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Virology > Block 4 > Flashcards

Block 4 Flashcards

1
Q

2 defense mechanisms of respiratory tract

A

Mucociliary blanket
Temperature Gradient

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2
Q

Temperature Gradient

A

There is a temperature gradient between the nasal passage (33 C) and the alveoli (37) that plays an important role in the localization of infection. Thus, rhinoviruses, which infect the nasopharynx and caue the common cold, replicate well at 33 C but grow poorly at 37 C, while influenza virus, which infects the lower respiratory tract, shows the inverse temperature preference.

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3
Q

Pattern Recognition Receptors (PRR)

A

viral surface receptors that recognize specific pathogen-associated molecular patterns (PAMPs), which are macromolecules present in virus and othe microbes, but not on host cell. One class of PRRs are Toll-like receptors (TLRs)

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4
Q

T/F Interferons show no virus specificity

A

True

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5
Q

T/F DNA viruses are stronger inducers of interferons than RNA Viruses

A

FALSE: RNA viruses are stronger inducers

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6
Q

How should interferons be administered to a patient?

A

Parenteral route (injection) because they are glycoproteins

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7
Q

Interferons

A

A group of cytokines (complex glycoproteins) that are secreted by somatic cells in response to viral infections and to other stimuli. They possess potent antiviral, immunomodulating and anticancer properties

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8
Q

IFN-a

A

Leukocyte interferon. Produced in large quantities by plasmacytoid dendritic cells

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9
Q

What produces Type II interferons?

A

Antigen-stimulated T cells and Natural Killer (NK) cells

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9
Q

IFN-B

A

Fibroblast interferon. Secreted by virus-infected fibroblast.

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10
Q

IFN-y

A

Only type of Type II Interferon

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11
Q

When are Type III interferons expressed?

A

In response to viral infections and activation of TLRs

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11
Q

3 types of Type III Interferons

A

k

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12
Q

Primary function of Type III interferons

A

Immunoregulator

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13
Q

Purpose of IFN-y

A

Mostly immunoregulatory (Type II)

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14
Q

What mediates humoral immunity

A

Antibodies released from B lymphocytes

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15
Q

What mediates cellular immunity

A

T lymphocytes

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16
Q

What elicits Cellular Mediated Immune (CMI) response? (2)

A

Internal viral antigens
Surface antigens (+ humoral response)

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17
Q

What can antibodies be directed against? (2)

A

1) Viral proteins on free virions (capsid or envelope)
2) Viral proteins expressed on surface of infected cell

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18
Q

Virus Neutralization

A

Neutralizing antibodies prevent virus attachment and entry into host cells. They bind to the viral capsid or host envelope.

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19
Q

Opsonization

A

Coating of virions with antibodies. Antibody coated virion is recognized and phagocytosed by macrophages, and sometimes by neutrophils.

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20
Q

Antigenic Plasticity

A

Rapid changes in the structure of the viral antigen. May be result of mutation, resassortment or recombination.
Due to change in antigen structure, the virus may become resistant to immunity generated by previous infection.

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21
Q

Antigenic Multiplicity

A

Antigenic variants with little or no cross-reactivity

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22
Q

Virokines

A

Some viruses synthesize proteins which are homologs of cytokines/interferons

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23
Q

Viroceptors

A

Some viruses encode proteins that are homologous to the receptors for cytokines. Serves as a competitive agonist.

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24
Q

Virus epidemiology

A

The study of the determinants, frequency, dynamics, and distribution of viral diseases in populations

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25
Q

Case Fatality Rate

A

The number (%) of deaths among the clinically ill animals

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26
Q

Mortality Rate

A

The number (%) of animals in a population that die from a particular disease over a specified period of time

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27
Q

Morbidity Rate

A

The percentage of animals in a population that develop clinical signs attributable to a particular virus over a defined period of time (commonly the duration of an outbreak)

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28
Q

Incidence

A

The number of new cases that occur in a population over a specified period of time.

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29
Q

Incidence/Attack Rate

A

A measure of the occurence of infection or disease in a population over time–for example, a month or a year, and is especially useful for describing acute diseases of short duration

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30
Q

Prevalence

A

The number of occurrences of disease (old and new cases), infection, or related attributes (antibodies) in a population, at a particular point of time

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31
Q

Sporadic viral diseases

A

Viral diseases occurring occasionally, singly, or in scattered instances, and in a irregular and haphazard manner

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32
Q

Enzootic viral diseases (endemic in humans)

A

The constant presence of a viral disease within a given geographic area or population group

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32
Q

Epizootic viral diseases (epidemic in humans)

A

The occurrence of more cases of viral diseases than expected in a given area or among a specific roup of people/animals over a particular period of time. Refers to peaks in disease incidence that exceed the endemic/enzootic baseline or expected incidence of disease.

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32
Q

Panzootic viral diseases (pandemic in humans)

A

A virus epidemic occurring over a very wide area (several countries or continents) and usually affecting a large proportion of the population.

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32
Q

Asymptomatic carrier

A

Animals that have contracted an infectious viral disease, but display no clinical symptoms.
Shed virus, transmitting disease to others.
Shedding of virus may be continuous or intermittent.

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32
Q

Incubatory (acute) carriers

A

Animals that shed virus during the incubation period of the disease

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33
Q

Convalescent (chronic) carriers

A

Animals that shed virus during recovery from disease

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34
Q

Inapparent carriers

A

Carrier state may exist in an animal with an infection that is inapparent throughout its course

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34
Q

Contagious disease

A

A disease that is spread from one person or organism to another by direct or indirect contact

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35
Q

Period of contagiousness

A

Refers to the time during which an infected animal sheds virus

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36
Q

Exotic disease

A

A disease not known to occur in a particular country or geographical area

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37
Q

Seroepidemiology

A

Denotes the use of serological data as the basis of epidemiological investigation, as determined by diagnostic serological techniques

38
Q

Molecular epidemiology of viruses

A

The use of molecular biological data as the basis of epidemiology investigation of viral disease

39
Q

Horizontal (lateral) transmission

A

The spread of an infectious agent from one person/animal to another person/animal or group

40
Q

Most viruses are transmitted by the ____ route

A

Horizontal

41
Q

Contact transmission

A

Spread of the infectious agent by direct or indirect contact

42
Q

Direct-Contact Transmission

A

Involves actual physical contact between an infected animal and a susceptible animal (ie licking, rubbing, biting). This category also includes sexual contact.

43
Q

Droplet Transmission

A

A type of direct contact transmission.
Transmission of virus in droplet nuclei (saliva or mucus) that travel less than 1 meter from the source to the susceptible host.
Sneezing, coughing, etc

44
Q

Why is droplet transmission not considered as an air-borne disease?

A

Due to short travel distance

45
Q

Indirect-contact transmission

A

Occurs via fomites, such as shared eating containers, bedding, dander, restraint devices, vehicles, clothing, improperly sterilized surgical equipment, or improperly sterilized syringes or needles

46
Q

Fomite

A

An inanimate object or substance that is contaminated with the infectious agent and is capable of transmitting infectious organisms from one individual to another

47
Q

Airborne transmission

A

A type of indirect-contact transmission.
The spread of infectious agents by droplet nuclei in dust that travel more than one meter, sometimes for miles, from the infected to the susceptible host.

48
Q

Vector Transmission / Arthropod-borne Transmission

A

Arthropod vectors carry the viruses from the infected host to susceptible host

49
Q

Two types of vector transmission

A

Mechanical and Biological

50
Q

Mechanical Transmission

A

Passive transport of the infectious agent on the feet or other body parts of the arthropod vector

51
Q

Biological Transmission

A

Infectious agent undergoes either a necessary part of its life cycle, or multiplication, in the vector before transmission to susceptible host

52
Q

What is the mechanical vector for Fowlpox virus?

A

Mosquitos and other biting insects

53
Q

Transovarial Transmission

A

Type of biological transmission. The virus transmitted from the mother tick through infected eggs to next generation of ticks.

54
Q

Trans-stadial Transmission

A

Type of biological transmission. The virus is transmitted from larva or nymph to next stage of development (nymph of adult). But not transmitted vertically (from other tick to eggs and next generation). Ex: tick-borne flaviviruses.

55
Q

Arboviruses

A

A class of viruses transmitted to humans by arthropods such as mosquitos and ticks

56
Q

Enzootic Cycle (Sylvatic or Jungle Cycle)

A

The natural transmission of virus between wild animals/birds (vertebrate hosts) and primary insect vectors.

57
Q

Epizootic Cycle (Rural Cycle)

A

The virus is transmitted between non-wild or domestic animals and the primary or accessory insect vectors.

58
Q

Urban Cycle

A

The virus cycles between human and insect vectors

59
Q

Amplifying Host

A

The level of virus can become high enough that an insect vector such as a mosquito that feeds on it will probably become infectious

60
Q

Dead-end host

A

A host from which infectious agents are not transmitted to other susceptible hosts. They do not develop sufficient viremia to be picked up by the insect vectors.

61
Q

Bridge Vector

A

An arthropod that acquires virus from an infected wil animal and subsequently transmits the agent to human or secondary host.

62
Q

Common-vehicle transmission

A

Type of horizontal/lateral transmission.
Includes fecal contamination of food and water supplies (fecal-oral transmission) and virus-contaminated meat or bone products.

63
Q

Latrogenic Transmission

A

Type of horizontal/lateral transmission.
Infection that is transferred during medical or surgical practice.

64
Q

Two ways latrogenic transmission can happen

A

1) Introduction of pathogens by contaminated instruments (non-sterile surgical instruments, syringes), or contaminated body surface (inadequate hand washing). Ex: spread of equine infectious anemia virus via multiple-use syringes
2) Introduction of pathogen through contaminated prophylactic or therapeutic preparations

65
Q

Nosocomial transmission / Hospital Acquired Infection

A

Occurs while an animal is in a veterinary hospital or clinic

66
Q

Vertical transmission

A

To describe infection that is transferred from dam to embryo, or fetus, or newborn before, during, or shortly after partuition (colostrum, milk, or fecal contamination of teats)

67
Q

Zoonosis

A

Infections that are transmissible from animals to humans

68
Q

Do viruses transmitted by respiratory route or fecal-oral route have higher environmental stability

A

Fecal-oral route have higher environmental stability than respiratory route

69
Q

Herd Immunity

A

A form of immunity that occurs when the vaccination of a significant large portion of a population (or herd) provides a measure of protection for individuals who have not developed immunity.

70
Q

Incubation Period

A

The interval between infection and the onset of clinical signs. In many diseases there is a period during which animals are infectious before they become sick.

71
Q

Prodromal Period

A

The first signs and feelings of illness after incubation period. The period of early symptoms of a disease occurring after the incubation period and just before the appearance of the characteristic symptoms of disease

72
Q

Acute Period

A

When the disease is at its height. Severe clinical signs.

73
Q

Decline period

A

Period when clinical signs begin to subside.

74
Q

Convalescent period

A

The body gradually returns to its pre-diseased state, and health is restored.

75
Q

Risk group 1

A

No or low individual and community risk

76
Q

Risk group 2

A

Moderate individual risk, low community risk

77
Q

Risk group 3

A

High individual risk, low community risk.
A pathogen that usually causes serious human or animal disease but does not ordinarily spread from one infected individual to another. Effective treatment and preventative measures are available.

78
Q

Risk group 4

A

High individual and community risk.
A pathogen that usually causes serious human or animal disease and that can be readily transmitted from one individual to another, directly or indirectly. Effective treatment and preventative measurers are not usually available.

79
Q

What risk category is FMD in livestock?

A

Risk category 4

80
Q

BSL-4

A

The maximum containment laboratory. They handle dangerous and exotic pathogens belonging to the highest risk group (ie risk group 4, ie ebola virus)

81
Q

Qualities of BSL-4 Lab (4)

A

1) Negative air-pressure must be maintained in the laboratory room
2) Incoming and outgoing air should be HEPA-filtered (High Efficiency Particulate Air)
3) Sterilization through double door autoclaving system
4) Suit decontamination shower after leaving the containment laboratory area

82
Q

Biohazard

A

Biological sybstances that pose a threat to the health of living organimss, primarily that of humans

83
Q

Biosafety

A

Laboratory biosafety describes the containment principles, technologies and practices that are implemented to prevent the unintentional exposure to pathogens and toxins, or their accidental release.

84
Q

Aerosol

A

Very small droplets of fluid that can spread via air. Viruses can spread in lab through aerosol route.

85
Q

Biosecurity

A

Laboratory biosecurity describes the protection, control, and accountability for valuable biological materials (VBM) within laboratories, in order to prevent their unauthorized access, loss, theft, misuse, diversion, or intentional release

86
Q

Timing of sample collection for virus isolation

A

Specimens should be collected as soon after onset of symptoms as possible, because maximal amounts (titers) of virus are usually present at the onset of signs. The chance of viral recovery is best during the first three days after onset and is greatly reduced beyond 5 days with many viruses.

87
Q

Timing of sample collection for serological tests

A

Two blood specimens are generally collected – one during acute phase of the illness and the second sample during the convalescence period (varies upon type of virus, 10-14 days after 1st sample of even more)

88
Q

Timing of sample collection for molecular diagnostics (ie PCR)

A

Obtained during the early parts of the illness

89
Q

Viral Transport Medium (VTM)

A

Swabs

90
Q

What do you do to prevent spillage while transporting infectious materials?

A

Basic triple packaging system

91
Q

Electron Microscopy

A

Can be used to demonstrate viruses in samples and detect viruses that cannot be grown in-vitro

92
Q

Negative-stain electron microscopy

A

1
2
3

93
Q

Transmission electron microscope (TEM)

A

The method used in TEM is based on transmitted electrons. TEM seeks to see what is inside or beyond the surface

94
Q

SEM

A

The method used in SEM is based on scattered electrons. SEM focuses on the sample’s surface and its composition.

95
Q

Advantages of TEM over SEM (2)

A

TEM can produce images that have higher magnification and greater resolution than SEM

96
Q

Advantages of SEM over TEM (1)

A

SEM produces 3D images while TEM only produces 2D images.

97
Q

Assay

A

Qualitative or quantitative measuremtn of a target entity/analyte, such as drug of biomolecule

98
Q

Gold Standard Test

A

A diagnostic test that is considered to be the most accurate and best available under a particular condition or set of conditions

99
Q

Sensitivity

A

The probability (%) that cases with the infection (determined by the result of reference or ‘gold standard’ test) will have a positive result using the test under evaluation.

100
Q

Specificity

A

The probability (%) that cases without the infection (determined by the result of reference or ‘gold standard’ test) will have a negative result using the test under evaluation.

101
Q

Serum

A

The clear-yellowish fluid obtained upon separating whole blood into its solid and liquid components after it has been allowed to clot. The clot is removed by centrifugation and the resulting supernatant, designated serum, is carefully removed using a Pasteur pipette. (Red-top vacutainer tube)

102
Q

Plasma

A

Is produced when whole blood is collected in tubes that are treated with an anticoagulant. The blood does not clot in the plasma tube (Lavender-top EDTA Vacutainer Tube)

Virology (5 decks)

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