Respiratory Syncytial virus

Question 1

Characteristics of RSV

Answer 1

Most important cause of lower respiratory tract infections in children
2 serotypes ( A and B)
Serotype B is more severe
Produces extensive syncytia in cell culture
Envelope contains G ( facilitates binding to cell receptors) and F proteins
Lacks HA, NA and hemolysin
Does not grow in embryonated eggs

Question 2

Pathogenesis of RSV

Answer 2

Virus enters through the respiratory tract in droplets or contact with contaminated hands
Virus replicates in epithelial cells of nasopharynx
Spreads into lower respiratory tract through secretions
In adults and older children infection ends in URT
In infants less than 4 months sprads to bronchi and bronchioles
some children develop otitis media

Question 3

Immunity of RSV

Answer 3

Maternal antibodies protective for two months
Disease starts between 2-4 months
Poor induer of interferons

Question 4

Laboratory diagnosis

Answer 4

Samples: Nasal swab or wash
Virus is thermoliable and must be inoculated immediately
Antigen detection using ELISA
Virus isolation in HELA or Hep-2

Question 5

Treatment

Answer 5

Supportive care

• Suction of nasal secretions
• Administration of oxygen

Ribovirin in aerosol form for 3-6 days ( minimizes severity and reduces shedding)

Question 6

Prevention

Answer 6

Hand washing after patient contact