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Molecules and Cells II > Viruses > Flashcards

Viruses 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
Smallpox virus
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.
26
Molluscum Contagiosum Virus
Often sexually transmitted
27
Which structure is unique to Herpesvirus?
Tegument
28
Side effect of smallpox virus vaccination
Encephalopathy
29
Poxvirus Structure
* 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.
30
Picornavirus Structure
31
Rotavirus Structure
32
Influenza virus Structure
* 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).
33
Vesicular Stomatitis Virus Structure
•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. .
34
Ebola Virus Strucure
* 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
35
Positive sense
RNA that can be translated to proteins
36
Only RNA virus family with DS RNA
Reovirus
37
Poliovirus
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"
38
Rhinovirus
Picornavirus Major cause of the common cold Grow optimally at 25 C- 30 C
39
Hepatitis A virus
Picornavirus Liver hepatitis Spread by the fecal Only causes **acute** hepatitis \*Hepatitis B causes both acute and cronic hepatitis
40
Hepatitis E
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
41
Which type of Hepatitis affects pregnant women?
E
42
43
Norovirus (Norwalk virus)
Calicivirus Viral gastroenteritis Projectile vomiting Virus spread by the fecal-oral route
44
Rotavirus
Reovirus Rotavirus infects children at a young age but older infants and young children tend to be more symptomatic with diarrhea.
45
Yellow fever virus
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
Dengue Virus
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
West Nile Virus
Flavivirus Affects neurons in brain
48
Hepatitis C
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
Rubella Virus
Togavirus Really bad in pregnancy Causes a rash that starts in face and goes to extremities Congenitial infection and malformaions
50
Zika virus
Flavivirus Microencephalopathy
51
HIV
Retrovirus Genome is deep diploid RNA (2 copies of the same RNA) Reverse transcription (transcribed DNA is incorporated into host chromosome
52
Antigenic drift
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
Influenza virus
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
Mumps
Paramyxovirus Nonsegmented negative sense RNA Paratid glands are swollen Can causes Sterility in males Orchitis Oral meningitis
55
Measles
Paramyxovirus Rash starts behind the ears Lesions in mouth Koplik's spots
56
Rabies
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
Ebola virus
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
DNA enveloped viruses
Herpesviruses Varicella-zoster virus Cytomegalovirus EBV Human Herpesvirus B Hepatitis B virus Smallpox virus
59
DNA nucleocapsid viruses
Adeovirus Papillomaviruses Parovirus B19
60
RNA enveloped viruses
Influenza Rubella Rabies HIV Hepatitis C virus
61
RNA nucleocapsid viruses
Enteroviruses
62
Cultivation of Viruses
* 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
Which viruses can detected by culturing green monkey kidney cells?
Enteroviruses Respiratory viruses Herpes Simplex Virus
64
Which viruses can detected by culturing human fibroblasts?
Cytomegalovirus Varicella-zoster virus Rhinoviruses
65
Which viruses can detected by culturing human epithelial cells?
Respiratory Syncytial Virus
66
Cytopathic Effect (CPE):
•microscopically visible changes in cultured cells; which cells are affected; timing and rate of progression; nature of the morphological changes
67
Hemadsorption
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
Interference
infection with a virus prevents an infection by a test virus.
69
\_\_\_\_\_\_\_\_\_\_\_ is usually a secondary result of changes in the host metabolism caused by viral replication
•CPE
70
\_\_\_\_\_\_\_\_, \_\_\_\_\_\_\_\_\_\_, or ___________ cells are used to cultivate viruses
•Primary, continuous or transformed
71
Which cells maintian continous cell lines?
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
What viruses can grown in the chorioallantoi membrane of a chick egg?
HSV Poxvirus Rous sarcoma virus
73
What viruses can grown in the amniotic sac of a chick egg?
Influenza virus Mumps virus
74
What viruses can grown in the yolk sac of a chick egg?
HSV
75
What viruses can grown in the allantoic of a chick egg?
Influenza Mumps virus Newcastle disease virus Avian adenovirus
76
Descibed to cause multinucleated cell pneumonia
Measles
77
How do multinucleated cells form?
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
One of first countries to undergo an Ebola outbreak?
Zaire
79
Negri bodies are often found in cells affected with\_\_\_\_\_\_\_\_\_\_.
Rabies Virus
80
Lytic infection
Infection in which the host cell is killed
81
What's unique about tumor viruses?
They don't kill the cell and many times become immortalized
82
Viruses that can cause gastroenteritis
Rotavirus Astrovirus Adenovirus Norovirus
83
Electron microscopy can be used to directly examine species for which viruses?
Herpesvirus Poxvirus Ebola
84
Electron microscopy
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
86
Transmission Electron Microscopy
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
Cryo-Electron Microscopy
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
Viral capsid
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
What are the three basic nucleocapside structures?
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
High symmetry is associated with which type of assembly?
Self assembly. Contain assembly "instructions"
91
What three cubic (isohedral) symmetries exist?
Tetrahedral- 12 identical subunits Octahedral- 24 identical subunits Icosahedral- 60 identical subunits
92
What type of symmetry leads to isometric (same measurement in three dimensions) particle?
Cubic
93
Helical viruses
* 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
Components of an envelope
Lipids, protein, carbs Spikes (found only in some) that allow them to attach to the host
95
What's the problem with a lipid bilayer as an envelope? How do viruses overcome this challenge?
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
Formation of enveloped viral particles
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
For which viruses is the site of assembly for enveloped particles the cytoplasmic membranes?
Corona virus Pox virus Rhabdovirus
98
For which viruses is the site of assembly for enveloped particles the nuclear membrane?
Herpesviruses
99
Three types of electron microscopy
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
X-Ray crystallography
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

Molecules and Cells II (14 decks)

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