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Viruses Flashcards

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Biology 101 flashcards
1
Q

Recombination

A

Exchange of genes between 2 chromosomes by crossing over within regions of significant base sequence homology

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2
Q

Reassortment

A

When viruses with segmented genomes (flu) exchange segments. High frequency recombination. Cause of worldwide influenze pandemics

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3
Q

Complementation

A

When 1 or 2 viruses that infect the cell has a mutation that results in a nonfunctional protein. The nonmutated virus “complements” the mutated one by making a functional protein that serves both viruses.

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4
Q

Phenotypic mixing

A

Occurs with simultaneous infection of a cell with 2 viruses. Genome of virus A can be partially or completely coated (forming pseudovirion) with the surface protiens of virus B. Type B protein coat determines the tropism (infectivity) of the hybrid virus. However, the progeny from this infection have a type A coat that is encoded by its type A genetic material.

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5
Q

Live attenuated vaccine - what response?

Types?

A

Induce hemoral and cell-mediated immunity but have reverted to virulence on rare occasions.
Smallpox, yellow fever, chickenpox, Sabin’s polio virus, MMR, influenza (intranasal)
Dangerous to give to IC and no booster needed

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6
Q

Killed vaccine

A

Rabies, influenza (IV), Salk Polio, HAV

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7
Q

Recombinant vaccine

A

HBV, HPV

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8
Q

Only ssDNA virus

A

Parvoviridae

All others are dsDNA

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9
Q

Circular DNA virus

A

Papilloma
Polyoma
Hepadnaviruses
All others are linear

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10
Q

Only dsRNA virus

A

Reoviridae

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11
Q

Positive stranded RNA viruses

A

retrovirus, togavirus, flavivirus, coronavirus, hepevirus, calicivirus, picornavirus (I went to a retro toga party, where I drank flavored Corona and ate hippy California pickles.

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12
Q

Ploidy of viruses

A

all viruses are haploid (1 copy of DNA or RNA) except retroviruses which have 2 identical ssRNA molecules

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13
Q

Where does DNA viruses replicate? RNA?

A

nucleus (except poxvirus)

cytoplasm (except influenza, retroviruses)

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14
Q

Non-enveloped viruses (Naked)

A

Papillomavirus, Adenovirus, Picornavirus, Polyomavirus, Calcivirus, Parvovirus, Reovirus, Hepevirus (Give PAPP (DNA) smears and CPR (RNA) to a naked Heppy)

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15
Q

Herpesviruses
Envelope:
Structure:
Dz: 8

A 
Herpesviruses
Envelope: yes
Structure: dsDNA and linear
Dz: 
(1) HSV1 - oral/genital lesions, temporal lobe encephalitis, keratoconjunctivitis
(2) HSV2 - genital lesions
(3) VSV - chickenpox, zoster (shingles)
(4) EBV - mono, Burkitt's lymphoma, Hodgkin's lymphoma
(5) CMV - infxn in IC patients esp transplant recipients; congenital defects 
(6) HHV6 - roseola (exanthem subitum)
(7) HHV7 - less common cause of roseola
(8) HHV8 - Kaposi's sarcoma
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16
Q

Hepadnavirus
Envelope:
Structure:
Dz:

A

Hepadnavirus
Envelope: Yes
Structure: dsDNA and partial circular
Dz: (1) HBV - acute/chronic hepatitis, vaccine available (HBV surface Ag), reverse transcriptase

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17
Q

Adenovirus
Envelope:
Structure:
Dz:

A

Adenovirus
Envelope: No
Structure: dsDNA and linear
Dz: Febrile pharyngitis (sore throat, acute hemorrhagic cystitis), pneumonia, conjunctivitis (pink eye)

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18
Q

Parvovirus
Envelope:
Structure:
Dz:

A

Parvovirus
Envelope: No
Structure: ssDNA and linear
Dz: B19 virus - aplastic crises in sickle cell disease with slapped cheeks rash in children, erythema infectiosum (fifth disease), RBC destruction in fetus leads to hydrops fetalis and death, pure RBC aplasia and rheumatoid arthritis like symptoms in adults

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19
Q

Papillomavirus
Envelope:
Structure:
Dz:

A

Papillomavirus
Envelope: No
Structure: dsDNA and circular
Dz: HPV - warts (1, 2, 6, 11), CIN/cervical cancer (16, 18); vaccine available

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20
Q

Polyomavirus
Envelope:
Structure:
Dz: 2

A

Polyomavirus
Envelope: No
Structure: dsDNA and circular
Dz: JC virus - progressive multifocal leukoencephalopathy in HIV
BK virus - transplant patients (targets kidney)

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21
Q

Poxvirus
Envelope:
Structure:
Dz:

A

Poxvirus
Envelope: Yes
Structure: dsDNA and linear (largest DNA virus)
Dz: Smallpox
Vaccinia - cowpox
Molluscum contagiosum - flesh colored dome lesions with central dimple

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22
Q

HSV-1
Transmission:
Dz:

A

HSV-1
Transmission: respiratory secretions, saliva
Dz: gingivostomatitis, keratoconjunctivitis, temporal love encephalitis (MCC sporadic encephalitis in US), herpes labialis, latent in trigeminal ganglia

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23
Q

HSV-2
Transmission:
Dz:

A

HSV-2
Transmission: Sexual contact, perinatal
Dz: Herpes genitalis, neonatal herpes, latent in sacral ganglia

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24
Q

VZV
Transmission:
Dz:

A

VZV
Transmission: respiratory secretions
Dz: varicella-zoster (chickenpox, shingles), encephalitis, pneumonia, latent in dorsal root or trigeminal ganglia

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25
Q

EBV
Transmission:
Dz:
Clinical:

A

EBV
Transmission: respiratory secretions, saliva
Dz: Infectious mono, Burkitt’s/Hodgkin’s lymphoma, nasopharyngeal carcinoma, latent in B cells
Clinical: fever, hepatosplenomegaly, pharyngitis, lymphadenopathy (posterior cervical nodes), 15-20 yoa, atypical lymphocytes on peripheral - reactive cytotoxic T cells; positive Monospot

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26
Q

CMV
Transmission:
Dz:

A

CMV
Transmission: congenital, transfusion, sexual contact, saliva, urine, transplant
Dz: congenital infxn, mono (negative monospot), pneumonia, retinitis; owl’s eye inclusions; latent in mononuclear cells

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27
Q

HHV-6

Dz:

A

HHV-6

Dz: roseola - high fevers for several days that can cause seizures, followed by a diffuse macular rash

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28
Q

HHV-8
Transmission:
Dz:

A

HHV-8
Transmission: sexual contact
Dz: Kaposi’s sarcoma (HIV patietns)

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29
Q

HSV diagnosis

A

PCR is test of choice
Tzanck test - smear of opened skin vesicle to detect multinucleared giant cell
Intranuclear Cowdry A inclusions

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30
Q 
Reovirus
Envelope:
Structure:
Capsid:
Dz: 2
A 
Reovirus
Envelope: no
Structure: dsRNA linear
Capsid: icosahedral
Dz: (1) coltivirus - Colorado tick fever
(2) rotavirus - fatal diarrhea in children
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31
Q 
Picornaviruses
Envelope:
Structure:
Capsid:
Dz: 5
A 
Picornaviruses
Envelope: no
Structure: ssRNA linear
Capsid: icosahedral
Dz: (1) poliovirus - Salk/Sabin vaccine
(2) echovirus - aseptic meningitis
(3) Rhinovirus - common cold, acid labile so destroyed in stomach
(4) Coxsackievirus - aseptic meningitis; herpangina (mouth blisters, fever); hand, food, and mouth disease, myocarditis
(5) HAV - acute viral hepatitis

PERCH

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32
Q 
Hepevirus
Envelope:
Structure:
Capsid:
Dz:
A 
Hepevirus
Envelope: No
Structure: ssRNA linear
Capsid: Icosahedral
Dz: HEV
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33
Q 
Caliciviruses
Envelope:
Structure:
Capsid:
Dz:
A 
Caliciviruses
Envelope: no
Structure: ssRNA linear
Capsid: icosahedral
Dz: Norovirus - viral gastroenteritis
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34
Q 
Flaviviruses
Envelope:
Structure:
Capsid:
Dz: 5
A 
Flaviviruses
Envelope: Yes
Structure: ssRNA linear
Capsid: icosahedral
Dz: HCV
Yellow fever
Dengue
St. Louis encephalitis
West Nile virus
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35
Q 
Togaviruses
Envelope:
Structure:
Capsid:
Dz: 3
A 
Togaviruses
Envelope: yes
Structure: ssRNA linear
Capsid: icosahedral 
Dz: Rubella
Eastern equine encephalitis
Western equine encephalitis
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36
Q 
Retroviruses
Envelope:
Structure:
Capsid:
Dz: 2
A 
Retroviruses
Envelope: yes
Structure: ssRNA linear
Capsid: icosahedral (HTLV), complex&conical (HIV)
Dz: HTLV - t cell leukemia
HIV - AIDS
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37
Q 
Coronaviruses
Envelope:
Structure:
Capsid:
Dz: 2
A 
Coronaviruses
Envelope: yes
Structure: ssRNA linear
Capsid: helical
Dz: coronavirus - common cold
SARS
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38
Q 
Orthomyxoviruses
Envelope:
Structure:
Capsid:
Dz:
A 
Orthomyxoviruses
Envelope: yes
Structure: ssRNA (-) linear, 8 segments
Capsid: helical
Dz: Influenza virus
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39
Q 
Paramyxoviruses
Envelope:
Structure:
Capsid:
Dz: 4
A 
Paramyxoviruses
Envelope: yes
Structure: ssRNA (-) linear, nonsegmented
Capsid: helical
Dz: Parainfluenza - croup
RSV - bronchiolitis in babies give ribavirin for tx
Measels
Mumps
40
Q 
Rhabdoviruses
Envelope:
Structure:
Capsid:
Dz:
A 
Rhabdoviruses
Envelope: yes
Structure: ssRNA (-) linear
Capsid: helical
Dz: rabies
41
Q 
Filoviruses
Envelope:
Structure:
Capsid:
Dz:
A 
Filoviruses
Envelope: yes
Structure: ssRNA (-) linear
Capsid: helical
Dz: Ebola/Marburg hemorrhagic fever
often fatal
42
Q 
Arenaviruses
Envelope:
Structure:
Capsid:
Dz: 2
A

Arenaviruses
Envelope: yes
Structure: ssRNA (-) circular, 2 segments
Capsid: helical
Dz: LCMV - lymphocytic choriomeningitis virus
Lassa fever encephalitis - spread by mice

43
Q 
Bunyaviruses
Envelope:
Structure:
Capsid:
Dz: 4
A 
Bunyaviruses
Envelope: yes
Structure: ssRNA (-) circular, 3 segments
Capsid: helical
Dz: California encephalitis
Sandfly/Rift Valley fever
Crimean-Congo hemorrhagic fever
Hantavirus - hemorrhagic fever, pneumonia
44
Q 
Delta virus
Envelope:
Structure:
Capsid:
Dz:
A 
Delta virus
Envelope: yes
Structure: ssRNA (-) circular
Capsid: not sure
Dz: HDV - "defective" virus that requires HBV co-infection
45
Q

Importance of (-) stranded viruses

A 
must transcribe (-) to (+) - virion brings its own RNA-dependent RNA polymerase
Arenaviruses
Bunyaviruses
Paramyxoviruses
Orthomyxoviruses
Filoviruses
Rhabdoviruses
(Always Bring Polymerase Or Fail Replication)
46
Q

Segmented viruses

A 
All are RNA
Bunyaviruses
Orthomyxoviruses
Arenaviruses
Reovirus
(BOAR)
47
Q

Yellow fever

A

flaviviruse
Aedes mosquitos (monkey or human reservoir)
high fever, black vomitus, jaundice

48
Q

most important global cause of infantile gastroenteritis?

A

segmetned dsRNA virus - Rotavirus
acute diarrhea in US during winter esp in day-care, kindergartens
villous destruction with atrophy leads to decreased absorption of Na and loss of K

49
Q

influenza

A

orthomyxoviruses - enveloped, (-) ssRNA with 8 segments
contain hemagglutinin (viral entry) and neuraminidase (progeny virion release) antigens
rapid genetic changes
killed viral vaccine is major mode of protection, reformulated vaccine offered each fall

50
Q

genetic shift

A

cuases pandemics
reassortment of viral genome
segments undergo high frequency recombination, such as when human flu A virus recombines with swine flu A virus

51
Q

genetic drift

A

causes epidemics, minor changes based on random mutation

52
Q

rubella virus

A

togavirus
German measles - fever, postauricular adenopathy, lymphadenopathy, arthralgias, fine truncal rash that starts at head and moves down.
Mild disease in children but serious congenital disease (TORCH)

53
Q

paramyxoviruses

A

disease in children
croup, mumps, measles, RSV (respiratory tract infection in infants)
contain surface F (fusion) protein causes respiratory epi cells to fuse and form multinucleated cells
Palivizumab (monoclonal Ab against F protein) prevents pneumonia caused by RSV infection in premature infants

54
Q

measles virus

A

paramyxoviruse
Kopli spots (red spots with blue-white center on buccal mucosa) and descending maculopapular rash
SSPE (subacute sclerosing panencephalitis), encephalitis, giant cell pneumonia
Rash from head to toe - hands/feet

55
Q

mumps viruse

A

paramyxovirus
Parotitis, orchitis, aseptic meningitis
can cause sterility

56
Q

rabies virus

A

Bullet shaped virus
Negri bodies characteristic cytoplasmic inclusions in neurons infected by rabies (Purkinje cells of cerebellum - travels retrograde up nerve axons)
Weeks to months incubation
Fever, malaise –> agitation, photophobia, hydrophobia –> paralysis, coma –> death
Bat, raccoon, skunk bites

57
Q 
HAV
Type:
Transmission:
Incubation:
Cancer risk:
Clinical:
A 
HAV
Type: RNA picornavirus
Transmission: fecal-oral
Incubation: short
Cancer risk: No
Clinical: asymptomatic, acute, no carrier
58
Q 
HBV
Type:
Transmission:
Incubation:
Cancer risk:
Clinical:
A

HBV
Type: DNA hepadnavirus
Transmission: parenteral, sexual, materal-fetal
Incubation: long
Cancer risk: yes bc integrates into host genome
Clinical: carrier

59
Q 
HCV
Type:
Transmission:
Incubation:
Cancer risk:
Clinical:
A

HCV
Type: RNA flavivirus
Transmission: blood, IVDU, post-transfusion
Incubation: long
Cancer risk: yes from chronic inflamm
Clinical: chronic, cirrhosis, carcinoma, carrier

60
Q 
HDV
Type:
Transmission:
Incubation:
Cancer risk:
Clinical:
A

HDV
Type: RNA delta virus
Transmission: parenteral, sexual, maternal-fetal
Incubation: superinfection is short; co-infection is long
Cancer risk: yes
Clinical: defective virus that is dependent on HBV superinfection - decrease prognosis

61
Q 
HEV
Type:
Transmission:
Incubation:
Cancer risk:
Clinical:
A

HEV
Type: RNA hepevirus
Transmission: fecal-oral (waterborne epidemics)
Incubation: short
Cancer risk: none
Clinical: high mortality in pregnant, enteric, expctant mothers, epidemic

62
Q

Anti-HAV - IgM

A

IgM antibody to HAV

best test to detect active hepatitis A

63
Q

Anti-HAV - IgG

A

IgG antibody indicates prior HAV infection and/or prior vaccination; protects against reinfection

64
Q

HBsAg

A

Antigen found on surface of HBV; indicates hepatitis B infection

65
Q

Anti-HBs

A

Antibody to HBsAg

Indicates immunity to hepatitis B

66
Q

HBcAg

A

Antigen associated with core of HBV

67
Q

Anti-HBc

A

Antibody to HBcAg
IgM - acute/recent infection
IgG - prior exposure or chronic infection
Positive during window period

68
Q

HBeAg

A

A second, different antigenic determinant in the HBV core, HBeAg indicates active viral replication and therefore high transmissibility

69
Q

Anti-HBe

A

Antibody to e antigen; indicates low transmissibility

70
Q

viral hepatitis ALT vs AST

A

ALT > AST

71
Q

alcoholic hepatitis ALT vs AST

A

AST > ALT

72
Q

Acute HBV serologic markers

A

HBsAg, HBeAg, IgM Anti-HBc

73
Q

Window period of HBV serologic markers

A

Anti-HBe and IgM Anti-HBc

74
Q

Chronic HBV with high infectivity serologic markers

A

HBsAg, HBeAg, IgG Anti-HBc

75
Q

Chronic HBV with low infectivity serologic markers

A

HBsAg, Anti-HBe, IgG Anti-HBc

76
Q

Recovery from HBV serologic markers

A

Anti-HBs, Anti-HBe, IgG Anti-HBc

77
Q

Immunized to HBV serologic markers

A

Anti-HBs

78
Q 
HIV
Structure:
Virulence:
Immunity:
Slower Course:
A

HIV
Structure: diploid genome (2 molecules of RNA); 3 genes (1) env from gp120 attachment to host CD5+ T cell and gp41 fusion and entry (2) gag - capsid protein (3) pol - reverse transcriptase, aspartate protease, integrase
Virulence: reverse transcriptase synthesizes dsDNA from RNA –> dsDNA integrates into host genome
Immunity: homozygous CCR5 mutation (virus binds this late) co-receptor
Slower Course: heterozygous CCR5 mutation (virus binds this early)

79
Q

HIV diagnosis

A

Presumptive dx: ELISA (sensitive, high false positive rate and low threshold rule out test)
Western blot assay (specific, high false negative rate and high threshold, rule in test)
Both look for antibodies to viral proteins - falsely neg in first 1-2 months of HIV infection and falsely positive initially in babies born to infected mothers

80
Q

HIV prognostic test

A

PCR/viral load test - amount of viral RNA in the plasma
High viral load associated with poor prognosis
Also used to monitor effect of drug therapy

81
Q

AIDS Dx

A

diagnosis <1.5

  1. flu-like (acute)
  2. feeling fine (latent)
  3. falling count
  4. final crisis
82
Q

Immunocompromised CD4

A

<400 CD4+ cell/mm3

83
Q

AIDS-defining illnesses emerge

A

<200 CD4+ cells/mm3

84
Q

Systemic disease of HIV +

A

Low grade fevers, cough, hepatosplenomegaly, tongue ulcer
Oval yeast cells w/i macrophages
CD4 < 100
Histoplasma capsulatum (usually just pulmonary sx in healthy)

85
Q

Dermatologic disease of HIV +

A

Fluffy white cottage-cheese lesions: pseudohyphae, commonly oral if CD4 C. albicans
Superficial vascular proliferation: PMN inflammation –> Bartonella henselae (bacillary angiomatosis)

86
Q

Gastrointestinal disease of HIV +

A

Chronic, watery diarrhea: acid fast cysts seen in stool when CD4 < 200 –> Cryptosporidum

87
Q

Encephalopathy of HIV +

A

reactivation of latent virus –> demyelination (CD4 < 200) –> JC virus reactivation (PML)

88
Q

Abscesses of HIV +

A

Many ring enhancing lesions on imaging, CD4 Toxoplasma gondii

89
Q

Meningitis of HIV +

A

India ink stain reveals yeast with narrow based budding and large capsule, CD4 < 50 –> cryptococcus neoformans

90
Q

Retinitis of HIV +

A

Cotton wool spots on funduscopic exam and may also occur with esophagitis, CD4 < 40 –> CMV

91
Q

Dementia of HIV +

A

Directly associated with HIV

92
Q

Oncologic disease of HIV +

A

HHV-8 (Kaposi’s sarcoma): biopsy reveals lymphocytic inflamm –> superficial neoplastic proliferation of vasculature
EBV: lateral tongue –> hairy leukoplakia
EBV: oropharynx (Waldeyer’s ring) –> Non-Hodgkin’s lymphoma (large cell type)
HPV: often in anus or cervix –> SCC
EBV: focal or multiple –> primary CNS lymphoma

93
Q

Respiratory diseases of HIV +

A

CMV –> biopsy reveals cells with intranuclear (owl’s eye) inclusion bodies –> interstitial pneumonia
Aspergillus fumigatus –> pleuritic pain, hemoptysis, infiltrates on imaging –> invasive aspergillosis
Pneumocystis jirovecii –> CD4 Pneumonia
Mycobacterium avium-intracellulare –> CD4 tuberculosis like disease

94
Q

Prions
Mutation?
Presentation?
Types?

A

Caused by conversion of a normal cellular protein termed prion protein (PrPc) to a beta-pleated form (PrPsc) which is transmissible.
PrPsc resists degradation and facilitates the conversion of still more PrPc to PrPsc.
Spongiform encephalopathy and dementia, ataxia, and death.
Creutzfeldt-Jakob diseae = sporadic with rapidly progressive dementia
Gerstmann-Straussler-Scheinker syndrome = inherited
Kuru = acquired

95
Q

Prions
Mutation?
Presentation?
Types?

A

Caused by conversion of a normal cellular protein termed prion protein (PrPc) to a beta-pleated form (PrPsc) which is transmissible.
PrPsc resists degradation and facilitates the conversion of still more PrPc to PrPsc.
Spongiform encephalopathy and dementia, ataxia, and death.
Creutzfeldt-Jakob diseae = sporadic with rapidly progressive dementia
Gerstmann-Straussler-Scheinker syndrome = inherited
Kuru = acquired

Microbiology (7 decks)

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