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Microbiology > Virology: quick characteristics > Flashcards

Virology: quick characteristics Flashcards

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Biology 101 flashcards
1
Q

ssRNA enveloped

A
  • Orthomyxovirus
    • Influenza A/B/C
  • Coronavirus
    • Respiratory viruses
  • Togavirus
    • Rubella
  • Flavivirus
    • Hepatitis C, West Nile virus
  • Paramyxovirus
    • Mumps, measles, parainfluenza
  • Rhabdovirus
    • rabies
  • Retrovirus
    • HIV, Adult T-cell leukemia
  • Hepatitis D
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2
Q

ssRNA naked

A
  • Picornavirus
    • enteroviruses, polio, coxsackie, rhinovirus, hepatitis A
  • Calicivirus
    • Norwalk virus
  • Hepatitis E
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3
Q

dsRNA naked

A
  • Reovirus
    • rotavirus
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4
Q

dsDNA enveloped

A
  • Herpesvirus
    • Herpes simplex virus 1/2, Varicella zoster virus, cytomegalovirus, Epstein-Barr virus, Human herpes virus 6/7/8
  • Hepadnavirus
    • Hepatitis B
  • Poxvirus
    • Smallpox, Molluscum contagiosum
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5
Q

dsDNA naked

A
  • Adenovirus
    • Respiratory diseases & gastroenteritis
  • Papillomavirus
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6
Q

ssDNA naked

A

Parvovirus

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7
Q

DNA Viruses - enveloped

A

Herpesvirus
• Herpes simplex virus 1 & 2
• Varicella-zoster virus
• Cytomegalovirus
• Epstein-Barr virus
• Human herpesvirus 6, 7, 8

  • Hepadnavirus
  • Hepatitis B
  • Poxvirus
  • Smallpox
  • Molluscum contagiosum

DNA Viruses – Nonenveloped

  • Adenovirus
  • Respiratory diseases and gastroenteritis
  • Papillomavirus
  • Parvovirus – SINGLE STRANDED
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8
Q

DNA Viruses “naked” - nonenveloped

A
  • Adenovirus
  • Respiratory diseases and gastroenteritis
  • Papillomavirus
  • Parvovirus – SINGLE STRANDED
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9
Q

Prions

A

• Exception to the basic viral
structure
• Composed entirely of protein

• Normal, misconfigured human
proteins

• Disrupts neuron function

• Causes transmissible spongiform
encephalopathies
• Mad cow disease

  • Creutzfeldt-Jakob disease
  • Kuru
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10
Q

Viral Transmission & Replication – Early steps

A

Attachment to host cell
• Penetration/Entry
• Virion surface proteins attach to
• Naked viruses engulfed by vesicle
receptor proteins on the cell
• Enveloped viruses undergo fusion
surface

Uncoating to release the
genome
• Low vesicle pH uncoats virion • Rupture or fusion

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11
Q

Viral Transmission & Replication – Middle step

A

Gene expression
• Virus specific mRNA synthesis • Synthesis of viral proteins
• Genome replication
• DNA viruses replicate in the nucleus using host cell DNA-dependent RNA
polymerase
• Exception = poxviruses – cytoplasm
• RNA viruses replicate in the cytoplasm
• Exception = retroviruses and influenza viruses – nucleus

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12
Q

Viral Transmission & Replication – Late steps

A

• Assembly
• Viral nucleic acid packaged within
capsid proteins • Release from cell
• Rupture of cell membrane
releasing assembled virions
(usually naked viruses) OR • Budding process (enveloped
viruses)

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13
Q

Infected cells

A
  • Death
    • Host cell protein synthesis inhibited
  • Fusion of cells to form multinucleated cells
    • Due to cell membrane changes
  • Malignant transformation
    • Unrestrained growth
    • Prolonged survival
    • Morphologic changes
  • No effect - rare
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14
Q

Infection stages

A
  • Incubation
    • Asymptomatic
  • Prodromal
    • Non-specific symptoms
  • Specific-illness
    • Characteristic symptoms and signs
  • Recovery
    • Illness wanes
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15
Q

Cell culture

A

• Monitor for characteristic cytopathic
effect – provides presumptive diagnosis
• Can arrive at definitive identification
by using known antibody with a variety of tests
• Complement fixation,
• Hemagluttination inhibition
• CPE neutralization
• Fluorescent antibody
• Radioimmunoassay
• ELISA
• Immunoelectron microscopy

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16
Q

Microscopic identification

A

Identified by microscopic exam of
clinical specimen
• Light microscopy – characteristic
inclusion bodies or multinucleated giant cells
• Tzanck smear – shows herpesvirus-
induced multinucleated giant cells • UV microscopy – fluorescent antibody
staining of virus • Electron microscopy – detects virus
particles characterized by size and
shape

17
Q

Serology

A

Antibody to the virus is measured
• Acute and convalescent phase
samples

18
Q

Viral antigen detection

A

• Enzyme-linked immunosorbent
assay (ELISA)

19
Q

Viral nucleic acid detection

A

Test for viral genome or viral
mRNA by using complementary DNA or RNA
• Can use polymerase chain reaction
(PCR) to amplify small amounts of viral nucleic acids

20
Q

Disease prevention

A

Active immunity
• Attenuated live virus – greater, longer lasting protection
• Killed virus
• Subunit vaccines – contain purified viral proteins • Passive immunity
• Preformed antibody administered in immune globulins • Herd immunity – “community immunity”

21
Q

Disease control

A

Challenges: • Difficult to obtain selective toxicity
against the virus since replication
so closely involved with normal
synthetic processes of the cell
• Extensive viral replication occurs
during the incubation period
• Drug-resistant viral mutants

22
Q

Virion

A
  • Contains: Genome PLUS protein coat
  • +/-enzymesneededfortranscription - RNA-dependent RNA polymerase
  • No energy source
  • No metabolic processes
23
Q

Internal core

A

Contains the genetic sequence

24
Q

Coat

A
  • protein capsid or envelope
    • Protection
    • Attachment
    • Recognition
25
Q

Enveloped virus

A
  • Outer lipid bilayer
  • More sensitive to heat, drying, detergents, and lipid solvents (alcohol, ether)
  • Usually transmitted by direct contact (blood, sexual) or respiratory aerosol droplets
  • Other terminology
    • Nucleocapsidvs.nakednucleocapsid
26
Q

Glycoprotein spikes

A
  • Facilitate attachment to host
  • After infection act as an antigen
  • Surface antigens
    • Responsibleforserotypes
27
Q

Important points

A
  • All viral genomes must make mRNA
  • mRNA is then translated to start making proteins
    • RNA Viruses
      • Most replicate in cytoplasm
      • Different strategies for synthesizing mRNA
    • DNA Viruses
      • Most replicate in the nucleus
      • Use host-cell DNA dependent RNA polymerase
28
Q

Positive stranded RNA viruses

A
  • Equivalent of preformed mRNA
  • Ready for translation once they enter the cell
  • Use host ribosomal proteins
29
Q

Negative stranded RNA viruses

A
  • A copy of mRNA
  • Can not be directly translated
  • Carry viral RNA-dependent RNA polymerase
  • Used to transcribe a positive strand
  • Canthenbetranslated
30
Q

RNA Retroviruses

A
  • Single stranded (+) RNA virus with DNA intermediate
  • Reverse transcriptase – allows for incorporation of viral genome into host genome
31
Q

Reverse transcriptase

A
  • RNA of retrovirus is converted to double stranded(ds) DNA
    • Original genome RNA degraded
  • dsDNA is integrated into host cell DNA
  • Integrated DNA transcribed by host cell RNA polymerase to produce more viral mRNA
32
Q

List the RNA Viruses – Enveloped

A
  • Orthomyxovirus
    • Influenza A, B, C
    • 8 piece segmented RNA
  • Coronavirus
    • Respiratory viruses
  • Togavirus
    • Rubella
  • Flavivirus
    • Hepatitis C
    • West Nile virus
  • Paramyxovirus
    • Mumps
    • Measles
    • Parainfluenza
  • Rhabdovirus
    • Rabies
  • Retrovirus
    • HIV
    • Adult T cell leukemia
  • Hepatitis D
33
Q

List the RNA Viruses – Nonenveloped

A
  • Picornavirus
    • Enteroviruses
    • Polio
    • Coxsackie
    • Rhinovirus
    • Hepatitis A
  • Reovirus – DOUBLE STRANDED
    • Rotavirus
  • Calicivirus
    • Norwalk virus
  • Hepatitis E
34
Q

DNA Viruses

A
  • DNA must first be transcribed into RNA, then translated into proteins • Synthesize their mRNA using host RNA polymerase
  • Most DNA viruses are double stranded, having both a positive and negative strand
  • Positive strand is read and transcribed into mRNA • Negative strand is ignored
  • Exception: Parvoviruses – single stranded DNA

MOST ARE DOUBLE STRANDED

35
Q

Viral exanthems

A

Chickenpox, shingles, measles, roseola, rubella, and fifth disease

36
Q

Viral respiratory illnesses:

A

common cold, viral pharyngitis, influenza, covid-19

37
Q

Viral gastrointestinal illness

A

Rotavirus, Norwalk virus, and Hepatitis A-E

38
Q

Viral CNS diseases

A

Enterovirus, meningitis, encephalitis, arthropod-borne viral meningitis and encephalitis, and rabies encephalitis

39
Q
A

Microbiology (11 decks)

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