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Health & Healing > Viruses & Infections > Flashcards

Viruses & Infections Flashcards

1
Q

What is another name for viruses

A

Obligate intracellular parasite as they grow only within cells

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2
Q

Can you use antibiotics on viruses

A

No, because they use our bodies machinery. For an antibody to work it needs to bind to something so it would be binding to our own body and attacking it.

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3
Q

How do viruses infect

A

They float around and when in contact with the appropriate cell, they invade it and start replicating

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4
Q

Do viruses release enzymes

A

No, except a few, or toxins

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5
Q

How do viruses cause disease

A

Due to their destruction off cells rather than toxin releasing

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6
Q

Viral morphology

A

nucleic acids (genetic material), capsid/covering, envelope

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7
Q

What does the nucleic acid look like inside a virus

A

It is either DNA or RNA, never both

There is a (+) RNA and (-) RNA. (+) RNA can enter directly into ribosomes and translate into protein molecules. (-) RNA needs to be transcribed into (+) RNA before it can be translated

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8
Q

What is a retroviral RNA

A

transcribed into DNA using a unique enzyme called reverse transcriptase

RNA -> DNA

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9
Q

Capsids

A

Geometric shapes with flat surfaces. Helical capsids are long rods that may be rigid or flexible

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10
Q

Envelope

A

Covers the capsids (outer layer) only sometimes

Viruses that do not have membranes are referred to as naked or non enveloped

Those with membranes are referred to as enveloped

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11
Q

What is a characteristic that distinguishes the family of a virus

A

having viridae at the end

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12
Q

How do viruses replicate

A

Viruses so not reproduce on their own, they have nucleic acids but do not possess a ribosome to make proteins.

They possess no energy or energy producing mechanisms.

They must invade a cell and take over its machinery and use its resources in order to form new viral particles.

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13
Q

The 6 steps of viral replication

A
  1. Attachement
  2. Penetration
  3. Uncoating
  4. Synthesis of viral DNA or RNA and proteins
  5. Maturation
  6. Release
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14
Q

Explain attachment in viral replication

A

The virus attaches/adheres to the cell by special receptors on the human cells

Viruses are usually cell specific (each virus have a special target cell)

ex. HIV viruses attacks CD4 helper T cells only. Brazil women prostitutes didn’t have receptors for HIV virus so never got it

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15
Q

Explain penetration in viral replication

A

Occurs by two types according to the virus itself

  • Endocytosis for non-enveloped viruses
  • Fusion for enveloped viruses
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16
Q

Explain uncoating in viral replication

A

The protein capsid of the virus separates from the nucleic acids

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17
Q

Explain synthesis of viral DNA or RNA and proteins

A

The viral DNA or RNA replicates inside the nucleus of the host, they also synthesize their proteins by using the cell ribosomes

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18
Q

Explain maturation in viral replication

A

The new nucleic acids join with the new proteins synthesized to form new viruses

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19
Q

Explain release in viral replication

A

The mature viruses are released from the cell

  • Enveloped viruses are released by budding (hide under membrane) from the plasma membrane taking a part of the cell’s membrane
  • Non-enveloped viruses are released by rupturing the host cell
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20
Q

Route of transmission of viruses

A

1) Enteric viruses
2) Respiratory viruses
3) Zoonosers
4) Arbovirus
5) Sexually transmitted

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21
Q

Enteric viruses

A

transmitted by oral route, enter the intestinal tract where they replicate and cause gastroenteritis

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22
Q

Respiratory viruses

A

Transmitted by inhaling infected droplets and replicate in the respiratory tract: influenza viruses, maps, measles

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23
Q

Zoonosers

A

Transmitted by animals: rabies

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24
Q

Arboviruses

A

Transmitted by mosquitoes, ticks, and flies

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25
Q

Sexually transmitted viruses

A

HIV, Herpes, Hepatitis

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26
Q

What type of virus causes sore throat and conjunctivitis

A

Adenoviruses

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27
Q

What virus causes influenza

A

orthomyxoviruses

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28
Q

What virus causes HIV

A

retrovirus

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29
Q

What virus causes chickenpox, shingles, herpes

A

Herpesviruses

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30
Q

What virus causes warts

A

papovaviruses

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31
Q

What virus causes viral hepatitis

A

hepadnaviruses

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32
Q

How do viruses gain access to cells

A

Because they have attachment sites for cellular receptors

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33
Q

Do viruses cause allergic reaction

A

no

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34
Q

What happens when viruses leave our cells

A

They leave a nucleic acid within our genetic material, this leads to pathologic modifications of the cell’s properties

When this happens the cells should undergo apoptosis, if this doesn’t happen it will likely lead to cancer

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35
Q

The release of non enveloped viruses leads to

A

The rupture and lysis of cells

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36
Q

What are cytopathic effects (CPE) of Viruses

A

The effect of Viral infections

two types

used to diagnose many viral infections

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37
Q

Cytocidal effect

A

When the effect results in cellular death

38
Q

Non-cytocidal effect

A

The effect results in cell damage/loss of function but not cell death

39
Q

CPE effects

A

Inhibit protein synthesis and mitosis of cells (Herpes virus)

Changes in infected cell’s function with no visible changes in its shape. Ex. an infected hormone secreting cell will not be able to secret hormones anymore

Inducing chromosomal abnormalities that can be malignant

40
Q

What is autolysis

A

When a cytocidal virus infects a cell, It causes the cell’s lysosomes to release their enzymes leading to autolysis

41
Q

Synctium

A

At times, several adjacent infected cells fuse to form a very large cell.

42
Q

Inclusion bodies

A

Are intracellular granules whose presence is a result of viral infection (useful for the identification of some viral infections)

43
Q

Influenza virus types

A

A, B, and C

44
Q

What type of influenza is typically associated with pandemics and wide-spread epidemics

A

Type A

45
Q

Symptoms of influenza

A

A specific acute viral respiratory infection with fever, chills, headache, cough, nasal discharge, sometimes causing bronchitis, pneumonia, and death in severe cases
Rare nausea, vomiting, and diarrhea

46
Q

Morphology of influenza virus

A

Influenza virus particles are highly pleomorphic, mostly spherical/ovoid, but many forms occur, including long filamentous particles

High levels or mutations, because it can’t catch mutations in DNA/RNA replications

47
Q

Explain the outer surface of the influenza virus

A

Consistis of a lipid envelope from which project prominent glycoprotein spikes of two types:

Hemagglutinin (HA), and
Neuraminidase (NA)

48
Q

Hemagglutinin (HA)

A

HA is considered a ligand it helps enter by binding to a receptor

HA needs to be in a certain shape to attach

49
Q

Neuraminidase (NA)

A

Helps exit and infect other cells

50
Q

What determines if influenza virus is going to affect us humans

A

Hemagglutinin (HA), and Neuraminidase (NA) (glycoproteins) they are basically spikes on the outer surface of the virus

51
Q

Who does influenza A viruses infect

A

a wide variety of mammals, including man, horse, pigs, ferrets, and birds (reassortment)

52
Q

Who does influenza B viruses infect

A

Man and birds

Causes human disease
Epidemiologically important

53
Q

Who does influenza C viruses infect

A

Man alone

Do not cause disease
They are genetically and morphologically distinct from A and B types

54
Q

Pathogenesis of influenza virus

A

the spread is by aerosols-very efficient

55
Q

What does the primary infection of influenza virus involve

A

Primary infection involves the ciliated epithelial cells of the URT

Normally self-limited infection usually lasts 3-7 days (+ convalescence)

Damage to respiratory epithelium predisposes to secondary bacterial infections which accounts for most death

56
Q

What is the virus that causes Covid-19

A

SARS-CoV-2 (severe acute respiratory syndrome coronavirus)

57
Q

How many strains of coronavirus are there

A

7 strains (mostly symptoms similar to colds)

58
Q

How long is the incubation period for Covid-19

A

14 days, maidan of 4-5 days

59
Q

Most common symptoms of Covid-19

A

cough (86%), fever or chills (85%), and shortness of breath (80%), diarrhea (27%), and nausea (24%)

sputum production, headache, dizziness, rhinorrhea

anosmia (loss of sense of smell)
dysgeusia (changes in sense of taste)

sore throat, abdominal pain, anorexia and vomiting

60
Q

Can you receive antibiotics if you have a virus and bacteria

A

Yes

61
Q

How is COIVD-19 spread

A

Respiratory droplets

62
Q

Severe manifestations/complications of COVID-19

A

Pneumonia

Actue respiratory distress syndrome (ARDS)

Multi Organ Failture

Inflammatory response moves to other parts of the body Systemic inflammatory response syndrome (SIRS): inflammation in every organ

Septic shock (decrease in BP)

Cytokine Storm

Death

63
Q

Pathopphysiology od COVID-19 virus

A

Virus binds with angiotensin converting enzyme 1 (ACE-2) on the Type II pneumoncytes (produce surfactant) in alveoli of lungs

Virus replicates, destroys type II pneumocyte and leads to inflammation

Leads to more blood supply and vasodilation and increased permeability

Fluid moves into interstitial apace around alveoli

Less room for gas exchange (decrease O2)

Increase in breathing (dyspnea)

64
Q

Is COVID-19 in the upper or lower tract

A

upper but pneumonia is in lower

65
Q

What type of microorganism is fungi

A

aerobic eukaryotic

obligate parasites because they cannot make their own food

66
Q

Saprophytes (decomposers)

A

Live on decomposing dead organisms

Thus help get rid of dead bodies and turning to mineral salts

67
Q

What can fungi tolerate well

A

High concentrations of salts, sugars, and acids

68
Q

Are bacteria or fungi normally responsible for spoilage of food

A

Fungi

69
Q

What type of medium to fungi prefer

A

moist

70
Q

What range of pH and temp does fungi tolerate

A

2 to 9 and -6 C to 50 C

71
Q

What are the 3 major groups of fungi

A

1) Yeasts
2) Molds
3) Dimorphic fungi

72
Q

Yeasts structure

A

Unicellular, oval or cylindrical microorganisms

Larger than bacteria in size

73
Q

How do yeasts reproduce

A

by budding

74
Q

Molds structure

A

Filamentous multicellular fungi

75
Q

How do molds reproduce

A

spores, which spread to form mycelia

76
Q

How do dimorphic fungi grow

A

grow as either Yeats or mold depending on the temperature and environmentalconditions

77
Q

What is the usual temperature that yeast and typically form in our bodies

A

Yeast - 37 C

Mold - form in soil

78
Q

What are Fungal cell membranes like

A

Contains the sterol, ergosterol (compared to cholesterol in human cells)

79
Q

What part of fungi is the target for most anti fungal drugs

A

Their cell membrane

80
Q

What is fungi’s cell wall like

A

made of chitin (complex of polysaccharide close to cellulose)

81
Q

Do fungi have a capsule

A

Some fungi have an antiphagocytic capsule which coats the fungal cell and protects it

82
Q

Fungal infections in humans (mycosis)

A

1) Superficial Mycosis
2) Cutaneous Mycosis
3) Systemic Mycosis

83
Q

Superfical Mycosis

A

Mild infection of the epidermal layer characterized by pigment change of the skin

Ex. Tinea versicolor & Tinea nigris

84
Q

Where does cutaneous Mycosis occur

A

Located at the epidermis, hair follicles or nails

85
Q

What are the manifestations of cutaneous mycosis

A

Scaling, crumbling of nail, and loss of hair

Ex. Tinea infections

86
Q

What is systemic mycosis caused by

A

dimorphic fungi and not contagious

87
Q

What happens when spores are inhaled in systemic mycosis

A

Fungi live as mycelia in nature and release spores to the atmosphere

They grow as yeast cells and infect the lung

this is followed by blood stream dissemination and in most cases the fungus is destroyed at this point

88
Q

What are systemic mycosis

A

It is a deep fungal infection that affects many organs and tissues

89
Q

what symptoms does systemic mycosis cause

A

Can be asymptomatic, mild pneumonia, or severe tuberculosis-like infections

90
Q

What does candidiasis cause

A

Infection caused by Candida albicans yeast in normal host it causes cutaneous infections in the mouth and vagina

In immunocompromised patients candidiasis is disseminated to almost all organs

91
Q

Aspergillosis

A

It is a mild infection caused by spores of Aspergillus flakes mold

The spores float in the air and develop asthma type reaction

In immunocompromised, aspergillosis is severe and leads to liver damage

92
Q

Fungal mechanisms of pathogenicity

A

These do not have a well defines set of virulence factors

Some fungi have metabolic products that are toxic to human host

May provoke an allergic reaction

Enzymes produces by some fungi such as proteases and keratinases (mainly superficial fungi)

Health & Healing (5 decks)

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