MIC221 Lecture 1 PDF

Faculty of Veterinary Medicine UVMED Lecture : Introduction and History of Virology Dr : Ayman El-Deeb Date :09/10/2023 Virology Definition Science which deals with study of the viruses either: *Human viruses: Small pox - HIV(AIDS) -Hepatitis- A,B,C,D,E,G - Poliomyelitis-...

Faculty of Veterinary Medicine UVMED Lecture : Introduction and History of Virology Dr : Ayman El-Deeb Date :09/10/2023 Virology Definition Science which deals with study of the viruses either: *Human viruses: Small pox - HIV(AIDS) -Hepatitis- A,B,C,D,E,G - Poliomyelitis- Rabies. *Animal viruses: RVF - FMD - RP - BVD. *Bird viruses: NDV- Gumboro- IBV- ILT. * Bacterial viruses: Bacteriophages. * Insect viruses: Baculovirus. * Mycoplasma: Mycoplasmalphages. Virus Origin of the term ( Venum = Poison ) Virus Definition Very small obligatory intracellular parasite which lacks the metabolic enzymes. Very small: 20-300 nm. (nm = 10-7 cm). Obligatory intracellular parasite: Absolutely dependent on the host cell for its replication. Lack the metabolic enzymes: Devoid from the machinery for energy production and biosynthesis of macromolecules. Virology Differences between virus and bacteria Item Bacteria Virus Cell wall +ve -ve Organelles +ve -ve Nuclear membrane +ve -ve Metabolism +ve -ve Type of nucleic acid DNA and RNA DNA or RNA Infectious NA -ve +ve Size Over 300 nm Under 300 nm Sensitivity to interferon -ve +ve Sensitivity to antibiotics +ve -ve Replication Binary fission Host cell dependant Virology First record Virology Historical background Virology Historical background Virology History of virology The Early Period: The 19th Century By the last half of the 19th century, the existence of a diverse microbial world of bacteria, fungi, and protozoa was well established. As early as 1840, the noted German anatomist Jacob Henle of Gottingen (the discoverer of Henle's loop and the grandfather of 20th- century virologist Werner Henle) hypothesized the existence of infectious agents that were too small to be observed with the light microscope and that were able to cause specific diseases. In the absence of any direct evidence for such entities, however, his ideas failed to be accepted. Virology History of virology The Discovery Period: 1886–1903 Adolf Mayer (1843–1942), a German scientist trained in the field of chemical technology (who had studied fermentation and plant nutrition), became the director of the Agricultural Experiment Station at Wageningen, Holland, in 1876. A few years later (1879), he began his research on diseases of tobacco and, although he was not the first to describe such diseases, he named the disease tobacco mosaic disease after the dark and light spots on infected leaves. In one of Mayer's experiments, he inoculated healthy plants with the juice extracted from diseased plants by grinding up the infected leaves in water. Virology History of virology Virology History of virology Virology History of virology Virology History of virology Virology History of virology Virology History of virology Virology History of virology Virology Cell Culture Method Virology Serological/Immunological methods Virology Electron Microscope Virology Virus Shapes