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Y1 - Infection > Lecture 18 - Influenza SARS-CoV-2 > Flashcards

Lecture 18 - Influenza SARS-CoV-2 Flashcards

1
Q

What is the name of the family of Influenza viruses?

A

Orthomyxoviridae

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2
Q

What are some viruses part of the Herpesviridae family?

A

Herpes
EBV
Varicella zoster

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3
Q

What type of genetic material does Orthomyxoviridae have?

A

ssRNA
-ve sense

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4
Q

What type of genetic material does the Coronarviridae specifically SARS-CoV-2 have?

A

ssRNA
+ve sense

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5
Q

What area of the body does influenza/flu affect?

A

Acute viral infection of respiratory tract

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6
Q

How infectious is influenza (relatively)?
Can people with mild or no symptoms transmit influenza?

A

Highly infectious

Even with mild or no symptoms, people with influenza can infect others

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7
Q

What are the shapes of orthomyxoviruses?

A

Spherical

Segmented negative single stranded RNA

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8
Q

What is the important viral enzyme that is important in the replication of the orthomyxoviruses which leads to them having high mutation rates?

A

Viral RNA polymerase

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9
Q

Why does presence of viral RNA polymerase lead to high levels of mutations in Orthomyxoviridae?

A

Viral RNA polymerase = high error rate

High error rate because RNA polymerase has no proof reading like DNA polymerase which leads to mutations

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10
Q

What are the 2 main surface antigens for Orthomyxoviridae?

A

Haemagglutinin (H)

Neuraminidase (N)

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11
Q

What is the function of the H surface antigen (Haemagglutinin) on Orthomyxoviridae?

A

Binds to the surface receptor on host cells starting the process for the virus to enter the host cell

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12
Q

What is the function of neuraminidase surface antigen (N) on the orthomyxoviruses?

A

Allows the virus to move away from the cell

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13
Q

What are the 3 types of influenza viruses seen in humans?

A

Influenza A
Influenza B
Influenza C

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14
Q

What is the order of severity of the 3 Influenza viruses seen in humans?

From most severe to least severe:

A

Influenza A (most severe)
Influenza B
Influenza C (least severe)

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15
Q

Which of the 3 strains of influenza has the most potential host organisms and what are a few examples?

A

Influenza A

Humans
Swine
Equine
Birds
Marine
Mammals

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16
Q

Which strain of influenza has only human hosts?

A

Influenza B

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17
Q

Which of the influenzas has both Antigenic shift + Antigenic drift?

A

Influenza A

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18
Q

What influenzas only have Antigenic drift (NOT antigenic shift)?

A

Influenza B
Influenza C

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19
Q

Which influenza is a mild disease WITHOUT seasonality?

A

Influenza C

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20
Q

Which influenza can cause large pandemics with significant mortality in young persons?

A

Influenza A

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21
Q

Which influenza can cause severe diseases which is generally confined to older adults or persons at high risk where pandemics are not normally seen?

A

Influenza B

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22
Q

What is the main animal reservoir for Influezna A viruses?

A

Birds (mainly wildfowl)

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23
Q

Which Influenza virus is the main cause of outbreaks, epidemics and pandemics?

Which Influenza virus causes less severe disease and smaller outbreaks?

A

Influenza A

Influenza B

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24
Q

Which group of people does Influenza B normally affect?

A

Children
Older adults
Immunocompromised

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25
How does influenza replicate (not an ILO)?
-ve ssRNA converted to +ve ssRNA +ve ssRNA translated back to -ve ssRNA by RNA polymerase to be packaged
26
What route is Influenza transmitted?
Via the respiratory route (coughing, sneezing and inhaling)
27
What are the 3 potential modes of transmission of influenza?
Small particle aerosols suspended in air Larger particle or droplets on ground near infected person (direct contact) Virus particles on surfaces where the influenza remains infectious (indirect contact)
28
What are the 3 types of innate barriers to the entry of influenza via the respiratory route?
Respiratory epithelial cells covered in thick glycocalyx and tracheobronchial mucus Ciliated epithelial cells sweep mucus up from lower respiratory tract (mucocillary escalator) Secretion of IgA, Natural killer cells and macrophages in the lungs
29
What type of residue does the influenza virus bind to on the glycoprotein/glycolipid receptor for the influenza virus?
Neu5Ac residue which is a Sialic acid
30
How does the Influenza virus actually enter the cell?
Haemagglutinin protein on virus surface binds to sialic acid Neu5Ac residues on the receptor Receptor mediated endocytosis takes in the virus
31
How does the virus leave the cell?
The Neuraminidase cleaves the connection between the viruses Haemagglutinin and the glycoprotien/sialic acid receptor residue so its released
32
What are some symptoms of Influenza?
Fever Fatigue Headache Sore throat Cough Aches (myalgia) Nausea Vomiting Diarrhoea Many more potential symptoms
33
What are some complications of influenza that are more common in children?
Febrile convulsions Reye’s syndrome Otitis media Croup
34
What is the average incubation period of influenza A?
Between 1-5 days Average 2-3 days
35
Who are at risk of most serious complications of influenza?
Children under 6months Elderly Underlying conditions like respiratory disease cardiac disease, immunosuppressive, long term neurological conditions Pregnant Morbidly obese
36
How long does it normally take for someone to recover from influenza?
About 7 days
37
How is influenza usually diagnosed?
By symptoms and clinical assessment Rapid antigen tests Influenza PCRs
38
What are the 2 types of drugs that can be used to treat influenza?
Antivirals Neuraminidase inhibitors
39
What are 2 antivirals used to treat influenza? Which influenza can these treat?
Rimantadine Amantadine Only works for Influenza A
40
How do antivirals work to treat influenza? (Rimantadine and amantadine)
Inhibit viral uncoating after uptake
41
What are 2 examples of Neuraminidase Inhibitors that can treat influenza?
Oseltamivir Zanamivir
42
How do Neuraminidase inhibitors (Oseltamivir + Zanamivir) work to treat Influenza? Which Influenzas do these work against?
Prevent the virus releasing from the infected cell Influenza A and B
43
What is the main treatment against influenza?
Prevention = vaccination (vulnerable groups)
44
What are the 2 types of of Vaccination for influenza and who are their target groups?
Formalin-inactivated vaccine (quadrivalent/trivalent) for Adults Live attenuated cold adapted vaccine (quadrivalent) for children
45
What is meant by the influenza vaccines being quadrivalent?
Protects against 4 strains of influenza: -2 Influenza A strains -2 Influenza B strains
46
How are the formalin-inactivated vaccines for influenza administered?
Injection
47
How are the live attenuated vaccines of influenza for children administered?
Nasal spray
48
What is meant by the term “cold-adapted vaccine” for the influenza vaccine administered to kids?
Attenuated influenzae virus can only survive in the cold environment in the child’s nose Any warmer conditions like deeper in the body it will die
49
What is the approximate life cycle of influenza A?
6hrs
50
What is Antigenic drift?
Minor changes/natural mutations in the genes of flu viruses that occur gradually over time (this causes seasonal epidemics
51
What mutates as a result of the high error rate of viral RNA polymerase in Influenza viruses leading to Antigenic Drift?
Surface antigens: -Haemagglutinin (H) -neuraminidase (N) This can lead to resistance
52
Does the viral subtype change as a result of Antigenic drift?
No Only minor antigenic changes in H and N proteins occur
53
How does WHO decide which influenza strains should be vaccinated against each year?
Follows the virus epidemiolog/antigenic drift of the mutations of the H and N proteins of the virus
54
Which Influenza virus can have infrequently have dramatic changes in the antigenic properties of H and/or N proteins?
Influenza A
55
Which type of influenza can show Antigenic Shift?
Influenza A
56
What is antigenic shift?
When theres a dramatic change in the H and/or N proteins The H and N surface antigens come from different species Major changes in the genes of flu viruses that occur suddenly when 2 or more different strains combine. This results in NEW SUBTYPE causing widespread epidemics/pandemics
57
How does Antigenic shift occur?
Major changes in H and N proteins occurring due to several species of influenza viruses being in the same host This causes the viral subtype to change Happens due to reassortment of different RNA segments from each species
58
How does reassortment of Influenza A occur?
When multiple Influenza A species infect a single host The mRNAs encoding the H and N antigens get reassorted into unique combinations
59
Why is antigenic shift occurring in Influenza A dangerous?
New subtype develops Peoples immune systems dont have defence against new subtype Causing epidemics and pandemics
60
What is an Epidemic?
A widespread occurrence of an infectious disease in a community at a particular time
61
What is a pandemic?
Epidemic over a very large area, affecting a large proportion of a population - often the world
62
What causes the symptoms of flu?
Body’s immune response to viral infection Antibodies triggered and immune cells move to site of infection Release of cytokines leads to local inflammation
63
How does flu actually kill people?
Immune system overreacts (T cells attack + destroy cells with the virus in like in the lungs) Opportunistic secondary infection like Streptococcus or staphylococcus in lungs
64
What does SARS-CoV-2 stand for?
Severe Acute Respiratory Syndrome Coronavirus 2
65
What is the lay term for SARS-CoV-2?
COVID-19
66
Which part of the body does SARS-CoV-2 affect (COVID-19)?
Acute viral infection of respiratory tract
67
How infectious is COVID-19? Can people with mild or no symptoms infect others?
Highly infectious Yes can infect others
68
What is the genetic material of Coronaviridae?
+ve sense ssRNA
69
What is the general structure of Coronaviridae?
+ve ssRNA with spike proteins projecting from their surfaces
70
What is the function of the major Spike glycoprotein surface antigen of Coronaviridae?
Needed for entry into cells
71
What protein does SARS-CoV-1 bind to in the lungs?
ACE2 protein
72
What organism did zoonotic transfer of SARS-CoV-1 to humans happen from?
Civets to humans
73
What protein does MERS (Middle East Respiratory Syndrome) bind to?
DDP4
74
What organism did zoonotic transfer of MERS to humans happen from?
Camels
75
What protein does SARS-CoV-2 bind to?
ACE2
76
What organism did zoonotic transfer of SARS-CoV-2 to humans happen from?
Likely bats
77
What are the animal reservoirs for the Coronaviridae family?
SARS-CoV-1 = Bats —> Civets MERS = Bats —> Camels SARS-CoV-2/COVID-19 = Bats —> Unknown
78
How does SARS-CoV-2 (COVID-19) enter cells?
Spike glycoprotein on vision binds to ACE2 receptor in lungs, heart, kidney and GI tissue Receptor mediated endocytosis of virus into cells
79
How is COVID-19 diagnosed?
Lateral flow test PCR
80
What is the significance of a positive lateral flow test for COVID-19?
Surface proteins of COVID-19 detected indicating individual is infectious
81
What is the significance of a COVID-19 PCR being positive?
Detects the viral RNA which can be present for weeks after a person is no longer infectious So a +ve PCR does not always mean infectious
82
Why do we get variants in Corona viruses? (Similar to influenza)
Viral RNA polymerase has a high error rate (lack of proof reading) Leads to mutations
83
What is the approximate life cycle of a coronavirus?
10hrs
84
What are the 3 methods of transmission of COVID-19?
Via respiratory tract Small droplets (inhaled) Large droplets (over short distances) Larger droplets settle on surface, person touches it and touches the self
85
What type of vaccine is used for COVID-19?
Nucleic acid vaccine
86
How does the Nucleic acid vaccine for SARS-CoV-2 work?
Segment of SARS-CoV-2 viruses genetic material in vaccine Hosts body uses it to make the SARS-CoV-2 protein which it recognises and triggers an immune response

Y1 - Infection (21 decks)

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