Micro - Paramyxoviruses (RSV, hPIV, hMPV)

Question 1

RSV, hPIV, hMPV are (enveloped, nonenveloped) (segmented, nonsegmented) (RNA+, RNA-, DNA)

Answer 1

Enveloped nonsegmented RNA-

Question 2

What distinguishes paramyxoviruses from influenza?

Answer 2

They are nonsegmented so antigenicity doesn’t change much unlike the segmented influenza virus

Question 3

RSV is the leading cause of:

Answer 3

Viral LRI in infants

Question 4

hMPV is the second leading cause of:

Answer 4

LRI in kids (behind RSV)

Question 5

What can hMPV cause in older children and adults?

Answer 5

ARDS

Question 6

Cause of croup? Another name for croup?

Answer 6

hPIV1-3

Laryngotracheobronchitis

Question 7

What faction of the adult population is susceptible to hPIV infection?

Answer 7

Elderly

Immunocompromised

Question 8

What are the two most important distinguishing factors of an RSV/hPIV/hMPV infection?

Answer 8

Age and seasonality

Question 9

When is RSV most common in Memphis?

Answer 9

Oct-Mar

Question 10

At what age is RSV infection most common?

Answer 10

2-8

Question 11

When is hMPV most common?

Answer 11

Winter-spring

Question 12

Most kids have been infected by hMPV by age ___ and seroconversion rates for hMPV ~ 100% by age ___

Answer 12

3

10

Question 13

When is each strain of hPIV1-4 most common?

Answer 13

hPIV1 = autumn of odd # years (biennial)
hPIV2 = follows hPIV1 outbreak
hPIV3 = spring and summer
hPIV4 = sporadic

Question 14

Where do the paramyxoviruses replicate?

Answer 14

CYTOPLASM***

Question 15

Describe the entry of paramyxoviruses

Answer 15

Receptor binding protein and fusion protein mediate fusion of viral envelope with membrane of host cell

Question 16

What other function besides entry does fusion protein mediate?

Answer 16

Fusion of infected cell with adjacent cell = forms SYNCYTIUM*****

Question 17

Tropism of paramyxoviruses?

Answer 17

URT and LRT only; do NOT cause systemic infection

Question 18

Why don’t paramyxoviruses cause systemic infection?

Answer 18

hPIV and hMPV use their HN protein to bind to sialic acid, which is found in the mucus membrane layer lining respiratory epithelium.
Less is known about HSV binding protein, so it’s just called G (for glycoprotein) and it binds nucleolin, found on all cells, and GAGs of the respiratory epithelium

Question 19

Attachment of hPIV/hMPV vs. RSV

Answer 19

RSV does NOT bind sialic acid

Question 20

Two major envelope proteins of RSV

Answer 20

G & F (fusion protein)

Question 21

Two major envelope proteins of hMPV and hPIV

Answer 21

F & HN (hemagglutinin, neuraminidase)

Question 22

Characteristic feature of paramyxoviruses

Answer 22

Syncytia formation (due to F protein)

Question 23

Two primary cell types targeted by RSV

Answer 23

Airway epithelial cells and dendritic cells

Question 24

Progression of RSV,hPIV,hMPV pathogenesis

Answer 24

Infects URT epithelial cells then moves to the LRT via dendritic cells &/or cell-to-cell transfer

Question 25

6 key pathological findings of RSV,hPIV,hMPV infection

Answer 25

``` Airway inflammation Necrosis Sloughing of airway epithelial cells Edema Excessive mucus production Interstitial infiltrates ```

Question 26

What would you expect to see on CXR of pt with RSV infection?

Answer 26

Hyperinflation Increased interstitial markings Atelectasis (sometimes) Pulmonary infiltrates (sometimes)

Question 27

What is croup? Characteristic sx?

Answer 27

Laryngotracheobronchitis = edema of the mucus layer and swelling due to hPIV1-4 infection Barking cough with inspiratory stridor

Question 28

#1 cause of bronciolitis and pneumonia in infants < 1 yo

Answer 28

RSV

Question 29

Where does RSV initially infect? Possible chronic complication?

Answer 29

Nasopharynx | Damage to lung can become permanent and result in chronic lung disease like asthma

Question 30

Sx progression in RSV infection

Answer 30

1-3 days after infection = cough, low-grade fever, wheezing (URI sx) 2 days later = tachypnea, polyphonic wheezing, retractions, rales, cyanosis, hypoxemia (LRI sx)

Question 31

RSV sx in adult

Answer 31

``` Rhinorrhea Cough HA Fever Fatigue ```

Question 32

High risk factors for developing severe RSV infx

Answer 32

``` Prematurity Infected before 3 months of age Chronic lung disease Congenital heart problem SCID O2 sat < 95% RR > 70 Atelectasis Pneumonitis Toxic appearance on presentation Neuromuscular disease ```

Question 33

Most common presentation of hMPV infection

Answer 33

Bronchiolitis +/- pneumonia

Question 34

Who is most susceptible to a severe hMPV infection?

Answer 34

Infants < 1 yo Elderly Pt on immunosuppressants

Question 35

hPIV is second only to HSV as cause of:

Answer 35

Bronchiolitis and pneumonia in infants and young children

Question 36

What other infection is common with RSV and hMPV?

Answer 36

Otitis media (think S. pneumoniae)

Question 37

Sx of hMPV infection?

Answer 37

``` HIGH fever Rhinorrhea Tachypnea Dyspnea Wheezing ```

Question 38

Sx of hPIV infection?

Answer 38

``` Pharyngeal erythema Nonproductive to minimally productive cough Nasal congestion Fever Cough that develops into croup Hoarseness (inflammation of vocal cords) ```

Question 39

How are the paramyxoviruses transmitted?

Answer 39

Person-to-person via large droplets

Question 40

What is special about the epidemiology of RSV?

Answer 40

It is the most predictable epidemic disease in the US | occurs Oct-Mar

Question 41

Which causes more widespread illness: RSV or influenza?

Answer 41

Influenza (RSV emerges only within a community)

Question 42

~100% seroconversion of RSV by age ___; ~100% seroconversion of hMPV by age ___

Answer 42

3 | 10

Question 43

RSV sx vs. common cold sx

Answer 43

RSV is more severe

Question 44

(T/F): Most people only get infected with a paramyxovirus once

Answer 44

False; reinfection occurs throughout life

Question 45

High risk factors for acquiring RSV

Answer 45

``` Young kid in daycare Older sibling in daycare Crowding Low SES Multiple birth sets (especially triplets+) Minimal breastfeeding Exposure to pollutants (smoking) ```

Question 46

Primary RSV infection vs. recurrent RSV infection

Answer 46

Recurrent more likely to be confined to URT | also, RSV infection with increasing age likely to be restricted to URT

Question 47

When are you most likely to see croup?

Answer 47

Autumn of odd numbered years

Question 48

Diagnostic options for RSV

Answer 48

1. Culture from nasal secretions 2. ELISA for antigen 3. RT-PCR

Question 49

Gold standard for diagnosing hMPV

Answer 49

RT-PCR (most sensitive test)

Question 50

Although diagnostic assays are generally not used for hPIV, what could be used?

Answer 50

High IgM/IgG titer RT-PCR Culture Immunoassay

Question 51

Why isn't serological testing commonly done is paramyxovirus suspected?

Answer 51

Seroconversion is almost universal

Question 52

Which paramyxovirus has a vaccine?

Answer 52

None

Question 53

Tx of paramyxovirus infection is mainly:

Answer 53

Supportive

Question 54

Goals of supportive tx for paramyxovirus infection?

Answer 54

Oxygenation, hydration, nutrition

Question 55

Give some examples of supportive tx used for paramyxovirus infection

Answer 55

``` Bronchodilator O2 Ventilation Fluids Aerosolized epi ```

Question 56

Two Rx used for RSV and their MOA

Answer 56

1. Palvizumab - mab that neutralizes RSV | 2. Ribavirin - nucleoside analog that prevents replication

Question 57

AE of ribavirin

Answer 57

Teratogen

Question 58

Indication for palvizumab vs. ribavirin

Answer 58

Palvizumab - premies, high risk pt < 6 months | Ribavirin - pts on immunosuppresant