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Immuno mikro eng > Viral Respiratory Infections - RNA Viruses > Flashcards

Viral Respiratory Infections - RNA Viruses Flashcards

1
Q

What family are the influenzaviruses in, and what are its physical characteristics?

A

Orthomyxovirus

Enveloped, negative-sense RNA geneome with 8 segments

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2
Q

What influenza protein is primarily involved in attachment and what does it bind?

A

Hemagglutinin (HA) - binds sialic acid (blocked via mucins)

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3
Q

How is influenza virus uptaken and envelope fused?

A

Uptaken by receptor-mediated endocytosis, endosome fuses with viral membrane due to pH drop triggering conformational change in HA

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4
Q

What is the function of the M2 protein?

A

Ion channel which allows protons to enter the virion interior, facilitating pH drop. This frees the ribonuclear complex (RNP) which is RNA + protein

This was targeted by some anti-influenza drugs, but now resistant

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5
Q

Where does influenza-virus replicate?

A

In the nucleus -> a rarity for RNA viruses

Similar to how poxviruses are DNA and replicate in cytoplasm

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6
Q

What is the function of transcribing RNPs?

A

Yields + sense RNA, which can be used to transcribe more RNA or viral genomes

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7
Q

What is the function of M1 protein?

A

Interacts with nascent RNP’s to acquire envelopes by budding thru plasma membrane

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8
Q

What is the function of viral neuraminidase (NA)?

A

Removes sialic acid from cell surface as well as surrounding mucous decoy receptors. Guarantees the virus will not re-infect a previously infected cell, and thins mucuous

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9
Q

What are the two protein components of HA?

A

Formed from HA0,

HA1 - Binds sialic acid
HA2 - Contains transmembrane domain and fusion peptide for endosome

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10
Q

How do Oseltamivir and Zamanivir work?

A

Neuraminidase inhibitors

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11
Q

What are the three most common influenza forms and what is the best protective antibody?

A

H1N1, H2N2, H3N2

Best protective antibody is anti-hemagglutinin

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12
Q

What is antigenic shift vs antigenic drift?

A

Shift - large change via genetic reassortment and coinfection of two influenza A viruses - cause pandemics

Drift - minor antigenic changes via point mutations - seasonal flu - cause epidemics

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13
Q

What does a typical season flu vaccine formulation contain in it?

A

Trivalent

Most likely H1N1 strain (Influenza A)
Most likely H3N2 strain (Influenza A)
Most likely Influenza B

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14
Q

What makes an influenza strain especially virulent?

A

When it has a broad cell tropism (not trypsin dependent, which is only in lungs), which can cause disease in young adults.

Also causes cytokine storm causing inflammation, and predisposes to nasty bacterial superinfections.

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15
Q

Why is trypsin required for influenza?

A

It is a part of human cells -> required for cleavage of HA0 into HA1 and HA2

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16
Q

How do influenza viruses suppression antiviral interferon responses?

A

Via NS1 protein, which blocks interferon-induced RNaseL pathway

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17
Q

What type of viruses are Paramyxoviruses?

A

negative (-) sense RNA genomes, unsegmented

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18
Q

What are the major viruses of the paramyxovirus subfamily?

A

Human parainfluenza viruses (HPIV 1-4), Mumps Virus, Measles Virus

(Rubella is a Togavirus)

19
Q

What are the major viruses of the pneumovirus subfamily? This is a part of the paramyxoviridae family

A 
Respiratory syncytial virus (RSV)
Human Metapneumovirus (MPV)
20
Q

How common are paramyxovirus infections and how are they spread?

A

Extremely common, especially in childhood. Spread via direct contact with respiratory secretions, aerosols, and fomites.

Most people will have had HPIV and RSV by age 2.

21
Q

Are repeated infections of paramyxovirus common?

A

Yes, they are RNA viruses

22
Q

What is croup? What clinical finding is associated with it?

A

Laryngotracheobronchitis - An infection and inflammation of the larynx, trachea, and bronchi, narrowing the airway leading to difficulty breathing (upper airway inflammation)

Associated with “stridor” - characteristic sound on inhalation

23
Q

What viruses tend to cause croup? Do patients need treatment?

A

HPIV-1 is the most common cause

Other HPIV’s and RSV / MPV can cause it too.

Patient needs rapid medical attention due to respiratory distress

24
Q

What do the paramyxoviruses typically cause in adults?

A

Laryngitis and pneumonia

25
Q

What are all the viral causes of pneumonia?

A

HPIV’s, RSV, hMPV, Influenzavirus, Adenovirus, Coronavirus

26
Q

What is bronchiolitis, does it happen in adults, and what causes it?

A

Infection and inflammation of the bronchioles
-> small airways between bronchi and alveolae

Symptoms are dyspnea or cough
Rare in adults, mostly in children under 2, primarily caused by RSV

27
Q

What is Measles Virus also called, and what are its prodomal symptoms?

A

Rubeola virus

Remember the 4 C's of the prodrome:
Cough
Coryza
Conjunctivitis
Coplik's spots

okay so its spelled Koplik but whatever

28
Q

What are Koplik’s spots?

A

Tiny blue-white spots on red buccal mucosa in measles prodrome = pathonomonic

29
Q

What is the pattern of rash in measles? What type of rash it it?

A

Begins on face, then spreads to trunk and limbs like Rubella

Can form a confluent rash -> spots will start to blend together into a sheet of red

30
Q

How are mumps transmitted?

A

Salivary or respiratory secretions -> less infectious than measles

31
Q

What are the most common manifestations of mumps? Atypical?

A

Painful swelling of parotid glands (unilateral or bilateral), ear pain

Atypical:
Orchitis -> more severe, can cause infertility if bilateral
Also meningitis

32
Q

What is german measles and its genome structure?

A

Rubella

Togavirus with enveloped icosahedral virus, single stranded +sense RNA

33
Q

What are the symptoms of Rubella?

A
  1. Lymph node swelling, especially postauricular and occipital nodes
  2. Maculopapular rash starting in head and going down (same as measles)

Arthritis in adult women

34
Q

How long is the incubation period of M,M, and R?

A

All about 2-3 weeks

35
Q

What are the features of congenital rubella syndrome?

A

Sensorineural deafness, intellectual impairment, jaundice / hepatosplenomegaly, cataracts, blueberry muffin rash, patent ductus arteriosus, CNS infection

36
Q

How many doses of MMR Vaccine should be given?

A

1st dose at 12-18 months, 2nd dose at 4-6 years

37
Q

What is the structure of a coronavirus?

A

Large ss+RNA genome, with envelope and HELICAL nucleocapsid

38
Q

What type of infection are coronaviruses generally associated with?

A

Mild to moderately severe URI

39
Q

What are two coronaviruses of consequence?

A

SARS - Severe Acute RS - zoonosis from China, caused pneumonia and acute respiratory distress

MERS - Middle East RS - zoonosis from camels, high case fatality

40
Q

What is the main distinguishing feature of a cold? What is the most common viral cause?

A

Usually no or mild fever

Rhinovirus

41
Q

What is the structure of picornaviruses?

A

naked ss+RNA

42
Q

How are picornaviruses spread and what are two main viral subfamilies?

A

They infect skin and mucous membranes, and thus spread by saliva, mucous, or feces

  1. Coxsackievirus
  2. Echovirus
43
Q

What two major diseases does Coxsackie A virus cause?

A
  1. Hand, Foot, and Mouth Disease

2. Herpangina (mouth blisters and ulcers, especially on soft palate)

44
Q

What are rare complications of measles?

A

SSPE - Subacute Sclerosing Pan Encephalitis - from measles reactivation in brain
Pneumonia

Immuno mikro eng (56 decks)

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