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Step 1 Flash Cards > Viruses > Flashcards

Viruses 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 virsuses with segmented genomes (inflenza) exchange segments. high-frequency recombination. cause of worldwide influenza pandemics

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3
Q

complementation

A

when 1 of 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 A can be partially or completely coated with surface proteins from B. therefore virus A can infect a new type of cell, although its progeny will not be able to

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5
Q

live attenuated vaccines

A
  • humoral and cell mediated immunity
  • boosters not needed
  • ex: smallpox, yellow fever, chicken pox, sabin polio virus, MMR, influenza (intranasal)
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6
Q

killed vaccines

A
  • produce only humoral immunity

- rabies, influenza, salk polio, and HAV

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7
Q

recombinant vaccines

A
  • HBV, HPV
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8
Q

DNA viral genomes

A
  • all dsDNA except parvoviridae

- all are linear except papilloma, polyoma and hepadnaviruses (circular)

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9
Q

RNA viral genomes

A

all are ssRNA excpet reoviridae
- positive stranded RNA viruses: I went to a retro(virus) toga(virus) party, where I drank flavored (flavivirus) corona(virus) and ate hippy (hepevirus) california (calicivirus) pickles (picornavirus)

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10
Q

which naked genomes are infectious?

A

dsDNA and + sense ssRNA (dsRNA and -ve sense ssRNA are not)

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11
Q

naked viruses

A

I gave PAPP smears and CPR to a naked Heppy

  • DNA: papilloma, adenovirus, parvovirus, polyomavirus
  • RNA: calicivirus, picornavirus, reovirus, hepevirus
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12
Q

theres something weird about all the “P” DNA viruses

A
  • pox - not icosahedral, replicates outside the nucleus
  • polyoma and papilloma - circular DNA
  • parvo - single stranded DNA
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13
Q

HSV-1

A

gingivostomatitis, keratoconjunctivitis, temporal lobe encephalitis, herpes labalis

  • latent infection in the trigeminal ganglia
  • transmitted via respiratory secretions, saliva
  • intranuclear inclusions seen on oral scrapings
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14
Q

HSV-2

A
  • herpes genitalis, neonatal herpes
  • latent in the sacral ganglia
  • transmitted by sexual contact, perinatally
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15
Q

VZV

A

HHV-3

  • chickenpox, shingles, encephalitis, pneumonia
  • latent in the dorsal root or trigeminal ganglia
  • most common complication of shingles is post-herpetic neuralgia
  • transmitted by respiratory secretions
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16
Q

EBV

A

HHV-4

  • mono (feer, HSmegaly, pharyngitis, lymphadenopathy - esp post cervical nodes)
  • transmitted via respiratory secretions and saliva
  • infects B cells by binding to CD21 on B cells and nasopharyngeal epithelial cells
  • atypical lymphocytes (abundant pale blue cytoplasm with basophilic rim) seen on PBS - reactive cytotoxic T cells
  • assoc with Hodgkin lymphoma, endemic burkitt lyphoma, nasopharyngeal carcinoma
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17
Q

CMV

A

HHV-5

  • congenital infection, mono with negative monospo, pneumonia, retinitis
  • “owl eye” inclusions
  • latent mononuclear cells
  • transmitted congenitally and via transfusion, sex, saliva, urine, transplant
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18
Q

HHV-6

A

roseola - high fevers for several days that can cause seizures, followed by diffuse maculopapular rash
- transmitted by saliva

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19
Q

HHV-8

A

Kaposi sarcoma, neoplasm of endothelial cells

  • seen in HIV/AIDS, transplants
  • dark/violaceous flat and nodular skin lesions representing endothelial growhts
  • can also affect GI tract and lungs
  • transmitted by sexual contact
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20
Q

HSV identification

A
  • viral culture for skin/genitalia
  • CSF PCR for encephalitis
  • Tzank smear - multinucleated giant cells
  • infected cells also have a intranuclear Cowdry A inclusions
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21
Q

Hepadnavirus

A

Hep B - not a retrovirus but has a reverse transcriptase

- enveloped, partially DS DNA and circular

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22
Q

Adenovirus

A
  • no envelope, DS and linear

- febrile pharyngitis, acute hemorrhagic cystitis, pneumonia, pink eye

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23
Q

parvovirus

A
  • ssDNA, not enveloped, linear
  • aplastic crises in sickle cell pts, 5th disease, hydrops fetalis, pure RBC aplasia/rhematoid arthritis-like disease in adults
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24
Q

papillomavirus

A
  • dsDNA, not enveloped, circular

- HPV warnts (1,2,6,11), CIN, cervical cancer (16, 18)

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25
Q

polyomavirus

A
  • dsDNA, not enveloped, circular
  • JC virus - PML
  • BK virus - transplant patients, affects the kidney
26
Q

poxvirus

A
  • dsDNA, enveloped, linear, replicates outside the nucleus, not icosahedral
  • smallpox, cowpox (“milkmaid blisters”), and molluscum contagiosum
27
Q

reoviruses

A
  • no envelope, dsRNA, icosahedral capsid
  • coltivirus - Colorado tick fever
  • rotavirus - #1 cause of fatal diarrhea in kids
28
Q

picornaviruses

A
  • no envelope, + ssRNA, icosahedral capsid
  • PERCH: poliovirus, echovirus (aseptic meningitis), rhinovirus, coxsackievirus* (aseptic meningitis, herpangina, HFM, myocarditis, pericarditis), HAV
  • 1 large polypeptide that is cleaved by proteases into functional viral proteins
    • aseptic meningitis
  • are all enteroviruses (fecal-oral), except rhinovirus
29
Q

hepevirus

A
  • no envelope, + ssRNA, icosahedral capsid

- HEV

30
Q

caliciviruses

A
  • no envelope, + ssRNA, icosahedral capsid

- norovirus - viral gastroenteritis

31
Q

flavivirus

A
  • enveloped, + ssRNA, icosahedral capsid

- HCV, yellow fever, dengue, St. louis encephalitis, West Nile virus

32
Q

togaviruses

A
  • enveloped, + ssRNA, icosahedral

- rubella, eastern and western equine encephalitis

33
Q

retroviruses

A
  • enveloped, + ssRNA
  • HTLV - T cell leukemia (icosahedral)
  • HIV (complex and conical) - AIDS
34
Q

coronaviruses

A
  • enveloped, + ssRNA, helical capsid

- common cold and SARS

35
Q

orthomyxoviruses

A
  • enveloped, - ssRNA, helical capsid

- influenza

36
Q

paramyxoviruses

A
  • enveloped, - ssRNA, nonsegmented, helical capsid
  • PaRaMyxovirus
  • parainfluenza (croup), RSV (bronchiolitis) {{Rx - ribavarin}}, Measles, Mumps
  • all contain surface F (fusion) protein, which causes resp epi cells to fuse –> multinucleated cells
  • palivizumab prevents RSV pneumonia
37
Q

Rhabdoviruses

A
  • enveloped, -ssRNA, helical capsid

- rabies

38
Q

filoviruses

A
  • enveloped, - ssRNA, helical capsid

- ebola/marburg hemorrhagic fever - often fatal!

39
Q

arenaviruses

A
  • enveloped, -ssRNA circular (2 segments), helical capsid
  • LCMV - lymphocytic choriomeningitis virus
  • lassa fever encephalitis - spread by mice
40
Q

bunyaviruses

A
  • enveloped, -ssRNA circular (3 segments), helical capsid
  • california encephalitis, sandlfy/Rift valley fevers, crimean-congo hemorrhagic fever, hantavirus - hemorrhagic fever, pneumonia
41
Q

delta virus

A
  • enveloped, - ssRNA circular, uncertain capsid

- HDV - “defective” without HBV coinfection

42
Q

segmented viruses

A

BOAR

- bunyavirus, orthomyxoviruses, arenaviruses, reoviruses

43
Q

rhinovirus

A
  • picornavirus, nonenveloped RNA virus
  • cause of the common cold
  • acid labile - destroyed in stomach, does not infect the GI tract like the enteroviruses
44
Q

yellow fever virus

A
  • flavivirus/arbovirus transmitted by Aedes mosquito
  • virus has monkey and human reservoir
  • high fever, black vomit, jaundice
45
Q

rotavirus

A
  • segmented RNA virus, the most important cause of infantile gastroenteritis
  • day care centers and kindergartens
  • villous destruction with atrophy leads to dec absorption of Na and loss of K
46
Q

influenza viruses

A
  • orthomyxoviruses, enveloped -ssRNA with 9 segment genome
  • contain hemagglutinin (promotes viral entry) and neuraminidase (promotes progeny release)
  • anti-hemagglutining IgA and IgG mediate immunity
47
Q

genetic shift/antigenic shifts

A

causes pandemics

  • reassortment of viral genome, segments undergo high-freq recombination
  • ex: flu and swine flu recombination
48
Q

genetic drigt

A

causes epidemics

- minor changes based on random mutation

49
Q

rubella

A
  • togavirus
  • fever, postauricular adenopathy, arthralgias, fine rash
  • blueberry muffin baby
50
Q

measles virus

A
  • paramyxovirus
  • Koplik spots and descending maculopapular rash
  • possible sequelae: SSPE, encephalitis, and giant cell pneumonia
51
Q

mumps

A
  • paramyxovirus
  • parotidis, orchitis, aseptic meningitis
  • may cause sterility
52
Q

rabies virus

A

bullet shaped virus

  • Negri bodies commonly found in Purkinje cells (cerebellum, hippocampus)
  • travels to the CNS via retrograde motion
  • more commonly from bat, racoon and skunk in the US
53
Q

HBV

A

DNA hepadnavirus

  • parenteral, sexual and maternal-fetal transmission
  • dsDNA –> + ssRNA –> dsDNA
  • incorporates into host genome
  • acute infection - “serum sickness”: malaise, fever, skin rash, pruritis, lymphadenopathy, joint pain
54
Q

HCV

A

DNA flavivirus

- has no 3’-5’ proofreading, so many errors are made during replication and many subspecies can coexist in one person)

55
Q

HDV

A

RNA delta virus

  • parenteral, sexual and MFM transmission
  • dependent on HBV
56
Q

HEVv

A
  • RNA hepevirus
  • fecal-oral
  • high mort in preggos
57
Q

HBsAg

A
  • noninfective envelope glyoprotein –> spheres/tubules 22nm in diameter
  • indicative of active Hep B infection
58
Q

3 structural genes of HIV

A
  • env (gp120 for attachment and gp41 for fusion/entry)
  • gag - capsid protein
  • pol - reverse trascriptase
59
Q

HIV diagnosis

A

ELISA is sensitive, Western Blot is specific

- AIDS if < 200 CD4, AIDS-defining condition or CD % < 14%

60
Q

prion diseases

A
  • conversion of a normal (usually alpha helical) protein to a B-pleated form, cannot be degraded by proteases
  • sporadic (CJD), inherited (Gerstmann-Staussler-Scheinker) or acquired (kuru)

Step 1 Flash Cards (36 decks)

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