2014 Ebola outbreak in West Africa Unit 3 Viruses and Human Diseases Objectives Chapter 1 o Understand the relative size ranges of molecules viruses bacteria and eukaryotic cells as measured by the appropriate units Micron 1 micron 1 micrometer Bacterial and eukaryotic cells are in this range 10 100 micrometers A filter with 0 2 micron sized pores will effectively remove bacterial contamination by trapping them in the filter Nanometer nm Viruses are in this range 20 100 nm is the typical range of diameters for viruses The same filter mentioned above will not remove most viruses Angstrom Molecules are in this range A nanometer nm 10 o Understand the difference between light microscopes and electron angstrom microscopes Sources of illumination are different photons light versus electrons Level of resolution Different types of EM techniques TEM SEM cryoEM EM tomography o Know the viral causes of some common diseases Common cold rhinovirus flu influenza virus warts human papillomavirus 1 2 4 cold sores Herpes virus diarrhea enterovirus AIDS HIV poliomyelitis Poliovirus hemorrhagic fever Ebola Dengue SARS coronavirus Chapter 2 o Understand the general steps of a virus life cycle Entry this includes receptor binding all the way to membrane penetration Replication of viral genomes which requires the expression of Viral assembly and exit which requires the expression of structural replication enzymes proteins o Understand the structure of biological membranes Lipid bilayer with embedded Transmembrane proteins A barrier that viruses must cross to deliver its genome into the cells o Understand the importance of studying viral receptors Elucidation of viral tropism Help predicting viral pathogenesis Reveal drug targets for therapy o Know the four possible routes of viral entry following receptor binding Pore formation at the cell surface neutral pH Membrane fusion at the cell surface neutral pH Pore formation in the endosomes acidic pH Membrane fusion in the endosomes acidic pH Chapter 3 o Know the seven types of viral genes Notice the lack of a double stranded genome type with one strand of DNA and one strand of RNA These molecules are physically unstable o Understand why viruses are successful despite having limited coding capacity in their genomes Host provides much of the service Viral genomes are more efficient in carrying information o RNA viruses have a much higher mutation rate why The enzymes used to copy RNA genomes have low fidelity during replication These include the reverse transcriptase and RNA dependent RNA polymerase The DNA polymerases which the host cell and DNA viruses use have much higher fidelity o Understand the general scientific principles of reconstructing extinct viruses Obtain viral genome sequence and use it to synthesize a man made o Understand the differences between positive sense and negative sense RNA genome genomes Positive sense RNA directly spells out the code for protein translation Negative sense RNA needs to be converted to positive sense RNA via the base pairing rule to spell out the code for protein translation As a result negative sense RNA viruses need to carry their own RNA dependent RNA polymerase in their viral particles Chapter 4 shapes of viruses o Understand the general consideration of viral assembly and the two general Should be able to use very simple single repeating protein units The structure needs to close Virions should be mobile easy to roll helical and icosahedron Should be amenable to scaling up o Know the basic characteristics of an icosahedron 20 faces and three types of symmetry Sphere like properties and readily available o Understand the three modes of virion assembly Self assembly Chaperones and scaffolds Virion maturation Cell lysis Budding out at the plasma membrane Exocytosis the reversal of endocytosis o Understand the different ways that assembled virions exit from the host cell Chapter 5 infection o Understand the difference between in vitro and in vivo studies of viral In vitro outside a body in cultured cells In vivo in the body of a living organism o Understand the difference between primary cells and immortalized cell lines Primary cells are directly isolated from organisms short lived Cell lines grow forever but usually are altered from the original cell type in many aspects o Know the four levels of biosafety containment o Understand the following examples of normal functions of viral receptors Signal transduction cell junction formation receptor mediated endocytosis o Understand the functions of tRNA To bring amino acids to mRNA in an ordered fashion translating the mRNA code to protein sequence in the process o Understand the similarities between exocytosis and virus exit Require membrane bound secretory vesicles Travels from the center of the cell endoplasmic reticulum to the outer edge of the cell plasma membrane Chapter 6 o Understand the multiple layers of host defense against infections Primary barrier and chemical defense intrinsic cellular response innate immunity adapted immunity o Know the examples of the different PRRs Toll like receptors localize on cell membrane or endosome membranes RNA helicases RIG I MDA5 localized in the cytoplasm o Understand the production and action of interferons Virtually all viral infections trigger the production of interferons Interferons act through signal transduction pathways and establish an antiviral state in the cells of viral infection o IFN action results in many common early flu like symptoms Viruses have evolved to counter the effect of interferons o Understand RNA silencing as an antiviral defense mechanism for both plants and animal cells interferon is only present in higher organisms o Understand the triggers and characteristics of apoptosis Developmental signals and insults such as viral infection Membrane blebbing DNA fragmentation and apoptotic body formation Caspase activation and cascade o Understand immune memory and vaccination The secondary response produces more antibodies which can cause neutralized viral infections Chapter 7 o Know the main portal of entry for common human viruses Respiratory tract GI tract skin blood genital tract o Understand the three modes of viral infection and circulation Encephalitis viruses get in by mosquito biting blood and cause disease in the nervous system o Understand that similar viruses can cause different diseases and that different viruses can cause the same disease Know the examples listed o Understand what
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