Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

USMLE Step 1 > Microbiology - Virology > Flashcards

Microbiology - Virology Flashcards

(122 cards)

Start Studying
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
DNA virus characteristics
- double stran ded (except parvovirus) - linear (except papolloma, polyoma, and hepadna) - are icosahedral except poxvirus - replicate in the nucleus party (except pox)
26
Herpesviruses
- enveloped | - ds and linear
27
HSV-1
- 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
28
HSV-2
- Herpes genitalis - Neonatal herpes - Latent in sacral ganglia - transmitted via sexual contact, perinatal
29
VZV
Varicella-zoster (chicken pox, shingles) - Encephalitis - Pneumonia - Latent in dorsal root or trigeminal ganglia - transmitted via respiratory secretions
30
EBV
HHV-4 - mononucleosis - Burkitt's lymphoma - Hodgkin's lymphoma - Nasopharyngeal carcinoma - Latent in B cells
31
CMV
Congenital infection Mononucleosis (negative monospot) - immunocompetent patietnts Pneumonia Retinitis Infected cells have "owl's eye" inclusions - Latent in mononuclear cells
32
HHV-6
Roseola | High fevers for several days that can cause seizures, followed by a diffuse macular rash
33
HHV-8
Kaposi's sarcoma (HIV patients)
34
Hepadnavirus
- enveloped - double stranded and partial circular - acute or chronic hepatitis - vaccine available - contains HBV surface antigen - not retrovirus but has reverse transcriptase
35
Adenovirus
- non-enveloped - double stranded and linear - febrile pharyngitis - sore throat; acute hemorrhagic cystitis - pneumonia - conjunctivitis
36
Parvovirus
- 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
37
Papillomavirus
- non-enveloped - double stranded and circular - HPV - warts (1,2,6,11) - Cervical cancer (16, 18) - Vaccine is available
38
Polyoma virus
- non-enveloped - double stranded and circular JC virus - associated with PML in HIV BK virus - transplant patients, commonly kidney
39
Poxvirus
- enveloped - double stranded and linear (largest DNA virus) - smallpox - vaccinia (cowpox) - molluscum contagiosum - flesh colored dome lesions with central dimple
40
HSV identification
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
41
EBV
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
42
Positive Monospot
- heterophile antibodies detected by agglutination of sheep/horse RBCS
43
Reoviruses
- nonenveloped - linear dsRNA with 10-12 segments - icosahedral (double) - Coltivirus - Colorado tick fever - Rotavirus - #1 cause of fatal diarrhea in children
44
Picornaviruses
``` - non-enveloped + SS linear RNA - icosahedral "PERCH" Poliovirus Echovirus Rhinovirus Coxsackievirus Hep A virus ```
45
Hepevirus
-non-enveloped + SS linear RNA - icosahedral HEV
46
Calciviruses
- nonenveloped - SS + linear RNA virus - icosahedral capsid - Norovirus - viral gatsroenteritis
47
Flaviviruses
- enveloped SS + linear RNA - icosahedral - HCV - Yellow fever - Dengue - St. Louis encephalitis - West Nile virus
48
Togaviruses
- enveloped - SS + linear RNA and icosahedral - Rubella - Eastern & Western equine encephalitis
49
Retroviruses
- enveloped - SS + linear RNA - icosahedral - have reverse transcriptase - HTLV - T-cell leukemia - HIV - AIDS
50
Coronaviruses
enveloped SS + linear RNA Helical Common cold and SARS
51
Orthomyxoviruses
Enveloped SS - linear RNA 8 segments Influenza virus
52
Paramyxoviruses
``` Enveloped SS - linear RNA Nonsegmented Parainfluenza - croup RSV - bronchiolitis in babies - treated w/ ribavirin Measles Mumps ```
53
Rhabdoviruses
Enveloped SS - linear RNA Helical Rabies
54
Filoviruses
Enveloped SS - linear RNA Helical Ebola/Marbug hemorrhagic fever - often fatal!
55
Arenaviruses
Enveloped SS - CIRCULAR RNA 2 segments Helical LCMV - lymphocytic choriomeningitic virus Lassa fever encephalitis - spread by mice
56
Bunyaviruses
``` Enveloped SS - CIRCULAR RNA 3 segments Helical California encephalitis Sandfly/Rift valley fevers Crimean-Congo hemorrhagic fever Hantavirus - hemorrhagic fever, pneumonia ```
57
Delta virus
Enveloped SS - CIRCULAR RNA Uncertain capsid HDV - defective virus that requires HBV co-infection
58
Negative stranded viruses
must transcribe negative strand to positive | Virion brings its own RNA-dependent RNA polymerase
59
Mneumonic for negative stranded viruses
``` "Always Bring Polymerase Or Fail Replication" A = Arenaviruses B = Bunyaviruses P = Paramyxoviruses O = Orthomyxoviruses F = Filoviruses R = Rhabdoviruses ```
60
Segmented viruses
``` All are RNA viruses "BOAR" B = Bunyavirus O = Orthomyxoviruses (influenza viruses) A = Arenavirueses R = Reoviruses ```
61
Picornaviruses
``` Poliovirus Echovirus Rhinovirus Coxsackievirus Hepatitis A ```
62
Picornaviruses
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
Rhinovirus
``` 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
Yellow fever virus
Flavivurs (also an arbovirus) - transmitted by Aedes mosquitos - Has monkey or human resevoir Sx: high fever, black vomitis, and jaundice
65
Rotavirus
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
Influenza viruses
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
Mode of protection from influenza viruses
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
Genetic shift/antigenic shift
- causes pandemics - reassortment of viral genome - segments undergo high-frequency recombination such as human flu A virus with swine flu A virus
69
Genetic drift
- causes epidemics | - minor (antigenic drift) - changes based on random mutation
70
Rubella virus
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
Paramyxovirus
- 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
RSV
Paramyxovirus - causes brionchiolitis, pneumonia in infants | Palivizumab (monoclonal antibody against F portein) prevents pneumonia caused by RSV infection in premature infants
73
Measles
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
3 C's of Measles
Cough Coryza (rhinitis, inflammation of nasal mucosa) Conjunctivitis
75
Mumps
``` Paramyxovirus Parotitis Orchitis (inflammation of testes) Asceptic meningitis - Can cause sterility in puberty ```
76
``` Paramyxovirus Parotitis Orchitis (inflammation of testes) Asceptic meningitis - Can cause sterility in puberty ```
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
Rabies
- 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
Hep A virus
RNA picornavirus - transmitted fecal-orally - no carries - short incubation (weeks) - no HCC risk - assymptomatic, acute, alone
79
HBV
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
HCV
RNA flavivirus - transmitted primarily in blood, IV drug users, post-transfusion - carrier state - long incubation - HCC risk from chronic inflammation - associated with cryoglobulin
81
HDV
``` RNA deltavirus transmission: Parental, Sexual, Maternal-Fetal Carrier state -Superinfection (after chronic HBV) - Co-infection (with acute HBV) - defective virus, dependent on HBV ```
82
HEV
RNA hepevirus - transmitted fecal orally, especially with waterborne epidemics - no carrier ste - short incubation - no HCC risk - high mortality in pregnent women
83
Anti-HAV (IgM)
IgM antibody to HAV, best test to detect active Hep A
84
Anti-HAV (IgG)
IgG antibody indicates prior HAV infection and/or prior vaccination; protects against new infection
85
HBsAg
antigen found on surface of HBV | indicates HBV infection
86
Anti-HBsAg
antibody to HBsAg | - indicates immunity to Hep B
87
HBcAg
Antigen associated with core of HBV
88
Anti-HBV
antibody to HBcAg IgM = acute/recent infection IgG = prior exposure or chronic infection
89
HBeAg
indicates active viral HBV replication and thus high transmissibility
90
Anti-HBe
antibody to e antigen; indicates low transmissibility
91
Window period
- can occur 5-6 months after exposure | - no HBsAg but Anti-HBe Anti-HBcIgM
92
HIV
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
Homozygous CCR5 mutation
= immmunity from HIV
94
Heterozygous CCr5 mutation
= slower course of HIV
95
Structural proteins associated with HIV
- 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
HIV diagnosis
- intially with ELISA (high sensitivity, low specificity) | - confirmed with Western blot (high specificity)
97
HIV/PCR viral load
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
AIDS diagnosis
< 200 CD4 - HIV with AIDS defining condition (e.g PCP pneumonia) - CD4/CD8 < 1.5
99
ELISA/Western blot
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
Four stages of infection
1. Flu-like (acute) 2. Feeling fine (latent) - virus is replicating in lymph nodes 3. Falling count 4. Final crisis
101
HIV + with low grade fevers, cough, hepatosplenomegaly, tongue ulcer
Histoplasmosis capsulatum - causes pulm symptoms in "healthy" patients - oval yeast cells within macrophages, CD4 < 100
102
HIV + w/ fluffy white cottage cheese lesions
C. albicans - pseudohyphase - oral if CD4 < 400 - esophageal if CD4 < 100
103
HIV + w/ superficial vascular proliferation
``` Bartonella henselae (causes bacillary angiomatosis) - biopsy shows neutrophilic inflammation ```
104
HIV+ w/ chronic watery diarrhea
Cryptosporidium | - acid fast cysts seen in stool when CD4 < 200
105
HIV + w/ encephalopathy
- JC virus reactivation (cause of PML) | - results in demyelination of oligodendrocytes CD4 < 200
106
HIV + w/ brain abscesses
Toxoplasmosis gondii - many ring-enhancing lesions on imaging - CD4 < 100
107
HIV+ w/ meningitis
- C. neoforms - India ink stain reveals yeast with narrow-based budding and large capsule - CD4 < 50
108
HIV + w/ retinitis
CMV - cotton wool sports on fundoscopic exam and may occur with esophagitis CD4 < 50 cells
109
HIV + dementia
Directly associated with HIV | - may have differentiate from other causes
110
HIV + with superficial neoplastic proliferation of vasculature
HHV-8 (Kaposi's sarcoma) - biopsy reveals lymphocytic inflammation * * don't confuse with bacilliary angiomatosis
111
HIV + with hairy leukoplakia
EBV | - often on lateral tongue
112
HIV+ w/ non-Hodgkin's lymphoma
EBV | - often on oropharynx (Waldeyer's ring)
113
HIV+ w/ squamous cell carcinoma (of anything!!)
HPV | - in gay men, may have anal HPV
114
HIV + with primary CNS lymphoma
EBV | - multiple or focal, differentiate from toxoplasmosis
115
HIV + with interstitial pneumonia
CMV | - biopsy reveals cells with intranuclear (owl's eye) inclusion bodies
116
HIV + with invasive aspergillosis
Aspergilosis fumigatus | - pleuritic pain, hemoptysis, infiltrates on imaging (acute angled hyphae)
117
HIV+ with pneumonia
Pneumocystis jirovecci | - especially in CD4 < 200 cells
118
HIV + with TB-like disease
Mycobacterium avium-intracelluaire | - esp in CD4 < 50 cells
119
Envelope proteins for HIV
- acquired from budding from host cell plasma membrane - gp120: docking protein for attachment to CD4 - gp41: transmembrane protein for fusion and entry
120
Gap(p24) protein
HIV capsid protein
121
p17 associated with HIV
Matrix protein
122
pol gene
HIV - reverse transcriptase - aspartate protease - integrase

USMLE Step 1 (34 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions