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Virology > Respiratory Viruses > Flashcards

Respiratory Viruses Flashcards

1
Q

What viruses are contained within the group Orthomyxoviruses?

A

Influenza A, B, C

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2
Q

What are the distinguishing characteristics of the members of Orthomyxovirus and how can you differentiate between them?

A
  • Hemaglutinin
  • Neuramindase
    Each type of Influenza has different combination of H–N–.
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3
Q

What is the difference between Antigenic Drift vs Antigenic Shift?

A

Drift - minor changes, mutations, in hemaglutinin and neuramindase over time.
Shift - Reassortment of the genes of hemaglutinin and neuroamidase - happens in PIGS!

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4
Q

What kind of cells does influenza target?

A

Ciliated cells in the respiratory tract

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5
Q

What are factors that contribute to the pathogenesis of influenza?

A
  • Aerosol of influenza - infection in the respiratory tract
  • Desquamousation of ciliated cells
  • Destruction of cells via CTL
  • Interferon induction
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6
Q

What are the timeline of events of infection of influenza?

A
  • Can be up to 7 days of incubation
  • interferon induction occurs first at the onset, which causes the flu-like symptoms
  • CTL mediated response is activated and antibodies are formed and eliminate the virus
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7
Q

What are common flu-like symptoms?

A

Rapid onset fever, chills, malaise, myalgias, sore throat, and unproductive cough.

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8
Q

How are influenza symptoms different in children?

A

Children usually experience worse symptoms and the virus is harder on them.
Higher fever, GI symptoms, otitis media, croup

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9
Q

What are complications of influenza?

A

Due to the infection of the respiratory tract cells it breaks down the defenses of the body, which can lead to primary viral pneumonia or secondary bacterial pneumonia. Neurologic pathologies too due to similar antibody structure.

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10
Q

What are the best ways to diagnose influenza?

A

Rapid Antigen serotyping between influenza A and B. Tests for nucleoprotein - 15 minutes.
- rtPCR and/or serotyping

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11
Q

What and how does influenza attach to in order to invade a cell?

A

Hemaglutinin - binds to the sialic acid - galactose bond
Remember - Humans have 2,6 Bond - Influenza Binds
Avian has 2,3 bonds
Swine have both 2,3 and 2,6, which is why avian influenza can cross over to humans

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12
Q

What does neuroamidase do?

A

Neuroamidase - cleaves the sialic acid - galactose bond in order to release the virion from the cell, if this is inhibited by Oseltamivir the virus cannot spread

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13
Q

What is key for uncoating of influenza?

A

When the vesicle that contains the virion begins changing into late endosome the pH lowers, which M2 protein opens a channel allowing the protons into the virion activating hemaglutinin to fuse with the membrane and uncoat.

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14
Q

Where does influenza replicate its genome and transcribe?

A

Replicates and Transcribes in the genome of the host cell, which is different than most other RNA viruses.

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15
Q

What does the influenza vaccine contain?

A

Different Hemaglutinins and Neuramindases from different strains predicted for the next season.
Eggs used in production of the virus to be used in vaccines

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16
Q

What are common antivirals used for influenza?

A

Amanatadine and Rimantidine - blocks M2 channel/uncoating
Ribavirin - inhibits viral RNA synthesis
Oseltamivir and Zanamivir - inhibits neuramindase

17
Q

How do they get the proper/desired antigen production for the inlfuenza vaccines?

A

They inoculate the egg with two strains, one has the desired surface antigens and the other is designed to grow well in avian models, and the desired antigens are selected for using antibodies against the other.

18
Q

What are the most common strains of influenza in the seasonal vaccine?

A

H3N2

H1N1

19
Q

Where does Rhinovirus localize its infection and why?

A

Upper respiratory tract, because it grows better at lower temperatures.
–most common cause of common cold–

20
Q

What causes the symptoms of a Rhinovirus?

A

Immune response in the upper respiratory tract, the infected cells release bradykinin and histamine causing the runny nose and sore throat (inflammation).

21
Q

What kind of virus is the Rhinovirus and what replication cycle does it exhibit?

A

Picornavirus - Polio replication

Many serotypes, thus there is no prevention

22
Q

What is the 2nd most common cause of the cold in humans?

A

Coronaviruses

23
Q

How are Coronaviruses similar to Rhinoviruses?

A

They both infect the upper respiratory tract and grow best at lower temperatures

24
Q

What are two notable coronaviruses in recent times?

A

SARS and MERS virus.

25
Q

How is MERS virus different from SARS virus?

A

Contains different receptor and is able to infect more than one species other than humans.
Not easily transferred and fatalities usually due to another causative agent like chronic disease.

26
Q

What are the characteristics of a paramyxoviridae virus?

A

Envelope, ssRNA
Fusion Proteins on surface needed for entry
HN - Hemaglutinin and Neuramidase together
NS1/NS2

27
Q

Where does a paramyxovirus replicate?

A

Cytoplasm for transcription and replication

28
Q

What patients are susceptible for paramyxoviruses?

A

infants and young children

elderly and immunocompromised

29
Q

If a young child is infected with HSIV1 or HSIV2, what are they likely to be experiencing?

A

Croup - HSIV1/2 are most common cause in young children, broncholitis and pneumonia

30
Q

What paramyxovirus infects in the first year of life and is highly fetal?

A

Respiratory Syncytial Virus - RSV

31
Q

What is characteristic of RSV?

A

Infects the respiratory tract and spreads to pneumonia causing constriction of the airways, most severe in infants under the age of 1.

32
Q

What causes the symptoms of RSV to be worse in young children compared to older children and adults?

A

Difference in CD4+ pathway activation.

  • Normal = Th1 pathway for antiviral defense
  • Abnormal = Th2, induces mast cells and eosinophils, causing further swelling of the airways worsening the pathogenesis of RSV
33
Q

What can you see in cells that are infected with RSV?

A

They are giant cells with pink intracellular inclusions.

34
Q

Why is there not a vaccine to RSV?

A

There is not a long term immune memory to RSV, which is why children can get re-infected again.

35
Q

What is a common human metapneumonvirus and who is effected by it?

A

hMPV - similar to RSV, causes significant infections in infants, elderly, immunocompromised, and chronic pulmonary disease. (COPD)
Vaccine Strategy would be different for infant vs elderly

36
Q

What viruses have recently jumped from bats/rodents to humans with high mortality?

A

Paramyxovirus - Hendra and Nipah Viruses

37
Q

What are common locations of infection of Adenovirus?

A

URI, Conjunctivitis, GI, and UTI

–Respiratory Tract tends to become severe–

38
Q

In Adenoviruses, what tissue is the target of their infection, shedding, and latent infections?

A

Lymphoid Tissue

39
Q

What virus was typically contracted by military recruits in close quarters?

A

Adenovirus - Acute Respiratory Disease

Virology (8 decks)

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