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Immunity, Infection and Disease > Myxoviruses and Coronaviruses > Flashcards

Myxoviruses and Coronaviruses Flashcards

1
Q

What are myxoviruses and what is the difference between ortho- and paramyxoviruses?

A

Myxoviruses have affinity for mucus (Greek myxa means mucous). Ortho are the originally-described myxoviruses, para are similar but not identical to the orthos

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2
Q

List clinically significant orthomyxoviurses and paramyxoviruses (6 total)

A

Ortho - influenza, para - parainfluenza, mumps, pneumovirus (RSV), human metapneumovirus, and nipah virus (also measles)

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3
Q

What type of genome do orthomyxoviruses have and where do they replicate?

A

Segmented, Negative sense RNA, replicate in nucleus

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4
Q

Influenza is type as A, B, or C. What two designations is an influenza type A virus given and what are the possible designations for each?

A

Hemagglutinin (HA) and Neuraminidase (NA). H1 through H13 and N1 through N9 (e.g. H1N1)

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5
Q

What influenza strain appeared in Hong Kong in 1997, why was it surprising, and what is the strains current status?

A

H5N1, previously thought humans only got H1 through 3 (and N1 and N2), currently circulating through SE Asia

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6
Q

Which types of influenza (A, B, or C) are most responsible for human disease?

A

A and B

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7
Q

How many segments does each influenza type (A, B, and C) have?

A

A - 8, B - 8, C - 7

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8
Q

Is influenza nucleocapsid helical or icosahedral?

A

Helical

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9
Q

What does the influenza HA protein do and what must be done to it for the virus to be infectious?

A

It helps virus attach to and penetrate cell. Must be cleaved into HA1 and HA2 for viral infectivity

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10
Q

What is the difference between antigenic drift and antigenic shift?

A

Drift implies small changes (e.g. point mutations), while shift suggests major changes (e.g. HA and NA reassortment in pigs)

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11
Q

Drift in which influenza protein tends to have more clinical impact?

A

HA

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12
Q

How many HA epitopes typically have to undergo antigenic drift for it to be clinically significant?

A

Two or more

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13
Q

What form does influenza virus tend to take outside the body?

A

Small particle aerosol (can survive for long periods of time)

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14
Q

Within 24 hours of onset of influenza symptoms, what is seen histologically?

A

Destruction of ciliated epithelial cells and mucous-secreting cells. Then edema, hyperemia, PMN and mononuclear cell infiltration

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15
Q

What is the incubation period of influenza?

A

1 to 5 days

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16
Q

Typical symptoms of uncomplicated adult influenza infection

A

Tracheobronchitis, headache, fever, chills, dry cough, myalgia, malaise, anorexia (chest x-ray usually normal)

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17
Q

What additional influenza symptoms are often seen in pediatric infections?

A

High fever, GI issues, pulmonary issues, ear infections, enlarged cervical lymph nodes

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18
Q

Reyes syndrome is associated with salicylate administration during influenza in children. Which type of influenza is most commonly associated with Reyes?

A

Influenza B infection

19
Q

Amantadine and Rimantadine are used as antivirals. How do they work?

A

Target M2 protein and viral uncoating

20
Q

How does Tamiflu work against influenza virus?

A

It is a neuraminidase (NA) inhibitor. It affects viral assembly and release

21
Q

What is FLU-MIST?

A

A new, live, cold-adapted, temperature sensitive, attenuated influenza vaccine. Might work better than traditional deactivated influenza vaccine

22
Q

The term Avian flu is usually used to describe influenza viruses of what HA and NA numbers?

A

H5N1

23
Q

Why is the recent H1N1 called a quadruple reassortant virus?

A

It has genes from European and Asian pig strains (2 genes) as well genes from avian and human strains

24
Q

The current flu vaccine protects against what flu strains?

A

H3N2, H1N1, and an Influenza B strain

25
Q

List the differences between paramyxoviruses and orthomyxoviruses

A

Paramyxoviruses are non-segmented, replicate in cytoplasm, have very low rate of recombination, and their HA and NA are a single protein

26
Q

What are the serotypes of parainfluenza?

A

1,2,3,4a and 4b

27
Q

Generally speaking, what do parainfluenza viruses cause?

A

Respiratory infections in children and adults

28
Q

How do parainfluenza viruses spread in the body?

A

Cell-to-cell (although viremia may also occur)

29
Q

What is the most common cause of croup (laryngeotracheobronchitis)?

A

Type 1 parainfluenza

30
Q

What is the presentation of parainfluenza in infants and what other virus is this similar to?

A

Pneumonia or bronchitis. Similar to respiratory syncytial virus

31
Q

What is the major human pathogen for pneumoviruses?

A

Respiratory Syncytial Virus (RSV)

32
Q

What is the number one cause of pneumonia and bronchiolitis in infancy and childhood?

A

RSV

33
Q

How are parainfluenza and RSV spread?

A

Large droplets, secretions

34
Q

What is the incubation period of RSV?

A

2 to 8 days

35
Q

What is seen in high incidence after RSV infection?

A

Asthma

36
Q

Generally speaking, what is the course of a primary RSV infection?

A

Pneumonia and bronchiolitis in children, URI in adults

37
Q

Which myxovirus can become significantly more severe in the presence of underlying disease?

A

RSV (esp congenital heart disease in children or pulmonary hypertension)

38
Q

Human Metapneumovirus (HMPV) is clinically similar to what virus?

A

RSV

39
Q

Symptoms of nipah and hendra viruses

A

Respiratory illness, fever, encephalitis

40
Q

How are Nipah and Hendra viruses spread in humans

A

No human to human spread has been observed thus far (they probably come from a bat reservoir)

41
Q

What type of genome do Coronaviruses have?

A

(+)-stranded RNA genome

42
Q

From where do coronaviruses get their name?

A

A crown shape on viral surface projections from virion attachment proteins

43
Q

What type of virus is SARS?

A

A coronavirus

44
Q

Lab findings in SARS

A

Decreased lymphocyte count, elevated lactic dehydrogenase (non-specific indicator of tissue damage)

Immunity, Infection and Disease (86 decks)

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