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Viruses & Infections Flashcards

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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
Sexually transmitted viruses
HIV, Herpes, Hepatitis
26
What type of virus causes sore throat and conjunctivitis
Adenoviruses
27
What virus causes influenza
orthomyxoviruses
28
What virus causes HIV
retrovirus
29
What virus causes chickenpox, shingles, herpes
Herpesviruses
30
What virus causes warts
papovaviruses
31
What virus causes viral hepatitis
hepadnaviruses
32
How do viruses gain access to cells
Because they have attachment sites for cellular receptors
33
Do viruses cause allergic reaction
no
34
What happens when viruses leave our cells
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
35
The release of non enveloped viruses leads to
The rupture and lysis of cells
36
What are cytopathic effects (CPE) of Viruses
The effect of Viral infections two types used to diagnose many viral infections
37
Cytocidal effect
When the effect results in cellular death
38
Non-cytocidal effect
The effect results in cell damage/loss of function but not cell death
39
CPE effects
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
What is autolysis
When a cytocidal virus infects a cell, It causes the cell's lysosomes to release their enzymes leading to autolysis
41
Synctium
At times, several adjacent infected cells fuse to form a very large cell.
42
Inclusion bodies
Are intracellular granules whose presence is a result of viral infection (useful for the identification of some viral infections)
43
Influenza virus types
A, B, and C
44
What type of influenza is typically associated with pandemics and wide-spread epidemics
Type A
45
Symptoms of influenza
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
Morphology of influenza virus
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
Explain the outer surface of the influenza virus
Consistis of a lipid envelope from which project prominent glycoprotein spikes of two types: Hemagglutinin (HA), and Neuraminidase (NA)
48
Hemagglutinin (HA)
HA is considered a ligand it helps enter by binding to a receptor HA needs to be in a certain shape to attach
49
Neuraminidase (NA)
Helps exit and infect other cells
50
What determines if influenza virus is going to affect us humans
Hemagglutinin (HA), and Neuraminidase (NA) (glycoproteins) they are basically spikes on the outer surface of the virus
51
Who does influenza A viruses infect
a wide variety of mammals, including man, horse, pigs, ferrets, and birds (reassortment)
52
Who does influenza B viruses infect
Man and birds Causes human disease Epidemiologically important
53
Who does influenza C viruses infect
Man alone Do not cause disease They are genetically and morphologically distinct from A and B types
54
Pathogenesis of influenza virus
the spread is by aerosols-very efficient
55
What does the primary infection of influenza virus involve
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
What is the virus that causes Covid-19
SARS-CoV-2 (severe acute respiratory syndrome coronavirus)
57
How many strains of coronavirus are there
7 strains (mostly symptoms similar to colds)
58
How long is the incubation period for Covid-19
14 days, maidan of 4-5 days
59
Most common symptoms of Covid-19
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
Can you receive antibiotics if you have a virus and bacteria
Yes
61
How is COIVD-19 spread
Respiratory droplets
62
Severe manifestations/complications of COVID-19
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
Pathopphysiology od COVID-19 virus
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
Is COVID-19 in the upper or lower tract
upper but pneumonia is in lower
65
What type of microorganism is fungi
aerobic eukaryotic obligate parasites because they cannot make their own food
66
Saprophytes (decomposers)
Live on decomposing dead organisms Thus help get rid of dead bodies and turning to mineral salts
67
What can fungi tolerate well
High concentrations of salts, sugars, and acids
68
Are bacteria or fungi normally responsible for spoilage of food
Fungi
69
What type of medium to fungi prefer
moist
70
What range of pH and temp does fungi tolerate
2 to 9 and -6 C to 50 C
71
What are the 3 major groups of fungi
1) Yeasts 2) Molds 3) Dimorphic fungi
72
Yeasts structure
Unicellular, oval or cylindrical microorganisms Larger than bacteria in size
73
How do yeasts reproduce
by budding
74
Molds structure
Filamentous multicellular fungi
75
How do molds reproduce
spores, which spread to form mycelia
76
How do dimorphic fungi grow
grow as either Yeats or mold depending on the temperature and environmentalconditions
77
What is the usual temperature that yeast and typically form in our bodies
Yeast - 37 C Mold - form in soil
78
What are Fungal cell membranes like
Contains the sterol, ergosterol (compared to cholesterol in human cells)
79
What part of fungi is the target for most anti fungal drugs
Their cell membrane
80
What is fungi's cell wall like
made of chitin (complex of polysaccharide close to cellulose)
81
Do fungi have a capsule
Some fungi have an antiphagocytic capsule which coats the fungal cell and protects it
82
Fungal infections in humans (mycosis)
1) Superficial Mycosis 2) Cutaneous Mycosis 3) Systemic Mycosis
83
Superfical Mycosis
Mild infection of the epidermal layer characterized by pigment change of the skin Ex. Tinea versicolor & Tinea nigris
84
Where does cutaneous Mycosis occur
Located at the epidermis, hair follicles or nails
85
What are the manifestations of cutaneous mycosis
Scaling, crumbling of nail, and loss of hair Ex. Tinea infections
86
What is systemic mycosis caused by
dimorphic fungi and not contagious
87
What happens when spores are inhaled in systemic mycosis
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
What are systemic mycosis
It is a deep fungal infection that affects many organs and tissues
89
what symptoms does systemic mycosis cause
Can be asymptomatic, mild pneumonia, or severe tuberculosis-like infections
90
What does candidiasis cause
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
Aspergillosis
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
Fungal mechanisms of pathogenicity
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)

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