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Veterinary Virology DMP851 > Virus Structure > Flashcards

Virus Structure Flashcards

1
Q

Size

A

Viruses are small ~ 100nm

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2
Q

Types of host:

Arthropods

A

Dengue

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3
Q

Types of Hosts:

Bacteria

A

T4 phage

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4
Q

Types of Hosts:

Animals

A

Foot and Mouth Virus

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5
Q

Types of hosts:

Plants

A

Tobacco Mosaic Virus

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6
Q

Shape

A

Icosahedral

Helical

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7
Q

Nucleic Acids

A

Double stranded:

DNA or RNA

Single Stranded:

DNA or RNA

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8
Q

Virus Basics:

Classification

A
  • Originally viruses were classified only by size
    • Filterability
  • Viruses were then classified by pathogenic properties, transmission, ecology, or organ tropisms
    • yellow fever, hepatitis A, B, and C; Rift Valley Fever virus would all be hepatitis viruses
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9
Q

Virus Basics:

Classification

lineage

A
  • Order:
    • -virales
  • Family
    • -viridae
    • most common grouping
  • Sub-family
    • -virinae
  • Genus
    • -virus
  • Species or common name
  • Isolate, strain, variants, genotype, group, clade
  • “Species” not commonly used but can be best defined as viruses that “share common features”
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10
Q

Virus Basics:

Classification:

Types of Viral Genomes

A
  • composition
    • DNA or RNA
  • Form
    • Single stranded, or double stranded
    • Polarity for single stranded RNA genomes
      • positive
      • negative
      • ambisense
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11
Q

Virus Basics:

Viral Genome

A

Must make mRNA that can be read by the host ribosomes

mRNA is + sense RNA

mRNA can be translated into a protein

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12
Q

Virus Basics:

Reverse Transcriptase

A

Unique to Retroviruses

Cells do not have a polymerase to turn RNA into DNA - the virus must bring its own reverse transcriptase

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13
Q

Virus Basics:

Viral Genome:

Coding regions

A

genes that produce proteins

  • Open reading frame (ORF):
    • has a start codon, stop codon, and intervening sequence that codes for a polypeptide of at least 100 amino acids
      • non-structural proteins
        • participate in processes important to the virus.
      • Structural Proteins
        • components of the virion. Envelope proteins, matrix proteins, capsid proteins, additional virion associated proteins, provide receptor binding sites
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14
Q

Virus Basics:

Viral Genome:

Non-Coding regions

A

Untranslated regions

  • Contains:
    • regulatory elements
    • Scaffolding
    • Terminal repeats
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15
Q

Virus Basics:

Viral Genome

Contain information for

A

Replication

Assembly and packaging

Regulation of the replication cycle

Modulation of host defense

Spread

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16
Q

Virus Basics:

Viral Genomes

DO NOT contain information for

A

complete protein synthesis

Membrane synthesis

Energy production

17
Q

Virus Basics:

Capsid

A

Protein shell surrounding the nucleic acid genome

  • Slef-assemble into a “minimum structure, maximal space” to stably package the genome
  • Two main types
    • symmetrical
      • icosahedral and helical
    • Complex
18
Q

Virus Basics:

Symmetrical Capsid

Icosahedral

A

Parvovirus

20 equilateral triangles

Made up of 60 identical copies of the capsid protein

Minimal Structure, maximal space to stably package the genome

19
Q

Virus BadicsL

Summetrical Capsid

Helical Symmetry

A
  • Cylindrical structure
  • Capsomeres are arranged in a spiral straircase with a central pole as the axis
  • Rhabdovirus (rabies)
  • Coiled helical nucleocapsid with a bullet shaped virion morphology
20
Q

Virus Basics:

Capsid:

Complex Capsid

A

Not helical or icosahedral

Possess no symmetry

Filoviridae and poxviridae

21
Q

Virus Basics:

Capsid:

Function

A

Genome packaging

Host cell attachment and entry

Un-packaging of hte genome and release into cells

22
Q

Viral Basics:

Nucleocapsid

A

The complete protein - nucleic acid complex that is the packaged form of the genome in a virus particle

23
Q

Virus Basics:

Envelop

Enveloped Viruses

A
  • Lipid Envelop
  • Capsid
  • Genome
  • Derived or “stolen” from the host cell membrane because the viral genome does not have the machinery to encode a lipid bilayer
24
Q

Virus Basics:

Envelope:

Function

A
  • Membrane Glycoproteins
    • antigenic sites, attachment, fusion
  • Protects the nucleocapsid
    • capsid with the viral nucleotides
  • Facilitates direct transmission of virions to adjacent cells
  • Camouflage
    • surrounded by host material
  • More unstable in the environment
25
Q

Virus Basics:

Envelope:

Structure

A

The E protein is the major structural protein on the surface of mature flaviviurs virion

Each monomer of E protein consists of three domains

26
Q

Virus Basics:

Envelope:

Fusion with host cell

A
27
Q

What is a Virus?

A
  • Obligate intracellular parasite
  • Infectious to a variety of living organisms
    • Humans, Animals, Plants, Bacteria, Invertebrates, Fungus
  • Viral genome is packaged in a cell and has all the information that a virus will need to replicate and be transmitted form one host to another
  • Viruses are not alive
    • maybe viruses are a transitional life form between things that are not living to things that are living
    • Also a transition form RNA genome to DNA genome
  • Virus partile is not alive on its own it needs to infect a cell
  • Viruses do NOT
    • reproduce
    • Evolve
    • Metabolize
    • … without first infecting a cell

Veterinary Virology DMP851 (12 decks)

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