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Virology Flashcards

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Biology 101 flashcards
0
Q

Mutations can produce antigenic, drug-resistant or attenuated variants
Genomic reassortment causes epidemics
Complementation: one virus produces a protein that can be used by another virus
Phenotypic mixing: two different viruses infect the same cell

A

Viral genetics

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1
Q

Naked viruses with double-stranded circular DNA and an icosahedral nucleocapsid
Least 100 types
Direct contact or sexually
Infect squamous cells and induce formation of cytoplasmic vacuole (koilocytes)
Genes E6 and E7

A

HPV

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2
Q

Only causes disease in immunocompromised hosts

Causes progressive multifocal leukoencephalopathy (PML) in patients with AIDS

A

JC Polyoma Virus

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3
Q

Only causes disease in immunocompromised hosts

Causes hemorrhagic cystitis and neuropathy and in patients with solid organ (kidney) and bone marrow transplants

A

BK Polyoma Virus

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4
Q

Enveloped virus with icosahedral nucleocapsid and linear double-stranded DNA

A

Herpes Simplex Viruses

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5
Q 
Member of flavivirus family
Most common cause of epidemic encephalitis
Most prevalent in SEA
transmitted by Culex mosquitoes
Thalamus infarcts on CT scan
A

Japanese B Encephalitis

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6
Q

Flavivirus
Bird-mosquitoes-man cycle
Initial self-limited febrile illness with progression to neuroinvasive disease

A

West Nile Fever

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7
Q

“Thread-like” viruses
Longest viruses
Outbreak of hemorrhagic fever in Zaire (1976)
100% mortality rate

A

Ebola Hemorrhagic Fever

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8
Q

Retrovirus causing adult T-cell leukemia and a HTLV-associated myelopathy
HP: malignant T cells with flower-shaped nucleus

A

Human T-cell lymphotropic virus (HTLV)

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9
Q

Envelope virus with two copies (diploid) of a single-stranded, positive-polarity RNA genome
Most complex of the known retroviruses
Many serotypes

A

Human Immunodeficiency Virus

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10
Q

Enveloped virus with an icosahedral nucleocapsid and one ss-positive-RNA
Transmission: respiratory droplet, transplacental

Infection confers lifelong immunity
Prevented by giving live-attenuated vaccine
Should not be given to immunocompromised patients or to pregnant women

A

Rubella virus

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11
Q

Incubation of 14-21 days
Prodrome followed by 3-day maculopapular rash and posterior auricular LAD
Face-trunk-arms-legs
Immune complex polyarthritis in adults

A

German measles

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12
Q

p24, p7 proteins

p17 protein

A

Gag gene

Function:

  • nucleocapsid (p24, p7)
  • matrix (p17)
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13
Q

Reverse transcriptase protein

Protease protein

Integrase protein

A

Pol gene

Function:

  • transcribes RNA genome into DNA (reverse transcriptase)
  • cleaves precursor polypeptides (protease)
  • integrates viral DNA into host cell DNA (integrase)
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14
Q

gp120 protein

gp41 protein

A

env gene

Function:

  • attachment to CD4 protein ANTIGENICITY CHANGES RAPIDLY (gp120)
  • fusion with host cell (gp41)
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15
Q

Group-specific antigen

Located in the core

Not known to vary

Antibodies against p24 do not neutralize HIV infectivity but serve as important serologic markers of infection

A

p24

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16
Q

Interacts with the CD4 receptor

Gene mutates rapidly –> many antigenic variants

Antibody neutralizes HIV infectivity, but the rapid appearance of variants –> difficult to prepare vaccine

High mutation rate may be due to lack of an editing function in the reverse transcriptase

A

gp120

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17
Q

Most immunogenic region of gp120

A

V3 loop

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18
Q

Mediates the fusion of the viral envelope with the cell membrane at the time of infection

A

gp41

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19
Q

Proteins: tat

Function: activation of transcription of viral genes

A

Tat gene

20
Q

Proteins: rev

Function: transport of late mRNAs to cytoplasm

A

rev gene

21
Q

Proteins: Nef

Function: decreases CD4 and class I MHC proteins

A

nef gene

22
Q

Proteins: Vif

Function: enhances hypermutation

A

vif gene

23
Q

Proteins: vpr

Function: transport in nondividing cells

A

vpr gene

24
Q

Proteins: vpu

Function: enhances virion release

A

vpu gene

25
Q 
Transmission:
Original source - chimpanzee
Transfer of body fluids
Transplacental and perinatal
Needlestick
A

Human Immunodeficiency Virus

26
Q

Stages of infection (HIV)

A
  • phase 0 (infection)
  • phase 1 (window period)
  • phase 2 (seroconversion)
  • phase 3 (latent period)
  • phase 4 (early symptomatic)
  • phase 5 (aids)
27
Q

HIV acquired through sexual intercourse, blood, or perinatally

A

Phase 0 - INFECTION

28
Q

Rapid viral replication but HIV test is negative

A

Phase 1 - WINDOW PERIOD

29
Q

Peak of viral load, positive HIV test, mild flu-like illness, lasting 1-2 weeks

A

Phase 2 - SEROCONVERSION

30
Q

Asymptomatic, CD4 goes down, lasts 1-15 years

A

Phase 3 - LATENT PERIOD

31
Q

CD4 500 to 200, lasts 5 years, mild mucocutaneous, dermatologic and hematologic illnesses

A

Phase 4 - EARLY SYMPTOMATIC

32
Q

CD4 <200, lasts 2 years, AIDS-defining illnesses develop

A

Phase 5 - AIDS

33
Q

Distinguished from all other RNA viruses by the presence of an unusual enzyme, reverse transcriptase

Reverse transcriptase - which converts a single-stranded RNA viral genome into double-stranded viral DNA

A

Retroviridae

34
Q

Infected during the 1st trimester

Associated abnormalities:
Patent ductus arteriosus
Congenital cataracts
Sensorineural deafness
Mental retardation
A

Congenital Rubella Syndrome

35
Q

Enveloped virus with one piece of single-stranded, positive-polarity RNA

Hypervariable region in envelope glycoprotein

6 serotypes

Diagnosis by anti-HCV or HCV RNA

Transmission:

  • most prevalent blood-borne pathogen
  • major mode: blood-borne (IV drug abusers)
  • minor modes: needle-stick, vertical transmission, sexual

Pathogenesis:

  • replication in liver by liver-specific micro-RNA
  • hepatocellular injury due to immune attack
  • alcoholism greatly enhances rate of hepatocellular CA
  • chronic carriage of HCV is much higher than HBV

Spectrum of disease:

  • incubation period of 8 weeks
  • clinical presentation resembles hepatitis B
  • autoimmune reactions
  • main cause of essential mixed cryoglobulinemia
A

Hepatitis C Virus

Treatment:
Acute hepatitis C - interferon
Chronic hepatitis - peginterferon
Liver transplantation for severe cirrhosis

36
Q

Enveloped virus with helical nucleocapsid and one piece of single-stranded, positive-polarity RNA

Prominent club-shaped spikes form a “corona”

2 serotypes

Transmission:

  • horseshoe bat (reservoir)
  • Civet cat (intermediate host)
  • respiratory droplet transmission

Spectrum of disease:

  • COMMON COLDS (2nd most common colds)
  • severe acute respiratory syndrome (SARS)
A

Coronavirus

37
Q

DNA VIRUSES

DNA Viruses are HHAPPPy viruses

A

Hepadna

Herpes

Adeno

Pox

Parvo

Polyoma

Papilloma

38
Q

All DNA viruses have DOUBLE-stranded DNA except

A

PARVOVIRUS

39
Q

All DNA viruses have linear DNA except

A

Papilloma

Polyoma

Hepadna

40
Q

All DNA viruses are icosahedral except

All DNA viruses replicated in the nucleus except

A

POXVIRUS

41
Q

Naked virus with icosahedral symmetry
Single-stranded DNA genome
One serotypes

MOT: respiratory droplets & transplacental

Not oncogenic

No vaccine

A

Parvovirus B19 (FIFTH DISEASE)

42
Q

NAKED DNA viruses double-stranded linear DNA and an icosahedral nucleocapsid

Only virus with fiber (PENTON)
41 antigenic types

MOT: aerosol droplet, respiratory fecal-oral, direct contact

Spectrum of disease:
URT: pharyngitis, conjunctivitis, coryza
LRT: bronchitis, atypical pneumonia
GIT: acute gastroenteritis
GUT: hemorrhagic cystitis 
Histopath: COWDRY TYPE B intranuclear inclusions

Not oncogenic

Has vaccine

A

Adenovirus

43
Q

NAKED DNA viruses with double-stranded circular DNA and an icosahedral nucleocapsid

Least 100 types

MOT: direct contact or sexually

Pathogenesis:
Infect squamous cells and induce formation of cytoplasmic vacuole (koilocytes)

Genes E6&E7

Is oncogenic

Has vaccine

A

Human Papillomavirus

44
Q

Bright red cheek rash (slapped cheeks) with fever, coryza and sore throat

A

Erythema Infectiosum (FIFTH DISEASE)

45
Q

Transient by put severe aplastic anemia in children

Sickle cell anemia, thalassemia or spherocytosis

A

Aplastic crisis

46
Q

Fetal infections on PARVOVIRUS

A

1st trimester: fetal death

2nd trimester: hydrops fetalis

47
Q

Immune-complex arthritis of small joints

A

Arthritis

48
Q

Pancytopenia in immunodeficiency patients in PARVOVIRUS

A

CHRONIC B19 infection

Microbiology (23 decks)

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