2-11 RNA Viruses II Flashcards Preview

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Flashcards in 2-11 RNA Viruses II Deck (10):
1

What are the clinical features of rotavirus?

  • Reovirus, dsRNA, segmented, naked icosahedron
  • Causes severe gastroenteritis: profuse watery diarrhea, dehydration, maladsorption
  • Infants and children (adults usu. asymptomatic)
  • >600,000 deaths/yr, mostly in developing world
  • Peak incidence during winter

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2

What is the life cycle of rotavirus?

  • Genome is segmented, one gene each
  • RDRP in the virion first transcribes mRNA
  • Viral proteins are translated
  • New virions and genome segments are synthesized in cytoplasm
  • Virions assemble, bud into the rough ER
  • Egress via exocytosis/cell lysis
  • Virions mature in gut lumen, then infect more enterocytes or are shed in profuse diarrhea

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3

What are the clinical features of influenza virus?

  • Orthomyxovirus, (-) ssRNA, segmented, enveloped
  • Acute respiratory illness; mainly wintertime
  • “Uncomplicated”: upper and/or lower respiratory tract involvement, fever, headache, myalgia, weakness
  • “Complicated”: 1° pneumonia caused by influenza, 2° bacterial pneumonia, mixed viral and bacterial pneumonia, muscle pain (myositis) and breakdown (rhabdomyelitis)
     

4

What is the life cycle of influenza virus?

  • Genome is segmented, (-) ssRNA
  • Genome segments traffic to nucleus for transcription and replication by RDRP
  • Viral proteins and genome segments accumulate at the plasma membrane
  • Virions assemble and egress by budding
  • Neuraminidase (N antigen) releases virions from sialic acid on cell surface
  • Virions are shed in respiratory droplets (coughs and sneezes)

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5

What are the clinical features of HIV?

  • Retrovirus, (+) ssRNA, 2 copies, enveloped
  • Only humans infected
  • Virus binds to CD4 and chemokine receptors on T cells and macrophages
  • Depletion of these cells + chronic immune activation → immunodeficiency
  • Symptoms include: fever, weight loss, headache, oral sores and thrust, lymphadenopathy, myalgia, rash, hepatosplenomegaly, nausea/vomiting

6

What are the stages of HIV disease?

  • Exposure to virus (transmission)
  • Primary HIV infection (acute phase)
  • Seroconversion
  • Latent period
  • Early symptomatic HIV infection
  • AIDS (CD4 cell count below 200/mm3)
  • Advanced HIV infection (CD4 cell count below 50/mm3)

7

What is the life cycle of HIV?

  • Virion fuses with the plasma membrane
  • Reverse Transcriptase enzyme (RT, included in the virion): (+) ssRNA genomes → dsDNA
  • dsDNA genomes integrate into the host chromosome for life
  • Host RNA Pol II transcribes mRNA from the integrated genome, which also serves as the genome that is packaged into new virions
  • Viral proteins + 2 genomes bud from the plasma membrane
  • Viral protease cleaves the capsid proteins, forming the final trapezoidal shape
  • Virion maturation occurs outside the cell

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8

What are the main symptoms of AIDS?

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9

What types of HIV drugs are there?

  • Nucleoside reverse transcriptase inhibitors (NRTIs)
  • Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
  • Protease inhibitors (PIs)
  • Integrase strand transfer inhibitors (INSTIs)
  • CCR5 antagonists

10

What are the goals of HIV treatment?

  • Durable suppression of HIV viral load
  • Restoration of immune function
  • Prevention of HIV transmission
  • Prevention of drug resistance
  • Improvement in quality of life