Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

USMLE Step 1 > Microbiology - Virology > Flashcards

Microbiology - Virology Flashcards

You may prefer our related Brainscape-certified flashcards:
USMLE® Step 1 flashcards
1
Q

Naked virus with icosahedral capsid components

A

Capsid + Nucleic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Enveloped virus with icosahedral capsid

A

Surface protein
Lipid bilayer
Capsid
Nucleic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Enveloped virus with helical capsid

A

Surface protein
Lipid bilayer
Helical capsid with nucleic acid inside

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Recombination

A

exchange of genes between two chromosomes by crossing over within regions of significant base sequence homology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Reassortment

A

when viruses with SEGMENTED genomes (e.g. influenza virus) exchange segments. High-frequency recombination.
- Cause of influenza pandemics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Complementation

A

when 1 of 2 viruses that infect cell has a mutation that results in nonfunctional protein
Nonmutated virus “complements” the mutated one by making a functional protein that serves both viruses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Phenotype mixing

A
  • occurs co-infection of a cell by two viruses
    Genome of virus A can be partially or completed coated (forming pseudovirion) with surface proteins of virus B
    Type B protein coat determines infectivity (tropism) of hybrid virus
  • Progeny from infection have a type A coat that is encoded in type A genetic material
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Live attenuated viruses

A

induce humoral and cell-mediated immunity but have reverted back to virulence on rare occasions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Examples of live attenuated viruses

A
  • Smallpox
  • Yellow fever
  • Chickenpox (VZV)
  • Sabin’s polio virus
  • MMR
  • Influenza (intranasal)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Killed virus vaccine

A

induce only humoral immunity but are stable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Examples of killed viruses

A

Rabies
Influenza (injected
Salk Polio
HAV vaccines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Recombinant

A

HBV antigen (antigen = HBsAg), HPV (6, 11, 16, 18)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

DNA viral genomes

A

All DNA viruses except PARVOVIRIDAE are dsDNA

- all are linear except (PAPILLOMA-, POLYOMA-, and HEPADNAVIRUSES [circular])

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Parvovirus

A

ssDNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

RNA viral genomes

A

All RNA viruses except Reoviridae are ssRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Reoviridae

A

dsRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Positive stranded RNA viruses

A

“I went to a “RETRO” “TOGA” partry where I drank “FLAV”ored “CORONA” and ate “HIPPY” “CALI”fornia “PIC”kles

  • Retrovirus
  • Togavirus
  • Flavovirus
  • Coronavirus
  • Hepevirus
  • Calcivirus
  • Picornavirus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Infectious naked viral genomes

A

purified nucleic acids of most dsDNA (except poxviruses and HBV) and (+) ssRNA viruses are infectious.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Non-infectious naked viral genomes

A
  • Naked nucleid acids of (-) ssRNA and dsRNA viruses are not infectious. They need polymerases contained in complete virion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Virus ploidy

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

DNA virus replication

A

all replicate within nucleus (except poxvirus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

RNA virus replication

A

all replicate in the cytoplasm (except influenza virus and retroviruses)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Viral envelopes

A 
Give "PAPP" smears and "CPR" to a "NAKED HEPP"y
Naked include
- Papillomavirus
- Adenovirus
- Picornavirus
- Polyomavirus
- Calcivirus
- Hepevirus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

DNA viruses

A 
"HHAPPPPy"
H= Hepadna
H= Herpes
A = Adenoviruses
P = Pox
P = Parvo
P = Papilloma
P = Polyoma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

DNA virus characteristics

A
  • double stran ded (except parvovirus)
  • linear (except papolloma, polyoma, and hepadna)
  • are icosahedral except poxvirus
  • replicate in the nucleus party (except pox)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Herpesviruses

A
  • enveloped

- ds and linear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

HSV-1

A
  • oral (and some genital lesions), spontaneous temporal lobe encephalitis (most common cause of spontaneous encephaltitis in US)
    keratoconjunctivitis
  • Latent in trigeminal ganglia
  • transmitted through respiratory and saliva secretions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

HSV-2

A
  • Herpes genitalis
  • Neonatal herpes
  • Latent in sacral ganglia
  • transmitted via sexual contact, perinatal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

VZV

A

Varicella-zoster (chicken pox, shingles)

  • Encephalitis
  • Pneumonia
  • Latent in dorsal root or trigeminal ganglia
  • transmitted via respiratory secretions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

EBV

A

HHV-4

  • mononucleosis
  • Burkitt’s lymphoma
  • Hodgkin’s lymphoma
  • Nasopharyngeal carcinoma
  • Latent in B cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

CMV

A

Congenital infection
Mononucleosis (negative monospot) - immunocompetent patietnts
Pneumonia
Retinitis
Infected cells have “owl’s eye” inclusions
- Latent in mononuclear cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

HHV-6

A

Roseola

High fevers for several days that can cause seizures, followed by a diffuse macular rash

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

HHV-8

A

Kaposi’s sarcoma (HIV patients)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Hepadnavirus

A
  • enveloped
  • double stranded and partial circular
  • acute or chronic hepatitis
  • vaccine available - contains HBV surface antigen
  • not retrovirus but has reverse transcriptase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Adenovirus

A
  • non-enveloped
  • double stranded and linear
  • febrile pharyngitis - sore throat; acute hemorrhagic cystitis
  • pneumonia
  • conjunctivitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Parvovirus

A
  • non- enveloped
  • single stranded and linear negative DNA
  • B19 - aplastic crises in sicke cell disease, “slapped cheeks” rash in children - erythema infectiosym (fifth disease)
  • RBC destruction in fetus leads to hydrops fetalis and death
  • Pure RBC aplasia and rheumatoid arthritis-like symptoms in adults
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Papillomavirus

A
  • non-enveloped
  • double stranded and circular
  • HPV - warts (1,2,6,11)
  • Cervical cancer (16, 18)
  • Vaccine is available
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Polyoma virus

A
  • non-enveloped
  • double stranded and circular
    JC virus - associated with PML in HIV
    BK virus - transplant patients, commonly kidney
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Poxvirus

A
  • enveloped
  • double stranded and linear (largest DNA virus)
  • smallpox
  • vaccinia (cowpox)
  • molluscum contagiosum - flesh colored dome lesions with central dimple
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

HSV identification

A

PCR is test of choice
Tzanck test - a smear of an opened skin vesicle to detect multinucleated giant cells seen HSV-1, HSV-2, and VZV
** Infected cells have intranuclear Cowdry A inclusions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

EBV

A

A herpesvisus

  • can cause mononucleosis, hepatosplenomegaly, pharyngitis, and lymphadenopathy
  • peak incidence (15 - 20 y.o)
  • Atypical lymphocytes seen in peripheral smear are not infected B cells but rather cytotoxic T cells
  • Positive Monospot test
  • associated with Hodgkin’s, Burkitt lymphomas as naseopharyngeal carcinoma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Positive Monospot

A
  • heterophile antibodies detected by agglutination of sheep/horse RBCS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Reoviruses

A
  • nonenveloped
  • linear dsRNA with 10-12 segments
  • icosahedral (double)
  • Coltivirus - Colorado tick fever
  • Rotavirus - #1 cause of fatal diarrhea in children
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Picornaviruses

A 
- non-enveloped
 \+ SS linear RNA
-  icosahedral
"PERCH"
Poliovirus 
Echovirus
Rhinovirus
Coxsackievirus 
Hep A virus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Hepevirus

A

-non-enveloped
+ SS linear RNA
- icosahedral
HEV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Calciviruses

A
  • nonenveloped
  • SS + linear RNA virus
  • icosahedral capsid
  • Norovirus - viral gatsroenteritis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Flaviviruses

A
  • enveloped SS + linear RNA
  • icosahedral
  • HCV
  • Yellow fever
  • Dengue
  • St. Louis encephalitis
  • West Nile virus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Togaviruses

A
  • enveloped
  • SS + linear RNA and icosahedral
  • Rubella
  • Eastern & Western equine encephalitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Retroviruses

A
  • enveloped
  • SS + linear RNA
  • icosahedral
  • have reverse transcriptase
  • HTLV - T-cell leukemia
  • HIV - AIDS
50
Q

Coronaviruses

A

enveloped SS + linear RNA
Helical
Common cold and SARS

51
Q

Orthomyxoviruses

A

Enveloped
SS - linear RNA
8 segments
Influenza virus

52
Q

Paramyxoviruses

A 
Enveloped SS - linear RNA
Nonsegmented
Parainfluenza - croup
RSV - bronchiolitis in babies - treated w/ ribavirin
Measles
Mumps
53
Q

Rhabdoviruses

A

Enveloped
SS - linear RNA
Helical
Rabies

54
Q

Filoviruses

A

Enveloped
SS - linear RNA
Helical
Ebola/Marbug hemorrhagic fever - often fatal!

55
Q

Arenaviruses

A

Enveloped
SS - CIRCULAR RNA
2 segments
Helical
LCMV - lymphocytic choriomeningitic virus
Lassa fever encephalitis - spread by mice

56
Q

Bunyaviruses

A 
Enveloped 
SS - CIRCULAR RNA
3 segments
Helical 
California encephalitis
Sandfly/Rift valley fevers
Crimean-Congo hemorrhagic fever
Hantavirus - hemorrhagic fever, pneumonia
57
Q

Delta virus

A

Enveloped
SS - CIRCULAR RNA
Uncertain capsid
HDV - defective virus that requires HBV co-infection

58
Q

Negative stranded viruses

A

must transcribe negative strand to positive

Virion brings its own RNA-dependent RNA polymerase

59
Q

Mneumonic for negative stranded viruses

A 
"Always Bring Polymerase Or Fail Replication"
A = Arenaviruses
B = Bunyaviruses
P = Paramyxoviruses
O = Orthomyxoviruses
F = Filoviruses
R = Rhabdoviruses
60
Q

Segmented viruses

A 
All are RNA viruses
"BOAR"
B = Bunyavirus
O = Orthomyxoviruses (influenza viruses)
A = Arenavirueses
R = Reoviruses
61
Q

Picornaviruses

A 
Poliovirus
Echovirus
Rhinovirus
Coxsackievirus
Hepatitis A
62
Q

Picornaviruses

A

RNA is translated into 1 large polypeptide that is cleaved by proteases into functional viral proteins

  • Can cause viral meningitis (EXCEPT Rhinovirus and HAV)
  • All are enteroviruses (fecal-oral spread) except rhinovirus
63
Q

Rhinovirus

A 
A picornavirus
Non-enveloped RNA virus
Causes common cold 
> 100 serologic types
Acid labile - destroyed by stomach acid
Doesn't infect GI tract (unlike other picornaviruses)
64
Q

Yellow fever virus

A

Flavivurs (also an arbovirus)
- transmitted by Aedes mosquitos
- Has monkey or human resevoir
Sx: high fever, black vomitis, and jaundice

65
Q

Rotavirus

A

Common WORLDWIDE cause of infantile gastroenteritis

  • segmented dsRNA virus
  • major cause of acute diarrhea during winter esp. in day care centers, kindergartens
  • villous destruction with atrophuy leads to decreased absorption of NA and loss K
66
Q

Influenza viruses

A

Orthomyxoviruses
Enveloped, negative ss RNA viruses with 8 segments
Hemagglutinin - promotes viral entry
Neuraminidase - promotes progeny virion release
- patient at risk for fatal bacterial superinfection
Rapid genetic changes

67
Q

Mode of protection from influenza viruses

A

Killed viral vaccine is MAJOR mode of protection

Another vaccine contains live, temp sensitive mutant that replicates in the nose but not in lung

68
Q

Genetic shift/antigenic shift

A
  • causes pandemics
  • reassortment of viral genome
  • segments undergo high-frequency recombination such as human flu A virus with swine flu A virus
69
Q

Genetic drift

A
  • causes epidemics

- minor (antigenic drift) - changes based on random mutation

70
Q

Rubella virus

A

togavirus
causes rubella, known as German measles
- Fever, posterior auricular lymphadenopathy,
- Truncal rash that starts at head and descends
- causes mild disease in children but serious congenital disease

71
Q

Paramyxovirus

A
  • disease in children
  • parainfluenza (croup: seal-like barking cough)
  • Mumps, Measles
  • Contain surface F protein, which causes respiratory epithelial cells to fuse and form multinucleated cells
72
Q

RSV

A

Paramyxovirus - causes brionchiolitis, pneumonia in infants

Palivizumab (monoclonal antibody against F portein) prevents pneumonia caused by RSV infection in premature infants

73
Q

Measles

A

paramyxovirus

  • Kolik spots (red spots with blue-white cente on buccal mucosa)
  • descending maculopapular rash
  • subacute sclerosing panencephalitis and giant cell pneumonia (in immunosuppresed)
  • rash presents last and spreads from head to toe, includes hands and feet (vs. trunk in Rubella)
74
Q

3 C’s of Measles

A

Cough
Coryza (rhinitis, inflammation of nasal mucosa)
Conjunctivitis

75
Q

Mumps

A 
Paramyxovirus
Parotitis
Orchitis (inflammation of testes)
Asceptic meningitis
- Can cause sterility in puberty
76
Q 
Paramyxovirus
Parotitis
Orchitis (inflammation of testes)
Asceptic meningitis
- Can cause sterility in puberty
A

Bullet-shaped virus

  • Negri bodies - cytoplasmic inclusions in neurons infected by rabies virus
  • Found in Purkinke cells of cerebellium
  • Post exposure treatment is wound cleansing and vaccine with/without rabies immunoglobulin
77
Q

Rabies

A
  • Has long incubation period (weeks to months) before symptom onset
  • Travels to CNS by migrating in a retrograde fashion up nerve axons
  • Progression of disease: fever, malaise –> agitation, photophobia, hydrophobia –> paralysis, coma –> death
  • Associated with bat, raccoon, skunk bites than dog bites in US
78
Q

Hep A virus

A

RNA picornavirus

  • transmitted fecal-orally
  • no carries
  • short incubation (weeks)
  • no HCC risk
  • assymptomatic, acute, alone
79
Q

HBV

A

DNA hepadnavirus

  • transmitted parentally, sexually, maternal-fetal
  • carrier state possible
  • long incubation (months)
  • HCC risk as it integrates with host genome and acts as oncogene
80
Q

HCV

A

RNA flavivirus

  • transmitted primarily in blood, IV drug users, post-transfusion
  • carrier state
  • long incubation
  • HCC risk from chronic inflammation
  • associated with cryoglobulin
81
Q

HDV

A 
RNA deltavirus
 transmission: Parental, Sexual, Maternal-Fetal
Carrier state
-Superinfection (after chronic HBV)
- Co-infection (with acute HBV)
- defective virus, dependent on HBV
82
Q

HEV

A

RNA hepevirus

  • transmitted fecal orally, especially with waterborne epidemics
  • no carrier ste
  • short incubation
  • no HCC risk
  • high mortality in pregnent women
83
Q

Anti-HAV (IgM)

A

IgM antibody to HAV, best test to detect active Hep A

84
Q

Anti-HAV (IgG)

A

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

85
Q

HBsAg

A

antigen found on surface of HBV

indicates HBV infection

86
Q

Anti-HBsAg

A

antibody to HBsAg

- indicates immunity to Hep B

87
Q

HBcAg

A

Antigen associated with core of HBV

88
Q

Anti-HBV

A

antibody to HBcAg
IgM = acute/recent infection
IgG = prior exposure or chronic infection

89
Q

HBeAg

A

indicates active viral HBV replication and thus high transmissibility

90
Q

Anti-HBe

A

antibody to e antigen; indicates low transmissibility

91
Q

Window period

A
  • can occur 5-6 months after exposure

- no HBsAg but Anti-HBe Anti-HBcIgM

92
Q

HIV

A

diploid genome (2 molecules of RNA)
reverse transcriptase synthesizes dsDNA from RNA
dsDNA integrates into host genome
- virus binds to CCR5 (early) or CXCR4 (lates) co-receptor and CD4 on T cells
- binds to CCR5 and CD4 on macrophages

93
Q

Homozygous CCR5 mutation

A

= immmunity from HIV

94
Q

Heterozygous CCr5 mutation

A

= slower course of HIV

95
Q

Structural proteins associated with HIV

A
  • env (gp 120 and gp41) - formed from cleavage of gp160 to form envelope proteins
  • gp120 - attachment to CD4+ T cells
  • gp41 - fusion and entry
    -gag (p24) - capsid protein
    pol - reverse transcriptase, aspartate protease integrase
96
Q

HIV diagnosis

A
  • intially with ELISA (high sensitivity, low specificity)

- confirmed with Western blot (high specificity)

97
Q

HIV/PCR viral load

A

tests determine the amount of viral RNA in plasma.
High viral load associated with poor prognosis
Also use viral load to monitor drug therapy

98
Q

AIDS diagnosis

A

< 200 CD4

  • HIV with AIDS defining condition (e.g PCP pneumonia)
  • CD4/CD8 < 1.5
99
Q

ELISA/Western blot

A

looks for antibodies to viral proteins
are often falsely negative in the first 1-2 months of HIV infection
- Falsely positive initially in babies born to infected mothers (anti-gp120 crosses placenta)

100
Q

Four stages of infection

A
  1. Flu-like (acute)
  2. Feeling fine (latent) - virus is replicating in lymph nodes
  3. Falling count
  4. Final crisis
101
Q

HIV + with low grade fevers, cough, hepatosplenomegaly, tongue ulcer

A

Histoplasmosis capsulatum

  • causes pulm symptoms in “healthy” patients
  • oval yeast cells within macrophages, CD4 < 100
102
Q

HIV + w/ fluffy white cottage cheese lesions

A

C. albicans

  • pseudohyphase
  • oral if CD4 < 400
  • esophageal if CD4 < 100
103
Q

HIV + w/ superficial vascular proliferation

A 
Bartonella henselae (causes bacillary angiomatosis)
- biopsy shows neutrophilic inflammation
104
Q

HIV+ w/ chronic watery diarrhea

A

Cryptosporidium

- acid fast cysts seen in stool when CD4 < 200

105
Q

HIV + w/ encephalopathy

A
  • JC virus reactivation (cause of PML)

- results in demyelination of oligodendrocytes CD4 < 200

106
Q

HIV + w/ brain abscesses

A

Toxoplasmosis gondii

  • many ring-enhancing lesions on imaging
  • CD4 < 100
107
Q

HIV+ w/ meningitis

A
  • C. neoforms
  • India ink stain reveals yeast with narrow-based budding and large capsule
  • CD4 < 50
108
Q

HIV + w/ retinitis

A

CMV
- cotton wool sports on fundoscopic exam and may occur with esophagitis
CD4 < 50 cells

109
Q

HIV + dementia

A

Directly associated with HIV

- may have differentiate from other causes

110
Q

HIV + with superficial neoplastic proliferation of vasculature

A

HHV-8 (Kaposi’s sarcoma)

  • biopsy reveals lymphocytic inflammation
    • don’t confuse with bacilliary angiomatosis
111
Q

HIV + with hairy leukoplakia

A

EBV

- often on lateral tongue

112
Q

HIV+ w/ non-Hodgkin’s lymphoma

A

EBV

- often on oropharynx (Waldeyer’s ring)

113
Q

HIV+ w/ squamous cell carcinoma (of anything!!)

A

HPV

- in gay men, may have anal HPV

114
Q

HIV + with primary CNS lymphoma

A

EBV

- multiple or focal, differentiate from toxoplasmosis

115
Q

HIV + with interstitial pneumonia

A

CMV

- biopsy reveals cells with intranuclear (owl’s eye) inclusion bodies

116
Q

HIV + with invasive aspergillosis

A

Aspergilosis fumigatus

- pleuritic pain, hemoptysis, infiltrates on imaging (acute angled hyphae)

117
Q

HIV+ with pneumonia

A

Pneumocystis jirovecci

- especially in CD4 < 200 cells

118
Q

HIV + with TB-like disease

A

Mycobacterium avium-intracelluaire

- esp in CD4 < 50 cells

119
Q

Envelope proteins for HIV

A
  • acquired from budding from host cell plasma membrane
  • gp120: docking protein for attachment to CD4
  • gp41: transmembrane protein for fusion and entry
120
Q

Gap(p24) protein

A

HIV capsid protein

121
Q

p17 associated with HIV

A

Matrix protein

122
Q

pol gene

A

HIV

  • reverse transcriptase
  • aspartate protease
  • integrase

USMLE Step 1 (34 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions