Respiratory Syncytial Virus (RSV), Human Metapneumovirus (hMPV), and Human Parainfluenzaviruses 1-4 (hPIVs)

Question 1

What is the leading viral cause of serious LRT infections (i.e. bronchiolitis) in infants worldwide?

Answer 1

RSV

Question 2

What is the 2nd most commonly identified cause of pediatric LRT illness?

Answer 2

hMPV (human MetaPneumoVirus), especially hPIV-3

*behind RSV

Question 3

Can adults have serious disease from RSV, hMPV, and HPIV?

Answer 3

Rarely, but it is seen in elderly, immunocompromised, and those on immunosuppression

Question 4

Classify these viruses:

Answer 4

Paramyxoviridae family:

1) negative sense RNA
2) nonsegmented
3) enveloped

Question 5

What two proteins on the viral envelope are important in their pathogenesis?

Answer 5

1) receptor binding protein

2) F (fusion) protein

Question 6

Which protein is responsible for both virus entry and fusion of adjacent cells to from syncytia?

Answer 6

F protein

Question 7

What are the chief pathological features of paramyxovirus infections?

Answer 7

Airway inflammation, necrosis and sloughing of respiratory epithelium, edema, excessive mucus production, and interstitial infiltration of the lung.

Question 8

How does RSV normally present in an adult?

Answer 8

rhinorrhea, cough, HA, fatigue, and fever

Question 9

What is the most common presentation of hMPV?

Answer 9

Bronchiolitis with or without pneumonia. Ranges from mild to severe.

Severe is seen in extremes of age and immunocompromised.

Question 10

What does hPIV cause in children?

Answer 10

Croup (laryngyotracheal bronchitis) –> high pitch seal-like barking cough with inspiratory stridor

Question 11

Does paramyxoviruses undego reassortment?

Answer 11

No since they are nonsegmented.

Question 12

What is the seasonality of RSV?

Answer 12

It is the MOST PREDICTABLE epidemic, seasonal disease in the US, with infections from the MID-FALL to EARLY SPRING
**peaks in early January

Question 13

Are vaccines available for paramyxoviruses?

How do you treat infections?

Answer 13

No vaccines are available

Treatment is mostly supportive.

**RSV can be treated with ribavirin (nucleoside analog), reduces viral shedding and illness

Question 14

Is there a drug to prevent RSV infections in at risk infants?

Answer 14

Yes. Pavilizumab (binds F protein). Can also reduce viral load in those infected, but it doesn’t affect disease severity.