Respiratory Syncytial Virus (RSV)
Morphology
- SS negative-sense RNA virus
- From the paramyxoviridae family
- Enveloped nucleocapsid that encodes for 10 viral proteins
- Matrix is made of M and M2 proteins
- The viral envelope has two glycoproteins :
G protein:
- By which virus attaches to cell surface
F- protein ( Fusion protein:
- which bring about the fusion between viral and host cell membranes.
- It is also responsible for cell to cell fusion, which leads to the characteristic syncytial formation.
Types
RSV can be subtyped into:
- Type A
- Type B
Types account for differences in:
- The G protein composition
- The conservation of the F protein in these 2 subtypes
Transmission:
- Direct contact with respiratory droplets such as sneezing or coughing
- Close indirect contact with contaminated fomites such as used tissues
Clinical Manifestations:
- RSV infection leads to a wide spectrum of respiratory illnesses.
In infant cause:
- pneumonia
- bronchiolitis
- tracheobronchitis.
- In this age group, illness begins most frequently with rhinorrhea, low-grade fever, often accompanied by a cough and wheezing.
In adults, the most common symptoms are:
- a common cold, with rhinorrhea
- sore throat
- cough.
- It causes severe pneumonia in elderly.
Sinusitis, otitis media, and worsening of chronic obstructive and reactive airway disease are also associated with RSV infection.
Diagnosis
For Bronchiolitis:
- Chest X-ray shows:
- Hyperinflation
- Mul
- tiple areas of interstitial infiltration
Bud tree Appearance:
- MC cause of tree in bud (bronchiectasis) appearance is Mycobacterium tuberculosis (endobronchial).
- Most common specific cause of tree in bud appearance in HSL (bone marrow) transplant patients is:
- CMV (30-70%) > RSV (18%) > M. tuberculosis (5-6%) > Pneumocystis > Invasive aspergillosis.
Treatment
- Oxygen: Mainstay of therapy.
- Aerosolized ribavirin is used in the treatment of bronchiolitis with RSv
Prevention
- Palivizumab:
- Humanized monoclonal antibody
- Directed against an epitope in the A antigen site on the F surface protein of RSV.
- Licensed for the prevention of RSV infection in high-risk infants and children.
- Once-monthly intramuscular injections (15 mg/kg) for 5 months beginning at the start of the RSV season
Exam Question
Morphology
- SS negative-sense RNA virus
- The viral envelope has two glycoproteins :
G protein:
- By which virus attaches to cell surface
F- protein ( Fusion protein:
- which bring about the fusion between viral and host cell membranes.
Types
- RSV can be subtyped into:
- Type A
- Type B
Clinical Manifestations:
- RSV infection leads to a wide spectrum of respiratory illnesses.
In infant cause:
- pneumonia
- bronchiolitis
- tracheobronchitis.
- In this age group, illness begins most frequently with rhinorrhea, low-grade fever, often accompanied by a cough and wheezing.
In adults, the most common symptoms are:
- a common cold, with rhinorrhea
- sore throat
- cough.
- It causes severe pneumonia in elderly.
Sinusitis, otitis media, and worsening of chronic obstructive and reactive airway disease are also associated with RSV infection.Diagnosis
For Bronchiolitis:
- Chest X-ray shows:
- Hyperinflation
- Mu
- ltiple areas of interstitial infiltration
Bud tree Appearance:
- MC cause of tree in bud (bronchiectasis) appearance is Mycobacterium tuberculosis (endobronchial).
- Most common specific cause of tree in bud appearance in HSL (bone marrow) transplant patients is:
- CMV (30-70%) > RSV (18%) > M. tuberculosis (5-6%) > Pneumocystis > Invasive aspergillosis.
Treatment
- Oxygen: Mainstay of therapy.
- Aerosolized ribavirin is used in the treatment of bronchiolitis with RSv
Prevention
- Palivizumab:
- Humanized monoclonal antibody
- Directed against an epitope in the A antigen site on the F surface protein of RSV.
- Licensed for the prevention of RSV infection in high-risk infants and children.
- Once-monthly intramuscular injections (15 mg/kg) for 5 months beginning at the start of the RSV season
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