous viruses - Useful viruses  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 ATYPICAL VIRUS LIKE AGENTS - Virion - Viroids - Satallites (Satellite Viruses, Virusoids) - Prions - PseudoVirions  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 SATALITTE AND VIROIDS Character Satalites Viroids Helper virus + _ Proteins encoded + _ Genome replication Enzymes of helper Cellular enzyme virus polymerase Replication Site As helper (C or N) N Type of NA and its SS circular RNA SS circular RNA, 360 length molecule, 500-2000 nucleotides nucleotides  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY-- GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 PRION AND VIRUSES Charater Prion Virus NA _ + Contain Protein + encoded by cellular + encoded by viral genes gene U.V. and Heat effect _ + Under E.M. Rod/ Filamentous Icosahydron or helical Ab production _ + Inflammation _ + production  FACULTY OF VETERINARY MEDICINE DEPARTMENT OF VIROLOGY– GENERAL VIROLOGY- 3RD LEVEL STUDENTS- FIRST SEMESTER- FIRST WEEK- 2023 Thank you for your attention