EBIO 3400 1st Edition Lecture 25Outline of Last Lecture I. Vectors II.Population Characteristics that affect epidemiologyIII. Genomic Strategies Help Identify Nonculturable PathogensIV. Technology helps to spread diseaseV. Endotoxin (Lipid A) VI. Type III secretionVII. Gram Positive pathogens Outline of Current Lecture VIII. Caused by Mycobacterium lepraeIX. Two different forms of diseaseX. Influenza Virus XI. 2 main types of influenza XII. Influenza Attachment and Host Cell EntryXIII. Replication Cycle of Influenza ACurrent LectureI. LeprosyA. Caused by Mycobacterium leprae- Bacteria have never been grown in cell-free culture- Cases of leprosy are becoming relatively rare- Transmission is via person-to-person contact or through a break in the skin- The earliest account of Leprosy appears in an Egyptian Papyrus document writtenaround 1550 B.C. “Around 600 B.C. Indian writings describe a disease that resembles leprosy. In Europe, leprosy first appeared in the records of ancient Greece after the army of Alexander the Great came back from India and then in Rome in 62 B.C. coinciding with the return of Pompeii's troops from Asia Minor.”- M. leprae was the first convincing association of a bacterium with a disease (evenbefore Koch and TB or Anthrax) by Armauer Hansen* (Leprosy is also called Hansen’s disease). These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- But M. leprae has never been grown in pure culture - it is usually cultured in Armadillos which have a body temp of ~30°C near the opt. temp for growth of M. leprae - it only does well on the extremities of humans- Mycobacterium leprae multiply very slowly = incubation period (the time between infection and the appearance of the first symptoms) of up to five years. Symptoms may not appear for as long as 20 yearsII. Two different forms of diseaseA. Tuberculoid leprosyNonprogressive disease that is characterized by loss of sensation in regions of the skinB. Lepromatous leprosy (multiplies in skin and nerve cells) Produces gradual tissue destruction that results in the loss of facial features, digits, and other body structuresC. DiagnosisBased on the signs and symptoms of the disease- Loss of sensation in skin lesions in the case of tuberculoid leprosy- Disfigurement in the case of lepromatous leprosyD. TreatmentTreatment with a combination of antimicrobial drugs- Lifelong treatment is sometimes neededE. PreventionPrimarily prevented by limiting exposure to the pathogen;BCG vaccine provides some protectionIII. Influenza Virus - Causes about 36,000 deaths in the United States per year and periodic pandemics.- 1918: more people died than in World War I- 2009: “Swine flu” caused relatively mild illness- Influenza has a segmented genome, with eight separate linear (–) strands of RNA- Primarily transmitted by respiratory route - (1,000,000 virions per droplet)- Incubation period = 1-5 days after exposure, rapid onset of symptoms- > Highly mutable virus - changes antigens very quickly- > Animal reservoirsIV. 2 main types of influenza A. Type AEpidemics and pandemics, animals and humans (including domestic animals and wild birds), all agesCapable of antigenic shift and antigenic driftB. Type BMilder epidemics, humans only, primarily affects children, antigenic drift less commonC. Type CType C rarely causes many problems – very mildV. Influenza Attachment and Host Cell EntryA. The hemagglutinin envelope protein attaches to a host cell by binding to a sialic acid receptor proteinB. The virion is taken up by endocytosis• Acidification induces a conformational change.C. Fusion of envelope and the host membrane• Virion contents are released into the cytoplasmVI. Replication Cycle of Influenza AA. Viral (–) strand RNA are uncoated and enter the nucleus. a. Influenza mRNA synthesis is primed by capped RNA fragments cleaved from host mRNA.i. Viral mRNA return to cytoplasm for translation.b. Genomic RNA synthesis is primed by NP.i. (+) strand RNA is synthesized by prepackaged RNA-RNA polymerase, which then uses it as a template for (–) RNA strands.- These are packaged in newly made nucleocapsid proteins (NPs) and exported to the cytoplasm- Envelope proteins are synthesized at the ER, where they are glycosylated by host enzymes and transferred to the Golgi for export to the cell membrane.- At the membrane, the packaged (–) RNA segments are enveloped by host membrane containing the envelope proteins.- Mature virions then bud out of the cell
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