Paramyxoviruses

Question 1

What are the characteristics of all 3 viruses?

Answer 1

1. Enveloped, non segmented (no reassortment), and negative RNA
2. Tropism restricts entry to respiratory tract cells, thus no systemic infxns

Question 2

What are the virulence factors?

Answer 2

Fusion protein, G, and HN

Question 3

What does fusion protein (F) do?

Answer 3

Viral entry/fusion to adjacent cells -> syncytia

Question 4

What does G do?

Answer 4

Unknown gp where RSV binds; RSV can also bind nuclein

Question 5

What does HN do?

Answer 5

hMNV + hPIV bind here

Question 6

What is the mechanism of disease?

Answer 6

Virus infects airway epithelium and upper resp. tract, it then spreads to the lower reps. tract via dendritic cells. This causes sloughing of epithelium, excessive mucin production, and interstitial lung infiltrates

Question 7

What’s the epidemiology of RSV?

Answer 7

1 cause of lower RT illness/pneumo in kids

Question 8

What’s the epidemiology of hMPV?

Answer 8

2 cause of lower RT illness in kids

Question 9

What’s the epidemiology of hPIV?

Answer 9

2 cause of pneumonia in kids. And it’s common in elderly/immunocompromised

Question 10

What is common among all three viruses transmission?

Answer 10

All transmit person-person via large droplets. Very seasonal (fall/spring); and they have community emergence (not widespread like flu)

Question 11

What diseases are associated with RSV?

Answer 11

RSV is the #1 cause of bronchiolotis and pneumonia in less than 1 yr old infants. The infection is also common in adults but it known more for children.

Question 12

Where does RSV infect in the body?

Answer 12

RSV infects nasopharynx, which leads to a LRT. The LRTs can be permanent (chronic lung disease or asthma)

Question 13

What are the predisposing factors to RSV infxn?

Answer 13

Prematurity, early infxn ( in infants less than 3mo), lung/heart disease, SCID, and low oxygen supply

Question 14

What is the presentation of RSV?

Answer 14

Begins with URT symptoms -> LRT symptoms in 2 days

Question 15

How do you make the Dx of RSV?

Answer 15

Culture from URT, ELISA for Antigen, RT-PCR

Question 16

How do you Tx RSV?

Answer 16

No vaccine. Care is supportive (FiO2, fluids, bronchodilator).

1. Palvizumab: Ab for RSV ( decrease viral loads so it’s not as severe)
2. Ribavirin: nucleoside analog interferes with viral replication

Question 17

What disease is caused by hMPV?

Answer 17

Bronchiolitis and +/- pneumonia in infants/elderly

Question 18

How does hMPV present?

Answer 18

Similar to RSV but also may see myalgia

Question 19

How do you Dx hMPV?

Answer 19

RT-PCT is best (Serological is bad; most kids are positive by 10yrs)

Question 20

How do you tx hMPV?

Answer 20

No vaccine; give supportive care

Question 21

What disease does hPIV cause?

Answer 21

hPIV2 is #2 cause of pneumonia and bronchiolitis in kids.

Question 22

How does hPIV present?

Answer 22

Croup, hoarseness, and systemic symptoms

Question 23

What’s the Dx of hPIV?

Answer 23

culture, RT-PCR, ELISA, or high IgG/IgM

Question 24

What’s the Tx for hPIV?

Answer 24

No vaccine, supportive care

Question 25

What protein facilitates syncytium formation?

Answer 25

F protein

Question 26

What do you see on CXR?

Answer 26

Hyperinflated lungs, atelectasis, interstitial disease (not specific)

Question 27

What are the two most important things to ID these viruses?

Answer 27

1. Age of pt (kids)

2. Season (late fall/early spring)