Lecture 10-11 Introduction to Viruses PDF

Module-II: CHS Lecture 10 - 11 Virology Structure and Classification Course: MLS-320 (Medical Microbiology II) AHD, College of Health Science University of Bahrain  Objectives...

Module-II: CHS Lecture 10 - 11 Virology Structure and Classification Course: MLS-320 (Medical Microbiology II) AHD, College of Health Science University of Bahrain  Objectives CHS The learning objectives of today’s session are to; 1. Describe the general characteristics of the Mycoplasmataceae, including microscopic and macroscopic appearances. 2. Identify key characteristic biochemical reactions for the differentiation of pathogenic Mycoplasma spp. 3. Describe the proper processing, collection, transport, and storage of specimens for the isolation of the mollicutes. 4. State the site for colonization in the human host for Mycoplasma genitalium, Mycoplasma hominis, M. pneumoniae, and Ureaplasma urealyticum. Dr. Naeem Anwar MLS-320 / Lecture 10 - 11 2  Objectives…. CHS 5. Describe the clinical manifestations associated with each of the major pathogenic species of mollecutes. 6. Describe the complications of serology of M. pneumoniae. 7. Identify M. genitalium as an emerging etiology of nongonococcal urethritis (NGU) in men, and inflammatory syndromes in women including cervicitis and pelvic inflammatory disease (PID) Dr. Naeem Anwar MLS-320 / Lecture 10 - 11 3  Brief History of Viruses Edward Jenner CHS – Vaccinating against smallpox with cowpox virus Luis Pasteur – Vaccinating against rabies Iwanoswki & Beijerink Tobacco Mosaic Virus – First isolated virus = TMV Ellerman, Bang and Rous – Rous sarcoma virus D`Herelle – 1st bacteriophage isolation Bacteriophage attacking a cell Dr. Naeem Anwar MLS-320 / Lecture 10 - 11 4 Viruses CHS Viruses have both living and nonliving characteristics 1. Living characteristics Reproduction Mutation Bacteriophage 2. Non-living characteristics Acellular No metabolism on their own MLS-320 / Lecture 10 - 11 5 Dr. Naeem Anwar Viruses CHS Virus (latin: poison or venome) – A complete intact infectious viral particle is called a virion A virion has Bacteriophage – > 1 DNA or RNA molecule as genetic material – A nucleic acid protecting protein coat (Capsid) – Additional lipid envelope may be present – Some surface glycoproteins may be present (Spikes) – Very few enzymes --- if present MLS-320 / Lecture 10 - 11 6 Dr. Naeem Anwar Virus Size 10-400nm in diameter CHS Bacteriophage MLS-320 / Lecture 10 - 11 7 Dr. Naeem Anwar Virus Structure CHS Bacteriophage MLS-320 / Lecture 10 - 11 8 Dr. Naeem Anwar Virus Structure CHS Virion Core – DNA or RNA of size 3500 bp to1.2 million bp – ssDNA, dsDNA, ssRNA or dsRNA – DNA is always a single molecule Bacteriophage – RNA as single molecule or segmented – RNA may be as segmented molecule – Linear or circular – Haploid with exceptions of diploid MLS-320 / Lecture 10 - 11 9 Dr. Naeem Anwar Virus Structure CHS Virion Core Bacteriophage MLS-320 / Lecture 10 - 11 10 Dr. Naeem Anwar Virus Structure CHS Capsid – large macromolecular structures which serve as protein coat of virus – Protect viral genetic material – Aid in transfer of virus – Made of protein subunits ----- capsomers Bacteriophage – Genetic material + capsid = nucleocapsid – Arrangement of capsomer subunits define the geometric symmetry – Capsomers has ability of self-assembly MLS-320 / Lecture 10 - 11 11 Dr. Naeem Anwar Virus Structure CHS Capsid symmetry – Arrangement of protomeric subunits define the geometric symmetry and shape of virus Bacteriophage Three capsid symmetries 1. Helical 2. Icosahedral 3. Complex MLS-320 / Lecture 10 - 11 12 Dr. Naeem Anwar  Virus Structure CHS Helical capsid – Hollow tube like structures with walls made up of capsomers (protomers) – Rigid or flexible – NA determine length. Bacteriophage TMV Influenza Virus MLS-320 / Lecture 10 - 11 13 Dr. Naeem Anwar Virus Structure CHS Icosahedral capsid – Regular polyhedron with 20 equilateral triangular faces and 12 vertices – Penton or hexon capsomers – Pentons at vertices and hexons making the facet Bacteriophage of triangles. MLS-320 / Lecture 10 - 11 14 Dr. Naeem Anwar Virus Structure CHS Complex capsid – Ovoid to brick shaped morphology – Binal symmetry Bacteriophage T-even coliphage Poxvirus MLS-320 / Lecture 10 - 11 15 Dr. Naeem Anwar Virus Structure CHS Viral envelop – Phospholipid bilayer derived from host during exit. – Almost all human viruses are enveloped viruses – Envelop studded by virus encoded proteins i.e. Bacteriophage spikes or peplomers MLS-320 / Lecture 10 - 11 16 Dr. Naeem Anwar Virus Structure CHS Viral proteins – Protection ----- capsid – Attachment ----- spikes – Antigenic – Structure and shape ----- capsid proteins Bacteriophage – Enzymes e.g. polymerases, nuraminidases – Envelop-capsid interaction ------ matrix protein – Regulatory proteins ------ Tegument MLS-320 / Lecture 10 - 11 17 Dr. Naeem Anwar Classification CHS International committee on taxonomy of viruses (ICTV) – Nucleic acid type Bacteriophage – Envelop (+ / -) – Symmetry of capsid – Dimensions of virion MLS-320 / Lecture 10 - 11 18 Dr. Naeem Anwar Classification David Baltimore CHS – Functional classification based on mode of replication and gene expression Bacteriophage – 7 groups ---- I - VII MLS-320 / Lecture 10 - 11 19 Dr. Naeem Anwar Classification David Baltimore CHS Bacteriophage MLS-320 / Lecture 10 - 11 20 Dr. Naeem Anwar Classification CHS Bacteriophage MLS-320 / Lecture 10 - 11 21 Dr. Naeem Anwar Classification CHS Bacteriophage MLS-320 / Lecture 10 - 11 22 Dr. Naeem Anwar Nomenclature International committee on taxonomy of CHS viruses (ICTV) Eighth ICTV report on nomenclature 3 orders, 73 families, 9 subfamilies 287 genera Bacteriophage MLS-320 / Lecture 10 - 11 23 Dr. Naeem Anwar