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Molecules and Cells II > Viruses > Flashcards

Viruses Flashcards

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Organic Chemistry 101 flashcards
1
Q

Definition of a Virus

A

Viruses are defined as obligate, intracellular parasites.

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2
Q

Obligate intracellular viruses

A

Chlamydia and Rickettsiae

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3
Q

DNA viruses families and medically important viruse

A

Pox Virus (Smallpox virus, molluscum contagiosum virus; DS, LINEAR)

Herpesvirus (Herpes Simple virus, varicella-zoster virus, cytomegalovirus, EBV; DS LINEAR)

Hepadnavirus (Hepatitis B virus; DS, INCOMPLETE CIRCULAR)

Adenovirus (Adenovirus; DS LINEAR)

Papillomavirus (Human papilloma virus, Warts virus; DS, CIRCULAR, SUPERCOILED)

Parvovirus (B19 virus; SS, LINEAR)

Polyamavirus (JC virus, BK virus; DS,CIRCULAR, SUPERCOILED)

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4
Q

RNA viruses families and medically important virus

A

Orthomyxovirus (Influenze virus)

Reoviris (Rotavirus)

Paramyxovirus (Mumps virus, measles virus, respiratory syncytial virus)

Rhabdovirus (Rabies Virus)

Retrovirus (HIV, human T-cell leukemia virus)

Corona virus

Arenavirus (LCM virus)

Picrornavirus (Polio virus, rhinovirus, hepatitis A virus)

Hepevirus (Hepatitis E virus)

Calcivirus (Norwalk virus)

Flavivirus (Yellow fever virus, dengue virus, West Nile Virus, Hepatitis C virus)

Togavirus (Rubella virus)

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5
Q

Virus structure

A

Naked Icosohedral

Naked helical

Enveloped icosahedral

Enveloped helica

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6
Q

Physical virus particle. Nucleocapsid alone for some viruses (picornaviruses) or including outer envelope structure for others (retroviruses).

A

Virion

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7
Q

Regular, shell-like structure composed of aggregated protein subunits which surrounds the viral nucleic acid

A

Capsid

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8
Q

•morphological unit detected seen under electron microscope

A

Capsomere

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9
Q

viral nucleic acid enclosed by a capsid protein coat

A

Nucleocapsid

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10
Q

•lipid bilayer containing viral glycoproteins. The phospholipids in the bylayer are derived from the cell that the virus arose from.

A

Envelope

*Not all viruses have envelopes some consist of only the nucleocapsid

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11
Q

Methods of inactivating Viruses for Various Purposes

A

Sterilization (Steam Under Pressure, Dry Heat, Ethylene oxide, y-Irradiation)

Disinfection (Sodium hypochlorite, glutaldehyde, formaldehye, peracetic acid)

Skin disinfection (chlorhexidine, 70% ethanol, iodophores)

Vaccine Production (Formaldehyde, Beta-propiolactone, Propiolactone, Psoralen+UV irradiation, Detergents)

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12
Q

There are about _________ families known. Of these, only _______families contain agents that are human pathogens. This groups is subdivided into _____DNA virus families and ________RNA virus families/

A

5450; 22; 7; 15

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13
Q

How does a given virus cause disease?

A

1.Lytic (productive) infection (cell death)

  • Productive means that there is a net increase of viral cells produced
  • Poliovirus, rabies virus and influenza virus cause disease by this mechanism

2.Non-productive infection (oncogenic conversion)

  • Cell is converted from a normal cell to a tumor cell
  • Human Herpesvirus -8 , Hepatitis B virus and Epstein-Barr virus cause disease by this mechanism
  1. Induction of an immunopathological response by the host
    * Hepatitis A virus and Hepatitis B virus
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14
Q

Structural properties of viruses

A

Nucleic acid

  • Either DNA or RNA, BUT NEVER BOTH
  • dsDNA,ssDNA,dsRNA, ssRNA
  • Linear or circular

Proteins

  • Capsid proteins, spikes proteins, Envelope proteins, nucleocaspid proteins, RNA-dependent RNA polymerase, reverse polymerase, transcriptional factors

Lipids

  • Host membrane that forms envelope

Carbohydrates

  • Viral glycoproteins
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15
Q

B19 virus

A

It is the classic cause of the childhood rash called fifth disease or erythema infectiosum, or “slapped cheek syndrome”.

Parvovirus

The virus is primarily spread by infected respiratory droplets; blood-borne transmission, however, has been reported. The secondary attack risk for exposed household persons is about 50%, and about half of that for classroom contacts

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16
Q

JC virus

A

Polyomavirus

The virus causes progressive multifocal encephalopathy, by destroying oligodendrocytes, and other diseases only in cases of immunodeficiency

Affects white matter of the brain

FATAL

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17
Q

BK virus

A

The BK virus rarely causes disease but is typically associated with patients who have had a kidney transplant; many people who are infected with this virus are asymptomatic.

Excreted in urine

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18
Q

HPV

A

Causes warts

Can lead to cervical cancer

Types

  • HPV1 (plantar warts)
  • HPV 16 AND 18 (Cervical cancer)

Vaccine: Gardis I

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19
Q

Adenovirus

A

found to cause a wide range of illnesses, from mild upper and lower respiratory infections in young children (known as the common cold) to life-threatening multi-organ disease in people with a weakened immune system.

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20
Q

Hepatitis B

A

Affects the liver

Many people have no symptoms during the initial infection. Some develop a rapid onset of sickness with vomiting, yellowish skin, tiredness, dark urine and abdominal pain.

The virus is transmitted by exposure to infectious blood or body fluids.

hepadnavirus family

Primary hepatocarcinoma

Common in HIV/AIDS

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21
Q

Herpes

A

Herpes cycles between periods of active disease followed by periods without symptoms.The first episode is often more severe and may be associated with fever, muscle pains, swollen lymph nodes and headaches. Over time, episodes of active disease decrease in frequency and severity.

Usually occurs by saliva in the mouth

Types

  • HSV-1: Associated with mouth blisters
  • HSV-2: Associated with genital infections

Following a primary infection, the virus enters the nerves at the site of primary infection, migrates to the cell body of the neuron, and becomes latent in the ganglion.

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22
Q

Varicella-zoster virus

A

It causes chickenpox (varicella), a disease most commonly affecting children, teens, and young adults, and herpes zoster (shingles) in adults

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23
Q

Cytomegalovirus

A

When cells are infected they are enlarged

It may cause infectious mononucleosis

Congenital birth defects (can travel to the placenta)

Can affect heart transplant patients

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24
Q

EBV

A

Latent infection in B cells

An oncogenic virus

Burkitt’s lymphoma (subsaharan Africa)

Nasopharyngeal carinoma (Asian descent)

Can cause infectious mononucleosis

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25
Q

Smallpox virus

A

Once inhaled, variola major virus invaded the oropharyngeal (mouth and throat) or the respiratory mucosa, migrated to regional lymph nodes, and began to multiply.

The initial symptoms were similar to other viral diseases such as influenza and the common cold: fever of at least 38.3 °C (101 °F), muscle pain, malaise, headache and prostration.

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26
Q

Molluscum Contagiosum Virus

A

Often sexually transmitted

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27
Q

Which structure is unique to Herpesvirus?

A

Tegument

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28
Q

Side effect of smallpox virus vaccination

A

Encephalopathy

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29
Q

Poxvirus Structure

A
  • The outer surface of the virion is composed of lipid and protein.
  • This surrounds the core, which is biconcave (dumbbell-shaped), & two ‘lateral bodies’ whose function is unknown.
  • The core is composed of a tightly compressed nucleoprotein & the double-stranded DNA genome is wound around it.
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30
Q

Picornavirus Structure

A
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31
Q

Rotavirus Structure

A
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32
Q

Influenza virus Structure

A
  • Influenza virus belongs to the to orthomixovirus group
  • Containes helical capsid, enclosed by an envelope.
  • Influenza A viruses are negative sense, single-stranded, segmented RNA viruses.
  • Viruses are labeled according to an H number (for the type of hemagglutinin) and an N number (for the type of neuraminidase). There are 16 different H antigens (H1 to H16) and nine different N antigens (N1 to N9).
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33
Q

Vesicular Stomatitis Virus Structure

A

•VSV coat protein (50 aa): alpha helical with 3 distinct domains:

+ charge interacts with nucleic acid, hydrophobic with proteins on either side, negative charge with polar environment

  • Subunits are tilted 20o relative to the long axis of the particle.
  • VSV Genome: 11,000 nt -ssRNA interacts with the nucleocapsid protein (N) to form a helical structure with P=5 nm. .
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34
Q

Ebola Virus Strucure

A
  • Filamentous Filovirus with single-stranded (-) RNA genome
  • The capsid has a helical morphology and is encased inside a membrane envelope.
  • VP30- matrix protein; L protein – RNA polymerase
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35
Q

Positive sense

A

RNA that can be translated to proteins

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36
Q

Only RNA virus family with DS RNA

A

Reovirus

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37
Q

Poliovirus

A

Picornavirus

Enterovirus

Poliomyelitis is a disease of the central nervous system

The three serotypes of poliovirus, PV1, PV2, and PV3, each have a slightly different capsid protein.

Ability to more or breath is impaired “iron lung”

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38
Q

Rhinovirus

A

Picornavirus

Major cause of the common cold

Grow optimally at 25 C- 30 C

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39
Q

Hepatitis A virus

A

Picornavirus

Liver hepatitis

Spread by the fecal

Only causes acute hepatitis

*Hepatitis B causes both acute and cronic hepatitis

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40
Q

Hepatitis E

A

Hepevirus

Transmitted by the fecal oral route

Generally only causes acute hepatitis

Mortality genrally low except in pregnant women

Hepatitis E different in that it affects pregnant women

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41
Q

Which type of Hepatitis affects pregnant women?

A

E

42
Q
A
43
Q

Norovirus (Norwalk virus)

A

Calicivirus

Viral gastroenteritis

Projectile vomiting

Virus spread by the fecal-oral route

44
Q

Rotavirus

A

Reovirus

Rotavirus infects children at a young age but older infants and young children tend to be more symptomatic with diarrhea.

45
Q

Yellow fever virus

A

Flavivirus

Symptoms include fever, chills, loss of appetite, nausea, muscle pains particularly in the back, and headaches

In 15% of cases, however, people enter a second, toxic phase of the disease with recurring fever, this time accompanied by jaundice due to liver damage, as well as abdominal pain.

46
Q

Dengue Virus

A

Flavivirus

Dengue virus causes dengue fever. Common names for dengue fever include breakbone fever and dandy fever; dengue hemorrhagic fever ([DHF] and dengue shock syndrome (DSS) are the severe forms.

47
Q

West Nile Virus

A

Flavivirus

Affects neurons in brain

48
Q

Hepatitis C

A

Flavivirus

leads to liver disease and occasionally cirrhosis

Causes both chronic and acute infections

Chronic Hep C can turn into cancer

Type 1: present in African Americans

Treatment

  • Harvoni- able to control or eliminated Hep C
  • INF (Inteferon Alfa-2B)
49
Q

Rubella Virus

A

Togavirus

Really bad in pregnancy

Causes a rash that starts in face and goes to extremities

Congenitial infection and malformaions

50
Q

Zika virus

A

Flavivirus

Microencephalopathy

51
Q

HIV

A

Retrovirus

Genome is deep diploid RNA (2 copies of the same RNA)

Reverse transcription (transcribed DNA is incorporated into host chromosome

52
Q

Antigenic drift

A

a mechanism for variation in viruses that involves the accumulation of mutations within the genes that code for antibody-binding sites.

Occurs as result of point mutation

53
Q

Influenza virus

A

Orthomyxovirus

RNA genome with negative sense polarity (cannot function directly as mRNA)

Influenza A

  • Influenza type A viruses are categorized into subtypes based on the type of two proteins on the surface of the viral envelope:
    • H = hemagglutinin, a protein that causes red blood cells to agglutinate.
    • N = neuraminidase, an enzyme that cleaves the glycosidic bonds of the monosaccharide sialic acid (previously called neuraminic acid

Influenza B

  • Only causes epidemic

Influenza C

  • Asymptomatic infection
54
Q

Mumps

A

Paramyxovirus

Nonsegmented negative sense RNA

Paratid glands are swollen

Can causes Sterility in males

Orchitis

Oral meningitis

55
Q

Measles

A

Paramyxovirus

Rash starts behind the ears

Lesions in mouth

Koplik’s spots

56
Q

Rabies

A

Rhabdovirus

Vesticular stomatis virus

causes inflammation of the brain

symptoms: violent movements, uncontrolled excitement, fear of water, an inability to move parts of the body, confusion, and loss of consciousness

57
Q

Ebola virus

A

Filovirus

a viral hemorrhagic fever of humans

a fever, sore throat, muscular pain, and headaches.

Vomiting, diarrhea and rash usually follow, along with decreased function of the liver and kidneys.

virus spreads through direct contact with body fluids

Can cause bleeding from all orafices

58
Q

DNA enveloped viruses

A

Herpesviruses

Varicella-zoster virus

Cytomegalovirus

EBV

Human Herpesvirus B

Hepatitis B virus

Smallpox virus

59
Q

DNA nucleocapsid viruses

A

Adeovirus

Papillomaviruses

Parovirus B19

60
Q

RNA enveloped viruses

A

Influenza

Rubella

Rabies

HIV

Hepatitis C virus

61
Q

RNA nucleocapsid viruses

A

Enteroviruses

62
Q

Cultivation of Viruses

A
  • Primary cell culture (differentiated cells, directly derived from a tissue, limited life span)
  • Diploid cell lines ( dedifferentiated, diploid, survive more passages than primary cell lines, but eventually die)

•

•Continuous cell lines (have a mutations that allow the cells to be

passaged many times, heteroploid, mostly originated from a tumor)

63
Q

Which viruses can detected by culturing green monkey kidney cells?

A

Enteroviruses

Respiratory viruses

Herpes Simplex Virus

64
Q

Which viruses can detected by culturing human fibroblasts?

A

Cytomegalovirus

Varicella-zoster virus

Rhinoviruses

65
Q

Which viruses can detected by culturing human epithelial cells?

A

Respiratory Syncytial Virus

66
Q

Cytopathic Effect (CPE):

A

•microscopically visible changes in cultured cells; which cells are affected; timing and rate of progression; nature of the morphological changes

67
Q

Hemadsorption

A

production by some viruses (I.e. paramyxoviruses: influenza, parainfluenza and mumps) of antigens that can bind erythrocytes of certain species (guinea pig, rat or monkey) - erythrocytes bind to the infected cells

68
Q

Interference

A

infection with a virus prevents an infection by a test virus.

69
Q

___________ is usually a secondary result of changes in the host metabolism caused by viral replication

A

•CPE

70
Q

________, __________, or ___________ cells are used to cultivate viruses

A

•Primary, continuous or transformed

71
Q

Which cells maintian continous cell lines?

A

Primary green monkey kidney cells (Vero)

Human fibroblasts (NIH 3T3)

Primary rabbit kidney cells

Human epithelial cells (HEp-2)

Engineered cell lines (HeLa-MAGI, CEM-GFP)

72
Q

What viruses can grown in the chorioallantoi membrane of a chick egg?

A

HSV

Poxvirus

Rous sarcoma virus

73
Q

What viruses can grown in the amniotic sac of a chick egg?

A

Influenza virus

Mumps virus

74
Q

What viruses can grown in the yolk sac of a chick egg?

A

HSV

75
Q

What viruses can grown in the allantoic of a chick egg?

A

Influenza

Mumps virus

Newcastle disease virus

Avian adenovirus

76
Q

Descibed to cause multinucleated cell pneumonia

A

Measles

77
Q

How do multinucleated cells form?

A
  1. Cell infected with HSV-1 or measles virus
  2. Cell undergoes antigenic changes on surface
  3. Cell will recruit uninfected cells to itself
  4. Virus infects second cell
  5. Propegation continues
78
Q

One of first countries to undergo an Ebola outbreak?

A

Zaire

79
Q

Negri bodies are often found in cells affected with__________.

A

Rabies Virus

80
Q

Lytic infection

A

Infection in which the host cell is killed

81
Q

What’s unique about tumor viruses?

A

They don’t kill the cell and many times become immortalized

82
Q

Viruses that can cause gastroenteritis

A

Rotavirus

Astrovirus

Adenovirus

Norovirus

83
Q

Electron microscopy can be used to directly examine species for which viruses?

A

Herpesvirus

Poxvirus

Ebola

84
Q

Electron microscopy

A

Staining with electron-contrast material, like phopsotungstic acid or uranyl acetate

Evaluation of stool specimens from patients with gastoenteritis

Direct detection of viral particles when viral culture conditions or reagents are not available

Direct examination of speciemens for heerpesvirus, poxvirus, or Ebola

Examination of infected tissue culture

85
Q
A
86
Q

Transmission Electron Microscopy

A

Beam of electrons is transmitted through an ultra-thin specimen, that fixed and stained with electron-contrast substrates

phosphotungstic acid H3[P(W3O10)4].xH2O

uranyl acetate UO2(CH3COO)2.H2O

An image is formed from the interaction of the electrons with the specimen.

The image is magnified and focused onto an imaging device, such as a fluorescent screen or CCD camera.

CCD- charge couple device

Resolution – 5-7.5 nm (50-75 Å)

87
Q

Cryo-Electron Microscopy

A

Rapid freeze and analysis at -1600C

No staining or fixing is needed

The Fourier Transform is used to create 3D structure

Resolution 1-2 nm (10-20 Å)

88
Q

Viral capsid

A

Capsids are made up of repeated protein subunits, whcih are held together by noncovalent bonds

Capsids are self-assembled

Mostly helicial or icosahedral symmetry

89
Q

What are the three basic nucleocapside structures?

A

Helical

  • Rod shaped, varying widths and specific architectures; no theoretical limit to the amount of nucleic acid that can be packaged

Cubic (Isosahedral)

  • •Spherical, amount of nucleic acid that can be packaged is limited by the number of capsomers and the size of the viral particle

Irregular

  • Without clear symmetry
90
Q

High symmetry is associated with which type of assembly?

A

Self assembly. Contain assembly “instructions”

91
Q

What three cubic (isohedral) symmetries exist?

A

Tetrahedral- 12 identical subunits

Octahedral- 24 identical subunits

Icosahedral- 60 identical subunits

92
Q

What type of symmetry leads to isometric (same measurement in three dimensions) particle?

A

Cubic

93
Q

Helical viruses

A
  • Organized around a single axis (the “helix axis”)
  • Probably evolved along with other helical structures like DNA, a-helix, etc.
  • Allow flexibility (bending)
  • Helical viruses form a closely related spring like helix instead.

–Note-all animal viruses that are helical are enveloped, unlike many of the phage and plant viruses.

•Most helixes are formed by a single major protein arranged with a constant relationship to each other (amplitude and pitch).

94
Q

Components of an envelope

A

Lipids, protein, carbs

Spikes (found only in some) that allow them to attach to the host

95
Q

What’s the problem with a lipid bilayer as an envelope? How do viruses overcome this challenge?

A

Such a coating is efficienct because it does not allow the recognition of receptor molecules on the host cell.

It does however protect the virus from desiccation or enzymatic damage

By the synthesis of several classes of proteins which are associated in one of three ways with the envelope

96
Q

Formation of enveloped viral particles

A

Uses celleular membranes for assembly

Formation of the particle inside the cell, maturation and release are in many cases a continuous process

The site of assembly varies for different viruses

97
Q

For which viruses is the site of assembly for enveloped particles the cytoplasmic membranes?

A

Corona virus

Pox virus

Rhabdovirus

98
Q

For which viruses is the site of assembly for enveloped particles the nuclear membrane?

A

Herpesviruses

99
Q

Three types of electron microscopy

A

Transmission EM- beam of electrons attempt to travel around and through the specimen that is presented on platform

Cryo EM- Viral suspensions are purified, frozen in liquid nitrogen, and placed in a chamber inside an EM

Scanning EM- Used when attempting to study the surface of viral particles or cells

100
Q

X-Ray crystallography

A

Viral particle or protein is purified and crystallized (to make the particle very dense so that it can be examined by an X-ray)

Gives detail down to angstrom level

101
Q
A

Molecules and Cells II (14 decks)

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