Parainfluenza

Question 1

Diseases caused by paramyxoviruses

Answer 1

Parainfluenza virus, RSV, measles/mumps

Question 2

Paramyxovirus life cycle

Answer 2

• Attachment to sialic acid by viral glycoprotein protein
• Entry into cell by fusion at cell membrane (viral F protein)
• Nucleocapsid uncoats
• Viral RNA polymerase (packaged inside virus) copies (-) RNA into (+) mRNA in the cytoplasm
• Protein synthesis, (-) RNA genome replication
• Virus assembly and budding

Question 3

PIV1

Answer 3

Fall trend; every other year in odd-numbered years

Question 4

PIV2

Answer 4

Fall, annual, erratic

Question 5

PIV3

Answer 5

Spring/early summer, prolonged seasonal occurrence, most prevalent serotype

Question 6

PIV4

Answer 6

Rare, erratic, mild

Question 7

RSV prevention

Answer 7

• passive immunization with palivizumab in high-risk infants and children (humanized monoclonal Ab against fusion of protein of RSV, inhibits viral entry into host cells)
• RSV-IGIV for prophylaxis in infants and children with chronic lung disease

Question 8

Ribavirin MOA

Answer 8

Guanosine analog that is phosphorylated intracellularly by host cell enzymes

• The phosphorylated ribavirin can inhibit the synthesis of viral guanosine triphosphate (GTP), further inhibits viral mRNA synthesis through
  
  • Inhibits the 5‘-capping of viral mRNA
  • Inhibits viral RNA-dependent polymerases

Question 9

Ribavirin route

Answer 9

oral, IV, inhalation (severely ill infants)

Question 10

Ribavirin clinical use

Answer 10

• Aerosol approved for bronchiolitis and pneumonia

- HCV (with interferon alpha)

Question 11

Ribavirin side effects

Answer 11

• Aerosolized use: conjunctival irritation, rash, transient wheezing, reversible decrease of pulmonary function
• Systemic use: dose related reversible anemia due to extravascular hemolysis and bone marrow suppression
• Other: depression, fatigue, nausea, pruritus

Question 12

Ribavirin contraindications

Answer 12

anemia, end-stage renal failure, ischemic vascular disease, pregnancy (teratogenic, embryotoxic)

Question 13

Prevention and treatment for croup

Answer 13

• benign, usually self-limiting
• no vaccine against parainfluenza
• corticosteroids (dexamethasone, prednisone) with or w/o epinephrine to reduce airway inflammation with severe symptoms

Question 14

MOA of corticosteroids with croup

Answer 14

Anti-inflammatory action reduces laryngeal mucosal edema

Question 15

MOA of nebulized epinephrine with croup

Answer 15

stimulates alpha and beta2 receptors and constricts precapillary arterioles, thus causing fluid resorption from the interstitial space and a decreasing airway edema. However, its usage is reserved for severe disease due to potential adverse effects of